Shigella

Microbios, 1993, 76(308), 161 - 6
Characterization of a plasmid codifying the synthesis of a beta-lactamase produced by Shigella flexneri; Echeverria V et al.; The resistance to beta-lactam antibiotics shown by a strain of Shigella flexneri was plasmid-coded . This plasmid, pMAM-1, when transferred to Escherichia coli K-12 by conjugation, presented the same molecular weight (100 kbp) and conferred the same high level of resistance to ampicillin in the transconjugant as in the wild type strains (MIC, 2048-4096) . Restriction analysis of the plasmid in transconjugants revealed various restrictive sites to some endonucleases (i.e . Bam HI, Eco RI, Pst I, Nco I, Cla I, Sf I and Sau 3AI, Nhe and Hin dIII), and no restrictive sites at all for other endonucleases (such as Xho I, Dra I, Kpn I, and Sal I) . Some restricted DNA fragments were appropriate for cloning and isolation of the beta-lactamase gene present in Shigella flexneri UCSF 129 . This work provides the first step in this direction.

Scand J Infect Dis, 1993, 25(5), 569 - 77
Serum antibody responses against shigella lipopolysaccharides and invasion plasmid-coded antigens in shigella infected Swedish patients; Li A et al.; Serum antibody responses to shigella lipopolysaccharide (LPS) and invasion plasmid-coded antigens (Ipa) were studied in 74 Swedish patients with culture verified bacillary dysentery using class-specific enzyme immunoassay (EIA) . Anti-LPS responses were found in 80% and 79% serum samples, respectively, from S . flexneri and S . sonnei infected patients and anti-Ipa responses in 60% and 43%, respectively . The mean anti-Ipa IgG antibody titres in S . flexneri infected patients remained high for 4-6 months after onset while the anti-LPS IgG antibody titres had dropped to normal levels . The specificity of EIA for shigella Ipa was 90% and for S . dysenteriae, S . flexneri and S . sonnei LPSs it varied between 84% and 90% . No close correlations between the anti-LPS and anti-Ipa antibody responses were observed indicating that they may be differently regulated . The dynamics of the serum antibody responses indicates that an anti-LPS response is a good indicator of a recent shigella infection and an anti-Ipa IgG response a good indicator of a previous infection.

Bull World Health Organ, 1993, 71(5), 571 - 8
Initiation of food supplements and stopping of breast-feeding as determinants of weanling shigellosis; Ahmed F et al.; The association between the period elapsed since weaning and the risk of shigellosis was assessed between 1 November 1987 and 30 November 1989 for a cohort of 1085 Bangladeshi children aged < 3 years . The children were followed for 1 month after exposure to Shigella spp . in their residential neighbourhoods, and the 268 who developed microbiologically confirmed (n = 118) or clinically presumptive (n = 150) shigellosis were compared with the 817 control children who did not develop either syndrome . No increase in risk was noted among breast-fed infants who received food supplements within the previous 3 months compared with those who had received supplements for longer (adjusted odds ratio (OR) = 1.2; 95% confidence interval (CI) = 0.4-3.0) . However, compared with breast-fed children, non-breast-fed children had an increased risk (adjusted OR = 2.0; 95% CI = 1.3-2.9; P < 0.001), which was largely attributable to a substantially increased risk in the 3 months after stopping breast-feeding (adjusted OR = 6.6; 95% CI = 2.9-14.6; P < 0.001) . The early post-cessation risk was equivalent for confirmed and presumptive shigellosis, but was particularly pronounced among the severely malnourished (adjusted OR = 10.2; 95% CI = 3.1-33.3; P < 0.001) . This complex temporal pattern of risk highlights the need for precise definitions of weaning to facilitate identification of children at high risk for invasive diarrhoeal syndromesPIP: Between November 1987 and November 1989, International Centre for Diarrhoeal Disease Research, Bangladesh, (ICDDR,B) scientists followed for 1 month 1085 children, younger than 3 years old, who lived in the Matlab . They compared data on the 268 children who developed microbiologically confirmed on clinically presumptive shigellosis during the 30-day period with data on 817 children who did not develop symptoms of shigellosis . Children who were not breast fed were at greater risk of shigellosis than those who were breast fed (adjusted odds ratio {AOR} = 2; p .001) . This risk of shigellosis was much higher during the 1st 3 months after a child stopped breast feeding (AOR = 6.6; p .001) than it was 3 months after cessation of breast feeding (AOR = 1.4) . Children who suffered from severe malnutrition were at an especially high post-cessation risk of shigellosis (AOR= 10.2; p .001) . These findings show a complex evolution of risk with different stages of weaning, which emphasizes the need for a precise definition of weaning in epidemiologic studies . The limited period of high risk for shigellosis (i.e., the 1st 3 months after breast feeding cessation) and the wide range in ages at which children cease breast feeding elevates the complexity of executing successful vaccination programs against shigellosis, especially live oral vaccines . The vaccines must be administered early in life, before cessation of breast feeding, in order for them to protect against shigellosis . Yet, ingestion of breast milk may reduce the immunogenicity of the vaccines .

Arch Immunol Ther Exp (Warsz), 1993, 41(2), 153 - 7
Induction of tumor necrosis factor and interleukin 6 by outer membrane proteins of Shigella in spleen cells and macrophages of mice; Czarny A et al.; The ability of outer membrane proteins (OMP) of Shigella flexneri to induce tumor necrosis factor (TNF) and interleukin 6 (IL-6) production by spleen cells and macrophages of mice was investigated . Treatment of spleen cells with OMP resulted in the release of only traces of TNF activity . In contrast, macrophages treated with OMP produced moderate levels of TNF . OMP was also found to be an inducer of IL-6 . Both spleen cells and macrophages, treated with OMP, were found to produce substantial levels of this cytokine . The effect of OMP on the release of TNF and IL-6 was dose and time dependent, maximal production being reached at 10 micrograms of OMP after 20 h . The ability of OMP to induce production of these cytokines may explain part of the previously described immunomodulatory effects of this preparation on the immune system.

Turk J Pediatr, 1993 Jan-Mar, 35(1), 23 - 36
Hemolytic-uremic syndrome (HUS): a clinicopathological study of 15 cases; Tinaztepe K et al.; Although hemolytic-uremic syndrome (HUS) is a clinico-pathological entity, renal biopsies are usually not indicated for diagnosis, and therefore, studies concerning the histological aspects of the syndrome are few . This study mainly describes the morphological characteristics of 15 tissue-diagnosed sporadic cases of HUS . The ages of the patients ranged between 10 mos . to 15 yrs., with five being under two . The male/female ratio was 2:3 . The prodromal phase was present in 10 patients (67%) with gastrointestinal symptoms in four patients (27%) with neurological symptoms, and in three patients (20%) with upper respiratory infections . Five patients had HUS associated with diarrhea (D+) (three infants and two children), while the remaining ten patients (two infants and eight children) had no diarrhea (D-) . E . coli was identified in the stool of four of the D+ cases, one of which was also associated with Shigella . The shortest clinical course was 14 days and the longest 55 days in 13 patients . The disease recurred after three months in one patient, and on three occasions in 15 months after onset of HUS in the other . Fourteen patients died and one biopsy-diagnosed case recovered after the acute phase . All patients had anemia (Hb 3.4-10 g/dl) and acute renal failure . Seven cases demonstrated Burr cells, eight cases had thrombocytopenia and six cases oliguria/anuria . Microscopic hematuria was detected in four cases and gross hematuria in two cases . All patients revealed proteinuria and azotemia (40-200 mg/dl) . Five/five (100%) cases had decreased creatinine clearance, 12/14 (86%) cases had increased uric acid levels, 9/14 (64%) cases had an electrolyte imbalance . Light microscopy revealed microangiopathic type involvement of the glomeruli in all cases . According to additional findings, the cases were classed into three histological groups: type 1 showing cortical necrosis (3 cases), type 2 predominant glomerular and arteriolar involvement (11 cases) and type 3 predominant arterial involvement (1 case) . All cases were considered primary HUS except for one which was associated with membranous glomerulonephritis . (D+) HUS cases were predominantly of the microangiopathic type, similar to the (D-) group; the latter being contrary to the literature . Hypertension was present in 67% of cases and there was no correlation found between the clinical duration of HUS and the histological type . All five patients studied immunohistologically revealed a nonspecific type fibrinogen deposition . Extra-renal microangiopathy was demonstrated in the adrenals, stomach, pancreas, liver and skin in two necropsies studied.

Chin J Biotechnol, 1993, 9(1), 49 - 55
High level expression of Shiga toxin B subunit of Shigella dysenteriae serotype 1 in Escherichia coli; Su G et al.; In this study the gene encoding the Shiga toxin (Stx) was cloned from the chromosomal DNA of Shigella dysenteriae serotype 1 (W30864) . The Stx gene was located in a 4.5kb EcoRI fragment . The biological assay revealed that the hybrid plasmid pMGC001 containing the Stx gene could produce Shiga toxin . The amount of Stx was 16 times more than that produced by its parent . The cloned strain showed cytotoxic, entorotoxic and neurotoxic activities . The gene for Stx-B subunit was subcloned into a plasmid vector pJLA503 from the plasmid pMGC001 . The B subunit could be expressed at high level in E . coli and has been purified in large quantities . The polyclonal and monoclonal antibodies against B subunit were raised . Western blot showed that they could react specifically to the B subunit.

Rev Latinoam Microbiol, 1993 Jan-Mar, 35(1), 1 - 6
{Antimicrobial activity of human colostrum against enteropathogens . Preliminary study}; Solorzano-Santos F et al.; The antimicrobial activity of the colostrum serum from ten women has been evaluated . The activity against Escherichia coli, Shigella sonnei and Klebsiella pneumonia at three different bacterial populations was determined (1 x 10(4), 1 x 10(5) and 1 x 10(6) UFC/ml) . Antimicrobial activity against the three strains was found . Bactericidal activity was observed to inocula of 1 x 10(4) UFC/ml in 8/10 sera against E . coli, in 6/10 sera against S . sonnei, and in 3/10 sera against K . pneumonia; in the rest of the cases, sera were bacteriostatic . With inocula of 1 x 10(5) UFC/ml there was bactericidal activity in 4/10 sera against E . coli and S . sonnei and in 1/10 against K . pneumonia . Lastly, with inocula of 1 x 10(6) UFC/ml there was bactericidal activity in 4/10 sera against E . coli, 1/10 against S . sonnei and none against K . pneumoniae . The results suggest that because of the antimicrobial properties of human milk the risk of intestinal infections by enteropathogens is less.

Scand J Infect Dis, 1993, 25(6), 713 - 9
Comparative efficacy of pivmecillinam and cotrimoxazole in acute shigellosis in children; Prado D et al.; In a prospective randomized double-blind trial, pivmecillinam was compared with cotrimoxazole (TMP-SMX), both given orally for a period of 5 days, for the treatment of 59 children with shigellosis . 29 patients were treated with pivmecillinam and 30 with cotrimoxazole . 14% of shigella organisms isolated were resistant to pivmecillinam and 21% to TMP-SMX . The diarrhea persisted for a mean (+/- SD) period of 74 +/- 24.8 h in the pivmecillinam-treated patients versus 73.8 +/- 34 h in the TMP-SMX-treated patients . Duration of fever, positive stool culture, visible blood, occult blood, and pus cells in the stools were similar for both treatment groups . Five patients (17%) in the pivmecillinam group and 4 patients (13%) in the cotrimoxazole group fulfilled the clinical criteria that defined treatment failure . One patient (3.4%) in the pivmecillinam group and 2 (6.6%) in the TMP-SMX group evidenced recurrence of the diarrheal symptoms at the follow-up visit . No major drug-related side effects were observed in either group . We concluded that pivmecillinam is equivalent to cotrimoxazole in the treatment of shigellosis in children.

Southeast Asian J Trop Med Public Health, 1993, 24 Suppl 1, 280 - 3
A clinico-hematological profile of hemolytic-uremic syndrome; Dayal R et al.; Hemolytic uremic syndrome (HUS) is defined as microangiopathic hemolytic anemia, thrombocytopenia and uremia . It is an important cause of acute renal failure (ARF) in children all over the world . The present study was carried out to assess the incidence, clinical presentation, hematological and biochemical profile of children presenting with HUS from 1987 to 1990 . Out of the 100 cases who presented with ARF 22 had HUS . A majority of these children were males below 1 year of age, and had a prodromal phase of mainly gastrointestinal manifestations lasting for about a week . Anemia was a constant feature followed by bleeding diathesis, mainly melena and purpura . Neurological manifestations included altered sensorium, irritability, coma, hypertensive encephalopathy and convulsions . Renal problems mainly included oliguria, hypertension, hematuria and edema . Investigations revealed thrombocytopenia and microangiopathic hemolytic anemia in all cases . Evidence of disseminated intravascular coagulation (DIC) was observed in 3 cases as decreased fibrinogen levels, increased fibrinogen degradation products and deranged clotting studies . Blood biochemistry revealed azotemia in all cases, hyponatremia in 5 cases, hypernatremia in 3 cases and hyperkalemia in 12 cases . Stool culture showed the presence of Shigella in 8, E . coli in 6 and Klebsiella in 4 cases . Out of 22 cases of HUS, 15 were treated conservatively; of these 2 died . Both of these deaths were due to DIC 7 children were put on peritoneal dialysis; only 1 child died in this group . Factors affecting the outcome were duration of oliguria, levels of blood urea and presence of encephalopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Microbiol Immunol, 1993, 37(4), 331 - 4
Chemical analysis of lipopolysaccharides of Shigella sonnei form II strains expressed by cloned form I antigen genes; Okamura N et al.; A compositional sugar analysis was carried out on lipopolysaccharide (LPS) from Shigella sonnei form II in which a plasmid with cloned form I antigen genes had been introduced . The recipient form II strains contained galactose, glucose, heptose, glucosamine, and 2-keto-3-deoxyoctonic acid (KDO) (2: 3: 1: 2: 2) in its LPS, while the transformant form I LPS contained, besides these sugars, N-acetyl-L-altrosaminouronic acid as an additional sugar constituent, which is known to be one of the antigenic determinants of form I antigen.

Ann Trop Paediatr, 1993, 13(2), 121 - 31
Diarrhoea caused by Escherichia coli; Hart CA et al.; Since the mid-1940s, Escherichia coli has been recognized as a cause of diarrhoea . Subsequently it has been shown that at least five different pathogenic mechanisms are used to cause disease . Enterotoxigenic E . coli (ETEC) and enteropathogenic E . coli (EPEC) produce a noninflammatory diarrhoea, whereas enteroinvasive E . coli (EIEC), enterohaemorrhagic E . coli (EHEC) and enteroaggregative E . coli (EAggEC) produce an inflammatory diarrhoea . ETEC are a major cause of diarrhoea in infants (up to three episodes per year) and travellers . They produce diarrhoea by attaching to the small intestinal mucosa and elaborate one or both of heat labile and heat stable toxins . EPEC attach firmly to the intestinal mucosa leading to dissolution of the brush border by inducing vesiculation of the microvilli . This process is known as attaching-effacement, and in the jejunum and ileum results in a loss of brush border disaccharidase enzymes and a large area of absorptive surface . EPEC are a major cause of summer diarrhoea in infants and neonatal diarrhoea . EIEC attach to colonic enterocytes, penetrate by an endocytotic mechanism and replicate therein . This results in necrosis and stripping of large areas of colonic mucosa and a dysentery similar to but usually less severe than Shigella dysentery . EHEC produce attaching-effacement to the terminal ileal and colonic mucosa and release the toxins, verocytotoxin (VT) 1 or 2 . These kill colonic enterocytes and produce haemorrhagic colitis . In addition, VT can damage vascular endothelial cells, leading to haemolytic uraemic syndrome . The role of EHEC in diarrhoea in children in the tropics is not known . The most recently described group are the EAggEC . They damage and blunt colonic villi by haemorrhagic necrosis, although the precise pathogenic mechanisms are unclear . EAggEC are a major cause of chronic diarrhoea in children . Although certain O-serotypes are associated with the different enteropathic E . coli, serotyping is not sufficiently specific or sensitive for use as a diagnostic tool . Specific diagnosis is expensive and time consuming and depends upon demonstration of the pathogenicity trait, and the pathogenicity gene(s) or their gene product(s) . At present, to undertake such testing is not recommended for routine diagnosis but is most useful when surveys of the aetiology of acute and chronic diarrhoea are undertaken.

J Pediatr, 1993 Jan, 122(1), 82 - 4
Acute myocarditis associated with Shigella sonnei gastroenteritis; Rubenstein JS et al.; We describe two patients with acute myocarditis temporally associated with an acute Shigella sonnei gastroenteritis . This association has not been described in children and should be considered in children with shigellosis who do not respond to rehydration therapies.

JAMA, 1992 Dec 9, 268(22), 3208 - 12
An international foodborne outbreak of shigellosis associated with a commercial airline; Hedberg CW et al.; OBJECTIVE--To determine the source of an international outbreak of shigellosis associated with consumption of food served by a Minnesota-based airline . DESIGN--Cohort studies of players and staff of a Minnesota-based professional football team and passengers on flights with a confirmed case of outbreak-associated Shigella sonnei infection . SETTING--Community- and industry-based studies conducted from October through November 1988 . PARTICIPANTS--Sixty-five football team players and staff, and 725 airline passengers in the cohort studies . RESULTS--Twenty-one (32%) of 65 football players and staff developed shigellosis that was associated with consumption of cold sandwiches prepared at the airline flight kitchen (relative risk {RR}, 17.1; 95% confidence interval {Cl}, 2.4 to 120; P < .001) . Confirmed or probable shigellosis was identified among 240 passengers on 219 flights to 24 states, the District of Columbia, and four countries between September 14 and October 13 . An outbreak-associated strain of S sonnei was isolated from football players and staff, airline passengers, and flight attendants . Thirty (4.1%) of 725 passengers on 13 flights with confirmed cases had confirmed or probable shigellosis . Illness was associated with consumption of cold food items served on the flights and prepared by hand at the airline flight kitchen (RR, 5.7; 95% Cl, 1.4 to 23.5; P < .01) . CONCLUSIONS--This international outbreak of shigellosis was identified only because of the occurrence of an index outbreak involving a professional football team . Prevention of Shigella transmission in mass catering establishments may require reduction of hand contact in the preparation of cold food items or elimination of these items from menus.

J Autoimmun, 1992 Dec, 5(6), 675 - 90
Bacterial agents protect against autoimmune disease . I . Mice pre-exposed to Bordetella pertussis or Mycobacterium tuberculosis are highly refractory to induction of experimental autoimmune encephalomyelitis; Lehmann D et al.; Infectious agents have often been implicated in the etiology of autoimmune diseases . Here we show that bacteria may also play a role in resistance to autoimmune diseases . SJL/J and (SJL/J x BALB/c)F1 mice are genetically susceptible to induction of experimental autoimmune encephalomyelitis (EAE), a murine model for human demyelinating autoimmune diseases such as multiple sclerosis . We studied the effect of several bacteria on the development of EAE and found that exposure of SJL/J or (SJL/J x BALB/c)F1 mice to Mycobacterium tuberculosis or Bordetella pertussis consistently rendered mice highly refractory to subsequent induction of the disease . Other bacteria such as Escherichia coli, Shigella and Staphylococcus aureus were found to be less effective, or were protective only if specific immunization procedures were used . Furthermore, M . tuberculosis and B . pertussis were protective irrespective of the route of administration and minute amounts (as low as 0.5 micrograms) of M . tuberculosis were sufficient to protect EAE-susceptible mice against induction of the disease . Interestingly, these bacteria, which are commonly used to promote development of EAE, conferred the highest degree of protection against the disease . The M . tuberculosis-induced protection was found to be associated with active suppression mechanisms mediated by T lymphocytes capable of transferring protection to naive syngeneic mice . These findings indicate that certain bacteria may protect against the development of autoimmune diseases . These results also suggest the potential use for still-unidentified bacterial agents in the manipulation of certain autoimmune diseases.

Epidemiol Infect, 1992 Dec, 109(3), 463 - 72
High level resistance to trimethoprim, cotrimoxazole and other antimicrobial agents among clinical isolates of Shigella species in Ontario, Canada--an update; Harnett N; A total of 598 isolates of Shigella species (24 S . dysenteriae, 254 S . flexneri, 30 S . boydii, 290 S . sonnei) submitted to the Ontario Public Health Laboratories in 1990 were tested for their susceptibility to 14 antimicrobial agents by the agar dilution method . Overall 79.6% of isolates were resistant to one or more antimicrobial agents and 52.0% were resistant to four or more . Trimethoprim resistance ranged from 26.7% among isolates of S . boydii to 39.4% among S . flexneri strains . The majority of the 224 TMP resistant isolates (88.8%) demonstrated high level resistance (MIC > 1000 mg/l) to trimethoprim . Resistance to cotrimoxazole increased from 3% in 1978 to between 26.7 and 37.6% in 1990 . MICs for 90% of isolates (MIC90s) for ampicillin, ticarcillin and piperacillin were 128 to > 256 mg/l, > 256 for tetracycline and chloramphenicol, and > 2.0/38.0 for cotrimoxazole . These results from the Canadian Province of Ontario emphasize the need for prudent use of antimicrobial agents in the treatment of shigellosis.

J Med Microbiol, 1992 Dec, 37(6), 382 - 4
Protection from Shigella sonnei infection by immunisation of rabbits with Plesiomonas shigelloides (SVC 01); Sayeed S et al.; Plesiomonas shigelloides, an organism commonly found in water, is only rarely associated with diarrhoea in man . P . shigelloides serotype O:17 (SVC O1), which is antigenically similar to Shigella sonnei, was found to be neither virulent nor toxic for rabbits . Rabbits immunised by feeding with P . shigelloides (SVC O1) were completely protected against an oral challenge with 10(10) cells of S . sonnei but non-immunised rabbits were not . P . shigelloides (SVC O1) may be a useful vaccine strain for shigellosis.

J Med Microbiol, 1992 Dec, 37(6), 364 - 7
Serum antibodies to verotoxin-producing Escherichia coli (VTEC) strains in patients with haemolytic uraemic syndrome; Kishore K et al.; Serological evidence of infection with verotoxin-producing Escherichia coli (VTEC) was sought in 28 patients suffering from haemolytic uraemic syndrome (HUS) and 25 age- and sex-matched controls . ELISA was used to detect anti-lipopolysaccharide (LPS) antibodies to E . coli strains O157, O111, O26 and NCTC 10418, a non-VTEC strain, and Shigella dysenteriae O1 . Sera from 19 of the HUS patients but from none of the 25 controls had significant antibody levels to the verotoxin-producing bacteria . Sera from 13 patients reacted with only one LPS of the four verotoxin-producing bacteria; sera from six reacted with more than one LPS antigen but not with LPS of E . coli NCTC 10418 . Paired sera taken 2-3 weeks apart were obtained from 20 HUS patients; 14 of these had high levels of antibody in the acute phase sample . Analysis of antibody levels in the convalescent sera showed that one patient had an increase, one was unchanged and 12 patients had a decrease in antibody to the verotoxin-producing bacteria.

J Pediatr, 1992 Dec, 121(6), 852 - 6
Concentration of milk secretory immunoglobulin A against Shigella virulence plasmid-associated antigens as a predictor of symptom status in Shigella-infected breast-fed infants; Hayani KC et al.; We conducted a prospective, community-based study of healthy breast-fed Mexican infants to determine the protective effects of anti-Shigella secretory IgA antibodies in milk . Milk samples were collected monthly, and stool culture specimens were obtained weekly and at the time of episodes of diarrhea . Nineteen breast-fed infants were found to have Shigella flexneri, Shigella boydii, or Shigella sonnei in stool samples . Ages of the 10 infants with symptomatic infection and the nine with asymptomatic infection did not differ significantly . Milk samples collected up to 12 weeks before infection were evaluated by enzyme-linked immunosorbent assay for secretory IgA antibodies against lipopolysaccharides of S . flexneri, S . boydii serotype 2, S . sonnei, and virulence plasmid-associated antigens . The geometric mean titers of anti-Shigella antibodies to virulence plasmid-associated antigens in milk received before infection were eightfold higher in infants who remained well than in those in whom diarrhea developed . The significance of milk secretory IgA directed against lipopolysaccharide was less clear . We conclude that human milk protects infants against symptomatic shigella infection when it contains high concentrations of secretory IgA against virulence plasmid-associated antigens.

J Bacteriol, 1992 Dec, 174(23), 7661 - 9
MxiJ, a lipoprotein involved in secretion of Shigella Ipa invasins, is homologous to YscJ, a secretion factor of the Yersinia Yop proteins; Allaoui A et al.; Shigella flexneri causes bacillary dysentery by invading epithelial cells of the colonic mucosa . The invasion process requires the synthesis and secretion of the virulence plasmid-encoded Ipa proteins . Using TnphoA mutagenesis, we have identified two virulence plasmid genes, mxiJ and mxiM, that encode proteins exported by the general export pathway . Analysis of the MxiJ and MxiM deduced amino acid sequences suggested that mxiJ and mxiM might encode lipoproteins, which was confirmed by {3H}palmitate labeling of MxiJ:PhoA and MxiM:PhoA fusion proteins . A mxiJ mutant was unable to invade HeLa cells, to induce the formation of plaques on confluent monolayers of HeLa cells, and to provoke keratoconjunctivitis in guinea pigs . In addition, secretion of seven polypeptides, including IpaA, IpaB, and IpaC, was abolished in the mxiJ mutant . Sequence comparisons indicated that MxiJ and MxiH, which is encoded by a gene located upstream from mxiJ, are homologous to the Yersinia enterocolitica YscJ and YscF proteins, respectively.

Zentralbl Bakteriol, 1992 Dec, 277(4), 429 - 35
Composition of lipid A in the S and R forms of Shigella dysenteriae serovar 1; Sourek J et al.; A chemical analysis was performed of lipid A, isolated by acid hydrolysis of the lipopolysaccharide from the S and R forms of Shigella dysenteriae serovar 1 . Differences in the moiety of both lipids and sugars were compared . The lipid portion consisted of a homologous series of fatty acids ranging from C12:0 to C18:0 (predominant homologues, C12:0, C14:0 and C16:0) and the homologous series of 3-hydroxy acids ranging from C12:0 to C16:0 (predominant homologue, 3-OH-C14:0) . The major sugar portion consisted of D-glucosamine . The toxicity of lipid A in mice (LD50) ranged between 300-400 micrograms/mouse, and values from the Limulus amebocyte lysate assay were recorded as titres of 10(-5) to 10(-6) mg/ml.

Kansenshogaku Zasshi, 1992 Dec, 66(12), 1628 - 33
{Shigella flexneri strains having a new type antigen 89-141}; Matsushita S et al.; Two Shigella strains (89-141 and 89-11) isolated from the stool of patients returning from abroad (both from India) in Tokyo in 1989 showed an atypical serologic reaction of agglutination with only polyvalent antiserum to S . flexneri prepared commercially . These strains had the typical biochemical characteristics of S . flexneri and were biochemically identical . Both strains were positive for Sereny test in guinea pig eye and cell-invasion test in HeLa cells . The strains also had virulence-plasmid encoding outer membrane proteins, indicating pathogenicity . The results of antigenic analyses showed that the strains were serologically identical to each other and gave significant cross-reactions with S . flexneri variant Y that has only group 3, 4 factor antigen . However, the results of reciprocal absorption tests showed that the O antigen of these strains was not identical to S . flexneri variant Y, and they were confirmed to have an additional type-specific antigen which is not included among the known S . flexneri type antigen I-VI or provisional type 88-893 which were proposed by us in 1992 . Furthermore, one stock strain (TSH508) formally identified as S . flexneri variant X has this type antigen, suggesting that the new antigen can be classified into two subtypes by combination of group factor antigen . Strain 89-141 is designated as the test strain for this new type antigen of S . flexneri.

Pediatr Res, 1992 Dec, 32(6), 689 - 92
Effects of a protein-rich diet during convalescence from shigellosis on catch-up growth, serum proteins, and insulin-like growth factor-I; Kabir I et al.; Shigellosis in children can cause growth retardation, worsening of malnutrition, and hypoproteinemia . To assess the effects of ingestion of a protein-rich diet during convalescence, 22 children aged 2 to 4 y with culture-proven shigellosis were randomly assigned after 5 d of antibiotic treatment to 21-d feeding regimens of either a 150 kcal/kg/d high-protein diet with 15% of calories as protein or an isocaloric control diet with 6% of calories as protein . At the start and end of dietary treatment, weight, height, mid-arm circumference, skinfold thickness, serum protein concentrations, and serum IGF-I were measured . Means of weight gain and increases in mid-arm circumference were greater in children fed high-protein diets than those fed control diets (1.23 versus 0.76 kg; 1.40 versus 0.96 cm; p < 0.05) . Mean increase in height in children fed high-protein diets (0.83 cm) was not significantly greater than with control diets (0.74 cm) . Mean increases in serum concentrations of total protein, prealbumin, and retinol-binding protein were greater in the high-protein group than in controls (p < 0.05) . Mean serum concentrations of IGF-I were low in both groups before treatment {4.2 +/- 2.6 nmol/L (31.9 +/- 19.6 ng/mL) in controls; 3.1 +/- 3.4 nmol/L (24.0 +/- 26.3 ng/mL) in the high-protein group} but increased more in the high-protein group {39.0 +/- 16.2 nmol/L (298 +/- 124 ng/mL)} than in the control group {16.7 +/- 9.2 nmol/L (128 +/- 70 ng/mL), p < 0.01}.(ABSTRACT TRUNCATED AT 250 WORDS)

Zentralbl Bakteriol, 1992 Dec, 277(4), 419 - 28
Characterization of a lipopolysaccharide encoded by a recombinant Shigella sonnei plasmid in Escherichia coli K-12; Seltmann G et al.; The genetic information to synthesize the S-specific region of Shigella sonnei phase I lipopolysaccharide (LPS) is localized on a 180 kb plasmid which is lost quite readily . A recombinant plasmid derivative remaining stable in the bacteria was shown to determine the S-specific region of the LPS which is completely identical with that of a S . sonnei phase I strain following transfer in Escherichia coli K-12 . However, the length control in polysaccharide biosynthesis is lost at least partially.

J Bacteriol, 1992 Dec, 174(23), 7500 - 8
Acetylation of O-specific lipopolysaccharides from Shigella flexneri 3a and 2a occurs in Escherichia coli K-12 carrying cloned S . flexneri 3a and 2a rfb genes; Yao Z et al.; Most of the Shigella flexneri O-specific serotypes result from O-acetyl and/or glucosyl groups added to a common O-repeating unit of the lipopolysaccharide (LPS) molecule . The genes involved in acetylation and/or glucosylation of S . flexneri LPS are physically located on lysogenic bacteriophages, whereas the rfb cluster contains the biosynthesis genes for the common O-repeating unit (D.A.R . Simmons and E . Romanowska, J . Med . Microbiol . 23:289-302, 1987) . Using a cosmid cloning strategy, we have cloned the rfb regions from S . flexneri 3a and 2a . Escherichia coli K-12 containing plasmids pYS1-5 (derived from S . flexneri 3a) and pEY5 (derived from S . flexneri 2a) expressed O-specific LPS which reacted immunologically with S . flexneri polyvalent O antiserum . However, O-specific LPS expressed in E . coli K-12 also reacted with group 6 antiserum, indicating the presence of O-acetyl groups attached to one of the rhamnose components of the O-repeating unit . This was confirmed by measuring the amounts of acetate released from purified LPS samples and also by the chemical removal of O-acetyl groups, which abolished group 6 reactivity . The O-acetylation phenotype was absent in an E . coli strain with an sbcB-his-rfb chromosomal deletion and could be restored upon conjugation of F' 129, which carries sequences corresponding to a portion of the deleted region . Our data demonstrate that E . coli K-12 strains possess a novel locus which directs the O acetylation of LPS and is located in the sbcB-rfb region of the chromosomal map.

Nippon Saikingaku Zasshi, 1992 Nov, 47(6), 777 - 81
{Chemical and serological study of lipopolysaccharide isolated from Shigella flexneri 88-893 possessing a new type-antigen}; Toshima Y et al.; The O-specific polysaccharide chain which represents a new type-antigen in lipopolysaccharide (LPS) of Shigella flexneri 88-893 was investigated . The O-polysaccharide chain was found to be composed of repeating units comprising rhamnose, N-acetylglucosamine and glucose (3:1:2) . In the passive hemolysis test, group-6 antiserum of S . flexneri exhibited a high hemolytic titer (50% hemolysis titer: 7,900) against sheep red blood cells (SRBC) sensitized with intact 893 LPS, but virtually no hemolytic activity against SRBC sensitized with alkali-treated 893 LPS . None of the type-specific antisera (I-VI), showed any significant hemolytic titer against SRBC sensitized with either intact or alkali-treated 893 LPS . Thus, 893 LPS contained both the group-6 antigen and a new type-antigen which is distinct from any known type-antigen of S . flexneri.

J Infect, 1992 Nov, 25(3), 273 - 8
Serological diagnosis of infection by Shigella dysenteriae-1 in patients with bacillary dysentery; de Silva DG et al.; A total of 192 samples of serum from 113 Sri Lankan patients with clinical dysentery was examined for antibodies of the IgM class to the lipopolysaccharides (LPSs) of Shigella dysenteriae-1 and Escherichia coli O157:H7 . By means of ELISA and immunoblotting, 59 patients were found to have serum antibodies to the LPS of S . dysenteriae-1 only . Four samples from one patient were found to contain serum antibodies to the LPSs of both S . dysenteriae-1 and E . coli O157:H7 . Antibodies to the LPS of S . dysenteriae-1 were also detected in 16 samples from 25 children, from Sri Lanka, with no previous history of dysentery; one of these children also had antibodies to the LPS of E . coli O157:H7 . Analysis of 16 samples from apparently healthy children in the U.K . showed that only one serum contained antibodies to the LPS of S . dysenteriae-1 . This patient had a history of recent travel to Pakistan . The isolation of S . dysenteriae-1 remains the preferred test for the diagnosis of bacillary dysentery . The use of serology as a means of providing evidence of infection with S . dysenteriae-1, however may prove to be a useful adjunct to cultural techniques but needs to be validated in an area where this organism is endemic.

FEMS Microbiol Lett, 1992 Nov 1, 77(1-3), 229 - 33
Purification and partial characterization of two azoreductases from Shigella dysenteriae type 1; Ghosh DK et al.; Two azoreductases (I and II) were purified to homogeneity from extracts of Shigella dysenteriae (type 1) . Azoreductase I was a dimer of identical subunits of M(r) 28,000, whereas azoreductase II was a monomer of 11,000 M(r) . Both were flavoproteins, each containing 1 mol of FMN per mol enzyme . Both NADH and NADPH functioned as electron donors for the azoreductases . Azoreductase I used Ponceau SX, Tartrazine, Amaranth and Orange II as substrates . Azoreductase II utilized all the dyes except Amaranth.

Eur J Clin Nutr, 1992 Nov, 46(11), 833 - 8
Decreased food intake in children with severe dysentery due to Shigella dysenteriae 1 infection; Rahman MM et al.; Factors that affect food intake in acute shigellosis were studied in 82 children aged 24-59 months . Children were offered an energy-dense milk-cereal-oil-based diet every 2 h . Food intake was compared between children with Shigella dysenteriae 1 infection and those infected with other Shigella spp (predominantly S . flexneri) . Mean energy intake in the first 48 h was 435 kJ/kg.d in children infected with S . dysenteriae 1 and 536 kJ/kg.d in children infected with other Shigella spp (P < 0.001) . Febrile children ate significantly (P < 0.05) less food than afebrile ones (469 vs 517 kJ/kg.d) . Food intake remained significantly (P < 0.001) less in children infected with S . dysenteriae 1 after controlling for the effect of fever . The results show that food intake is significantly reduced in dysentery due to S . dysenteriae 1 infection compared to that of other Shigella species; however, adequate calorie intake can be maintained by providing frequent energy-dense meals despite anorexia, fever, abdominal pain and diarrhoea.

Ann Intern Med, 1992 Nov 1, 117(9), 727 - 34
Treatment of shigellosis: III . Comparison of one- or two-dose ciprofloxacin with standard 5-day therapy . A randomized, blinded trial; Bennish ML et al.; OBJECTIVE: To determine whether a single dose, or 2 doses, of ciprofloxacin are as effective as 5-day, 10-dose therapy for the treatment of shigellosis in adult men who are moderately to severely ill . DESIGN: Randomized, double-blind clinical trial . SETTING: A diarrhea treatment center in the capital city of a developing country, Bangladesh . PATIENTS: A total of 128 adult men with dysentery of less than 96 hours duration . All had Shigella organisms isolated from a culture of stool . INTERVENTIONS: Patients were randomly assigned to receive either a single 1-gram dose of ciprofloxacin at admission to the study (single-dose group; n = 40), a 1-gram dose of ciprofloxacin at admission and 24 hours later (2-dose group; n = 43), or 500 mg of ciprofloxacin every 12 hours for 5 days (10 dose group; n = 35) . All patients were hospitalized for 6 days . MEASUREMENTS: Stools were collected individually; their character and consistency were recorded and cultured daily . A physical examination and recording of symptoms were done daily, and the temperature was measured every 4 hours . Therapy was considered to have failed in patients who did not have improvement in the signs and symptoms of dysentery after 72 hours of therapy or in patients who on study day 5 had more than nine stools, or more than two watery stools, or were febrile . RESULTS: There were no treatment failures in the 78 patients infected with species of Shigella other than Shigella dysenteriae type 1 . Among the 40 patients infected with S . dysenteriae type 1, treatment failed in 4 of the 10 patients who received single-dose therapy, 2 of the 15 patients who received 2-dose therapy, and none of the 15 patients who received 10-dose therapy (P = 0.017, single-dose therapy group compared with 10-dose group; P = 0.15 for the single-dose group compared with the 2-dose group; P > 0.2 for the 2-dose group compared with the 10-dose group) . CONCLUSIONS: A single 1-gram dose of ciprofloxacin is effective therapy for patients infected with species of Shigella other than S . dysenteriae type 1 . Single-dose therapy is inferior to 10-dose therapy for treating patients infected with S . dysenteriae type 1.

J Infect Dis, 1992 Nov, 166(5), 1181 - 4
An analysis of the quantitative relationship between oral temperature and severity of illness in experimental shigellosis; Mackowiak PA et al.; The relationship between oral temperature and other parameters of illness was examined in 139 adult volunteers infected experimentally with Shigella sonnei . In subjects developing clinical disease, peak temperature correlated positively with total number of signs and symptoms other than fever (rxy = .71, P < .001), stool volume (rxy = .41, P < .001) and number of stools produced during the illness (rxy = .46, P < .001) . Peak temperature correlated negatively with incubation period (rxy = -.34, P = .007) but exhibited no apparent correlation with duration of illness . The average oral temperature during illness correlated positively with number of other signs and symptoms of infection but not with stool volume or stool number . These results suggest that in clinical investigations involving S . sonnei, and perhaps with other pathogenic microorganisms, oral temperature is a useful quantitative marker for estimating disease severity.

J Bacteriol, 1992 Nov, 174(21), 6981 - 91
Molecular analysis of the glpFKX regions of Escherichia coli and Shigella flexneri; Truniger V et al.; We have identified a new gene, glpX, belonging to the glp regulon of Escherichia coli, located directly downstream of the glpK gene . The transcription of glpX is inducible with glycerol and sn-glycerol-3-phosphate and is constitutive in a glpR mutant . glpX is the third gene in the glpFKX operon . The function of GlpX remains unknown . GlpX has an apparent molecular weight of 40,000 on sodium dodecyl sulfate-polyacrylamide gels . In addition to determining the E . coli glpX sequence, we also sequenced the corresponding glpFKX region originating from Shigella flexneri, which after transfer into E . coli was instrumental in elucidating the function of glpF in glycerol transport (D . P . Richey and E . C . C . Lin, J . Bacteriol . 112:784-790, 1972) . Sequencing of the glpFKX region of this hybrid strain revealed an amber mutation instead of the tryptophan 215 codon in glpF . The most striking difference between the E . coli and S . flexneri DNA was found directly behind glpK, where two repetitive (REP) sequences were present in S . flexneri, but not in the E . coli sequence . The presence or absence of these REP sequences had no effect on transport or on growth on glycerol . Not including the REP sequence-containing region, only 1.1% of a total of 2,167 bp sequenced was different in the two sequences . Comparison of the sequence with those in the EMBL data library revealed a 99% identity between the last third of glpX and the first part of a gene called mvrA . We show that the cloned mvrA gene (M . Morimyo, J . Bacteriol . 170:2136-2142, 1988) originated from the 88-min region of the Escherichia coli chromosome and not, as reported, from the 7-min region and that the gene product identified as MvrA is in fact encoded by a gene distal to glpX.

FASEB J, 1992 Nov, 6(14), 3265 - 74
Structural basis of antigenic specificity and design of new vaccines; Arnon R et al.; This manuscript describes the design of new vaccines based on synthetic peptides . To this end, we first analyze the structural basis of antigenic reactivity and specificity and the various types of epitopes that form the mosaics of macromolecular antigens, as well as the regulatory mechanisms involved in immune recognition . A distinction is made between sequential or continuous epitopes, and discontinuous or conformational ones, which are the majority of epitopes in globular proteins . In this context it is of particular interest to identify epitopes reacting with B cells and T cells, respectively, or with cytotoxic T cells, in association with the major histocompatibility cell-surface antigens, and the role of these interactions in protective immunity . Identification of such epitopes in proteins of viral, bacterial, or parasitic organisms led to the synthesis of peptides, which when used in conjunction with appropriate carriers and/or adjuvants induced neutralizing antibodies . Particular examples are described, including: bacterial epitopes and mainly those of toxins of diphtheria, cholera, and shigella, leading not only to neutralizing antibodies but also to protective immunity against the deleterious effects of the respective toxins; parasite epitopes, such as those leading to anti-malaria vaccine, based on either the sporozoite or the merozoite stage antigens; viral epitopes leading to protective immunity, with special emphasis on influenza virus where induction of CTL is crucial; and finally, synthetic peptide vaccines against HIV, which should lead to broad specificity protective immunity while avoiding the risks of a vaccine based on the infectious agent . The rapid recent progress in this field, as described in this review, increases the prospect of constructing successful synthetic peptide vaccines in the not too distant future.

Rev Med Chil, 1992 Nov, 120(11), 1261 - 6
{Shigellosis in children of the IX region of Chile: clinical and epidemiologic aspects and antibiotic sensitivity}; Boehme C et al.; Ninety four children with diarrhea and a positive stool culture for Shigella, hospitalized at the Hospital Regional de Temuco, were studied . Forty six percent of patients were less than two years old . Forty two percent of microorganisms were resistant to Ampicillin, 45% to trimethoprim/sulfamethoxazole, 8% to tetracycline and none to chloramphenicol . Isolated species were Shigella flexneri 83% and Shigella sonnei 17% . Seventy nine percent of patients had fever, 60% dysentery and 21.3% seizures . Ninety two percent of symptomatic family contacts had a positive stool culture for Shigella . Due to the high incidence of resistance to ampicillin and trimethoprim/sulfamethoxazole, these antimicrobials are not recommended as the first choice treatment of Shigellosis in the Ninth region of Chile.

Eur J Epidemiol, 1992 Nov, 8(6), 856 - 60
Features of cholera and Vibrio parahaemolyticus diarrhoea endemicity in Calabar, Nigeria; Utsalo SJ et al.; The clinical and epidemiological features of acute vibrio diarrhoeal disease were studied in 881 patients seen at the University of Calabar Teaching Hospital (UCTH), Calabar, Nigeria, between January and December 1989 . Stools and rectal swabs of patients and randomly-selected control subjects were microscopically and culturally examined for the presence of enteric pathogens . Households of vibrio diarrhoea cases and matched controls were visited for ecologic studies . Of a total of 108 (12.3%) culturally-confirmed bacterial diarrhoeas, 47 (43.5%) were due to Escherichia coli, 33 (30.6%) to Vibrio cholerae-01 (classical and El Tor biotypes) and V . parahaemolyticus, while shigellae and salmonellae accounted for 29 (26.9%) and 9 (8.3%) cases, respectively . Most cholera case households clustered within the ancient neighbourhood of the inner city, characterized by poorly developed water and sewage disposal systems . A preponderance of vibrio diarrhoea patients were children < or = 10 years . Adult cases involved mostly females . The only case of diarrhoea-related death involved an eight-month old child with kwashiorkor and V . parahaemolyticus infection . Incidence of vibrio diarrhoeas was seasonal, with most cases occurring during the dry season followed by subsidence at the onset of rainy season . Bimodal peaks of vibrio diarrhoeal episodes observed over the period appeared to coincide with periods of acute water scarcity, high temperature, increased fishing activities and trade traffic on the Calabar River estuary . Of the environments sampled, only clam shells from a case household and river sediments yielded vibrio pathogens on culture . Ecological factors that are capable of stabilizing a focus of vibrio diarrhoea endemicity in this area are highlighted.

J Clin Microbiol, 1992 Nov, 30(11), 2996 - 9
Differentiation of Shigella flexneri strains by rRNA gene restriction patterns; Faruque SM et al.; We studied the restriction endonuclease cleavage patterns of rRNA genes (ribotypes) of 72 clinical isolates of Shigella flexneri representing eight serotypes to determine whether ribotyping could be used to distinguish S . flexneri strains and to compare the discriminating ability of the method with that of serotyping . By using a cloned Escherichia coli rRNA operon as the probe, Southern blot hybridization of restriction endonuclease-digested total DNA was carried out . Ribotyping of the isolates with each of the five restriction endonucleases BamHI, EcoRI, HindIII, PstI, and SalI generated reproducible restriction patterns . However, HindIII produced the optimum digestion pattern of the rRNA genes and was more useful than the other enzymes used in differentiating strains . Analysis of the 72 isolates showed 11 different HindIII cleavage patterns of their rRNA genes . Four of these HindIII-generated ribotypes could be further differentiated into two to four subribotypes by using PstI . The results indicate that ribotyping has an application for differentiation of S . flexneri strains and can complement serotyping . Definition of strains in terms of both serotype and ribotype may be of greater use in epidemiological studies.

Antimicrob Agents Chemother, 1992 Oct, 36(10), 2346 - 8
Activities of newer fluoroquinolones against Shigella sonnei; John JF Jr et al.; The activities of six fluoroquinolones were determined for 117 separate strains of Shigella sonnei . The order of increasing activity (MICs for 90% of strains tested) was enoxacin (0.25 micrograms/ml), temafloxacin (0.032 micrograms/ml), sparfloxacin (0.016 micrograms/ml), CI-960 (0.008 micrograms/ml), ciprofloxacin (0.008 micrograms/ml), and PD-131628-2 (0.008 micrograms/ml) . These data, along with results of killing and mutational rate studies, showed that all six fluoroquinolones were highly inhibitory against S . sonnei and five fluoroquinolones were rapidly and persistently bactericidal.

J Infect Dis, 1992 Oct, 166(4), 792 - 6
Enteropathogens associated with acute and persistent diarrhea in Bangladeshi children less than 5 years of age; Baqui AH et al.; A longitudinal study of diarrhea was carried out from May 1988 to April 1989 by household surveillance of 705 children less than 5 years old in rural Bangladesh . Stool samples were examined for enteric pathogens at the beginning of each diarrheal episode . For persistent episodes, stool examination was repeated on days 15-17 of the illness . For each case of persistent diarrhea, stool samples from age-matched acute diarrheal and healthy controls were examined . Compared with healthy controls, cases of diarrhea were associated with Shigella species (P = .07) and rotavirus (P less than .05) . Diffusely adherent Escherichia coli (P less than .05) and cryptosporidia (P = .07) were the only enteropathogens associated with persistent diarrhea in comparison with acute diarrhea . No more than 15% of children had the same class of pathogen identified from stool on both days 1-3 and days 15-17, indicating that persistent infection was uncommon . However, a different enteropathogen was frequently found on days 15-17, suggesting that sequential infection may be a cause of persistent diarrhea.

Zentralbl Bakteriol, 1992 Oct, 277(3), 334 - 9
The isolation of Plesiomonas shigelloides in polymicrobial septicaemia originating from the biliary tree; Korner RJ et al.; The first two cases are reported in which Plesiomonas shigelloides was isolated from patients with mixed aerobic/anaerobic septicaemia originating from the biliary tree . The first patient who was previously well survived after removal of a gangrenous gallbladder . The second patient suffered from an extrahepatic cholangiocarcinoma and died of infection thus highlighting the poor prognostic outcome of P . shigelloides septicaemia in immunocompromised patients . Furthermore these cases demonstrate that P . shigelloides can be isolated from mixed infections and may act synergistically with other bacteria to produce disease.

APMIS, 1992 Oct, 100(10), 954 - 6
beta-lactamases in Shigella; Schumacher H et al.; The occurrence of resistance and production of beta-lactamases was investigated in 60 Shigella strains . Ampicillin resistance was found in 28 (47%) of the isolates, the resistance being more frequent in Sh . flexneri than in Sh . sonnei . All strains were susceptible to cefotaxime, mecillinam, and ciprofloxacin . The beta-lactamases produced by Shigella were similar to TEM-1, OXA-1, or the low-level chromosomally mediated cephalosporinase produced by Escherichia coli . The beta-lactamases produced by Sh . flexneri were most often the OXA-1-like enzymes.

J Bacteriol, 1992 Oct, 174(20), 6498 - 507
Identification of a B subunit gene promoter in the Shiga toxin operon of Shigella dysenteriae 1; Habib NF et al.; The Shiga toxin operon (stx) is composed of A and B subunit genes which are transcribed as a bicistronic mRNA from a promoter which lies 5' to the stxA gene . Northern (RNA) blot and primer extension analyses revealed the existence of a second stxB gene transcript . Recombinant plasmids which carried the stxB gene without the stx operon promoter and with the influence of a vector promoter abrogated produced STX B polypeptides, suggesting that the stxB gene mRNA was transcribed from an independent promoter and was not produced by endoribonucleotic processing of the bicistronic mRNA . Examination of the DNA sequences 5' to the stxB gene transcription initiation site which were carried by the recombinant plasmids revealed a region with high homology to the consensus for Escherichia coli promoters . Deletion and mutation of this region affected StxB and holotoxin production, establishing its role in the regulation of the stxB gene . Comparison of the promoters by using a transcription analysis vector revealed that the stxB gene promoter differed from the stx operon promoter in that was approximately sixfold less efficient and was not repressed by iron . Identification of a second promoter in the stx operon indicates that independent transcription of the stxB gene may regulate overproduction of the STX B polypeptides and may contribute to the 1A:5B subunit stoichiometry of the holotoxin.

J Bacteriol, 1992 Oct, 174(20), 6359 - 67
vacB, a novel chromosomal gene required for expression of virulence genes on the large plasmid of Shigella flexneri; Tobe T et al.; Shigellae, the causative agents of bacillary dysentery, are capable of adhering to and invading epithelial cells and spreading into adjacent cells . A chromosomal mutant of Shigella flexneri 2a YSH6000 with reduced invasive capacity was isolated by Tn5 insertion mutagenesis . The linkage of the mutant phenotype to the Tn5 insertion was determined by P1 phage transduction . The site of the Tn5 insertion was assigned to a NotI chromosomal restriction map, confirming that the virulence-associated locus, designated vacB, is a new locus on the chromosome . In the vacB mutant, production of the four plasmid-encoded virulence antigens, IpaB, -C, and -D and VirG, decreased to a low level compared with that in the wild type . In contrast, levels of transcription of the operons for virG, ipa, region-3.4, region-5, virF, and virB on the large plasmid, as determined by Northern dot blotting, were unaffected in the vacB mutant . Furthermore, transcriptional activation of the ipa operon by exploiting a tac promoter could not restore the vacB mutant to production of the same levels of the IpaB, -C, and -D proteins as those in the wild type, indicating that the vacB locus is involved in expression of the vir genes on the large plasmid at the posttranscriptional level . Cloning followed by nucleotide sequencing of the vacB region showed it to contain a 2,280-bp open reading frame encoding an 86.9-kDa protein located 669 bp downstream from the 3' end of the open reading frame for the purA gene . Disruption of the vacB gene of other serotypes of Shigella spp . and enteroinvasive Escherichia coli (EIEC) resulted in reduced expression of virulence phenotypes, indicating that the vacB gene encodes a novel type of virulence-associated gene required for the full expression of the virulence phenotype of Shigella spp . and EIEC.

Infect Immun, 1992 Oct, 60(10), 4088 - 99
Unipolar reorganization of F-actin layer at bacterial division and bundling of actin filaments by plastin correlate with movement of Shigella flexneri within HeLa cells; Prevost MC et al.; Shigella flexneri causes bacillary dysentery, an invasive disease of colonic epithelial cells in humans . The capacity of bacteria, once they have entered into a cell and escaped the phagocytic vacuole, to spread intracellularly and directly to adjacent cells without further extracellular passage is a key factor in invasion of the epithelial layer . Movement of intracellular bacteria is dependent upon the polymerization of actin; concentration of the formed filaments to one end of the bacterium is associated with initiation of movement . This movement may lead to the formation of a protrusion at the cell surface through which the bacterium passes to an adjacent cell . Development of these protrusions in infected HeLa cells is described, with emphasis on two critical observations . First, initiation of movement is coupled with bacterial division since elongation of the bacterial body is associated with relocalization of the previously uniformly distributed layer of actin to one pole of the bacterium . Second, the actin-bundling protein plastin appears to bundle the actin filaments just posterior to the bacterium, producing an ongoing contraction of the cylindrical actin tail that may be associated with forward movement of the bacterium within the protrusion.

Acta Virol, 1992 Oct, 36(5), 443 - 9
Effect of enterovirus infection on susceptibility of HeLa cells to Shigella flexneri invasivity; Marchetti M et al.; Invasiveness of Shigella flexneri M90T in HeLa cells was significantly increased when cells were preinfected with poliovirus 1, coxsackievirus B3 and echovirus 6 . This effect was dependent on the dose of virus used, evident at early stages of viral infection and lasted hours before the appearance of a cytopathic effect . An increase of bacterial invasion ability was also noticed when HeLa cells were incubated with UV-inactivated enteroviruses . This enhancing effect obtained with both viable and UV-inactivated enteroviruses was not observed when in coinfection experiments HN555, a mutant of S . flexneri M90T which lacked invasive properties, was used . The data presented here suggest that the early steps of enterovirus infection induce some alterations of HeLa cells which are responsible for the enhancing of the invasiveness of S . flexneri M90T, but not sufficient to promote internalization of a non-invasive strain.

Epidemiol Infect, 1992 Oct, 109(2), 273 - 82
Molecular epidemiology of Shigella infections in Israel; Yavzori M et al.; The DNAs of Shigella sonnei or Shigella dysenteriae type 1 strains isolated in outbreaks of shigellosis or in sporadic cases were analysed by restriction fragment length polymorphism (RFLP) . Southern blots of the DNAs of 36 S . sonnei isolates digested by 8 restriction enzymes were hybridized with an Escherichia coli rRNA probe . The S . sonnei strains were unexpectedly diverse in their RFLP . Antibiotypes of the same isolates showed clusters of strains corresponding to the various outbreaks . On the other hand, RFLP analysis suggested concomitant multiple sources of infection rather than a common source and thereby introduced a new insight in the epidemiology of shigellosis . RFLP was also used to trace S . dysenteriae type 1 transmission in a recent cluster of clinical cases . Although antibiotic resistance patterns indicated the presence of more than one strain, RFLP analysis showed that the six isolates were identical clones and suggested the loss of an R episome after one person-to-person passage.

JAMA, 1992 Sep 23-30, 268(12), 1578 - 80
A critical appraisal of 98.6 degrees F, the upper limit of the normal body temperature, and other legacies of Carl Reinhold August Wunderlich; Mackowiak PA et al.; OBJECTIVE--To evaluate critically Carl Wunderlich's axioms on clinical thermometry . DESIGN--Descriptive analysis of baseline oral temperature data from volunteers participating in Shigella vaccine trials conducted at the University of Maryland Center for Vaccine Development, Baltimore . SETTING--Inpatient clinical research unit . PARTICIPANTS--One hundred forty-eight healthy men and women aged 18 through 40 years . MAIN MEASUREMENTS--Oral temperatures were measured one to four times daily for 3 consecutive days using an electronic digital thermometer . RESULTS--Our findings conflicted with Wunderlich's in that 36.8 degrees C (98.2 degrees F) rather than 37.0 degrees C (98.6 degrees F) was the mean oral temperature of our subjects; 37.7 degrees C (99.9 degrees F) rather than 38.0 degrees C (100.4 degrees F) was the upper limit of the normal temperature range; maximum temperatures, like mean temperatures, varied with time of day; and men and women exhibited comparable thermal variability . Our data corroborated Wunderlich's in that mean temperature varied diurnally, with a 6 AM nadir, a 4 to 6 PM zenith, and a mean amplitude of variability of 0.5 degrees C (0.9 degrees F); women had slightly higher normal temperatures than men; and there was a trend toward higher temperatures among black than among white subjects . CONCLUSIONS--Thirty-seven degrees centigrade (98.6 degrees F) should be abandoned as a concept relevant to clinical thermometry; 37.2 degrees C (98.9 degrees F) in the early morning and 37.7 degrees C (99.9 degrees F) overall should be regarded as the upper limit of the normal oral temperature range in healthy adults aged 40 years or younger, and several of Wunderlich's other cherished dictums should be revised.

Pharmacoeconomics, 1992 Oct, 2(4), 305 - 23
Pharmacoeconomics of the therapy of diarrhoeal disease; Nathavitharana KA et al.; We review the pathophysiology of intestinal water and electrolyte transport leading to diarrhoea, the currently available pharmacological strategies for its treatment, and the economic implications of such treatments . Diarrhoea occurs most frequently and is associated with highest mortality in children under 5 . Oral rehydration therapy (ORT) is the cornerstone of its management . The safety and efficacy of ORT in the prevention of death from dehydration, both in field and also in hospital settings, are now well established . Because it is also inexpensive, ORT is widely applicable worldwide . More recently, rice-based ORT has emerged, based on well known traditional remedies for diarrhoea in southeast Asia and the Far East . Rice-based ORT has the advantage of being more culturally acceptable, readily available even in rural homes in developing countries, and is more effective in reducing stool output and the duration of diarrhoea, compared with conventional glucose-electrolyte solutions such as World Health Organization ORT . For infants, the well known antidiarrhoeal properties of human milk needs emphasis for a variety of reasons including economic ones . Data concerning the economic benefits to a nations' health budget as a result of nationwide implementation of oral rehydration solution (ORS) use are limited . Available data from individual centres in developing countries, if projected to national level, would incur considerable economic advantage . Except for a few notable infections such as shigellosis, cholera, amoebiasis and giardiasis, the widespread use of antibiotics in acute diarrhoea, still a common practice in many developing countries, has no proven value and may be detrimental . The economic implications of antibiotic abuse in the treatment of diarrhoea in developing countries is enormous . Despite the availability of a wide spectrum of pharmacological agents for diarrhoea reviewed in this article, only a few such agents are of proven clinical efficacy: corticosteroids, aminosalicylates and immunosuppressants in the treatment of inflammatory bowel disease and opioid derivatives such as loperamide which may be useful in protracted diarrhoea in children and in disorders where rapid gastrointestinal transit is the main cause of diarrhoea . Opioids are not recommended for acute infective diarrhoea in childhood . Octreotide, a somatostatin analogue, is reported to be useful in the treatment of secretory diarrhoea due to noninfective causes and in the treatment of intractable diarrhoea associated with AIDS . Its high cost and need for parenteral administration prevent its wider application.(ABSTRACT TRUNCATED AT 400 WORDS)

Am J Trop Med Hyg, 1992 Sep, 47(3), 276 - 83
Efficacy of bovine milk immunoglobulin concentrate in preventing illness after Shigella flexneri challenge; Tacket CO et al.; The protective efficacy of oral bovine immunoglobulin concentrates derived from colostrum against challenge with Shigella flexneri was studied in healthy adult volunteers in a randomized, double-blind fashion . Volunteers were given a product consisting of hyperimmune immunoglobulin concentrate with a high titer of anti-S . flexneri 2a lipopolysaccharide (LPS) with sodium bicarbonate or a control preparation with sodium bicarbonate three times a day for seven days . On the third day of treatment, volunteers received a challenge of 10(3) colony-forming units of S . flexneri 2a strain 2457T . None of the volunteers who received the high-titered hyperimmune product became ill, compared with 45% of volunteers who received the placebo (P less than 0.05) . The duration of shedding of the challenge organism was decreased, and the active immune responses to S . flexneri LPS were less frequent and of lower magnitude in volunteers given the immunoglobulin concentrate than in those in the control group . High-titered, orally administered bovine immunoglobulin concentrate protects against shigellosis and may be useful in preventing shigellosis among travelers, military personnel, and individuals at risk during a Shigella outbreak.

Pediatrics, 1992 Sep, 90(3), 406 - 11
Community-based evaluation of the effect of breast-feeding on the risk of microbiologically confirmed or clinically presumptive shigellosis in Bangladeshi children; Ahmed F et al.; To assess the association between breast-feeding and the risk of microbiologically confirmed or clinically presumptive shigellosis, the authors performed a case-control analysis of Bangladeshi children younger than 3 years of age who were followed up for 1 month after exposure to Shigella in their residential neighborhoods . Two hundred sixty-nine cases with culture-confirmed shigellosis (n = 119) or clinically presumptive shigellosis (culture-negative dysentery, n = 150) were compared with 819 controls without Shigella diarrhea or other invasive diarrheal illnesses . The odds ratio relating breast-feeding to confirmed or presumptive shigellosis, adjusted for potentially confounding variables, was 0.48 (95% confidence interval = 0.32 to 0.72; P less than .001), suggesting a substantial protective effect . The protective association decreased with age but was still significant during the third year of life; appeared to be directly related to the degree of stunting; and was equivalent for confirmed and presumptive shigellosis . Notably, the protective association remained substantial against episodes due to Shigella which were resistant to at least one of the antibiotics customarily used for treatment of Shigella diarrhea (age-adjusted odds ratio = 0.40; 95% confidence interval = 0.22 to 0.74; P less than .01) . These data suggest that breast-feeding confers a high level of protection against shigellosis throughout the first 3 years of life, especially among nutritionally compromised children, and thereby underscore the importance of promotion of breast-feeding as a central component of Shigella control programs in less developed settings.

Mol Plant Microbe Interact, 1992 Sep-Oct, 5(5), 390 - 6
Determinants of pathogenicity in Xanthomonas campestris pv . vesicatoria are related to proteins involved in secretion in bacterial pathogens of animals; Fenselau S et al.; One of the model systems investigated for studying plant bacterial pathogenesis is Xanthomonas campestris pv vesicatoria, the causal agent of bacterial spot disease of pepper and tomato . Genes necessary for both basic pathogenicity and the induction of the hypersensitive response in resistant plants (hrp genes) were previously isolated from X . c . pv . vesicatoria and characterized genetically . As a first step toward functional analysis, part of the hrp gene cluster, making up several loci, was sequenced . Here, we report the first indications of the function of hrp genes . Striking similarities to proteins from the mammalian pathogens Shigella flexneri, Yersinia enterocolitica, Y . pestis, and other bacteria were discovered . Proteins encoded by genes within the X . c . pv . vesicatoria loci hrpA, hrpB, and hrpC are similar to ATPases and to Yersinia Ysc and LcrD proteins, which are involved in secretion of Yop proteins, a particular class of essential pathogenicity factors produced by Yersinia species . This finding indicates, for the first time, that the fundamental determinants of pathogenicity may be conserved among bacterial pathogens of plants and animals . We hypothesize that hrp genes are involved in the secretion of molecules essential for the interaction of X . c . pv . vesicatoria with the plant.

J Diarrhoeal Dis Res, 1992 Sep, 10(3), 146 - 50
Efficacy of norfloxacin for shigellosis: a double-blind randomised clinical trial; Bhattacharya MK et al.; In a double-blind, randomised, clinical trial on 122 adults with acute Shigella dysentery, 60 patients were treated with norfloxacin and 62 with nalidixic acid . Of these, 32 patients in the norfloxacin group and 28 patients in the nalidixic acid group had Shigella in their stool . Patients of the two treatment groups were clinically comparable on admission . No significant differences in clinical responses were observed in the two groups among the Shigella-positive cases, Shigella-negative cases and among the total cases . All isolates of Shigella were susceptible to norfloxacin, whereas 13.8% of the strains were resistant to nalidixic acid.

J Diarrhoeal Dis Res, 1992 Sep, 10(3), 139 - 45
Regulation of the SLT-1A toxin operon by a ferric uptake regulatory protein in toxinogenic strains of Shigella dysenteriae type 1; Svinarich DM et al.; The regulation of Shiga toxin expression in a clinical isolate of S . dysenteriae 1 by the Fe-Fur (Iron-ferric uptake regulatory protein) repressor complex was investigated . The presence of an endogenous Fur repressor protein capable of binding to either a Fur binding consensus sequence or the regulatory region of SLT-1A was determined in toxinogenic strains of S . dysenteriae . Plasmid constructs bearing Fur binding sites fused to readily assayable reporter genes were used . Plasmid pSC27.1 contains a 21 bp synthetic oligonucleotide Fur protein binding consensus sequence located upstream to the gene for beta-galactosidase . Plasmid pSC105 contains the regulatory sequences of Shiga-like toxin-1A located upstream to the gene for alkaline phosphatase . In an analogous fashion to Shiga toxin regulation in S . dysenteriae 1, transformants bearing either pSC27.1 or pSC105 plasmid DNA were repressed in gene product expression when grown in minimal medium supplemented with iron . Conversely, transformants were de-repressed when grown under iron limiting conditions . These data suggest the presence of Fe-Fur mediated regulation of toxinogenesis in clinical isolates of S . dysenteriae.

Acta Paediatr Suppl, 1992 Sep, 381, 27 - 31
Epidemiology of persistent diarrhea and etiologic agents in Mirzapur, Bangladesh; Henry FJ et al.; To determine the epidemiology and etiologic agents of persistent diarrhea we carried out an intensive diarrhea surveillance on children less than six years old in rural Bangladesh . From March 1987 to February 1989 we examined 363 children through diarrhea recall interviews and analyzed stool samples of all diarrhea cases for potential pathogens . Results showed that children had an average of two episodes per year and the incidence rate of diarrheal episodes defined as acute (< 14 d) and persistent (> or = 14 d) varied similarly with age . The peak incidence (episodes/child/year) of acute diarrhea (2.8) and persistent diarrhea (0.8) occurred in the 6-11 months age group . The data showed that an episode tended to be prolonged if the stool was loose/mucoid or bloody at onset . Aggregative adherent Escherichia coli was found significantly more often at onset in persistent than in acute episodes, whereas Shigella, Aeromonas, Giardia and toxigenic E . coli were isolated with less frequency in persistent than acute episodes . This suggests that other factors might be more important in the development of persistent diarrhea than specific pathogens.

Cesk Epidemiol Mikrobiol Imunol, 1992 Sep, 41(4), 215 - 7
{Isolation of a rare serovar of Plesiomonas shigelloides}; Moravcik P et al.; The authors describe the isolation of a rare serovar Plesiomonas shigelloides from a patient with diarrhoea . The isolated strain belongs according to a combined Japanese-Czechoslovak antigenic scheme to serovar 024 H"o" . The interesting finding draws attention to the possibility of routine departments to contribute to investigations of the incidence, importance and antigenic structure of this bacterial species.

Infect Immun, 1992 Aug, 60(8), 3287 - 95
mxiA of Shigella flexneri 2a, which facilitates export of invasion plasmid antigens, encodes a homolog of the low-calcium-response protein, LcrD, of Yersinia pestis; Andrews GP et al.; The plasmid-encoded invasion plasmid antigen (Ipa) export accessory locus of Shigella flexneri 2a, mxiA, was cloned, and the complete DNA sequence of the gene was determined . The mixA open reading frame was found to encode a polypeptide of 74.03 kDa with a pI of 5.02 . A hydropathy analysis of the predicted protein revealed a hydrophilic C terminus and an extremely hydrophobic N terminus without a cleavable signal sequence but with several potential membrane-spanning regions . While a homology search did not reveal any significant relatedness of the mxiA DNA sequence to any known bacterial gene sequences, the derived amino acid sequence of MxiA was found to be highly homologous (68%) to the sequence of the protein encoded by the low-calcium-response locus, lcrD, of Yersinia pestis . The lcrD encodes an inner membrane regulatory protein that has an N-terminal membrane anchor and that is implicated in facilitating the export of Y . pestis outer membrane proteins (G . V . Plano, S . S . Barve, and S . C . Straley, J . Bacteriol . 173:7293-7303, 1991) . Congo red binding, HeLa cell invasion, and Ipa excretion were restored in two avirulent mxiA fusion mutants when they were transformed with a cloned copy of the mxiA gene . Furthermore, the expression of the cloned mxiA gene was independent of any vector-specified promoter, suggesting that the transcription of mxiA is driven by its own promoter in this clone . In contrast, the overexpression of mxiA that resulted when it was placed under the control of the lac promoter was found to be deleterious in Escherichia coli . We conclude that mxiA is a homolog of the Y . pestis lcrD locus and may function similarly in S . flexneri, either by directly affecting the excretion of virulence factors or by regulating the expression of export accessory genes.

Pediatr Infect Dis J, 1992 Aug, 11(8), 644 - 7
Ceftibuten and trimethoprim-sulfamethoxazole for treatment of Shigella and enteroinvasive Escherichia coli disease; Prado D et al.; In a prospective randomized study at two clinical sites, ceftibuten was compared with trimethoprim-sulfamethoxazole (TMP-SMX), both given orally for a period of 5 days, for the treatment of dysentery . Twenty-two children were found to have bacillary dysentery caused by Shigella and/or enteroinvasive Escherichia coli . All organisms isolated were susceptible to ceftibuten; 6 of 20 Shigella strains and 4 of 5 enteroinvasive E . coli were resistant to TMP-SMX . The diarrhea persisted for a mean (+/- SD) period of 2.4 +/- 1.4 days in the ceftibuten-treated patients vs . 3.4 +/- 1.7 days in the TMP-SMX-treated patients . The duration of fever was similar for both treatment groups . Patients treated with ceftibuten or TMP-SMX had equivalent clinical responses unless the pathogen was found to be TMP-SMX-resistant . Those who were randomized to receive TMP-SMX but who were eventually found to have TMP-SMX-resistant organisms had significantly more stools at days 3, 4 and 5 (P less than 0.02 to less than 0.00006) with more watery consistency for these days (P less than 0.02 to less than 0.005) compared to patients treated with ceftibuten . No clinical relapses were reported and no drug-related side effects were observed . We conclude that ceftibuten is at least as effective as TMP-SMX in the treatment of diarrhea caused by Shigella and enteroinvasive E . coli in children.

J Clin Microbiol, 1992 Aug, 30(8), 2165 - 8
Presence of specific immunoglobulin A-secreting cells in peripheral blood after natural infection with Shigella sonnei; Orr N et al.; The appearance of antigen-specific immunoglobulin A (IgA) antibody-secreting cells (ASCs) following natural infection with Shigella sonnei during a common-source outbreak caused by this organism was evaluated in a modified enzyme-linked immunosorbent assay (ELISPOT) . A mean IgA ASC value of 2,131.6/10(6) cells against homologous S . sonnei lipopolysaccharide (LPS) was detected in blood samples obtained from patients with bacteriologically proven S . sonnei shigellosis 5 and 10 days after the onset of disease . In the same blood samples, the level of ASC measured against heterologous antigen (Shigella flexneri serotype 2a LPS) was significantly lower than that of the homologous antigen (mean value, 33.12/10(6) cells) . Furthermore, the mean number of activated B cells that secreted anti-S . sonnei LPS antibodies was significantly higher among patients with S . sonnei shigellosis than it was among patients with non-Shigella diarrhea (2.5/10(6) cells; standard error, 1.0) and healthy subjects (5.1/10(6) cells; standard error, 2.3) (P less than 0.05) . The anti-LPS IgA ASC activity was easily detected within 5 days of the onset of disease, a point at which the levels of anti-S . sonnei LPS IgG and even IgA antibodies were hardly detectable in serum.

Mol Microbiol, 1992 Aug, 6(16), 2387 - 95
Identification and characterization of virK, a virulence-associated large plasmid gene essential for intercellular spreading of Shigella flexneri; Nakata N et al.; Seven virulence loci have been identified by Tn5 insertion mutagenesis on the large 230 kb plasmid (pMYSH6000) of Shigella flexneri 2a . In this study, we used Tn10 insertion mutagenesis and identified a novel virulence locus on pMYSH6000 responsible for bacterial spread . Characterization of the invading bacteria of the Tn10 insertion mutants in the epithelial cells revealed that the bacteria were capable of at least some intracellular spreading but not intercellular spreading . Immunoblot analysis of lysates of the Tn10 insertion mutants with a VirG-specific antipeptide antibody revealed diminished levels of the 116 kDa VirG protein . The virG mRNA in the mutants, however, was expressed at the same level as that in the wild type . The DNA region required for the virulence phenotype was localized to a 1.6 kb DNA sequence in the SalI-K fragment on the plasmid, and thus the locus was designated virK . Expression of virK in Escherichia coli using a T7 RNA polymerase-dependent promoter system yielded a 36 kDa protein . The nucleotide sequence of 1642 bp encoding VirK function was determined, and an open reading frame encoding 316 amino acid residues was shown to encode the VirK protein . The virK region was highly conserved among the large virulence plasmids of shigellae and enteroinvasive Escherichia coli . These results suggest that VirK function is an essential virulence determinant for shigellae involved in the expression of virG gene product at post-transcriptional level.

Mol Microbiol, 1992 Aug, 6(15), 2113 - 24
Temperature regulation of Shigella virulence: identification of the repressor gene virR, an analogue of hns, and partial complementation by tyrosyl transfer RNA (tRNA1(Tyr)); Hromockyj AE et al.; virR is the central regulatory locus required for coordinate temperature-regulated virulence gene expression in the human enteric pathogens of Shigella species . Detailed characterization of VirR+ clones revealed that virR consisted of a 411 bp open reading frame (ORF) that mapped to a chromosomally located 1.8kb EcoRI-AccI DNA fragment from Shigella flexneri . Insertional inactivation of the virR ORF at a unique HpaI restriction site resulted in a loss of VirR+ activity . The virR ORF nucleotide sequence was virtually identical to the Escherichia coli hns gene, which encodes the histone-like protein, H-NS . Based on the predicted amino acid sequence of E . coli H-NS, only a single conservative base-pair change was identified in the virR gene . An additional clone, designated VirRP, which only partially complemented the virR mutation, was also characterized and determined by Southern hybridization and nucleotide sequence analysis to be unique from virR . Subclone mapping of this clone indicated that the VirRP phenotype was a result of the multiple copy expression of the S . flexneri gene for tRNA(Tyr) . These data constitute the first direct genetic evidence that virR is an analogue of the E . coli hns gene, and suggest a model for temperature regulation of Shigella species virulence via the bacterial translational machinery.

FEMS Microbiol Lett, 1992 Aug 1, 74(1), 57 - 62
Analysis of DNA encoding 23S rRNA and 16S-23S rRNA intergenic spacer regions from Plesiomonas shigelloides; East AK et al.; Amplification of the gene encoding 23S rRNA of Plesiomonas shigelloides by polymerase chain reaction (PCR), with primers complementary to conserved regions of 16S and the 3' end of 23S rRNA genes, resulted in a DNA fragment of approximately 3 kb . This fragment was cloned in Escherichia coli and its nucleotide sequence determined . The region encoding 23S rRNA shows high homology with the published sequences of 23S rRNA from other members of the gamma division of Proteobacteria . The sequence of the intergenic spacer region, between the 16S and 23S rRNA genes, was determined in a further two clones . In one the sequence of a single tRNA(Glu) was found which was absent from the other two . This variation in sequence suggests that the different clones may be derived from different ribosomal RNA operons.

Nature, 1992 Jul 9, 358(6382), 167 - 9
Shigella flexneri induces apoptosis in infected macrophages; Zychlinsky A et al.; The Gram-negative bacterial pathogen Shigella flexneri causes dysentery by invading the human colonic mucosa . Bacteria are phagocytosed by enterocytes, escape from the phagosome into the cytoplasm and spread to adjacent cells . After crossing the epithelium, Shigella reaches the lamina propria of intestinal villi, the first line of defence . This tissue is densely populated with phagocytes that are killed in great numbers, resulting in abscesses . The genes required for cell invasion and macrophage killing are located on a 220-kilobase plasmid . We report here on the mechanism of cytotoxicity used by S . flexneri to kill macrophages . Each of four different strains was tested for its capacity to induce cell death . An invasive strain induced programmed cell death (apoptosis), whereas its non-invasive, plasmidcured isogenic strain was not toxic; neither was a mutant in ipa B (ref . 10) (invasion protein antigen), a gene necessary for entry . A non-invasive strain expressing the haemolysin operon of Escherichia coli induced accidental cell death (necrosis), demonstrating that other bacterial cytotoxic mechanisms do not lead to apoptosis . This is the first evidence that an invasive bacterial pathogen can induce suicide in its host cells.

J Clin Microbiol, 1992 Jul, 30(7), 1636 - 41
Antibodies to shiga holotoxin and to two synthetic peptides of the B subunit in sera of patients with Shigella dysenteriae 1 dysentery; Levine MM et al.; Acute- and convalescent-phase sera from 18 Thai patients and convalescent-phase sera from two Israeli patients and one Bangladeshi patient with Shigella dysenteriae 1 (Shiga) dysentery were tested by enzyme-linked immunosorbent assay to detect antibodies that bind S . dysenteriae lipopolysaccharide (LPS), Shiga holotoxin, or two synthetic peptides representing epitopes from the B subunit of Shiga toxin . Paired sera from 24 Maryland adults with Shigella flexneri 2a or Shigella sonnei diarrhea served as negative controls . Of the 16 paired Thai serum samples tested for immunoglobulin G LPS antibody, 10 had greater than or equal to 4-fold rises (the two subjects with the highest convalescent-phase titers exhibited toxin-neutralizing activity); acute-phase specimens from four of the remaining six individuals already had elevated Shiga LPS titers in their acute specimens ranging from 1:800 to 1:12,800 . Similarly, convalescent-phase sera from the two Israeli patients and the Bangladeshi patient revealed LPS titers of 1:800 to 1:3,200 . In contrast, none of the Maryland volunteers with S . flexneri or S . sonnei diarrhea manifested rises in Shiga anti-LPS (P less than 0.00001 versus 10 of 16 Thai patients) . Only 4 of the 18 Thai patients had significant rise in antibody to purified Shiga toxin, while one of the two Israeli patients and the one Bangladeshi patient had elevated convalescent-phase titers . None of the sera that reacted with Shiga holotoxin had antibody that bound to the peptides . This report, which describes a search for serum antibodies that bind Shiga toxin in patients with Shiga dysentery, demonstrates such antibodies in only a minority of patients with bacteriologically confirmed disease . During Shiga dysentery, Shiga toxin may be elaborated in such small quantities in vivo that it fails to elicit an immune response in most patients even though it may exert biological effects . In this behavior Shiga toxin resembles tetanus toxin, another potent exotoxin that fails to elicit antitoxic responses in people who recover from clinical tetanus.

J Infect Dis, 1992 Jul, 166(1), 158 - 61
Age-specific prevalence of serum antibodies to the invasion plasmid and lipopolysaccharide antigens of Shigella species in Chilean and North American populations; Van de Verg LL et al.; Shigella species have virulence plasmids that encode outer membrane proteins (invasion plasmid antigens, Ipa) associated with pathogenicity . Western blots were used to detect antibodies to Ipa in sera from 390 Chilean children, and these responses were compared with those of a US population of infants and adults . Antibodies to lipopolysaccharide (LPS) of Plesiomonas shigelloides and Shigella flexneri 2a were measured by ELISA . Among the Chileans, there was an age-related acquisition of Ipa antibodies, with 28% of 1-year-olds and 100% of children greater than or equal to 10 years showing positive responses . In contrast, none of the US infants and only 38% of the adults had antibodies to Ipa . Levels of LPS antibodies were also found to increase in an age-related manner among the Chileans . These results corroborate findings of previous epidemiologic studies which show that Shigella infections are endemic in Chile, as in other developing countries . The measurement of Ipa and LPS antibodies is a useful seroepidemiologic tool for investigating previous exposure to Shigella species in populations.

Kansenshogaku Zasshi, 1992 Jul, 66(7), 930 - 4
{Shigella dysenteriae strains having a provisional serovar isolated from imported diarrheal cases in Tokyo}; Matsushita S et al.; Two bacterial strains (ME448 and ME474) isolated from stool cultures of imported cases in Tokyo in 1987 had typical biochemical characteristics of Shigella dysenteriae . The results of antigenic analyses showed that they were serologically identical to each other, but did not belong to any of the established Shigella serovars . These strains were positive for Sereny test in guinea pig eye and cell-invasion test in HeLa cells . The strains also had virulence-plasmid encoding outer membrane proteins, indicating that they were pathogenic . We then contacted the Centers for Disease Control in the United States and the Central Public Health Laboratory in the United Kingdom and arranged serological examinations of the strain ME448 . From the results, the strain was confirmed to have provisional S . dysenteriae serovar E23507 . Although the serovar had been isolated from a Swedish patient who developed diarrhea while in India, this is thought to be the first report of its isolation in Japan.

Eur J Pediatr, 1992 Jul, 151(7), 499 - 501
Plesiomonas shigelloides sepsis and meningoencephalitis in a neonate; Terpeluk C et al.; A newborn infant is described who presented with septicaemia and meningoencephalitis caused by Plesiomonas shigelloides, a Gram-negative rod belonging to the family Vibrionaceae . The patient in this case, the first to be documented in Europe, developed multilocular lysis of the brain despite immediate treatment with antibiotics active in vitro . A cranial CT revealed garland-like calcifications and a large amount of medullary necrosis was seen on MRI.

Roum Arch Microbiol Immunol, 1992 Jul-Sep, 51(3), 183 - 91
Study of strains agglutinable with enteroinvasive anti E . coli polyvalent sera isolated from ill and healthy subjects for optimizing the laboratory diagnosis of diarrhoea; Tonciu M et al.; 369 E . coli strains that are agglutinated in A or B anti E . coli enteroinvasive (EIEC) polyvalent sera and inducing no keratoconjunctivitis in the guinea pig's eye have been selected . The biochemical reactions of E . coli strains that can be agglutinated in A or B EIEC polyvalent sera occupy an intermediary position between those of Shigella genus and the classical features of Escherichia, i.e.; 87% are motile bacteria, 88%--ferment lactose, 81% form acid from sodium mucate and lysine is not decarboxylated by 87% of the strains . As for the antigenic behaviour with 15 out of the 16 sera employed, the strains under consideration have agglutinated by slide test in one or several sera, with varying intensities . None of the strains agglutinated on slide in the O164 antiserum . Subsequently, agglutinations have been performed in tubes only with the strains that agglutinated on the slide with a +3 or +4 intensity . Out of the 369 strains under consideration only 25 have agglutinated in the tube, all the false positive reactions representing 6.7% . The data presented lead to the conclusion that such strains that have been isolated from ill or healthy patients cannot be considered as pathogenic diarrhoea agents, the differentiation from the invasive strains (in the absence of the guinea pig for the pathogenicity test) cannot be made on the basis of the biochemical reactions, but only by means of a set of monovalent sera and by performing the tube agglutination tests.(ABSTRACT TRUNCATED AT 250 WORDS)

MMWR Morb Mortal Wkly Rep, 1992 Jun 26, 41(25), 440 - 2
Shigellosis in child day care centers--Lexington-Fayette County, Kentucky, 1991; AIDA-I et al.; Zentrum fur Molekulare Biologie Heidelberg (ZMBH), GermanyThe adherence mechanisms of enteropathogenic Escherichia coli (EPEC) to epithelial cells are still not understood . To study the molecular basis of the diffuse adherence (DA) phenotype exhibited by diarrhoeagenic E . coli expressing classical EPEC serotypes we investigated strain 2787 (O126:H27) isolated from a case of infantile diarrhoea . A 6.0 kb plasmid-derived DNA fragment mediates the DA phenotype and encodes the 100 kDa adhesin protein AIDA-I (adhesin involved in diffuse adherence) . Sequencing of the entire fragment revealed two open reading frames which encoded proteins of 45 kDa and 132 kDa, respectively . The 132 kDa protein has been identified as an AIDA-I precursor protein . After cleavage of the signal sequence further processing at the C-terminus of the 132 kDa precursor leads to the mature approximately 100 kDa AIDA-I . While the exact function of the cytoplasmic 45 kDa protein is not known, preliminary evidence indicates that it is necessary for the correct maturation of AIDA-I . The AIDA-I precursor exhibits significant homology with the virG(icsA) protein of Shigella flexneri which seems to be involved in the intercellular spread of invasive Shigella organisms.

J Clin Microbiol, 1992 Jun, 30(6), 1428 - 31
Molecular epidemiology of trimethoprim-resistant Shigella boydii serotype 2 strains from Bulgaria; Bratoeva MP et al.; In 1990 an increased number of strains of Shigella boydii serotype 2 were isolated from different regions of Bulgaria . Strains were reported as sporadic, although they showed identical phenotypic characteristics, including resistance to ampicillin, carbenicillin, streptomycin, sulfonamide, tetracycline, ticarcillin, and trimethoprim . The objective of this study was to determine the genetic relatedness of the strains and the mechanism of their antimicrobial resistance . Plasmid fingerprinting showed an identical pattern for 23 of 25 of the selected strains . All 25 strains tested transferred their resistances en bloc to an Escherichia coli recipient . Transconjugants contained a 112-kb R plasmid which carried all the resistance genes, including that conferring type I dihydrofolate reductase-mediated trimethoprim resistance (MIC greater than 2,000 micrograms/ml) . Riboprobe analysis showed identical restriction length fragment polymorphisms, suggesting a highly conserved genome . All findings indicate that strains of S . boydii serotype 2 isolated in 1990 from different regions of Bulgaria were highly related genetically and can be considered representatives of a single bacterial clone . The presence of an R plasmid and selection pressure because of the usage of antimicrobial agents, particularly trimethoprim, have likely facilitated the spread of the clone throughout the country.

J Med Microbiol, 1992 Jun, 36(6), 403 - 5
Adhesion of Shigella dysenteriae type 1 and Shigella flexneri to guinea-pig colonic epithelial cells in vitro; Guhathakurta B et al.; Adhesion of bacteria to guinea-pig colonic epithelial cells in vitro was inhibited by fucose with all the four strains tested (two of Shigella dysenteriae type 1 and two of S . flexneri) . N-acetyl neuraminic acid and N-acetyl mannosamine also caused inhibition, suggesting a multiplicity of receptors on the epithelial cell . Congo-red binding of the strains correlated with their adhesive ability, whereas haemagglutination of rabbit erythrocytes by the bacteria did not.

Pediatrics, 1992 Jun, 89(6 Pt 2), 1189 - 93
Lethal toxic encephalopathy due to childhood shigellosis in a developed country; Goren A et al.; Shigellosis results in considerable morbidity in endemic areas, but mortality is rare in developed countries . All pediatric deaths (n = 15) in Israel following shigellosis in the past 10 years were reviewed . The patients' ages ranged from 5 months to 11 years; there were eight boys and seven girls . Three were institutionalized mentally retarded patients, 11 were healthy children . Twelve had definite clinical signs of brain death within 48 hours of onset of disease . Cause of death in all patients was consistent with toxic encephalopathy . No other systemic complication was implicated as the cause of death except for one case consistent with a "Reye-like" syndrome . Shigella species were as follows: 8 flexneri, 4 sonnei, 1 dysenteriae, and 2 were not identified . Case-control study of these patients vs surviving, hospitalized patients with shigellosis showed similar severity of fever, diarrhea, vomiting, and dehydration and similar incidence of convulsions . Headache was a prominent feature of patients who died; 5 of 7 verbal patients complained of this symptom as opposed to 2 of 20 in the control group (P less than .01) . There were no significant differences in the hematological and biochemical profile (except for an increased incidence of hyponatremia in the study group), pattern of shigella species, or antibiotic sensitivity . These findings indicate that mortality from shigellosis in a developed country is due primarily to the toxic encephalopathy syndrome.

Infect Immun, 1992 Jun, 60(6), 2229 - 36
Novel invasion determinant of enteropathogenic Escherichia coli plasmid pLV501 encodes the ability to invade intestinal epithelial cells and HEp-2 cells; Fletcher JN et al.; An Escherichia coli K-12 transformant carrying 96.5-kb plasmid pLV501 from enteropathogenic E . coli (EPEC) strain K798 is able to produce the same characteristic attaching-effacing lesions in a rabbit ileal biopsy explant model as its parent strain . Cloned EcoRI-SalI DNA restriction fragments from this plasmid failed to reproduce the attaching-effacing lesions, but one recombinant plasmid, pLV527, containing 4.5 kb of pLV501 DNA, conferred on E . coli DH1 transformants the ability to invade enterocytes in the rabbit explant model . DH1(pLV527) was also able to adhere to and invade HEp-2 cells . The relative invasive ability of DH1(pLV527) was quantified by recovery of internalized bacteria following gentamicin treatment of infected HEp-2 monolayers . DH1(pLV527) was 1,000-fold more invasive than DH1 carrying pBR322 or a recombinant plasmid which had no physiological effect on ileal biopsy explants but was less invasive than an enteroinvasive E . coli strain or a transformant carrying the cloned invasion genes of Shigella flexneri . Invasion by DH1(pLV501) could also be detected but occurred at a level 30 times lower than that by DH1(pLV527) . Colony-hybridization of the pLV527 insert against a panel of 49 EPEC and related strains revealed that only 11 contained pLV527-hybridizing sequences; thus, the invasion determinant is not an essential component of the attachment-effacement pathogenic mechanism . One pLV527-hybridizing strain displayed both attachment-effacement and invasiveness in the rabbit ileal biopsy explant model . No significant hybridization was observed to non-EPEC invasive pathogenic enteric bacteria, indicating that the invasion determinant encoded on pLV527 is distinct from those used by these organisms.

Infect Immun, 1992 Jun, 60(6), 2218 - 24
Safety, immunogenicity, and efficacy in monkeys and humans of invasive Escherichia coli K-12 hybrid vaccine candidates expressing Shigella flexneri 2a somatic antigen; Kotloff KL et al.; A live, oral Shigella vaccine, constructed by transfer of the 140-MDa invasiveness plasmid from Shigella flexneri 5 and the chromosomal genes encoding the group- and type-specific O antigen of S . flexneri 2a to Escherichia coli K-12, was tested in humans . Designated EcSf2a-1, this vaccine produced adverse reactions (fever, diarrhea, or dysentery) in 4 (31%) of 13 subjects who ingested a single dose of 1.0 x 10(9) CFU, while at better-tolerated doses (5.0 x 10(6) to 5.0 x 10(7) CFU), it provided no significant protection against challenge with S . flexneri 2a . A further-attenuated aroD mutant derivative, EcSf2a-2, was then tested . Rhesus monkeys that received EcSf2a-2 in three oral doses of ca . 1.5 x 10(11) CFU experienced no increase in gastrointestinal symptoms compared with a control group that received an E . coli K-12 placebo . Compared with controls, the vaccinated monkeys were protected against shigellosis after challenge with S . flexneri 2a (60% efficacy; P = 0.001) . In humans, EcSf2a-2 was well tolerated at inocula ranging from 5.0 x 10(6) to 2.1 x 10(9) CFU . However, after a single dose of 2.5 x 10(9) CFU, 4 (17%) of 23 subjects experienced adverse reactions, including fever (3 subjects) and diarrhea (209 ml) (1 subject), and after a single dose of 1.8 x 10(10) CFU, 2 of 4 subjects developed dysentery . Recipients of three doses of 1.2 to 2.5 x 10(9) CFU had significant rises in serum antibody to lipopolysaccharide (61%) and invasiveness plasmid antigens (44%) and in gut-derived immunoglobulin A antibody-secreting cells specific for lipopolysaccharide (100%) and invasiveness plasmid antigens (60%) . Despite its immunogenicity, the vaccine conferred only 36% protection against illness (fever, diarrhea, or dysentery) induced by experimental challenge (P = 0.17) . These findings illustrate the use of an epithelial cell-invasive E . coli strain as a carrier for Shigella antigens . Future studies must explore dosing regimens that might optimize the protective effects of the vaccine while eliminating adverse clinical reactions.

Mol Microbiol, 1992 Jun, 6(12), 1605 - 16
icsB: a Shigella flexneri virulence gene necessary for the lysis of protrusions during intercellular spread; Allaoui A et al.; Shigella flexneri causes bacillary dysentery by invading epithelial cells of the colonic mucosa . We have characterized the icsB gene which is located on the virulence plasmid pWR100 . After inactivation of icsB, the mutant strain remained invasive, but formed abnormally small plaques on HeLa cell monolayers, colonized only the peripheral cells of Caco-2 islets, and was unable to provoke a keratoconjunctivitis in guinea-pigs . Examination of infected HeLa cells showed that the icsB mutant was able to lyse the phagocytic vacuole and to form protrusions at the surface of infected cells, but, unlike the wild type, remained trapped in protrusions surrounded by two membranes . These results indicate that IcsB is involved in the lysis of the protrusions, a step necessary for intercellular spread.

Microb Pathog, 1992 Jun, 12(6), 399 - 407
Induction of a humoral immune response to a Shiga toxin B subunit epitope expressed as a chimeric LamB protein in a Shigella flexneri live vaccine strain; Ryd M et al.; Shigella flexneri vaccine strain (SFL124) given orally, evokes humoral immune response in human volunteers . Such a strain, expressing antigenic epitope of B subunit of Shiga toxin, would also provide immunity to the toxin produced by some species of Shigella . A synthetic oligonucleotide, specifying an epitope {13-26 amino acids (aa)} of the B subunit of Shiga toxin, was inserted into the lamB gene of Escherichia coli and expressed in the S . flexneri vaccine strain . The chimeric LamB protein functioned normally and the epitope was expressed at the surface of the bacteria . The animals immunized with the live bacteria, expressing the epitope or sonicated lysates, showed a humoral response that was specific to the peptide (13-26 aa) and to the whole B subunit molecule . The elicited antisera neutralized the toxin activity on HeLa cells up to 40%, while the purified IgG fractions from the sera gave 90% neutralization.

Int J Epidemiol, 1992 Jun, 21(3), 594 - 8
Molecular probe analysis of Shigella dysenteriae type 1 isolates from 1940 to 1987; Blaser MJ et al.; Fourteen strains of Shigella dysenteriae type 1 (Shiga bacillus) isolated from people in diverse locations from 1940 to 1987 were studied . Southern hybridization with three cloned Escherichia coli genes, Shiga-like toxin I (SLTI), frd, and ompF, was used to determine restriction fragment length polymorphism (RFLP) of the genomic DNA of these strains . Digestion with each of four restriction endonucleases generated fragments of identical size to which the frd and ompF hybridized for each of the 14 strains, indicating the conservation of these genes and their flanking sequences . In contrast, after digestion with HindIII, EcoRV, and ClaI and probing with SLTI, there were RFLP among the strains . The results showed three clones of the Shiga bacillus, and suggested that dissemination of a single clone may continue for decades within a wide geographical area.

Lab Anim Sci, 1992 Jun, 42(3), 240 - 4
Enrofloxacin treatment of long-tailed macaques with acute bacillary dysentery due to multiresistant Shigella flexneri IV; Line AS et al.; Thirty-four cases of acute bacillary dysentery occurred within 90 days among macaques housed at the California Regional Primate Research Center . Cases were identified by depression, diarrhea with blood and leukocytic exudate, and/or leukocytosis with a left shift . Antimicrobial susceptibility testing of enteric isolates and plasmid profile analyses established an etiologic diagnosis of multiple antibiotic resistant Shigella flexneri IV infection . When standard therapies were invalidated by high frequencies of resistance among the isolates, therapy with enrofloxacin, a fluoroquinolone antimicrobial, was initiated to interrupt the epidemic . Serum concentrations of enrofloxacin and its primary metabolite ciprofloxacin were measured in selected cases . A serum concentration-time data analysis was performed to evaluate the oral enrofloxacin dose and dosing interval for nonfasted macaques . Once daily administration of 5 mg/kg enrofloxacin by gastric intubation produced 24-hour serum concentrations above the MICs for the Shigella isolates from this outbreak.

Carbohydr Res, 1992 May 14, 229(1), 103 - 16
Stereoselective syntheses of a di-, tri-, and tetra-saccharide fragment of Shigella dysenteriae type 1 O-antigen using 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride as a glycosyl donor; Pavliak V et al.; Methyl 2,4-di-O-benzoyl-alpha-L-rhamnopyranoside (1) furnished a crystalline 3-O-bromoacetyl derivative that was treated with the dichloromethyl methyl ether-ZnCl2 reagent to give 2,4-di-O-benzoyl-3-O-bromoacetyl-alpha-L-rhamnopyranosyl chloride (3) . Compounds 1 and 3 were condensed under the conditions of base-deficient, silver trifluoromethanesulfonate-mediated glycosylation to give a fully protected rhamnobioside, which on O-debromoacetylation afforded the disaccharide nucleophile 10 . Similar condensation of 3 with methyl 3-O-benzoyl-4,6-O-benzylidene-alpha-D-galactopyranoside, followed by O-debromoacetylation and condensation of the thus formed methyl O-(2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl)-(1----2)-4,6-O-benzylidene- 3-O-benzoyl-alpha-D-galactopyranoside again with 3, gave the trisaccharide glycoside . Subsequent O-debromoacetylation gave 17, having only HO-3(3) unsubstituted . Silver perchlorate-mediated glycosylations of 1, 10, and 17 with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride afforded, with high alpha stereoselectivity, protected di-, tri-, and tetra-saccharide glycosides . Subsequent hydrogenation, followed by N-acetylation and O-deacylation, afforded three oligosaccharide glycosides having nonreducing terminal 2-acetamido-2-deoxy-alpha-D-glucopyranosyl residues and comprising successively larger portions of the repeating unit of Shigella dysenteriae type 1 O-antigen.

FEMS Microbiol Lett, 1992 May 1, 71(3), 217 - 21
Virulence phenotypes of Shigella flexneri 2a avirulent mutant 24570 can be complemented by the plasmid-coded positive regulator virF gene; Qi MS et al.; Avirulent mutation of an opaque colony variant of Shigella flexneri 2a designated 24570 has been believed to be linked with the glpK locus of the chromosome . However, avirulent phenotypes of the 24570 strain could be complemented by the invasion plasmid-coded virF gene, a positive regulator for invasion genes . The 24570 strain had a DNA structural alteration upstream of the virF gene.

Diagn Microbiol Infect Dis, 1992 May-Jun, 15(4), 359 - 61
Fluorescent antibody staining test for rapid diagnosis of Shigella dysenteriae 1 infection; Albert MJ et al.; An indirect fluorescent antibody test for rapid detection of Shigella dysenteriae 1 in diarrheal stools was developed . A diagnosis could be made within 90 min of submission of specimens to the laboratory . On comparison with culture results, the test had a sensitivity of 92%, a specificity of 93%, and positive and negative predictive values of 94% and 92%, respectively.

Clin Infect Dis, 1992 May, 14(5), 1055 - 60
Antimicrobial resistance of Shigella isolates in Bangladesh, 1983-1990: increasing frequency of strains multiply resistant to ampicillin, trimethoprim-sulfamethoxazole, and nalidixic acid; Bennish ML et al.; The susceptibility to ampicillin and trimethoprim-sulfamethoxazole (TMP-SMZ) was determined for 15,824 isolates of Shigella obtained from patients attending a treatment center in Dhaka, Bangladesh, from 1983 through 1990 and for 520 isolates obtained during community surveys from 1988 through 1990 . Susceptibility to nalidixic acid was determined for isolates obtained after 1985 . In 1983 13% of isolates were resistant to ampicillin, 23.5% to TMP-SMZ, and 0.8% to both drugs . By 1990 51.2% of isolates obtained at the Diarrhea Treatment Centre were resistant to ampicillin, 47.7% to TMP-SMZ, and 40.5% to both drugs (for comparison with figures for 1983, P less than .001) . Resistance to nalidixic acid increased from 0.8% in 1986 to 20.2% in 1990 (P less than .001) . In 1990 71.5% of Shigella dysenteriae type 1 isolates were resistant to ampicillin, 68.5% to TMP-SMZ, 67.7% to both drugs, and 57.9% to nalidixic acid . The resistance pattern of isolates obtained during community surveillance was similar to that of Treatment Centre isolates . In Bangladesh ampicillin and TMP-SMZ are no longer useful for treatment of infection with any species of Shigella, and nalidixic acid is no longer useful for treatment of infections due to S . dysenteriae type 1.

J Clin Microbiol, 1992 May, 30(5), 1341 - 3
Characterization of Aeromonas caviae antigens which cross-react with Shigella boydii 5; Albert MJ et al.; Live and boiled cells of 16 strains of Aeromonas caviae, isolated from patients with diarrhea, agglutinated with Shigella boydii 5 antiserum in a slide test . Further studies with seven selected strains showed agglutination with boiled cells in a tube test . Lipopolysaccharide antigen extracted from one of these strains cross-reacted with S . boydii 5 in enzyme-linked immunosorbent assay and immunoblot studies . Either all or the majority of the seven strains possessed properties deemed to be diarrheagenic.

EMBO J, 1992 May, 11(5), 1991 - 9
IpaB of Shigella flexneri causes entry into epithelial cells and escape from the phagocytic vacuole; High N et al.; By creating mutations within the Shigella flexneri ipaB gene, we have demonstrated that the invasion of epithelial cells is a three-step process encompassing adhesion on the cell surface, entry and lysis of the phagocytic vacuole allowing subsequent access to the cytoplasm . SC403, an insertion mutant which lacks expression of IpaB but still expresses downstream genes, has been particularly studied . It is non-invasive, does not elicit actin polymerization, but binds to HeLa cells indicating that an adhesion step occurs immediately prior to the entry process . The consequence of the inactivation of ipaB on the intracellular behaviour of S.flexneri was investigated using the macrophage cell line J774 . SC403 was unable to lyse the phagocytic vacuole; moreover, this strain did not display the contact mediated haemolytic activity characteristics of Shigella . In addition to being a major component of the invasion complex, IpaB acts as a membrane-lysing toxin enabling escape to the cytoplasmic compartment.

Indian J Med Res, 1992 May, 95, 112 - 4
Immunoblot analysis of antibody responses to Shigella dysenteriae type 1 infection; Sinha AK et al.; Immunoblot analysis was used to identify the antigenic components of the outer membrane protein (OMP) extract from Sh . dysenteriae type 1 that may be relevant in protection against infection . The OMPs were extracted by ultrasonic disruption followed by Sarkosyl extraction . The macromolecular bands were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), electroeluted to a nitrocellulose matrix and complexed with peroxidase conjugated antibodies in human convalescent sera . IgG specific reaction was found to a major antigenic component at 57 kilodaltons . In addition, weakly reactive three antigenic determinants of greater than 57 kD and four of less than 57 kD were found . Control sera from a rabbit immunized against OMP also exhibited a similar pattern of antigenic reactivity . Some of the OMPs with high antigenicity may be important in immunoprophylaxis.

Infect Immun, 1992 May, 60(5), 1919 - 26
Identification and characterization of B-cell epitopes of IpaC, an invasion-associated protein of Shigella flexneri; Phalipon A et al.; Invasion plasmid antigen C (IpaC) is a 43-kDa plasmid-encoded protein associated with the ability of shigellae to invade epithelial cells . This protein is consistently strongly recognized by sera from convalescent patients and monkeys experimentally infected with shigellae . The strong immunogenicity of IpaC in the course of natural infection makes it a good candidate as a potentially protective antigen . To map the B-cell epitopes of this protein, the gene encoding IpaC was cloned and expressed at a high level in Escherichia coli . The partially purified recombinant protein was used to raise rabbit polyclonal antisera and murine monoclonal antibodies . A lambda gt11 ipaC gene library was screened with the antisera and antibodies . Recombinant DNA clones producing specific antigenic determinants were isolated, and the sequence of their DNA inserts was determined . The amino acid sequence of each determinant was deduced from the minimal overlap of DNA inserts of multiple antibody-positive DNA clones . Two distinct epitopes, located between amino acid residues 25 and 33 and 90 and 97, were identified . Two additional B-cell epitopes which were located between residues 297 and 349, near the carboxy-terminal end of the protein, were characterized . Each of these epitopes was also recognized by sera from convalescent humans and monkeys . Therefore, it seems likely that these epitopes are relevant to the humoral response against IpaC during natural infection.

Genetics, 1992 May, 131(1), 9 - 20
The evolution of insertion sequences within enteric bacteria; Lawrence JG et al.; To identify mechanisms that influence the evolution of bacterial transposons, DNA sequence variation was evaluated among homologs of insertion sequences IS1, IS3 and IS30 from natural strains of Escherichia coli and related enteric bacteria . The nucleotide sequences within each class of IS were highly conserved among E . coli strains, over 99.7% similar to a consensus sequence . When compared to the range of nucleotide divergence among chromosomal genes, these data indicate high turnover and rapid movement of the transposons among clonal lineages of E . coli . In addition, length polymorphism among IS appears to be far less frequent than in eukaryotic transposons, indicating that nonfunctional elements comprise a smaller fraction of bacterial transposon populations than found in eukaryotes . IS present in other species of enteric bacteria are substantially divergent from E . coli elements, indicating that IS are mobilized among bacterial species at a reduced rate . However, homologs of IS1 and IS3 from diverse species provide evidence that recombination events and horizontal transfer of IS among species have both played major roles in the evolution of these elements . IS3 elements from E . coli and Shigella show multiple, nested, intragenic recombinations with a distantly related transposon, and IS1 homologs from diverse taxa reveal a mosaic structure indicative of multiple recombination and horizontal transfer events.

JAMA, 1992 Apr 8, 267(14), 1932 - 5
Oral aztreonam, a poorly absorbed yet effective therapy for bacterial diarrhea in US travelers to Mexico; DuPont HL et al.; OBJECTIVE--To evaluate a poorly absorbed antimicrobial with in vitro activity against all major bacterial enteropathogens in oral therapy for bacterial diarrhea . DESIGN--One hundred ninety-one US students with diarrhea acquired in Mexico received 100 mg of aztreonam or matching placebo three times a day for 5 days . Stools were cultured for bacterial enteropathogens before and after therapy . SETTING--We studied US students who acquired diarrhea in Mexico (travelers' diarrhea) in view of the high frequency of bacterial agents in this setting . MAIN OUTCOME MEASURE--We examined time of clinical recovery, treatment failures, adverse experiences, and microbiologic eradication from stool of the etiologic agent in subjects randomized to receive aztreonam or placebo . RESULTS--Aztreonam reduced the average duration of diarrhea compared with the placebo: for all cases, by 40 hours (P much less than .01); for those with enterotoxigenic Escherichia coli diarrhea, by 50 hours (P less than .01); for those with shigellosis, by 90 hours (P, not significant {small sample size}); for all bacterial agents, by 57 hours (P much less than .01) . Clinical failures during the 5 days of therapy were seen in six patients (6%) receiving aztreonam and 25 (27%) receiving placebo (P less than .01) . Pathogen eradication occurred in 95% of those receiving aztreonam and in 70% of those receiving the placebo (P less than .01) . All bacterial enteropathogens were susceptible in vitro to aztreonam . The drug was well tolerated . CONCLUSIONS--Oral aztreonam, which is poorly absorbed, was well tolerated and was an effective therapy for bacterial diarrhea in US adults in Mexico.

Kansenshogaku Zasshi, 1992 Apr, 66(4), 503 - 7
{Shigella flexneri strains having a new type antigen}; Matsushita S et al.; Five Shigella strains isolated from stool cultures of two domestic dysentery cases and three imported cases in Tokyo in 1986-1989 had an atypial serotype that agglutinated with only antiserum to S . flexneri group 6 factor antigen . These strains showed typical biochemical reactions of S . flexneri and were biochemically identical . Four of the strains were positive for Sereny test with guinea pig eye and the cell-invasion test with HeLa cells . The strains also had the virulence-plasmid encoding outer membrane proteins, indicating that these were pathogenic . These strains were serologically identical and gave significant cross-reactions with S . flexneri 1b and 4b that had group 6 factor antigen . However, results of reciprocal absorption tests showed that the O antigen of these strains were not identical to S . flexneri 1b and 4b, and were confirmed to have a new type antigen which can not be included among the known S . flexneri type antigen I-VI . Strain 88-893 is designated as the test strain for this new type antigen of S . flexneri.

Kansenshogaku Zasshi, 1992 Apr, 66(4), 456 - 64
{Rapid differentiation method for Shigella and Escherichia coli--application of Indole (tryptophanase), PGUA (beta-glucuronidase) and ONPG (beta-galactosidase) tests}; Omura K et al.; For the differentiation of Shigella from Escherichia coli, Indole (tryptophanase), PGUA (beta-glucuronidase) and ONPG (beta-galactosidase) tests were used . A total of 377 Shigella and 124 E . coli strains was examined for each sero- and biosero-type by using these tests . The results were as follows . 1) There were no Shigella strains showing positive reactions for both Indole and ONPG tests . 2) No E . coli strains with Shigella-like characteristics (negative for lysine-decarboxylase, motility and lactose-fermentation tests) showed negative results for both Indole and PGUA tests . 3) The abovementioned strains were classified into twelve types according to the results of these tests . Shigella strains, thus, were differentiated from antigenically Shigella-like E . coli strains . Additional use of these tests together with the conventional methods may valuable for the identification of Shigella strains.

Infect Immun, 1992 Apr, 60(4), 1536 - 43
Shiga toxin-associated hemolytic uremic syndrome: combined cytotoxic effects of shiga toxin and lipopolysaccharide (endotoxin) on human vascular endothelial cells in vitro; Louise CB et al.; This study explores the in vitro relationship between Shiga toxin-producing Shigella spp . and Escherichia coli and the development of vascular complications in humans following bacillary dysentery . We propose that lipopolysaccharide (LPS; endotoxin) may combine with Shiga toxin to facilitate vascular damage characteristic of hemolytic uremic syndrome . We have examined the direct cytotoxic effects of Shiga toxin and LPS on human umbilical vein endothelial cells (HUVEC) in culture . Shiga toxin alone was cytotoxic to HUVEC, whereas LPS was noncytotoxic at concentrations at or below 10 micrograms/ml . Combinations of LPS with Shiga toxin resulted in a synergistic cytotoxic effect . The synergistic cytotoxic response of HUVEC to Shiga toxin plus LPS was dose dependent for both agents and was maximal at 24 h of exposure . This synergistic response was enhanced by preincubation of HUVEC with LPS . LPS (1 micrograms/ml) alone depressed HUVEC protein synthesis in a transient manner and enhanced the protein synthesis-inhibiting activity of Shiga toxin . The synergistic cytotoxic activity of LPS analogs was as follows, in decreasing order: complete LPS = diphosphoryl lipid A greater than monophosphoryl lipid A greater than deacylated LPS . These results are consistent with a role for Shiga toxin and LPS in the development of hemolytic uremic syndrome at the level of the vascular endothelium in humans.

Voen Med Zh, 1992 Apr-May, (4-5), 71 - 4
{The prevention of intestinal anthroponoses among military personnel}; Korol'kov VF et al.; In the 40th Army the hepatitis A and typhoid morbidity in enlisted personnel of the 1st year service period was 2.5 times higher than in enlisted personnel of the 2nd year service period . The greatest number of these sick cases took place in autumn and winter periods . The seasonal up-grade of shigellosis and acute intestinal infections of non-dysenteric etiology had its beginning in April-May and ended in November-January . Some garrisons had achieved a considerable efficiency in prophylaxis of hepatitis A by 2-3 ml immunoglobulin injections 2 months before the expected up-grade (morbidity reduction by 3-4 times) . The experience has shown that the struggle against intestinal anthroponoses had to be executed using a complex approach to its prophylaxis . This work must be done not only by physicians, but also by the representatives of the rear service.

Mol Cell Probes, 1992 Apr, 6(2), 153 - 61
Polymerase chain reaction for detection of verocytotoxigenic Escherichia coli isolated from animal and food sources; Read SC et al.; Animals and their by-products have been implicated as important sources of verocytotoxigenic Escherichia coli (VTEC) associated with disease in humans . VTEC comprise a wide range of serotypes and produce a variety of closely related verocytotoxins (VT) . A pair of oligonucleotide primers, targeting conserved sequences found in VT1, VT2 and VTE genes, was used to develop a polymerase chain reaction (PCR) procedure to detect all types of VTEC . Supernatants of boiled broth cultures of VTEC (223 strains) isolated from ground beef, ground pork, raw milk, bovine faeces and porcine faeces; non-VTEC E . coli (72 strains); and other enteric and food bacteria (76 strains) were tested by PCR . The verocytotoxigenicity of these strains was verified by the Vero cell assay . All 223 VTEC isolates, comprising over 50 different serotypes, were detected by the PCR procedure . Shigella dysenteriae type 1 was the only other bacterium that was positive in this assay . As little as 1 pg of VTEC DNA and as few as 17 cfu of VTEC could be detected with this method . The results indicate that these primers detect VTEC over a wide range of serotypes . This method may be applicable as a screening procedure for the detection of VTEC in samples of foods and faeces.

Indian Pediatr, 1992 Apr, 29(4), 461 - 5
Stool electrolytes in acute dehydrating gastroenteritis; Raizada N et al.; Stool electrolytes were studied in 100 cases of gastroenteritis . The duration of illness was 24-48 hours in 32% and 72-96 hours in 28% of the cases . On stool culture, 43% children had no growth, 23% had Enteropathogenic E . coli and 10% had cholera and rotavirus each . The stool sodium loss was more in cholera and shigella cases, diarrhea of shorter duration and in children between 24-30 months of age . Potassium loss in the stool was more in shiegella cases, diarrhea of short duration and in children between 30-36 months of age . In cases of gastroenteritis with severe malnutrition, stool sodium loss was less; stool potassium loss was not affected by the nutritional status . Total electrolytes lost in stools can be estimated by knowing purging rate and rehydration therapy can be planned accordingly.

Int J Epidemiol, 1992 Apr, 21(2), 381 - 6
The male predominance in the incidence of infectious diseases in children: a postulated explanation for disparities in the literature; Green MS; In children, a male predominance in the incidence of symptomatic disease has been reported for some infectious agents and not for others . Not only are the factors underlying these sex differences poorly understood, but it is also not clear why the differences are described only for selected infectious diseases . In this study of sex- and age-specific incidence of infectious diseases in children, a possible explanation for the inconsistencies in the literature was explored . The sex ratio in reported disease incidence in Israel during a period of about 20 years was examined for various viral and bacterial infections . In addition, an hypothetical mathematical model was developed which assumes increased susceptibility to infectious disease (such as in relative immune deficiency) in a proportion of males . In children aged under 4 years, a higher incidence among males was consistently observed for all diseases, and the sex ratio varied between 1.16 (95% confidence interval (CI): 1.13-1.18) for shigellosis to 1.98 (95% CI: 1.79-2.17) for viral meningitis . The highest ratios were associated with the diseases which tend to present asymptomatically most often, which is consistent with the predictions of the model . The male excess in symptomatic disease appears to be present for most infectious diseases and this should be taken into account in studies comparing observed disease incidence between groups with different sex ratios . The inconsistencies in reports on the excess male morbidity for infectious diseases may be due to variations in symptomatic to asymptomatic infection ratiosPIP: An explanation is provided for the male predominance in incidence of infectious diseases in children . A theoretical and mathematical model for predicting sex ratios for different prevalences of increased susceptibility to infectious disease in males is presented . The theoretical model states that males are more likely to experience symptomatic disease due to an increased prevalence of a factor such as immune deficiency . Variables are the proportion infected, the ratio of symptomatic (clinical) to asymptomatic (subclinical) infections, and the prevalence of males with increased susceptibility to infectious disease . Data included incidence of viral hepatitis, shigellosis and salmonellosis between 1966-85 and viral meningitis between 1971-85 by age and sex for Israeli Jews and nonJews . Other data for shorter time periods included poliomyelitis (1958-62), measles (1976-85), and diphtheria (1958-70) . Single years of age were used for those 0-4 years . In diseases where vaccination has reduced the case load, the male to female incidence ratio was estimated with incidence density computed for the whole time period . The results of the analysis showed that male incidence 5 years in all 3 bacterial and 4 viral diseases was higher . The incidence ratios showed an excess of 20-100% for infectious diseases . This consistent pattern is not apparent in the literature because sex differences may be difficult to detect among symptomatic diseases; i.e., measles . There is also a lower symptomatic to nonsymptomatic infection ratio and small sex incidence ratio for shigellosis, salmonellosis and viral hepatitis . Where the symptomatic to nonsymptomatic ratio is about 1:50 or 1:100, the male to female incidence ratio will be much higher at about 2:1 and more readily detected . The immunodeficiency prevalence among males as an explanation for the susceptibility of males for diseases was not supported by an excess frequency of 2-3% in overt symptoms, although it is still considered a viable hypothesis . It is suggested that the inconsistencies in reports on male predominance in infectious diseases may be an artifact of statistics showing variability in the proportion of symptomatic infectious diseases . The implications are that comparisons should be made between the sexes . The disease rates may be biased by different proportions of males in the study and placebo groups in vaccine testing . Sex differences and disease should be examined further .

Bangladesh Med Res Counc Bull, 1992 Apr, 18(1), 12 - 22
Studies on virulence determinants of Plesiomonas shigelloides; Amin II et al.; Virulence determinants of nineteen strains of Plesiomonas shigelloides isolated from stool samples of diarrhoeal children were studied . Heat-labile toxin was detected in seven strains using rat ileal loop model and in none of the strains using Chinese hamster ovary cell assay system and by Enzyme-linked immunosorbent assay . Rat ileal loop model was used for the first time to assay toxin in P . shigelloides and is suggested to be a cheap and effective method of detecting labile toxin in the organism . Heat stable toxin, cytotoxin, hemolysin and hemagglutinin were not detected in the strains tested . Invasiveness could not be established by using HEp-2 cell assay system . The results of this study provide some experimental support for an etiological role for P . shigelloides in the production of diarrhoea.

J Biol Regul Homeost Agents, 1992 Apr-Jun, 6(2), 35 - 45
Interferon treatment reduced adherence, invasiveness and intracellular multiplication of Shigella flexneri in coxsackie B1 virus-infected cells; Modalsli K et al.; The effect of interferon treatment on interaction of Shigella flexneri with in vitro cultured cells was investigated . Pretreatment of HEp-2 cells with human interferons had no effect on the susceptibility of cells to S . flexneri, measured by invasiveness and adhesiveness . Human leukocyte interferon and human recombinant interferon-alpha-A reduced adhesiveness, intracellular multiplication and invasiveness of S . flexneri in HEp-2 cells preinfected with coxsackie B1 virus . Also non-receptor mediated-phagocytosis was reduced by interferon treatment in virus infected cells . The interferon effects were dependent on continuous protein synthesis, because they were not expressed when cycloheximide or abrin was added to the virus infected cell cultures . No effect of interferon was detected on intracellular content of Na+ or K+, Na(+)-K+ activated ATPase activity or cytoplasma membrane polarity, in virus infected or control cell cultures . The interferon effect on bacterial invasiveness seems to be dependent on an interferon receptor interaction on cytoplasma membrane level because directly microinjected interferon showed no effect.

Pediatr Infect Dis J, 1992 Mar, 11(3), 215 - 9
Childhood shigellosis in Saudi Arabia; Kagalwalla AF et al.; In this study 234 children with shigellosis were evaluated during a 6-year period . The ages ranged from 2 days to 13 years (mean, 3.4 years) . Sixty percent of the children were in the 1- to 4-year age group . One hundred four children were hospitalized and 130 were outpatients . Most cases of shigellosis presented during the months of April-May and September-November . Shigella flexneri accounted for 44% and Shigella sonnei for 43% of the isolates . Susceptibility testing showed that 54% were resistant to ampicillin, 72% to trimethoprim-sulfamethoxazole and 77% to tetracycline . Eighty percent were resistant to two or more antimicrobial agents . Morbidity and mortality was higher in children who were initially treated with antimicrobials to which the organism was resistant than in those treated with antimicrobial agent to which the organism was susceptible.

Pediatr Infect Dis J, 1992 Mar, 11(3), 213 - 5
Shigellosis in Thai children: epidemiologic, clinical and laboratory features; Thisyakorn US et al.; Two hundred thirty cases of shigellosis in children managed at Chulalongkorn Hospital from 1984 to 1988 were reviewed . The most common presentation included diarrhea, most frequently with mucus and blood, and fever . There were no deaths . The most common species was Shigella flexneri (83.5%) which showed increasing resistance to trimethoprim-sulfamethoxazole.

Infect Immun, 1992 Mar, 60(3), 1163 - 9
Nucleotide sequence and transcriptional regulation of a positive regulatory gene of Shigella dysenteriae; Yao R et al.; A 1,937 bp PstI-HindIII fragment containing the ipaR locus was cloned from the large invasion plasmid of Shigella dysenteriae CG097, and its nucleotide sequence was completely determined . The IpaR protein (35 kDa, calculated from the DNA sequence) was synthesized in Escherichia coli chi 1411 minicells containing the 1,937-bp PstI-HindIII fragment . To determine the regulatory role of ipaR for ipa genes, we applied genetic complementation experiments using chloramphenicol acetyltransferase (CAT) as reporter . Analyses of CAT activity of the recombinant plasmids containing the 5' flanking sequences of the 24-kDa-protein gene and the ippI, ipaB, ipaC, and ipaD genes defined strong promoters upstream of the 24-kDa-protein gene and ipaD gene, weak promoters upstream of the ippI and ipaB genes, and the absence of any promoter activity for the ipaC gene . Complementation analyses showed that the CAT activity only under direction of the ippI promoter region increased 1.8-fold in the presence of IpaR protein . On the basis of our data, we suggest that an operon comprising ippI, ipaB, and ipaC is positively regulated by IpaR protein which has a trans effect on a DNA sequence upstream of the ippI promoter.

Infect Immun, 1992 Mar, 60(3), 1031 - 40
Movement along actin filaments of the perijunctional area and de novo polymerization of cellular actin are required for Shigella flexneri colonization of epithelial Caco-2 cell monolayers; Vasselon T et al.; Shigella flexneri invades eucaryotic cells and grows in the cytoplasm . Lysis of the phagosomal membrane is a prerequisite for both intracellular multiplication and movement of the bacteria that gain direct access to the host cell actin . In HeLa cells, bacteria generate their own movement essentially by inducing actin polymerization . Polymerization of actin enables them to move rapidly and randomly in the cytoplasm and to spread from one cell to another through protrusions of the host cell membrane . This movement was designated the Ics phenotype . In contrast, in chicken embryo fibroblasts, bacteria move along actin filaments in a very organized manner, following the cytoskeletal architecture; this movement was designated the Olm phenotype . Bacterial movement is a major virulence factor in that it is necessary for efficient colonization of the intestinal epithelium of infected macaque monkeys . Further characterization of the cellular events that lead to colonization of the colonic intestinal epithelium was needed . In order to characterize the movement in vitro in a cell assay system more closely related to the intestinal epithelium, we used human colonic epithelial Caco-2 cells . The movement of bacteria as observed by using immunofluorescence and confocal microscopy appeared to result from the expression of both the Olm and Ics phenotypes . The former allowed colonization of cells along the actin filament ring of the perijunctional area . The latter promoted passage from one cell to adjacent cells . This in vitro pattern of movement and multiplication gives S . flexneri, once it has entered an epithelial cell, the unique capacity to spread through the entire epithelial layer without having further contact with the extracellular compartment.

Zh Mikrobiol Epidemiol Immunobiol, 1992 Mar, (3), 44 - 6
{Etiological structure of dysentery in the republic of Armenia}; Agadzhanian SM; In this work materials on the etiological structure of Shigella infections at different territories of Armenia are presented . Four Shigella species have been found to circulate in Armenia . The dominating etiological agent is S . flexneri with S . sonnei also playing an important role . The serological picture of S . flexneri is characterized by the prevalence of subserovar 2a.

Immunol Lett, 1992 Mar, 32(1), 65 - 8
Gut mucosal lymphocyte subpopulations in the host-defence of Shigella infected guinea-pigs; Sinha AK et al.; Lymphocyte subpopulations from the gut mucosa were studied in Shigella-susceptible guinea-pigs to evaluate their role in mucosal immune responses to such organisms . Four weeks after infection, isolated lymphocytes were characterised by an immunofluorescent technique . The increase in the T cell intra-epithelial population was less (48%) in comparison to that in normal uninfected animals (74%) . On the other hand, Ig bearing B cells in the lamina propria showed an increased incidence and more than 15% of the total mucosal lymphocytes lacked any surface marker, which indicated that they were non-T and non-B cells . A significant rise in the intraepithelial T cell population (P less than 0.01) was observed 6 weeks after infection in comparison to that observed after 4 weeks.

Biull Eksp Biol Med, 1992 Mar, 113(3), 299 - 301
{Characteristics of lymphoid subpopulations of peripheral blood of patients with shigellosis}; Burmistrova AL et al.; This work presents some investigation results of lymphoid subpopulation functional activity: Tg+1, Tg-1, Theophylline-resistant and Theophylline-sensitive lymphocytes and O-1 isolated from the peripheral blood of patients with bacterial dysentery (BD) in local xenogenic GVHD . It has been established that Tg+1 and Tg-1 have stimulating effect on local xenogenic GVHD, but O-1 are inert though the quantity of Fcg+--receptor carrying lymphocytes among O-1 in BD and nonspecific ulcerative colitis is increased compared with donors . Theophylline-resistant and Theophylline-sensitive lymphocytes demonstrated inhibiting effect on GVHD formation which was evident in the latter case.

Hua Xi Yi Ke Da Xue Xue Bao, 1992 Mar, 23(1), 33 - 6
{Plasmid analysis and antibiotic resistance pattern measurement of Shigella in Chengdu}; Xu H et al.; A total of 81 strains of Shigella isolated from sporadic cases and cases in an outbreak of Shigella sonnei infection was analysed by plasmid profiles and antibiotic resistance patterns . The strains had a high resistance patterns . The strains had a high resistance of ampicillin, tetracycline, trimethoprim-sulfamethoxazole and chloramphenicol; while 97.2% of the strains were susceptible to gentamicin, kanamycin . The results showed that 50% of the strains harbored plasmid patterns within each species, which indicated that many genetically different strains of Shigella were responsible for dysentery epidemics in Chengdu . According to the results of the plasmid analysis and antibiotic resistance pattern measurement made in the outbreak strains, it was clearly seen that most of the strains were similar or fundamentally similar, which suggested that one or two strains with genetical homology were the main causative agent for the outbreak . We think that plasmid profiles and antibiotic resistance patterns are applicable to the identification of the outbreak strains of dysentery as an efficient epidemiologic tool.

APMIS, 1992 Mar, 100(3), 237 - 45
Correlation between Coxsackie B1 virus replication and enhanced invasiveness of Shigella flexneri; Modalsli K et al.; Coxsackie B1 virus infection enhances the susceptibility of cultured HEp-2 cells to Shigella flexneri invasiveness . This can be reproduced partially with UV-inactivated virus, particularly the effect observed shortly after viral inoculation . The following phases of viral multiplication were correlated with the enhancing effect: uncoating of viral particles, synthesis of viral RNA and proteins, and assembly of newly produced virus particles . Uncoating of virus particles was completed within 60 min . This process was not correlated with the development of the early effect on invasiveness . Intact virus capsids seem to be necessary to enhance bacterial invasiveness in the early phase of virus infection . Separated capsid proteins had no effect either when applied to the cell surface or when microinjected into the cells . Virus protein synthesis was not required for the virus effect on bacterial invasiveness in the early infection phase, but it seems to be necessary in the late phase.

Acta Virol, 1992 Mar, 36(2), 121 - 8
Effect of natural and synthetic immunomodulators on the synthesis of interferon by peritoneal cells of mice; Zaczynska E et al.; The effect of different natural and synthetic immunomodulators on the spontaneous interferon (IFN) synthesis by freshly isolated resident peritoneal cells of BALB/c, NZB and C3H mice was investigated . Actinomycetal glycolipids isolated from Curtobacterium betae, Faenia rectivirgula, Rothia dentocariosa and Saccharopolyspora hirsuta at the concentration 1-20 micrograms/ml were found to potentiate the IFN synthesis by the peritoneal cells of BALB/c mice . Similar results were obtained when dsRNA, LPS of Shigella sonnei and lipid A isolated from the LPS were used . The effect of potentiation of the physiological IFN production by the immunomodulators was observed also in the cells of C3H and NZB mice . In contrast, the inhibition of the IFN synthesis was observed when the peritoneal cells of BALB/c and NZB mice were treated with imuthiol at concentration 0.1-10 micrograms/ml . Thymomodulin (TFX-Polfa) at concentration of 1-100 micrograms/ml had no effect on the spontaneous IFN production.

Nature, 1992 Feb 20, 355(6362), 748 - 50
Crystal structure of the cell-binding B oligomer of verotoxin-1 from E . coli; Stein PE et al.; The Shiga toxin family, a group of cytotoxins associated with diarrhoeal diseases and the haemolytic uraemic syndrome, includes Shiga toxin from Shigella dysenteriae type 1 and verotoxins produced by enteropathogenic Escherichia coli . The family belongs to the A-B class of bacterial toxins, which includes the cholera toxin family, pertussis and diphtheria toxins . These toxins all have bipartite structures consisting of an enzymatic A subunit associated with a B oligomer which binds to specific cell-surface receptors, but their amino-acid sequences and pathogenic mechanisms differ . We have determined the crystal structure of the B oligomer of verotoxin-1 from E . coli . The structure unexpectedly resembles that of the B oligomer of the cholera toxin-like heat-labile enterotoxin from E . coli, despite the absence of detectable sequence similarity between these two proteins . This result implies a distant evolutionary relationship between the Shiga toxin and cholera toxin families . We suggest that the cell surface receptor-binding site lies in a cleft between adjacent subunits of the B pentamer, providing a potential target for drugs and vaccines to prevent toxin binding and effect.

J Bacteriol, 1992 Feb, 174(3), 947 - 52
The expression of virulence genes in Listeria monocytogenes is thermoregulated; Leimeister-Wachter M et al.; The expression of listeriolysin, a major virulence factor of the gram-positive facultative intracellular pathogen Listeria monocytogenes, is positively regulated by a transcriptional activator, the prfA gene product . We had previously shown that mutations within the prfA gene lead to loss of listeriolysin production . In this communication, the regulation of expression of listeriolysin by a specific environmental condition, namely, temperature, was studied in wild-type strains of Listeria monocytogenes . We found that expression of the hemolysis phenotype was thermoregulated . A lisA::lacZ fusion was constructed, and its expression in the wild-type strain was studied at various growth temperatures . The results showed that the fusion beta-galactosidase activity was expressed only when cultures were grown at temperatures above 30 degrees C . This activity could be either specifically repressed or induced, depending on growth temperature . No change in activity was detected in a strain harboring a control beta-galactosidase fusion at the various growth temperatures tested . Northern (RNA) blot analysis of lisA-specific RNA transcripts showed that thermoregulation is manifested at the level of transcription . We also found that the transcription of other PrfA-regulated virulence genes in L . monocytogenes was similarly affected by growth temperature . Hence, as in other facultative intracellular pathogens, Shigella and Yersinia spp., temperature is an important cue in the induction of expression of virulence genes in L . monocytogenes . Our studies revealed that a higher level of regulation is imposed on the PrfA-mediated activation of virulence genes in pathogenic L . monocytogenes.

Rozhl Chir, 1992 Feb, 71(2), 113 - 7
{Salmonellosis and shigellosis in the differential diagnosis of acute abdomen}; Duda J et al.; There are only very few reports in our literature on problems and pitfalls of the differential diagnosis and present incidence of acute abdominal salmonellosis and shigellosis . Based on evaluated results of a three-year investigation from their department the authors draw attention to the relatively frequent concurrent incidence of acute abdomen and infectious diarrhoeal disease, the difficulty of differential diagnosis and indication of surgery even when the results of cultivation examinations are known due to the common interlinked symptomatology and coincidence . The symptoms imitating acute abdomen in infectious diarrhoeal diseases predispose by concentration of infectious patients in surgical departments the development of nosocomial infections and epidemics.

Antibiot Khimioter, 1992 Feb, 37(2), 19 - 20
{Sensitivity of Shigella to antibiotics}; Garanin BA; Three hundred and twenty two Shigella cultures isolated from dysentery patients within 1986-1989 were tested with the use of standard paper disks for their sensitivity to levomycetin, streptomycin, tetracycline, monomycin, neomycin, kanamycin, erythromycin, gentamicin, carbenicillin, ampicillin, oxacillin, methicillin and doxycycline . The number of the cultures belonging to Shigella sonnei amounted to 85.1 per cent of the total number of the strains studied . 91.9, 89.5, 87.3, 87.3, 80.1 and 80.1 per cent of the cultures were sensitive to gentamicin, kanamycin, carbenicillin, neomycin, levomycetin and ampicillin, respectively . 99.4 per cent of the isolates were resistant to streptomycin and 97.2 per cent were resistant to tetracycline . The sensitivity to erythromycin remained rather high (70.2 per cent) . The overwhelming majority of the Shigella sonnei isolates had multiple resistance.

Zh Mikrobiol Epidemiol Immunobiol, 1992 Feb, (2), 15 - 8
{Lipopolysaccharide changes in smooth-type avirulent Shigella in comparison with initial virulent strains}; Nikolaeva AI et al.; The comparative study of the lipopolysaccharides (LPS) of virulent and avirulent strains of S . sonnei, phase I (smooth colonies), has been made . Electrophoresis of LPS and subsequent densitometry of electrophoregrams have revealed the increase of the fraction of long 0-chains with a considerable number of recurring elements in 2 out of 3 LPS preparations obtained from avirulent shigellae . In mice immunized with these LPS preparations a considerably greater number of antibody-producing cells can be detected in Jerne's test on sheep red blood cells (SRBC) sensitized with the LPS of a virulent strain than on those sensitized with the above LPS preparations . Long 0-specific chains supposedly inhibit the fixation of individual complement components on the corresponding sensitized SRBC . The LPS of the third avirulent strain of S . sonnei, phase I, with transposon integrated into its genome, which has led to the formation of the avirulent variant of a previously virulent strain, seems to contain fine structural differences from the initial virulent strain . The immunogenicity of the LPS of this avirulent strain is greatly (3-4 times) decreased, which is manifested by the number of antibody-producing cells detected in Jerne's test on SRBC sensitized with LPS preparations obtained from these two strains.

Eur J Clin Microbiol Infect Dis, 1992 Feb, 11(2), 164 - 7
Monitoring of antibiotic resistance in shigellae isolated in The Netherlands 1984-1989; Voogd CE et al.; During surveillance of antimicrobial resistance in Shigella strains isolated in the Netherlands from 1984 to 1989 and forwarded to the National Institute of Public Health and Environmental Protection for typing, sensitivity to twelve antimicrobial agents was assessed . High rates of resistance to the older drugs of choice in treating shigellosis were found, i.e . ampicillin and trimethoprim-sulfamethoxazole . Ampicillin resistance varied from 33 to 53% among Shigella flexneri strains and from 10 to 17% among Shigella sonnei strains . Trimethoprim and trimethoprim-sulfamethoxazole resistance increased from 8% to about 25% among Shigella flexneri and from 16 to 46% among Shigella sonnei isolates . All strains were susceptible to the newer quinolones, but five strains resistant to nalidixic acid showed decreased susceptibility to norfloxacin . Approximately 10% of the isolates were resistant to the combination of ampicillin, trimethoprim and sulfamethoxazole.

Infect Immun, 1992 Feb, 60(2), 557 - 64
Myosin-cross-reactive epitope of Shigella flexneri invasion plasmid antigen B; Oaks EV et al.; IpaB, invasion plasmid antigen B, of Shigella flexneri is a 62-kDa protein required for invasion of intestinal epithelial cells . IpaB is also one of several major protein antigens recognized by the humoral immune systems of most humans and monkeys after infection with shigellae . Computer analysis of the deduced IpaB amino acid sequence indicates that an alpha-helical structure is likely through much of the molecule . Homology searches with protein data banks show that one alpha-helical domain between amino acid residues 95 and 181 has a moderate level of identity with myosin and streptococcal M protein . By using a monoclonal antibody (2F1) which recognizes an epitope in the amino-terminal third of the IpaB protein, it was possible to demonstrate a cross-reactive epitope(s) on skeletal muscle myosin . Epitope mapping localized the 2F1 epitope to three noncontiguous regions of the IpaB protein within the alpha-helical domain that contains homology with myosin . Antibodies produced in rabbits immunized with synthetic peptides from one of the 2F1 epitope regions (residues 99 to 110) of IpaB were capable of reacting with IpaB as well as myosin . Furthermore, sera from several monkeys previously infected with S . flexneri 2a contained antibodies to IpaB pep 101-116 (IpaB peptide 101-116) and also myosin . Sera from animals with antibodies against other IpaB peptides did not contain antibodies against myosin.

Zh Mikrobiol Epidemiol Immunobiol, 1992 Feb, (2), 22 - 6
{The effect of Shigella sonnei strains opposite in their virulence on different links in the immune system}; Nikolaeva TN et al.; For the first time different action of S . sonnei strains, opposite in their virulence, on hematopoiesis and the functional activity of T- and B-lymphocytes has been shown . The hematopoiesis-disturbing action of virulent shigellae is manifested by their capacity, more pronounced than similar capacity of an avirulent (vaccine) strain, for stimulating the processes of endo- and exocolony formation, the proliferation of hematopoietic stem cells and their migration to the blood . The effect produced by shigellae on T-cell-mediated immune response is manifested by the suppression of macrophage migration and its subsequent activation, whose manifestations and duration depend on the virulence of S . sonnei strains under study . The modulating effect of S . sonnei on B-cell-mediated immune reactions is manifested by the inhibiting action of S . sonnei virulent strain and the stimulating action of S . sonnei vaccine strain on the formation of antibody-producing cells synthesizing S . sonnei lipopolysaccharide antibodies shortly after the injection of shigellae . The results of this study indicate that S . sonnei virulent and avirulent (vaccine) produce multifunctional and differing effects on cell-mediated immune reactions, these processes being dependent on the virulence of shigellae and their individual specific antigens.

Infect Immun, 1992 Jan, 60(1), 237 - 48
Shigella flexneri enters human colonic Caco-2 epithelial cells through the basolateral pole; Mounier J et al.; The commonly accepted view that enteroinvasive bacteria enter cells of the intestinal epithelial lining through the apical surface can be challenged in the case of shigellosis . This study is based on in vitro experiments that showed that the invasion of human colonic Caco-2 cells by Shigella flexneri occurred through the basolateral pole of these cells . In these experiments, the few bacteria that interacted with the apical surface either bound to microvilli of the cell dome without causing detectable alteration or bound at the level of intercellular junctions at which they demonstrated a limited capacity for paracellular invasion, which permitted subsequent entry through the lateral domain of the cells . Treatment of Caco-2 cell monolayers with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), which disrupts intercellular junctions, greatly enhanced the rate of cell infection . These observations suggest a physiopathological paradox that may have important consequences for the understanding of the process of colonic invasion in vivo during shigellosis.

J Infect Dis, 1992 Jan, 165(1), 144 - 7
Shigella and enteroinvasive Escherichia coli infections in households of children with dysentery in Bangkok; Echeverria P et al.; Shigellae and enteroinvasive Escherichia coli (EIEC) were identified in children with dysentery and their household contacts in Bangkok . Shigellae were isolated from 49% and EIEC from 6% of 306 children with dysentery seen at the outpatient department of Children's Hospital on weekdays during January through June 1989 and October 1989 through October 1990 . The same serotype infecting the index child was isolated from 21 (4%) of 522 household contacts of 151 index children with Shigella infections and from none of 60 household contacts of 19 index children with EIEC infections . Amplification of DNA sequences coding for the invasion-associated locus (ial) by polymerase chain reaction increased the identification of Shigella and EIEC infections from 57% (111/193) to 68% (132/193) . ial sequences were identified in 3 of 20 drinking water specimens from which shigellae or EIEC were not isolated . Amplification of ial sequences identified more shigellae and EIEC than did bacteriologic and colony hybridization methods in children with dysentery and in drinking water in Bangkok.

Acta Microbiol Hung, 1992, 39(1), 47 - 53
Shigella-type pathomechanism in the "mouse model"; Ketyi I et al.; A strain of Escherichia coli K-12 carrying the 140-Megadalton virulence plasmid of the enteroinvasive E . coli--J53(pSPl)--showed high virulence in the "mouse model", in chick embryos, but not in the Sereny test . It expresses the outer membrane proteins thermoregulatedly, encoded also by the virulence plasmid . In orally infected streptomycin-pretreated mice this strain infects only the large bowel, shows adherence to the epithelial surface, but in its first step preferentially to the mucus excreted by the goblet cells . Epithelial penetration and intracellular multiplication occurs with a characteristic localization of bacteria in the depth of crypts . Consequence of the infection is degeneration of the epithelial surface, its denudation.

Vaccine, 1992, 10(6), 389 - 94
Live oral auxotrophic Shigella flexneri SFL124 vaccine with a deleted aroD gene: characterization and monkey protection studies; Karnell A et al.; Shigella flexneri SFL124, with a deletion encompassing all, or nearly all, of the coding sequence of gene aroD was obtained after selection on a fusaric acid medium supplemented with 2,3-dihydroxybenzoic acid for tetracycline-sensitive mutants of S . flexneri SFL114 which is an aroD::Tn10 transductant . Two of 20 tetracycline-sensitive mutants tested in colony hybridization with a 32P-labelled DNA probe of approximately 1400 base pairs (comprising all except the 75 N-terminal base pairs of the coding region of gene aroD) did not hybridize . The selected mutant SFL124 is Congo-red positive, invades and shows a limited multiplication in HeLa cells and does not cause keratoconjunctivitis in guinea-pigs . It is well tolerated by Macaca fascicularis monkeys, is excreted for up to 4 days, elicits a slight inflammatory reaction in the colonic mucosa, stimulates significant secretory IgA responses in the intestine and serum IgA and IgG responses against the S . flexneri cell envelope lipopolysaccharide . The immune response conferred a complete protection against challenge with 1 x 10(11) (equivalent to a 100 LD50 dose) live S . flexneri SFL1.

Microbios, 1992, 69(280-281), 171 - 9
Induction of beta-lactamase from Shigella flexneri UCSF-129: purification by affinity chromatography and some properties; Campos M et al.; Lincomycin, an inhibitor of protein synthesis, was an excellent inductor of beta-lactamase, and its total activity and specific activity were increased 2.5- and 3.6-fold respectively . The beta-lactamase produced by Shigella flexneri UCSF-129 was purified by affinity chromatography on phenylboronic acid-agarose with a type B column using an hydrophobic spacer arm (6-aminohexanoic acid activated with succinimide) . The yield and specific activity were 96% and 29,283 U/mg, respectively . These were 1.7- and 3.8-fold higher, respectively, than those obtained by the traditional method using ion-exchange chromatography and gel filtration . The working-time was reduced to a third, and the enzyme preparation was shown to be pure by several criteria . From nine divalent cations assayed, only Sn(II) inhibited the enzyme by 74%, and the chloride ion did not have any effect on enzyme activity.

Antimicrob Agents Chemother, 1992 Jan, 36(1), 87 - 91
Five versus three days of ofloxacin therapy for traveler's diarrhea: a placebo-controlled study; DuPont HL et al.; In this double-blind study with 232 patients, 300 mg of ofloxacin given orally twice daily for 5 or 3 days was compared with placebo for the treatment of acute diarrhea in U.S . students visiting Guadalajara, Mexico . The 3-day regimen of ofloxacin was found to be as effective as the 5-day regimen in producing a clinical and microbiologic cure . Clinical cures for patients who received ofloxacin for 5 days occurred in 59 of 66 (89%) subjects, whereas clinical cure occurred in 77 of 81 (95%) of those who received ofloxacin for 3 days and in 56 of 79 (71%) of those who took placebo (P = 0.0001) . When the duration of diarrhea after therapy was begun was compared in subgroups, a significant (P less than 0.05) shortening of posttreatment illness occurred in comparison with that in the placebo group for the following groups: for 5 days of ofloxacin, cases of shigellosis (32 versus 98 h); for 3 days of ofloxacin, all cases (28 versus 56 h), cases of enterotoxigenic Escherichia coli diarrhea (26 versus 66 h), cases of shigellosis (24 versus 98 h), all cases of illnesses associated with a bacterial enteropathogen (28 versus 69 h), and cases of illnesses in which numerous leukocytes were found in stool by microscopy (22 versus 49 h) . Microbiologic eradication rates were 75 of 78 (96%) for patients who received ofloxacin and 37 of 46 (80%) for patients who received placebo (P = 0.009) . There was no significant difference in the number of adverse events reported by patients in either of the treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Indian J Med Res, 1992 Jan, 95, 21 - 2
Occurrence of a large plasmid in a strain of Plesiomonas shigelloides with cross-reactivity against Shigella sonnei; Sayeed S et al.; The plasmid profile of P . shigelloides SVC 01, strain with cross-reactivity with Sh . sonnei, (obtained from Dr Alf Lindberg, Stockholm University, Sweden), was assayed and compared with other local isolates of Plesiomonas spp . and also with Sh . sonnei . Diversity in occurrence of plasmids among different strains of P . shigelloides were observed . Further, the SVC 01 strain and Sh . sonnei differ in their plasmid profile.

Vaccine, 1992, 10(3), 167 - 74
Auxotrophic live oral Shigella flexneri vaccine protects monkeys against challenge with S . flexneri of different serotypes; Karnell A et al.; The aromatic-dependent live Shigella flexneri Y strain SFL114, attenuated by a Tn10-inactivated aroD gene, was given as an oral vaccine to 14 Macaca fascicularis monkeys . A significant clinical attenuation of SFL114 was seen (p = 0.0058) as all vaccinated monkeys tolerated 2 x 10(10)-1 x 10(11) bacteria of SFL114, whereas four out of seven monkeys orally given 1 x 10(11) of the virulent parent strain SFL1 developed shigellosis . The average excretion time for SFL114 and SFL1 were 2 and 18 days, respectively . As seen endoscopically SFL1 caused colonic lesions, whereas SFL114 did not . Histopathologic examination of colonic biopsies showed that SFL114 induced only slight acute inflammation, whereas SFL1 caused severe acute inflammation (p less than 0.01) . The vaccine strain SFL114 elicited significant species-specific serum immune responses (p less than 0.005) as seen in enzyme immune assays using lipopolysaccharides from S . flexneri serotypes Y, 1b, and 2a and Escherichia coli K-12 as antigens . The titres were comparable to those seen in monkeys given virulent S . flexneri strains . Western blot analyses showed that many prevaccination sera contained antibodies directed against the invasion plasmid-coded polypeptides . However, after vaccination with SFL114 increased amounts of such anti-polypeptide antibodies were seen, particularly in sera from monkeys having a low prevaccination antibody level . SFL114 also elicited a significant species-specific (p less than 0.025) local intestinal sIgA response against the homologous lipopolysaccharide antigen . Vaccinated monkeys were clinically protected against an oral challenge with 1-2 x 10(11) live, virulent S . flexneri strains of any of serotypes Y (strain SFL1), 1b (strain SFL27), or 2a (strain M4243).(ABSTRACT TRUNCATED AT 250 WORDS)

Ann Gastroenterol Hepatol (Paris), 1992 Jan-Feb, 28(1), 44 - 7
{Molecular and cellular bases of the virulence of Shigella flexneri}; Sansonetti PJ; Shigella flexneri, a Gram negative bacillus, causes bacillary dysentery, an ulcerative disease of the human colon, by invading intestinal epithelial cells . Entry into epithelial cells occurs via an induced phagocytic process which involves the actino-myosin complex . The host-cell receptor and the transmembrane signal which initiate reorganization of the cytoskeleton are under study . Binding to integrins has recently been demonstrated in related models such as the entry of Yersinia pseudotuberculosis and Bordetella pertussis into cells . Bacterial genes necessary to achieve entry are located on five contiguous loci covering 30 kb on a 220 kb virulence plasmid in S . flexneri . Locus 2 has been particularly studied . Six genes organized as an operon encode highly immunogenic proteins among which IpaB (62 kD) and IpaC (48 kD) are the invasins of this microorganism which subsequently grows very rapidly within infected cells due to its capacity to lyse the membrane bound phagocytic vacuole . Once free within the cytoplasm, bacteria interact again with the cell cytoskeleton . They first express Olm (organelle like movement), a phenotype reflecting intracellular movement along actin stress cables . They subsequently express lcs (intracellular spread), a phenotype by which intracellular bacteria induce nucleation and polymerization of actin followed by accumulation of this material at one end of the bacillus . This process causes rapid random movement leading to the formation of protrusions which allow passage to adjacent cells . A combination of these two movements achieves bacterial colonization of the epithelium.

FEMS Microbiol Immunol, 1992 Jan, 4(2), 65 - 72
Shigella-specific IgA in saliva of children with bacillary dysentery; Schultsz C et al.; To study the secretory immune response after Shigella infection, the anti-lipopolysaccharide and anti-Shiga-toxin response in saliva, obtained from children with confirmed shigellosis and healthy children, were determined by enzyme-linked immunosorbent assay and by Western blot . Children with infection showed high titers compared to healthy controls . After Shigella dysenteriae type 1 infection a significant change in titer could be observed in a large number of cases, in contrast to Shigella flexneri infection . It appeared that, in children living in endemic areas, infection with one serotype can give a rise in antibody titer to another serotype . This could be ascribed to polyclonal B cell activation since children in endemic areas routinely show relatively high titers to Shigella antigens . We conclude that the dynamics of salivary anti-Shigella LPS and anti-Shiga-toxin in children with dysentery indicate that it can be applied to studies of immune response in shigellosis for epidemiological and vaccination purposes.

Pediatriia, 1992, (7-9), 11 - 5
{The principles of the diagnosis of acute intestinal infections caused by opportunistic bacteria in children}; Bokovoi AG et al.; To specify criteria for the diagnosis of acute intestinal infections induced by opportunistic bacteria, the clinico-laboratory findings were compared in 3 groups of children: with acute intestinal infections induced by opportunistic bacteria (194 children); with shigellosis, salmonellosis and escherichiosis (260 children); with rotavirus gastroenteritis (133 children) . It has been demonstrated that in the diagnosis of acute intestinal infections induced by opportunistic bacteria, one should be very careful in excluding the etiological role of pathogenic bacteria and viruses not only clinically but also with the aid of laboratory virological, bacteriological and serological methods; in considering changes in the quantitative content of the intestinal microflora to be seen over time . It is also necessary that the age and the premorbid condition of the patients examined may be taken into account.

Vaccine, 1992, 10(14), 991 - 9
Synthetic approaches to vaccines for infectious and autoimmune diseases; Sela M et al.; The development is outlined of some synthetic vaccines against infectious diseases, in particular cholera, shigella and influenza . In the last case, use of the synthetic adjuvant MDP in combination with a haemagglutinin peptide has led to a synthetic vaccine with built-in adjuvanticity . The production of vaccines both by chemical synthesis and genetic engineering is described . The successful use of the synthetic amino acid copolymer COP-1 as an immunomodulatory vaccine to suppress the onset of allergic encephalomyelitis in experimental animals has led to clinical trials with patients suffering from exacerbating remitting multiple sclerosis . T-cell vaccination is an alternative approach to immunization against autoimmune diseases.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (7-8), 34 - 7
{The effect of a ribosomal Shigella sonnei vaccine on cellular immune reactions}; Nikolaeva TN et al.; The influence of S . sonnei ribosomal vaccine on hematopoiesis, T- and B-cell-mediated immune reactions has been studied in the course of the development of experimental vaccinal process . The vaccine stimulated hematopoiesis, that was characterized by a dose-dependent increase in colony-forming units in the spleen (CFUs), a rise in CFUs in the blood and bone marrow and an increase in the pool of proliferating stem cells in bone marrow, shortly after injection . A pronounced immunostimulating effect of the vaccine on the formation of antibody-producing cells (APC) to heterologous antigen (sheep red blood cells) in the spleen has been established, and the vaccine has also been found to stimulate, though to a lesser extent, APC synthetizing specific antibodies to S . sonnei LPS . The injection of S . sonnei ribosomal vaccine influences the functional activity of effector T-cells; in its turn this phenomenon produces phasic changes in the migration activity of spleen cells in the presence of specific LPS and surface polysaccharide antigen of S . sonnei in phase I.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (5-6), 49 - 51
{The clinical assessment of the immune status of patients with acute Flexner shigellosis}; Iushchuk ND et al.; A total of 192 patients with Flexner's dysentery 1 have been examined . As a result, sharply pronounced unbalance of cell-mediated and humoral immunity factors has developed in the acute period of dysentery, reaching its maximal manifestations in severe course of the disease . In case of a tendency to a prolonged course of dysentery at the period of convalescence, essential shifts in immunological characteristics persist and the infective agent is repeatedly isolated.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (5-6), 29 - 34
{The etiological structure of shigellosis in the former USSR--an indicator of the activity of the main routes of infection transmission}; Solodovnikov IuP; The data on the etiological structure of Shigella infections in the USSR in 1988-1989 are presented . The study showed the dominating role of S . flexneri with S . sonnei also retaining great importance in Shigella infections . The process of the liquidation of S . dysenteriae and S . boydii infections began in some large cities . The domination of dysentery caused by S . flexneri and a high typhoid rate, particularly in Central Asia, were due to poor water supply of the population . The spread of dysentery caused by S . sonnei was completely independent of the water factor . The decisive role in the transmission of S . sonnei in infective doses was explained by decentralized milk supply.

Vaccine, 1992, 10(11), 766 - 76
Genotypic and phenotypic characterization of an aroD deletion-attenuated Escherichia coli K12-Shigella flexneri hybrid vaccine expressing S . flexneri 2a somatic antigen; Newland JW et al.; The construction and characterization of EcSf2a-2, an aroD-deleted Escherichia coli-Shigella hybrid vaccine carrying chromosomal and plasmid genes from Shigella flexneri and expressing S . flexneri 2a somatic antigen in association with E . coli K12 core are described . Expression of hybrid lipopolysaccharide and deletion of aroD resulted in the attenuation of phenotypic characteristics associated with pathogenicity . The addition of an aroD deletion results in a requirement for an aromatic precursor of para-aminobenzoic acid (PABA), an essential bacterial metabolite not present in mammalian tissues . The biosynthesis of hybrid somatic antigen prevents expression of a Sereny-positive reaction by invasive bacteria capable of expressing a plaque-positive phenotype . A functional kcpA gene is required for expression of the plaque-positive phenotype . The presence of an aroD deletion does not interfere with expression of an invasive phenotype; however, in bacteria containing a functional kcpA gene, replication and spread by invading bacteria are limited, preventing development of the plaque-positive phenotype.

Microbiol Immunol, 1992, 36(8), 803 - 13
Studies on novel pili from Shigella flexneri . I . Detection of pili and hemagglutination activity; Utsunomiya A et al.; Pili were detected using electron microscopy in clinical isolates of Shigella flexneri which had been continuously subcultivated in liquid media . Morphologically, the pili appeared as thin, flexible, cylindrical structures of up to 2-5 microns in length and about 3-5 nm in diameter . Two strains showed mannose-resistant (MR) hemagglutination to fresh fowl erythrocytes (type 4), and one to tannic acid-treated horse erythrocyte (type 3) pili . These pili are novel and different from the mannose-sensitive (MS) type 1 pili described by Duguid and Gillies.

Res Microbiol, 1992 Jan, 143(1), 67 - 74
A model of interaction between Entamoeba histolytica and Shigella flexneri; Verdon R et al.; The establishment of a relationship between Entamoeba histolytica and certain bacteria may contribute to the expression and/or enhancement of the pathogenicity of this parasite . Recent experiments have shown that bacteria expressing mannose-binding lectins on their surface could attach to mannose-containing molecules on the surface of amoebae . In this study, we established a model of interaction between . E . histolytica and Shigella flexneri . Using well-characterized mutants of S . flexneri, we studied the role of type I pili expression and the invasive phenotype of S . flexneri in the interaction between amoebae and the bacteria . Type I pili expression allowed attachment and subsequent internalization of S . flexneri by amoebae, these events were not observed in isogenic strains that did not express type I pili . Invasive as well as non-invasive variants of S . flexneri expressing type I pili were slowly digested by amoebae following internalization . Morphological studies showed that the specific features of the interaction depend on the dynamics of the distribution of mannose residues on the amoebic membrane during the interaction.

Dakar Med, 1992, 37(2), 127 - 30
{Bacteriology of shigella isolated in a tropical zone CHU}; Sow AI et al.; From 1981 to 1991, five hundred eighty one Shigella's strains were isolated in the Laboratories of the CHU Fann of Dakar . They represent 24.8 per cent of enteropathogen agents and 4.3 per cent of diarrhoeae causative agents . Shigella flexneri was predominant (71%), following by Shigella dysenteriae (14.5%), Shigella sonnei (11.4%) and Shigella boydii (2.5%) . In pediatric hospital 90 per cent of strains were isolated between 1 and 5 years age; in adults, the pic was found from 20 to 30 years . Five of the 13 tested antibiotics had inhibited 89 to 96 per cent of strains . The isolation of multiresistant strains will be in rapport with the antibiotic resistant plasmide portage.

Acta Microbiol Hung, 1992, 39(3-4), 263 - 70
Antibodies against invasion plasmid coded antigens of shigellae in human colostrum and milk; Cam PD et al.; Colostral and milk samples of Swedish, Vietnamese and Costa Rican mothers living under various socioeconomic conditions were tested for the presence of shigella invasion plasmid coded antigen (Ipa) specific antibodies . IgA antibodies of this specificity were found in significantly higher titres in samples of Vietnamese (600 +/- 338) than in samples of Swedish or high income Costa Rican mothers (190 +/- 224 and 290 +/- 241, respectively; p < 0.05) . Specific IgA titres in the low income group of Costa Rican mothers (470 +/- 338) did not differ significantly from the values obtained in Vietnam . While no Ipa specific IgM could be detected in any of the samples tested, specific IgG was found in 90% of the Vietnamese colostrum . These data indicate that antibodies which could be responsible for the dysentery-preventing effect of breast feeding are indeed present in human colostrum and milk in areas where shigellosis occurs with relatively high incidence.

Acta Gastroenterol Latinoam, 1992, 22(4), 243 - 6
{Toxic megacolon due to Shigella: a report of a new case}; Bolzan HE et al.; A new case of Shigella-caused megacolon is described in detailed form . Some considerations are made about frequency, pathology, clinic and prognostic features.

Arch Virol, 1992, 124(3-4), 321 - 32
Coxsackie B1 virus-induced changes in cell membrane-associated functions are not responsible for altered sensitivity to bacterial invasiveness; Modalsli K et al.; To analyze the possible mechanisms by which coxsackie B1 virus infection affects the invasiveness of Shigella flexneri, we have studied the influence of intracellular levels of Na+ and K+, ATPase activity, cytoplasmic membrane potential, cAMP level and cell communication through gap junctions . 3h after adsorption of viable or UV-inactivated coxsackie B1 virus the Na(+)-K+ gradient of the cell collapsed, ATPase activity decreased, the cytoplasmic membranic potential-dependent tetraphosphonium ion uptake were reduced . No changes in cAMP or intercellular cell communication were observed . S . flexneri invasiveness in HEp-2 cell pretreated with viable or UV-inactivated coxsackie B 1 virus was enhanced, but bacterial invasiveness was unchanged in K(+)-depleted HEp-2 cells, cell cultures with high intracellular Na+ content or ouabain pre-treated cells compared to control cells . We found no correlation between the enhanced bacterial invasiveness in the early phase of coxsackie B 1 virus infection in HEp-2 cell cultures and intracellular K+ depletion, high intracellular Na+ content, inhibited Na(+)-K+ ATPase activity or membranic depolarization.

Infect Immun, 1992 Jan, 60(1), 175 - 82
Spontaneous insertion of an IS1-like element into the virF gene is responsible for avirulence in opaque colonial variants of Shigella flexneri 2a; Mills JA et al.; Colonial variation of Shigella flexneri serotype 2a from the translucent (2457T) to the opaque form (2457O) occurs spontaneously once in 10(4) cell divisions, with concomitant loss of ipa gene expression and virulence . The appearance of 2457O was associated with the insertional inactivation of virF, an invasion plasmid-encoded positive regulator of ipa gene expression . Plasmid pWR110, a Tn5-tagged invasion plasmid that restores the invasive phenotype to plasmid-cured Shigella derivatives, was conjugally transferred into 2457O . Synthesis of the invasion-associated IpaB and IpaC polypeptides, normally present on the surface of virulent shigellae, and the invasive phenotype were restored in 2457O(pWR110) transconjugants . Plasmid DNA restriction endonuclease patterns of 2457T and 2457O, along with hybridization analysis, showed that a SalI fragment carrying the virF gene in 2457O had increased in size relative to its counterpart in 2457T . Analysis of virF DNA sequences amplified by the polymerase chain reaction revealed that the virF sequence from 2457O was 780 bp larger than that amplified from 2457T . Moreover, the virF sequence amplified from 2457O hybridized to an IS1 DNA probe whereas the amplified 2457T virF sequence did not . DNA sequence analysis mapped the insertion element, designated IS1SFO, within an A.T-rich region of the virF open reading frame and identified a 9-bp virF target sequence that was duplicated at the insertion site of IS1SFO . The DNA sequence of IS1SFO was greater than 99% homologous to IS1F . Plasmid pWR600, carrying a 1,260-bp HpaII fragment encoding a wild-type virF gene, was able to restore the virulent phenotype and translucent colonial morphology to nine independently isolated 2457O hosts.

Acta Microbiol Hung, 1992, 39(2), 203 - 6
A 4-kilobase congo red binding plasmid DNA fragment of Shigella dysenteriae 1 suppresses the growth and cell differentiation in Escherichia coli; Biswas D et al.; A 4-kilobase congo red binding plasmid DNA fragment of pCAT 120 of Shigella dysenteriae 1 was transferred to an Escherichia coli K12 strain by transformation . Transformants were unable to grow in any liquid broth medium . Electron microscopic studies revealed that the transformants grown on tryptic soy agar were associated in clusters after cell division . Normal cell separation among the transformants in comparison with recipient E . coli K12 was only observed when the growth medium was supplemented with sterile culture filtrate of the recipient strain . An unknown factor(s) required for cell separation located on the chromosome was suppressed by a 4-kb congo red binding plasmid DNA (pCAT 120) fragment of S . dysenteriae 1.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (11-12), 57 - 9
{The clinical assessment of macrophage functional activity in patients with protracted dysentery and its correction with lysozyme and vitamin E}; Iushchuk ND et al.; Prospects for the correction of disturbances in the macrophagal system with a combination of lysozyme and vitamin E in patients with a protracted course of dysentery caused by Shigella flexneri 1b were studied . The phagocytic activity of macrophages (PAM) was found to be suppressed as early as at the beginning of the disease . Out of 38 persons repeatedly found to release shigellae 24 were administered polychemotherapy . PAM indices in patients treated with lysozyme and tocopherol acetate were likely to normalize, this being indicative of the positive effect of these preparations on the functional activity of the macrophagal system.

Arch Immunol Ther Exp (Warsz), 1992, 40(2), 135 - 7
Fraction of spleen cells responsible for suppression of cellular immune response to SRBC in mice treated with outer membrane proteins of Shigella; Czarny A et al.; Effect of splenocytes isolated from mice immunized with suppressive dose of OMP from Shigella on delayed hypersensitivity, induced in mice with sheep red blood cells was investigated . Only the population of T lymphocytes was found to suppress the delayed hypersensitivity, as measured by the footpad reaction . The results suggest that OMP of Shigella are able to induce in the spleens of animals active T cells which are responsible for the suppression of cellular response induced by SRBC.

Arch Immunol Ther Exp (Warsz), 1992, 40(2), 129 - 34
Effect of outer membrane proteins from Shigella on humoral immunity induced in mice by SRBC; Czarny A et al.; Shigella flexneri outer membrane proteins (OMP) which had been earlier found to exert immunomodulatory effect on cell mediated immune response were also found to act as immunomodulator of the humoral immune response . Effects of OMP were investigated in the experiments in vitro and in vivo, where the level of humoral immune response, measured as the number of plaque-forming cells (PFC) to SRBC in the spleen was evaluated . We demonstrate that small doses of OMP (1-5 micrograms) stimulate, whereas higher doses (10-50 micrograms) suppress the humoral immunity.

Folia Microbiol (Praha), 1992, 37(6), 450 - 4
Bacterial endotoxins as potential antitumor agents . Tumor mass loss in mice treated with bacterial lipopolysaccharides of Shigella dysenteriae serovar 1; Sourek J et al.; Natural and modified preparations of lipopolysaccharides and lipopolysaccharide-protein complexes isolated from the S- and R-form of Shigella dysenteriae serovar 1 were found to markedly inhibit the initial growth of mouse solid tumors derived from Nemeth-Kellner lymphoma, Gardner 6C3HED lymphoma, an ill-defined syngeneic lymphoma of DBA mice (Skalsky lymphoma) and LP-2 plasmacytoma . The biopreparations were given intraperitoneally, most frequently at a dose range from 50 to 200 micrograms per mouse; significant inhibitory effects on tumor growth were evidenced even in mice bearing tumors weighing 113 to 507 mg.

Scand J Infect Dis, 1992, 24(6), 733 - 9
Multiresistant Shigella species from African AIDS patients: antibacterial resistance patterns and application of the E-test for determination of minimum inhibitory concentration; Kruse H et al.; The antibacterial resistance pattern and minimum inhibitory concentrations (MIC) of 25 Shigella flexneri, 5 S . boydii, 8 S . sonnei, and 3 strains of S . dysenteriae type 2 isolated from Kenyan prostitutes with bacillary dysentery and AIDS were determined, and the applicability of the E-test for MIC determination evaluated . All strains were resistant to > or = 3 of 9 different antibacterial agents tested . All strains were resistant to tetracycline and erythromycin, 95% to trimethoprim/sulfonamide, 93% to streptomycin, 54% to ampicillin, 39% to chloramphenicol, 2% to nalidixic acid and none to gentamicin and ciprofloxacin . Six different resistance patterns were observed . The most common pattern was resistance to tetracycline, erythromycin, trimethoprim/sulfa and streptomycin (39%) . The E-test was shown to be well-suited for susceptibility testing of multiresistant Shigella spp.; the reproducibility was excellent and the correlation with the microtiter dilution method and the disk diffusion method were 98% in both instances . The MIC measured with E-test and the microdilution method were within +/- 1 dilution step for 94.4% of the combinations tested.

Infect Immun, 1991 Dec, 59(12), 4450 - 8
Preparation, characterization, and immunogenicity of conjugates composed of the O-specific polysaccharide of Shigella dysenteriae type 1 (Shiga's bacillus) bound to tetanus toxoid; Chu CY et al.; The background for developing conjugate vaccines for shigellosis composed of the O-specific polysaccharide (O-SP) bound to a protein is described elsewhere (C . Y . Chu, R . Schneerson, and J . B . Robbins, submitted for publication) . Briefly, there is direct evidence for type (lipopolysaccharide {LPS})-specific protection after infection with the wild type or with attenuated strains of shigellae . Prospective studies of Israeli armed forces recruits show a correlation between preexisting serum immunoglobulin G (IgG) LPS antibodies and resistance to shigellosis (D . Cohen, M . S . Green, C . Block, R . Slephon, and I . Ofek, J . Clin . Microbiol . 29:386-389, 1991) . In order to elicit IgG LPS-specific antibodies to Shigella dysenteriae type 1, the O-SP of this pathogen was purified and bound to tetanus toxoid (TT) by three schemes . The most immunogenic used a modification of a published method (C . Y . Chu, R . Schneerson, J . B . Robbins, and S . C . Rastogi, Infect . Immun . 40:245-256, 1983) . The resultant O-SP-TT conjugates were stable and elicited high levels of IgG O-SP antibodies and booster responses in young mice when injected subcutaneously in saline at 1/10 the proposed human dose . Adsorption onto alum or concurrent administration with monophosphoryl lipid A enhanced both the IgG and IgM antibody responses to the O-SP of the conjugate; both the nonadsorbed and adsorbed conjugates elicited higher rises of IgG than of IgM antibodies . Clinical evaluations of S . dysenteriae type 1 O-SP-TT conjugates are planned.

Wei Sheng Wu Xue Bao, 1991 Dec, 31(6), 466 - 72
{Antigenic analysis and identification of serotype for an arguable strain of Shigella}; Yang Z; A strain of Shigella, 51331, was isolated abroad in 1935, and stored in The Center for Medical Culture Collection, Beijing . Since the serotype of this strain was arguable in China . It was identified as Sh . flexneri var . X with antigenic analysis . As agglutinin absorption technic was used in preparing diagnostic factor serum, it appears that the culture of strain 51331 could be agglutinated by Shigella antiserum flexner type 3 (Sh . flexneri) made in China and England . The present author suggested that diagnostic serum for type 3 or Sh . flexneri should be checked up with the strain 51331 for type factor specific . Strain 51331 is, therefore, useful for purpose of identification when preparing diagnostic serum for Shigella.

Wei Sheng Wu Xue Bao, 1991 Dec, 31(6), 420 - 5
{Cloning and expression of Shiga-toxin gene from Shigella dysenteriae type I}; Li F et al.; The chromosomal DNA of S . dysenteriae type I W30864 was isolated and digested by EcoRI . The 3-7 kb DNA fragments were recovered and ligated with vector pUC-19 . After transformation, the recombinants were screened by SLT gene probe . The positive clones were obtained . The cloned EcoRI fragment containing both ST-A and ST-B subunit gene was about 4.5 kb . The cloned ST strain was also detected by Hela-S3 cell for cytotoxicity, and detected by rabbit ileal loop test for enterotoxicity . Besides, the cloned strain showed the neurotoxic activity when experimented with mouse . The production of shiga toxin in the cloned strain was 16 times of that of its parent strain S . dysenteriae W30864 . The production differences between ST producing stains and SLT producing strain was also tested in our experiment.

Ceylon Med J, 1991 Dec, 36(4), 159 - 61
Changing antibiotic sensitivity patterns in shigellosis; Lamabadusuriya SP et al.; Over five and a half months stool cultures were performed in 154 patients admitted with suspected bacillary dysentery to the Professorial Paediatric Unit of the Teaching Hospital, Galle . Thirty one patients had a positive stool culture; Shigella dysenteriae type 1 was isolated in 23 patients, and S flexneri in 8 . In both groups the antibiotic sensitivity pattern was uniform, the only difference being S dysenteriae type 1 being resistant to nalidixic acid while S flexneri was sensitive . This antibiotic sensitivity pattern was different to that reported from Colombo during the same period . Complications were observed in some patients with S flexneri infection.

J Diarrhoeal Dis Res, 1991 Dec, 9(4), 328 - 31
Serotype distribution and antimicrobial resistance of Shigella isolates in Singapore; Lim YS et al.; Serogrouping of 506 Shigella strains isolated in Singapore from 1986 to 1990 showed that Shigella flexneri (60.3%) was the most common, followed by S . sonnei (33.6%), S . boydii (3.2%) and S . dysenteriae (3%) . Of the 23 Shigella serotypes identified, the predominant ones were S . flexneri types 2a and 1b, S . boydii types 1 and 5, and S . dysenteriae types 1 and 3 . More than 80% of the Shigella species were resistant to at least one antimicrobial drug, and the incidence of multiresistance was particularly high in S . flexneri strains . Due to the high incidence of antimicrobial resistance, the susceptibility pattern of Shigella strains should be determined for treatment purposes.

Int J Epidemiol, 1991 Dec, 20(4), 1081 - 7
An epidemic of waterborne Shigella gastroenteritis in Kibbutzim of western Galilee in Israel; Simchen E et al.; In an epidemic of Shigella sonnei gastroenteritis, probably waterborne, 1216 people were affected within three weeks, 302 of them members of communal settlements, the kibbutzim . A descriptive study of the epidemic in six affected kibbutzim in the area showed that the highest rates of diarrhoea occurred in a kibbutz that received its drinking water solely from the allegedly contaminated well . People at high risk within the kibbutzim were temporary visitors from Europe and the US (the volunteers), children aged 1 to 5 years, adult women, and children and their mothers in kibbutzim where the sleeping arrangements for the children was in 'children's houses'.

Int J Epidemiol, 1991 Dec, 20(4), 1064 - 72
Prognostic indicators and risk factors for increased duration of acute diarrhoea and for persistent diarrhoea in children; Mahalanabis D et al.; To identify the prognostic indicators and risk factors for increased duration of acute diarrhoea and for occurrence of persistent diarrhoea (i.e . acute episodes lasting longer than 14 days) in children under three years, a systematic sample (3690) of patients attending a large treatment centre in Bangladesh was analysed using multiple regression, logistic regression and stratified (Mantel-Haenszel) analysis . Significant prognostic indicators or risk factors for increase in duration of acute diarrhoea, after adjusting for confounders, include bloody or mucoid diarrhoea, concomitant signs of chest infection, presence of vitamin A deficiency signs, decreased weight for age, routine use of contaminated surface water, lack of breastfeeding and increasing age; presence of rotavirus or enterotoxigenic Escherichia coli or Vibrio cholerae 01 in stool had negative association . In logistic regression and stratified analysis these factors, except for lack of breastfeeding and age, were also found to be risk factors or prognostic indicators of persistent diarrhoea . Policy implications of these findings for programmes to reduce morbidity and mortality from persistent diarrhoea include development of effective vaccines against dysentery-causing Shigella, programmes to prevent vitamin A deficiency, protein energy malnutrition and acute respiratory infections in children, and long-term programmes to provide clean water for all day-to-day needs.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Dec, (12), 38 - 41
{The effect of the synergistic action of enterotoxin on the specific protective complex of Shigella sonnei}; Korneeva SA et al.; The study has first established that enterotoxin enhances the protective potency of S . sonnei specific protective complex . This effect has been revealed both in experiments of the oral immunization of mice and in experiments of the conjunctival immunization of guinea pigs and depends on the dose of enterotoxin used in the experiment . The increase of protection has a specific character . These observations open prospects for further enhancement for the protective properties of S . sonnei specific protective complex, which should be taken into consideration in developing the vaccinal preparation.

MMWR CDC Surveill Summ, 1991 Dec, 40(3), 1 - 21
Waterborne-disease outbreaks, 1989-1990; Herwaldt BL et al.; For the 2-year period 1989-1990, 16 states reported 26 outbreaks due to water intended for drinking; an estimated total of 4,288 persons became ill in these outbreaks . Giardia lamblia was implicated as the etiologic agent for seven of the 12 outbreaks in which an agent was identified . The outbreaks of giardiasis were all associated with ingestion of unfiltered surface water or surface-influenced groundwater . An outbreak with four deaths was attributed to Escherichia coli O157:H7, the only bacterial pathogen implicated in any of the outbreak investigations . An outbreak of remitting, relapsing diarrhea was associated with cyanobacteria (blue-green algae)-like bodies, whose role in causing diarrheal illness is being studied . Two outbreaks due to hepatitis A and one due to a Norwalk-like agent were associated with use of well water . Eighteen states reported a total of 30 outbreaks due to the use of recreational water, which resulted in illness for an estimated total of 1,062 persons . These 30 reports comprised 13 outbreaks of whirlpool- or hot tub-associated Pseudomonas folliculitis; 13 outbreaks of swimming-associated gastroenteritis, including five outbreaks of shigellosis; one outbreak of hepatitis A associated with a swimming pool; and three cases of primary amebic meningoencephalitis caused by Naegleria . The national surveillance of outbreaks of waterborne diseases, which has proceeded for 2 decades, continues to be a useful means for characterizing the epidemiology of waterborne diseases.

Am J Trop Med Hyg, 1991 Dec, 45(6), 683 - 7
Randomized clinical trial of norfloxacin for shigellosis; Bhattacharya SK et al.; In a randomized clinical trial, norfloxacin was compared with nalidixic acid in the treatment of acute invasive diarrhea, with particular reference to shigellosis in adults . Of 104 patients studied, 40 were positive for Shigella in stool cultures, of which 22 received norfloxacin and 18 received nalidixic acid . The patients in these two groups were comparable on admission . In the treatment of culture-positive shigellosis cases, the responses to therapy with both drugs were similar, except that the duration of fever, anorexia, and abdominal pain were less in those who received norfloxacin . Norfloxacin appeared to be superior to nalidixic acid in the treatment of shigellosis cases caused by Shigella strains resistant to nalidixic acid.

J Trop Med Hyg, 1991 Dec, 94(6), 407 - 10
Antimicrobial resistance trends of shigellae isolates from Calabar, Nigeria; Eko FO et al.; During a 3-year study (January 1986-December 1988), stools of 2200 diarrhoeal or dysenteric patients were examined by culturing and 108 (4.9%) were found positive for shigellae . Shigella flexneri was the commonest species isolated (54.6%), followed by Sh . dysenteriae (24.1%) . Patients aged less than or equal to 15 years accounted for 51.4% of cases . Shigellae over the 3 years showed high and sometimes rising resistance to ampicillin, chloramphenicol, streptomycin and cotrimoxazole and complete resistance to tetracyclines and sulphonamides . Sh . sonnei strains isolated in 1986 and 1987 were almost invariably sensitive to all antimicrobial agents except ampicillin, while in 1988 strains were resistant to all . The isolation rate was higher (74.1%) during the dry season than in the rainy season (25.9%) (P less than 0.01) . Low standards of community and personal hygiene and improper sewage disposal are the prevailing epidemiological factors identified.

J Clin Microbiol, 1991 Dec, 29(12), 2850 - 5
Use of multiple markers for investigation of an epidemic of Shigella sonnei infections in Monroe County, New York; Yagupsky P et al.; Antibiotic susceptibility patterns, plasmid profiles, and endonuclease restriction analysis of plasmid DNA were used in the investigation of an epidemic of Shigella sonnei infections in Monroe County, New York, in 1988 and 1989 . The epidemic peaked during the winter, included the simultaneous transmission of the disease from person to person and from common food sources, and especially affected inhabitants of the poor, inner-city neighborhoods, young children of both sexes, and women . Resistance to ampicillin, tetracycline, or trimethoprim-sulfamethoxazole, encoded in a 70-MDa plasmid, was found in most of the examined isolates . Unexpectedly, isolates from patients involved in a food-borne outbreak exhibited three different antibiotic susceptibility patterns, suggesting deletion of antibiotic resistance determinants in some strains . Antibiograms clearly separated food-borne outbreak-related and non-foodborne outbreak-related strains, distinguished more strains than did the plasmid profiles, and were useful in tracing the dissemination of individual isolates in the community . Restriction endonuclease analysis substantially increased the discriminatory value of plasmid profiles and validated the antibiogram results . The present study illustrates the complexity of epidemics of S . sonnei infections and shows the value of combining different biological markers in the investigation.

J Med Microbiol, 1991 Dec, 35(6), 330 - 7
Contact-haemolysin production by entero-invasive Escherichia coli and shigellae; Haider K et al.; Entero-invasive Escherichia coli (EIEC) and shigellae were tested for contact-haemolysin (CH) with red blood cells (RBCs) of guinea-pig, rabbit, rat, mouse, monkey, man, sheep and chicken; all bacteria showed the best lysis with guinea-pig RBCs . The best culture medium for CH activity of shigellae was tryptic soy broth, and for EIEC it was casamino acid-yeast extract broth with 1 mM CaCl2 . CH production by all species was best at the slightly alkaline pH which is optimal for growth; it was also dependent on the presence of a large (140-Mda) plasmid . Pre-treatment of bacteria with homologous antisera inhibited CH activity . Various treatments of bacterial cells and RBCs suggested that CH may be a protein molecule, and that a chitotriose-like moiety may serve as CH receptor . RBCs that were incubated with bacteria at 4 degrees C, or with heat-killed bacteria at 37 degrees C, were not lysed; also, isolated cell-surface components (lipopolysaccharide and outer-membrane protein) did not lyse RBCs . This suggests that metabolically active cells are required for CH activity . Production of CH by both EIEC and shigellae is consistent with a common mechanism for the virulence of these organisms.

FEMS Microbiol Lett, 1991 Nov 15, 68(2), 231 - 6
Environmental signals induce major changes in virulence of Shigella spp; Sen A et al.; Growth conditions play a major role in expression of virulence by Shigella spp . both in vitro (adherence and internalization in eukaryotic host cells) and in vivo (keratoconjunctivitis) . Optimized expression of virulence required anaerobic growth to log phase in particular media such as brain heart infusion broth . Kinetic studies of guinea pig eye infections showed that as few as 2 x 10(5) S . dysenteriae CG097 or S . flexneri M90T, grown under these optimized conditions, produced keratoconjunctivitis in 15 h . In vitro studies demonstrated that adherence to and invasion of Henle 407 cells, at 37 degrees C, by organisms grown under these optimized conditions, were significantly greater than when organisms were grown aerobically under the same conditions.

N Engl J Med, 1991 Nov 14, 325(20), 1423 - 8
Diarrheal disease during Operation Desert Shield; Hyams KC et al.; BACKGROUND . Under combat conditions infectious disease can become a major threat to military forces . During Operation Desert Shield, there were numerous outbreaks of diarrhea among the U.S . forces . To evaluate the causes of and risk factors for diarrheal disease, we collected clinical and epidemiologic data from U.S . troops stationed in northeastern Saudi Arabia . METHODS . Between September and December 1990, stool cultures for enteric pathogens were obtained from 432 military personnel who presented with diarrhea, cramps, vomiting, or hematochezia . In addition, a questionnaire was administered to 2022 soldiers in U.S . military units located in various regions of Saudi Arabia . RESULTS . A bacterial enteric pathogen was identified in 49.5 percent of the troops with gastroenteritis . Enterotoxigenic Escherichia coli and Shigella sonnei were the most common bacterial pathogens . Of 125 E . coli infections, 39 percent were resistant to trimethoprim-sulfamethoxazole, 63 percent to tetracycline, and 48 percent to ampicillin . Of 113 shigella infections, 85 percent were resistant to trimethoprim-sulfamethoxazole, 68 percent to tetracycline, and 21 percent to ampicillin . All bacterial isolates were sensitive to norfloxacin and ciprofloxacin . After an average of two months in Saudi Arabia, 57 percent of the surveyed troops had at least one episode of diarrhea, and 20 percent reported that they were temporarily unable to carry out their duties because of diarrheal symptoms . Vomiting was infrequently reported as a primary symptom, but of 11 military personnel in whom vomiting was a major symptom, 9 (82 percent) had serologic evidence of infection with the Norwalk virus . CONCLUSIONS . Gastroenteritis caused by enterotoxigenic E . coli and shigella resistant to a number of drugs was a major problem that frequently interfered with the duties of U.S . troops during Operation Desert Shield.

J Infect Dis, 1991 Nov, 164(5), 979 - 82
Intestinal secretory immune response to infection with Aeromonas species and Plesiomonas shigelloides among students from the United States in Mexico; Jiang ZD et al.; Intestinal secretory IgA (sIgA) response or lack of response among adults in Mexico with diarrhea was used as an indicator of enteropathogenicity of Aeromonas species and Plesiomonas shigelloides . sIgA was extracted from stool specimens obtained at day of presentation and 5 days later . Total sIgA was standardized, and specific sIgA titer against the organism being shed by each patient was determined . Western blotting was used to determine which microbial antigens elicited an intestinal sIgA response . Of 12 subjects shedding Aeromonas sobria or Aeromonas hydrophila, 11 had a fourfold or greater sIgA titer rise against the infecting strain . Western blotting showed that somatic lipopolysaccharides were the immunodominant antigens . No sIgA titer rises were detected among two patients shedding Aeromonas caviae or in 14 shedding P . shigelloides . This study provides further evidence of the significance of A . sobria and A . hydrophila as pathogens in acute diarrhea but raises additional questions about the role of P . shigelloides, at least in US adults with travelers' diarrhea.

J Infect Dis, 1991 Nov, 164(5), 894 - 900
Hyperendemic shigellosis in the United States: a review of surveillance data for 1967-1988; Lee LA et al.; In 1988, 22,796 Shigella isolates were reported to the Centers for Disease Control, the highest number since national surveillance was begun in 1967 . From 1986 to 1988, isolation rates increased from 5.4 to 10.1 per 100,000 persons . Increased isolation of Shigella sonnei, primarily among children and young women, occurred throughout the United States in a manner similar to the nationwide increase that occurred during the early 1970s . The highest rates during 1987-1988 were reported from countries with relatively high proportions of urban, ethnic ethnic minority, and poor residents, groups traditionally at high risk . The greatest percentage increases in isolation rates, however, occurred in relatively wealthy counties with predominantly white residents . Between 1967 and 1988, the proportion of Shigella species isolated from persons greater than or equal to 20 years of age increased 118%, while the proportion of the resident population in this age group increased only 16% . These data indicate a shift toward increased infection at older ages and the potential for periodic hyperendemic rates of shigellosis nationwide, which may be due to changing levels of immunity to S . sonnei.

Infect Immun, 1991 Nov, 59(11), 4173 - 9
Shiga toxin-associated hemolytic-uremic syndrome: combined cytotoxic effects of Shiga toxin, interleukin-1 beta, and tumor necrosis factor alpha on human vascular endothelial cells in vitro; Louise CB et al.; This study explores the relationship between Shiga toxin-producing Shigella or Escherichia coli strains and the development of vascular complications in humans following bacillary dysentery . We propose that endotoxin-elicited interleukin-1 or tumor necrosis factor alpha (TNF) may combine with Shiga toxin to facilitate vascular damage characteristic of hemolytic-uremic syndrome . This study examines the cytotoxic effects of Shiga toxin, interleukin-1, and TNF on cultured human umbilical vein endothelial cells (HUVEC) . Both Shiga toxin and TNF were cytotoxic to HUVEC, although HUVEC obtained from individual umbilical cords differed in their sensitivities to these agents . With Shiga toxin-sensitive HUVEC, combinations of TNF with Shiga toxin resulted in a synergistic cytotoxic effect . In contrast, interleukin-1 was not cytotoxic to HUVEC, nor did it enhance cell death in combination with Shiga toxin . The synergistic cytotoxic response of HUVEC to Shiga toxin and TNF was dose and time dependent for both agents and could be neutralized by monoclonal antibodies directed against either Shiga toxin or TNF . This synergistic response was delayed, being maximal on day 2 . Preincubation (24 h) of HUVEC with TNF sensitized the cells to Shiga toxin . TNF alone had no effect on HUVEC protein synthesis but enhanced the inhibitory activity of Shiga toxin . These results are consistent with a role for Shiga toxin in the development of hemolytic-uremic syndrome at the level of the vascular endothelium in humans.

Infect Immun, 1991 Nov, 59(11), 4075 - 83
Small-animal model to measure efficacy and immunogenicity of Shigella vaccine strains; Hartman AB et al.; The development of a small-animal model to test the protective efficacy and immunogenicity of a vaccine strain against shigellosis would greatly facilitate the evaluation of potential vaccine candidates . In guinea pigs, the ability of shigellae to invade and multiply within the corneal epithelium, causing keratoconjunctivitis, closely mimics the invasion process in the intestinal epithelium (B . Sereny, Acta Microbiol . Acad . Sci . Hung . 4:367-376, 1957) . The serum response of animals recovering from a Shigella keratoconjunctival infection was determined and found to be consistent with that shown by convalescent humans and primates . This model was used to test the efficacy of two vaccine candidates, and the immune response of the guinea pigs to the vaccine strains was examined . Both vaccine strains demonstrated significant protection against challenge by homologous virulent Shigella strains, and the results were comparable with results obtained in trials with monkeys . The guinea pig model also provides a rapid and inexpensive means of evaluating different immunization regimens as well as of testing other variables such as length of protection against disease.

Enferm Infecc Microbiol Clin, 1991 Nov, 9(9), 530 - 6
{Epidemiology of shigellosis and colicin typing of Shigella sonnei . A 14-year study}; Castillo FJ et al.; To study the most important epidemiologic features of shigellosis and the application of colicinotyping as an epidemiologic marker for Shigella sonnei . A total of 44.818 stoll-cultures were performed . We classify, using colicinotyping, 156 Shigella sonnei strains isolated from different patients . The incidence of Shigellosis in our media is low (1.08% of all stool-cultures) . It is more frequent in pediatric population and increases on late summer and fall . We had been able to show an increasing incidence, with an hyperendemic situation during a three-years period (1981-1983) . Shigella sonnei is the most prevalent species (86% of cases), followed by S . boydii (7.3%) and S . flexneri (5.9%) . All S . sonnei strains epidemiologically related showed the same colicinotype . Only two strains were not typable and we identified 9 different colicinotypes, being type 13 (30.8%), type 8 (18.6%), type 6 (17.3%) and type 12 (11.54%) the more frequent types . Colicinotype 8 was the more prevalent between 1978-1979 . Type 13 was predominant between 1981 and 1985 . During 1987 and 1989, at the same time that incidence had risen, types 6 and 12 were prevalent . The total number of different colicinotypes identified during a single year is never greater than five . Colicinotyping of S . sonnei is a simple typing method that gives enough useful epidemiologic information, discriminative and reproducible . Although there are changes of circulating types incidence and the prevalen colicinotype colud vary from one year to another, during longer periods of time there is a reduced number of alternating colicinotypes, which sets up a situation that could be further classified as endemic.

Zhonghua Yu Fang Yi Xue Za Zhi, 1991 Nov, 25(6), 335 - 7
{A study on diarrhoea disease caused by Vibrionaceae along coast the east of Zhejiang Province}; Jiang WP; A study of the etiology of 1028 cases of acute diarrhoea due to vibrionaceae was carried out between August 1988 to July 1990 along the coast of east Zhejiang Province . From 417 clinical cases (40.56%) were found . 590 strains (57.39%) of pathogenic vibrios Among them, the detection rates of vibrio, aeromonas and plesionmonas were 48.14%, 44.74%, 7.12% respectively . There were 8 Species of vibrio detected: V . parahemolyticus (63.73%), V . fluvialis (11.97%), V . alginolyticus (10.215), non-01 vibrio cholera (9.86%), V . furnissii (2.47%), V . mimicus (1.06%), V . metchnikovii (0.35%), V . vulnificus (0.35%) . The detection rate of aeromonas species of A . sorbia, A . caviae, A . hydrophila and A . indefinite sp . were 30.68%, 27.27%, 22.73%, and 19.32% respectively . Plesionmonas shigellides was also found in this study . The age, sex, clinical features, detection rates of pathogenic vibrios of diarrhoea cases and sea food contact history were analyzed.

J Clin Microbiol, 1991 Nov, 29(11), 2599 - 603
Evidence for long-term memory of the mucosal immune system: milk secretory immunoglobulin A against Shigella lipopolysaccharides; Hayani KC et al.; Although the common mucosal immune system has generally been considered to have only short-term memory, recent data suggest that long-term memory exists for Shigella virulence plasmid antigens . Because such antigens might cross-react with environmental antigens, we investigated milk for the persistence of antibodies to the specific Shigella lipopolysaccharide (LPS) antigens . Enzyme-linked immunosorbent assays to detect secretory immunoglobulin A (sIgA) against Shigella flexneri and Shigella sonnei LPS in milk samples were developed; 15 random milk samples tested on different days correlated from one day to the next (P = 0.0001) . Of 18 Mexican mothers, 18 (100%) had one or more milk samples positive for anti-S . flexneri LPS, 14 (78%) had one or more milk samples positive for anti-S . sonnei LPS, and 14 (78%) had one or more milk samples positive for both . Of 27 Houston mothers, 16 (59%) had one or more milk samples positive for anti-S . flexneri LPS, 7 (26%) had one or more milk samples positive for anti-S . sonnei LPS, and 5 (19%) had one or more milk samples positive for both . Mexican mothers were significantly more likely than Houston mothers to have at least one sample with a positive titer for anti-S . flexneri LPS (P less than 0.02) and at least one sample with a positive titer for anti-S . sonnei LPS (P less than 0.002) . Although the Houston women had a lower rate of titer positivity for both Shigella species, the rate was too high to be consistent with short-lived mucosal immunity . It is unlikely that 18 of the 27 Houston women had shigellosis during or just prior to lactation . The data suggest that there exists a long-term hormonally driven memory in the secretory immune system for Shigella spp.

J Clin Microbiol, 1991 Nov, 29(11), 2380 - 4
Restriction fragment length polymorphisms in rRNA operons for subtyping Shigella sonnei; Hinojosa-Ahumada M et al.; Shigella sonnei is the most frequent cause of shigellosis in the United States . Epidemiologic studies of this organism have been hampered by the lack of adequate typing procedures . Ribosomal DNA analysis (ribotyping), a method which analyzes restriction fragment length polymorphisms in the chromosomal genes that encode rRNA, has recently been shown to be useful for microbial species identification and subtyping . To determine whether ribotyping could be used to distinguish between S . sonnei isolates, we conducted Southern hybridization studies on isolates from 16 different geographic locations and from four recent outbreaks . S . sonnei genomic DNA fragments generated following digestion with SalI hybridized with Escherichia coli 16S and 23S rRNAs to produce six distinct patterns; strains with patterns 1, 2, and 3 were each further subdivided into two additional patterns by using PvuII, SmaI, and SstI, respectively . Epidemiologically related strains had identical patterns . Ribotyping appears to be a useful tool for epidemiologic studies of shigellosis caused by S . sonnei.

Infect Immun, 1991 Nov, 59(11), 3917 - 23
Relatedness of O-specific lipopolysaccharide side chain genes from strains of Shigella boydii type 12 belonging to two clonal groups and from Escherichia coli O7:K1; Valvano MA et al.; The O-specific lipopolysaccharide side chains of Escherichia coli O7 and Shigella boydii type 12 possess similar but not identical chemical structures . We investigated the genetic relatedness between the O-specific side chain genes in members of these two species . Examination of outer membrane protein and lipopolysaccharide (LPS) banding patterns demonstrated that five strains which had been identified as S . boydii type 12 fell into two clonal groups, SB1 and SB2 . Hybridizations with O7-specific radiolabeled probes derived from the chromosomal DNA of an E . coli O7 strain detected identical fragments among the three SB1 strains of S . boydii type 12 and the two E . coli O7 reference isolates . The two other S . boydii type 12 strains, which belonged to the SB2 clone, did not show homologies with the O7 probe under high-stringency conditions of hybridization . The homology between the O7 and type 12 LPS gene regions from the SB1 strains was further confirmed by the construction of O-specific side chain-deficient mutations in these strains by homologous recombination of a suicide plasmid containing O7-specific DNA sequences . Immunoblot experiments with O7 antiserum gave a weak cross-reaction with LPS purified from the SB2 strains but a very strong cross-reaction with the LPS from SB1 isolates . Antiserum raised to one of the SB2 strains cross-reacted only with S . boydii type 12 LPS from the SB1 clone but failed to react with O7 LPS.

Ugeskr Laeger, 1991 Oct 21, 153(43), 3001 - 3
{Shigella sonnei . An epidemic in a day-care institution}; Vagn-Hansen L et al.; Epidemics caused by dysentery bacteria among children and adults in day-institutions are rare in Denmark . The course of an epidemic of this type is reviewed . Thirty children and six adults went on holiday to a deserted farmer's cottage under primitive conditions in the southern Swedish woods . Immediately prior to this holiday, two of the adults had had serious gastrointestinal infections during a hiking trip in South America . Shigella sonnei was subsequently demonstrated in the stools from a total of 11 children but not in the adults . Three cases of intrafamilial infection occurred . Prior to commencement of the school year in late summer 1988, treatment of the asymptomatic bacterial carriers was carried out . Treatment such as this cannot be recommended as a rule and should, therefore, be discussed with the Medical Officer of Health when accumulated cases of Shigella sonnei dysentery occur.

FEMS Microbiol Lett, 1991 Oct 15, 67(3), 323 - 8
Shigella dysenteriae 60R strain adheres to and invades tissue culture cells in the absence of virulence plasmid; Yao RJ et al.; Evidence is presented that a high level Shiga toxin-producing strain Shigella dysenteriae 60R adheres to and invades the epithelial cell lines Hct8 and Henle 407 . The invasive phenotype of S . dysenteriae 60R differs in four ways from the heretofore studied invasive Shigella phenotypes . First, S . dysenteriae 60R lacks the virulence plasmid characteristic of other invasive Shigella spp . and enteroinvasive Escherichia coli . Second, hybridization studies show that the known ipa genes are neither present in the chromosome nor in the small plasmid of 60R . Third, 60R adheres to and invades Hct8 and Henle 407 cells at 37 degrees C as well as at 30 degrees C . Fourth, the phenotype of adherence and invasion of 60R is remarkably stable, even during prolonged growth in laboratory media and storage.

Arch Dis Child, 1991 Oct, 66(10), 1231 - 4
Prostacyclin concentrations in haemolytic uraemic syndrome after acute shigellosis in children; Alam AN et al.; The role of prostacyclin in the pathogenesis of haemolytic uraemic syndrome was evaluated in 11 children with acute shigellosis . Plasma concentrations of 6-keto prostaglandin, F1 alpha, a stable metabolite of prostacyclin, were measured by radioimmunoassay during acute illness, early convalescence, and after clinical recovery . Its concentration was low during acute illness in each patient, returning to normal concentrations or above at the time of the last sample . These results suggest that plasma prostacyclin may be involved in the development of the syndrome.

Epidemiol Infect, 1991 Oct, 107(2), 321 - 34
Molecular epidemiology of plasmid patterns in Shigella flexneri types 1-6; Gebre-Yohannes A et al.; A total of 123 drug-resistant and drug-sensitive Shigella flexneri types 1-6, and their Escherichia coli K12 transconjugants were used for plasmid profile analysis by agarose gel electrophoresis . Resistance factors (R-factors) were further characterized by incompatibility testing . The overall distribution of small plasmids in S . flexneri showed that a cryptic plasmid of about 4.6 Kb was found in all serotypes, and a plasmid of about 4.2 Kb was found in serotypes 1-4 . Shigella flexneri types 2, 4 and 6 showed a 6.5 Kb plasmid which correlated with SSu-resistance . All S . flexneri serotypes harboured large plasmids of about 217 Kb . Plasmid profile analysis of S . flexneri in Ethiopia showed a high degree of uniformity within individual serotypes . However, there was a limited variability which, at times, could be useful for epidemiological investigation . Shigella flexneri serotypes 1-6 harboured resistance plasmids with diverse molecular weights but mostly belonging to incompatibility groups N and X.

Am J Public Health, 1991 Oct, 81(10), 1313 - 5
Timeliness of national reporting of communicable diseases: the experience of the National Electronic Telecommunications System for Surveillance; Birkhead G et al.; The timeliness of reporting four nationally notifiable diseases was examined using data reported via the National Electronic Telecommunications System for Surveillance . Timeliness of reporting varied by disease (bacterial meningitis: median 20 days; salmonellosis: median 22 days; shigellosis: median 23 days; and hepatitis A: median 33 days) and by state . These findings indicate a need to standardize surveillance definitions and to account for reporting differences between states in interpreting regional disease trends or detecting multistate disease outbreaks.

Infect Immun, 1991 Oct, 59(10), 3463 - 71
Intercellular spread of Shigella flexneri through a monolayer mediated by membranous protrusions and associated with reorganization of the cytoskeletal protein vinculin; Kadurugamuwa JL et al.; The spread of Shigella flexneri in a monolayer of infected Henle and HeLa cells was studied by using immunofluorescence and electron microscopy . Infected cells produced numerous bacterium-containing membranous protrusions up to 18 microns in length that penetrated adjacent cells and were subsequently phagocytosed . Fluorescence staining of actin and vinculin in infected cells with phalloidin and monoclonal antibody to vinculin, respectively, demonstrated that the protrusions containing the bacteria consisted of these cytoskeletal proteins . Actin accumulated predominantly at the poles of bacteria distal to the tip of protrusions and appeared as trails extending back towards the host cell cytoplasm . Vinculin, however, was distributed uniformly around the bacteria and throughout the protrusion . A profound rearrangement of vinculin occurred in Henle and HeLa cells following infection with shigellae: whereas in uninfected cells it was distributed mainly around the cell periphery, in infected cells it concentrated mainly around clusters of bacteria in the cytoplasm . This suggests a possible involvement of the vinculin cytoskeletal protein in the intercellular spread of shigellae during an infection.

J Clin Pharm Ther, 1991 Oct, 16(5), 309 - 35
Oral enteric vaccines--clinical trials; Gilligan CA et al.; Oral enteric vaccines are reviewed with particular reference to cholera and typhoid . Enterotoxigenic E . coli, Shigella and Rotavirus vaccines are also considered . Clinical trials of those potentially useful vaccines are surveyed.

Mikrobiyol Bul, 1991 Oct, 25(4), 340 - 8
{Plasmid analysis of antibiotic resistant Shigella isolates}; Ozcengiz G et al.; A correlation between the multiple drug resistance patterns and the plasmid profiles given by 70 clinical isolates of Shigella sonnei and Shigella flexneri was investigated in this study . The most common plasmids were purified from different isolates by electroelution and characterized via restriction endonuclease digestions.

Mol Microbiol, 1991 Oct, 5(10), 2435 - 45
Sequence variation in two ipaH genes of Shigella flexneri 5 and homology to the LRG-like family of proteins; Venkatesan MM et al.; Oligonucleotide primers derived from the ipaH7.8 sequence have been used to determine the boundaries of DNA sequence homology among five ipaH genes on the invasion plasmid (pWR100) of Shigella flexneri 5, strain M9OT-W . The primary structure of IpaH4.5 has been established from DNA sequence analysis . The first 197 amino acids in IpaH7.8 were replaced in IpaH4.5 by a unique set of 251 amino acids, generating two related proteins with variable and conserved sequences . The amino-terminal region of IpaH4.5 displayed an internal repeat structure, also seen in IpaH7.8, characteristic of members of the leucine-rich glycoprotein (LRG) family . The DNA sequences of ipaH2.5 and ipaH1.4 indicate that these genes are truncated versions of ipaH7.8 . Western blot analysis of a lambda gt11 ipaH recombinant (W7) subclone demonstrated that the antigenicity of IpaH7.8 resides outside the leucine-rich repetitive region.

Zhonghua Liu Xing Bing Xue Za Zhi, 1991 Oct, 12(5), 295 - 8
{A study of ecology of Plesiomonas shigelloides}; Wang S; In order to understand further about its natural character for Plesiomonas Shigelloides (Ps) and the disease caused by this bacterial genus, we reported a special studying about ecology of Ps . We tested 398 samples from different natural water 99 strains of Ps were isolated, the average positive rate is 24.87%, the highest positive rate is in sewage-water samples . The genus of Ps can be isolated in all seasons, this rate is more in summer than in winter, its rate in pig is 2.56%, duck 21.70%, fish of fresh-water 29.22%, decorative animal 32.35% . This study have proved that Ps has birds natural host . Its positive rate is 14.70% in all population, 13.15% in diarrhoea patient, there is no significance difference (chi 2 = 0.40 P greater than 0.05), between normal and diarrhea patients . Positive rate in rural is more than city, and children higher than adult . By all 50 O sera we found that 71.08%, strains was serotype however, they fell into 42 O ser-types.

Appl Environ Microbiol, 1991 Oct, 57(10), 2912 - 7
Possible mechanisms underlying the slow lactose fermentation phenotype in Shigella spp; Ito H et al.; A Southern hybridization analysis revealed that the region homologous to Escherichia coli lacZ was present on the chromosomal DNAs of beta-galactosidase-positive Shigella strains, such as Shigella dysenteriae serovar 1 and Shigella sonnei strains, whereas this region was absent from chromosomal DNAs of beta-galactosidase-negative strains of Shigella flexneri and Shigella boydii . We found that the lacY-A region was deficient in S . dysenteriae serovar 1 and believe that this is the reason for the slow fermentation of lactose by this strain . S . sonnei strains possessed the region which hybridized with E . coli lacY-A despite their slow hydrolysis of lactose . The whole lactose-fermenting region was cloned from S . sonnei and compared with the cloned lac operon of E . coli K-12 . Both clones directed the synthesis of beta-galactosidase in an E . coli K-12 strain lacking indigenous beta-galactosidase activity (strain JM109-1), and we observed no difference in the expression of beta-galactosidase activity in S . sonnei and E . coli . However, E . coli JM109-1 harboring the lactose-fermenting genes of S . sonnei exhibited the slow lactose fermentation phenotype like the parental strain . S . sonnei strains had no detectable lactose permease activities . E . coli JM109-1 harboring the lactose-fermenting genes of S . sonnei had a detectable permease activity, possibly because of the multicopy nature of the cloned genes, but this permease activity was much lower than that of strain JM109-1 harboring the lac operon of E . coli K-12 . From these results we concluded that slow lactose fermentation by S . sonnei is due to weak lactose permease activity.

Infect Immun, 1991 Oct, 59(10), 3610 - 8
Protective ribosomal preparation from Shigella sonnei as a parenteral candidate vaccine; Levenson VI et al.; A parenteral Shigella ribosomal vaccine (SRV) was investigated in animals for safety, antibody-inducing capacity, and protective activity . Ribosomal preparations from a Shigella sonnei phase I avirulent strain were obtained and shown to possess chemical, sedimentation, and other properties typical of bacterial ribosomes . No endotoxin contamination was revealed by a ketodeoxyoctonate assay, although the presence of some kind of O antigen was evidenced by serological findings and the high activity of SRV in inducing the O-antibody response and immunological memory in animals . SRV was nontoxic in mice, guinea pigs, and monkeys and induced no local reactions when injected subcutaneously in reasonable doses . Significant protection against a local Shigella infection (Sereny test) was seen in guinea pigs injected with SRV (efficiency index, about 60%) and the specificity of the protection was evident from cross-challenge experiments . The protective efficiency of SRV was especially high in rhesus monkeys challenged orally with virulent Shigella cells (89%, as calculated from the summarized data of several experiments in 71 animals) . Protection in monkeys was long lasting and could be demonstrated several months after injection of SRV . An inexpensive technique can be used for the production of SRV on a large scale . The high immunogenicity of SRV is discussed in terms of the amplifying effect of the ribosome, which serves as a delivery system for polysaccharide O antigen . Further study of SRV as a candidate vaccine for humans seems justified by the data obtained.

Am J Epidemiol, 1991 Sep 15, 134(6), 614 - 27
Epidemiologic patterns of acute diarrhea and endemic Shigella infections in children in a poor periurban setting in Santiago, Chile; Ferreccio C et al.; To prepare a field site for evaluating preventive interventions against endemic shigellosis, the authors followed prospectively a cohort of 360 children (90 each of children aged 0-11, 12-23, 24-35, and 36-47 months) in Santa Julia, a low socioeconomic area in Santiago, Chile, from November 1986 through April 1989 with twice weekly household visits for diarrheal disease; infants replaced children who reached 60 months of age . Coprocultures on 2 consecutive days from children with diarrhea and from age-matched controls within the cohort were cultured for Shigella . Bacteriologic surveillance was also maintained in the health center and children's hospital serving Santa Julia . In this community, where all households had access to potable water (68% inside) and all but 3% had access to a toilet, but where there was marked crowding, the overall incidence of diarrheal disease in the cohort was low (2.26 episodes/12 child months of observation in children aged 0-11 months and 2.09 in those aged 12-23 months), yet Shigella infections were common . Shigella accounted for 10% of diarrheal episodes in the cohort (vs . 3.2% isolation rate in controls, p less than 0.0001) . The incidence of shigellosis in children aged 12-47 months was 0.16 cases per 12 child months of observation; in the first 5 years of life, a child had a 67% chance of experiencing shigellosis . Shigella sonnei, Shigella flexneri 2a, and S . flexneri 6 caused greater than 79% of the infections . Shigella occurred more often in hospitalized cases of diarrhea than in age-matched cases detected in the health center or by household surveillance (p less than 0.0001) . An initial episode of Shigella diarrhea did not diminish overall the risk of subsequent shigellosis but did confer 72% protection (p = 0.05) against illness due to the homologous serotype . The high rate of both S . sonnei and S . flexneri shigellosis in a population with a low background rate of diarrhea makes Santa Julia an appropriate site for assessing the efficacy and effectiveness of measures to reduce Shigella infections.

Rev Infect Dis, 1991 Sep-Oct, 13(5), 865 - 6
Listeriosis following shigellosis; Lorber B; In 1987 an outbreak of illness due to Listeria monocytogenes occurred in Philadelphia . In contrast to previously studied outbreaks, no source of infection or vehicle of transmission could be identified, and several listerial strains were found to be involved . A hypothesis that was developed and eventually published suggests that clinical listeriosis may occur when individuals who are asymptomatic for listerial infection but whose gastrointestinal tract has been colonized by Listeria organisms become infected with another pathogen . The case of a farmer who developed a brain stem abscess due to L . monocytogenes following an episode of acute enteritis due to Shigella sonnei lends support to this hypothesis.

Parasite Immunol, 1991 Sep, 13(5), 551 - 64
The prophenoloxidase system and in vitro interaction of Trypanosoma rangeli with Rhodnius prolixus and Triatoma infestans haemolymph; Gregorio EA et al.; The presence of the prophenoloxidase (proPO) system in the haemolymph of Rhodnius prolixus and Triatoma infestans and the role played by Trypanosoma rangeli in the in vitro activation of proPO were tested . Both R . prolixus and T . infestans whole blood preparations showed a very active ProPO system . The proPO cascade of the two insect species were differentially activated by microbial-derived extracts: laminarin was a better activator of T . infestans haemolymph than of R . prolixus blood, and lipopolysaccharides from Shigella flexneri or Pseudomonas aeroginosa caused significant proPO activation of T . infestans haemolymph but not of R . prolixus preparations . For the two insect species, neither T . rangeli from culture nor parasite lysates were able to trigger proPO activation . The presence of the parasite in R . prolixus haemolymph/laminarin assays, however, significantly reduced the level of proPO activation to that of spontaneous activating controls . The immobilization of T . rangeli in vitro in haemolymph preparations occurred in both insect species and was dependent on the proPO activation intensity . Our results suggest that the susceptibility of R . prolixus to T . rangeli haemocoel infection may be explained, at least in part, by the suppression of the insect immune defence system i.e., inhibition of proPO in the presence of this protozoan parasite.

APMIS, 1991 Sep, 99(9), 787 - 96
Shigella flexneri infection: a histopathologic study of colonic biopsies in monkeys infected with virulent and attenuated bacterial strains; Karnell A et al.; Macaca fascicularis monkeys were orally infected with live virulent Shigella flexneri wild-type strains of either serotype Y (S . flexneri SFL1), 2a (S . flexneri M4243) or 1b (S . flexneri SFL27) . Clinical signs of shigellosis varied from mild watery diarrhea (SFL1) to dysentery (M4243, SFL27), with a fatal outcome in two monkeys (SFL27) . Colonoscopy showed slight pathologic changes in monkeys infected with SFL1, and pronounced changes in monkeys infected with SFL27 . In colonic biopsies the most severe acute inflammation, with surface epithelial erosions and ulcerations, was seen after infection with SFL27, followed by SFL1, and M4243 . The live S . flexneri serotype Y vaccine strain SFL114, derived from SFL1 and attenuated because of an inactivated aroD gene and hence auxotrophic for p-aminobenzoic acid, caused no diarrheal illness in 14 monkeys . In colonic biopsies, SFL114 only elicited a slight acute inflammatory reaction . Vaccinated monkeys were protected against clinical disease when challenged with any one of the three virulent S . flexneri wild-type strains . Histopathologically, the acute inflammation was of less intensity than that seen in non-vaccinated monkeys . A good correlation between clinical signs, endoscopic findings and the degree of acute inflammation was demonstrated for monkeys vaccinated with SFL114 and challenged with either SFL1 or SFL27.

J Infect Dis, 1991 Sep, 164(3), 533 - 7
Effect of prior infection with virulent Shigella flexneri 2a on the resistance of monkeys to subsequent infection with Shigella sonnei; Formal SB et al.; All virulent shigellae have large plasmids . Plasmid-associated genes encode the expression of membrane-associated proteins (MAP), some of which correlate with the ability to invade susceptible epithelial cells . These MAP are serologically related in all of the shigella serotypes and evoke an antibody response after infection . To determine whether the MAP have a significant role in protection, 24 monkeys were infected with virulent Shigella flexneri 2a . After recovery, one group (with controls) was rechallenged with S . flexneri 2a; another group (with controls) was fed Shigella sonnei . The animals that were rechallenged with S . flexneri 2a were protected, while those that were fed S . sonnei experienced the same incidence of disease as controls . No differences in serum immune response to MAP after primary infection with S . flexneri were detected in immunoblots using lysates of S . flexneri or S . sonnei or in ELISA using water extracts of these strains.

Gastroenterology, 1991 Sep, 101(3), 626 - 34
Intestinal obstruction during shigellosis: incidence, clinical features, risk factors, and outcome; Bennish ML et al.; To determine the incidence and outcome of intestinal obstruction during shigellosis, the authors assessed 1211 consecutive patients with shigellosis admitted during a 15-month period to a diarrhea treatment center in Dhaka, Bangladesh . Obstruction was identified in 30 (2.5%) patients . Ten (33.3%) of these patients died, compared with 97 (8.2%) of the 1181 patients without obstructions (P less than 0.001; RR = 4.1) . In a case-control study, patients with obstructions were compared with 30 control patients with shigellosis but without obstructions . Case and control patients were similar in age (median, 18 months vs . 24 months; NS) . Before admission to the hospital, case patients had less often been breast-fed than control patients (33% vs . 85%; P = 0.006) and had more often received antimicrobial agents (53% vs . 13%; P = 0.001) . Case patients more often had abdominal tenderness (73% vs . 13%; P less than 0.001), altered consciousness (50% vs . 17%; P = 0.006), and Shigella dysenteriae type 1 infection (73% vs . 27%, P = 0.001) and had a higher median blood leukocyte count (40 x 10(3)/microL vs . 14 x 10(3)/microL; P = 0.007) and serum potassium concentration (5.0 mmol/L vs . 4.3 mmol/L; P = 0.016), and lower median serum sodium (123 mmol/L vs . 131 mmol/L; P = 0.003) and total protein (52 g/L vs . 60 g/L; P = 0.025) concentrations than did control patients . Eight (27%) patients with obstructions developed the hemolytic-uremic syndrome, compared with none of the control patients (P = 0.003) . It was concluded that obstruction is an ominous complication of shigellosis and that therapies in addition to provision of antimicrobial agents need to be evaluated.

Am J Prev Med, 1991 Sep-Oct, 7(5), 292 - 7
Evaluation of an intervention program in the control of an urban outbreak of shigellosis; Mahoney FJ et al.; Community-wide outbreaks of shigellosis are a persistent public health problem . We evaluated the effect of a household-based intervention program on the control of an urban outbreak of S . sonnei gastroenteritis . During the intervention we attempted to contact all households with culture-confirmed S . sonnei and provide education in methods to prevent spread of Shigella . Subsequently we conducted a survey of intervention (n = 43) and nonintervention (n = 33) households . We also conducted a serosurvey of children three to five years of age . The number of new cases of S . sonnei infection declined steadily over several months after the intervention began . Members of the intervention households were more knowledgeable about handwashing (rate ratio {RR} 4.7, 95% confidence interval {CI} = 2.1-10.8) and others methods of S . sonnei transmission and control than members of nonintervention households . However, intervention households had higher attack rates of Shigella-associated diarrhea in susceptible household members (RR 1.4, 95% CI = 1.0-2.0) . During the intervention we were able to contact only 25% of households by the eighth day after onset of diarrhea in the index case, when 90% of intrahousehold transmission of Shigella had already occurred . Two months after the outbreak ended, 42% of children in the outbreak community had elevated antibody titers against S . sonnei; an additional 19% had borderline elevated titers . The intervention program improved knowledge but may have occurred too late to prevent intrahousehold transmission of Shigella . Exhaustion of susceptible hosts, rather than the education program, likely accounted for the decline in shigellosis cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Trans R Soc Trop Med Hyg, 1991 Sep-Oct, 85(5), 664 - 6
Effect of duration of diarrhoea and predictive values of stool leucocytes and red blood cells in the isolation of different serogroups or serotypes of Shigella; Hossain MA et al.; Diarrhoeal stools from 11,358 patients were microscopically examined for the presence of white and red blood cells (WBC and RBC) and cultured for enteric pathogens . Of the 3895 patients who had Shigella as sole pathogens, 2681 (72.3%) showed the presence of both WBC and RBC and the remainder had only WBC (P less than 0.001) . The presence of both WBC and RBC was as good a predictor of shigellosis as the presence of greater than 25 WBC per high power field (hpf) of the microscope with or without RBC . However, the best predictor of shigellosis (positive predictive value 85%, negative predictive value 83%) was the presence of greater than 25 WBC/hpf and the presence of RBC regardless of their number . More patients infected with S . dysenteriae 1, S . flexneri and S . boydii shed both WBC and RBC than those infected with S . sonnei, most of whom shed WBC only (P less than 0.001) . A greater number of patients infected with S . dysenteriae 1 shed more WBC and RBC than those infected with S . flexneri (P less than 0.001) . The same trend was found when patients infected with S . flexneri were compared with those infected with S . boydii (though the difference was not statistically significant) and when patients infected with S . boydii were compared with patients infected with S . sonnei (P less than 0.001) . There was a progressive decline in the isolation rate of Shigella as the duration of dysentery, before stool culture, increased.

J Clin Microbiol, 1991 Sep, 29(9), 1910 - 4
Detection of Shiga toxin-producing Shigella dysenteriae type 1 and Escherichia coli by using polymerase chain reaction with incorporation of digoxigenin-11-dUTP; Jackson MP; A technique has been developed for the detection of Shiga toxin- and Shiga-like toxin type I (ShT/SLT-I)-producing Shigella dysenteriae type 1 and Escherichia coli by using the polymerase chain reaction with the incorporation of digoxigenin-11-dUTP . Target DNA liberated from whole cells was amplified, using primer pairs homologous to the A-subunit genes of ShT/SLT-I . The TTP analog digoxigenin-11-dUTP was incorporated into the reaction mixture, permitting nonradioactive labeling of the amplified DNA . The labeled polymerase chain reaction products were hybridized to specific gene sequences immobilized on a nitrocellulose membrane and detected by using an alkaline phosphatase-conjugated antibody to digoxigenin and the enzyme substrates . Toxin-producing strains of E . coli and S . dysenteriae type 1 were identified as colored spots on the membrane . Because this technique does not require DNA purification, gel electrophoresis, or radioactive DNA probes, it is suitable for the clinical detection of ShT/SLT-I-producing strains of S . dysenteriae type 1 and E . coli.

Mol Microbiol, 1991 Sep, 5(9), 2217 - 21
Nucleotide sequence of the ipaBCD structural genes of Shigella dysenteriae; Yao R et al.; A 9 kb EcoRI and two PstI fragments from the virulence plasmid of Shigella dysenteriae CG097 were shown to contain all ipa genes by probing with Shigella flexneri ipaB, -C, -D and -A gene probes . The DNA sequences of S . dysenteriae ipaBC genes were very similar to those of S . flexneri M90T and S . flexneri YSH6000, but ipaD differed by 22 codons from that of S . flexneri . The differences in ipaD may account for the different in vitro host specificities shown by S . dysenteriae and S . flexneri . The nucleotide composition of ipa genes revealed an unusually large number of codons that are rarely used in Escherichia coli chromosomal genes, indicating a different origin.

Mol Microbiol, 1991 Sep, 5(9), 2171 - 80
Construction of a physical map of the chromosome of Shigella flexneri 2a and the direct assignment of nine virulence-associated loci identified by Tn5 insertions; Okada N et al.; To establish the molecular basis of the chromosomal virulence genes of Shigella flexneri 2a (YSH6000), a Notl restriction map of the chromosome was constructed by exploiting Notl-linking clones, partial Notl digestion and DNA probes from various genes of Escherichia coli K-12 . The map revealed at least three local differences in the placements of genes between YSH6000 and E . coli K-12 . Using the additional Notl sites introduced by Tn5 insertion, nine virulence loci identified previously by random Tn5 insertions were physically mapped on the chromosome . To demonstrate the versatility of the Notl map in direct assignment of the virulence loci tagged by Tn5 to a known genetic region in E . coli K-12, the major class of avirulent mutants defective in the core structure of lipopolysaccharide (LPS) was examined for the sites of Tn5 insertions . The two Notl segments created by the Tn5 insertion in the Notl fragment were analysed by Southern blotting with two DNA probes for the 5' and 3' flanking regions of the rfa region, and shown to hybridize separately with each of them, confirming the sites of Tn5 in the rfa locus . This approach will facilitate direct comparison genetically mapped Tn5 insertion mutations of S . flexneri with genes physically determined in E . coli K-12.

Am J Epidemiol, 1991 Aug 15, 134(4), 413 - 20
An outbreak of shigellosis aboard a cruise ship caused by a multiple-antibiotic-resistant strain of Shigella flexneri; Lew JF et al.; From October 23 to October 27, 1989, an outbreak of gastroenteritis occurred aboard a cruise ship in the Caribbean . The 818 passengers and 518 crew members were surveyed for gastrointestinal symptoms; 72 (14%) of 512 passengers and 12 (3%) of 388 crew members who answered the survey reported having a diarrheal illness . Multiple-antibiotic-resistant Shigella flexneri 4a was isolated from 19 ill passengers and two ill crew members . Thirteen people were hospitalized, and prolonged duration of illness was associated with taking an antibiotic to which the isolated strain of Shigella was resistant . A case-control study of food items implicated German potato salad as the vehicle of transmission . It was prepared and probably infected by a food handler from a country where multiple-antibiotic-resistant Shigella is common . Spread may have been facilitated by the limited availability of toilet facilities for the galley crew . This outbreak demonstrates how antibiotic-resistant strains can be introduced into the United States, where they can pose treatment problems . The continuing problem of foodborne gastrointestinal disease in settings such as cruise ships underscores the need for basic hygienic control for food handlers and food preparation areas . In addition, the availability of adequate working conditions for crew members, including appropriately furnished toilet facilities, may be important issues that must be addressed in order to decrease the frequency of diarrhea outbreaks aboard cruise ships.

Microb Pathog, 1991 Aug, 11(2), 129 - 35
Differences in blood group B-specific mucinase activity between virulent and avirulent Shigella flexneri 2a strains; Prizont R et al.; Based on our previous findings we postulate that the production of blood group B-degrading mucinase by Shigella flexneri 2a is related to virulence . The virulent S . flexneri 2a strain M4243 produced a blood group B mucinase which decreased the blood group B reactivity of germ-free mouse mucins by a factor of 16 and the B reactivity of human saliva by a factor of 32 . Avirulent S . flexneri 2a B-1, serologically similar, but not genetically identical to the M4243 strain, failed to degrade the blood group reactivity . The mucin-degrading ability of S . flexneri 2a M4243 harboring a large virulence-conferring 140 MDa plasmid was then compared with a genetically similar large plasmid-free avirulent S . flexneri 2a M4243A1 . Virulent S . flexneri M4243 grew in human salivary mucins while the genetically identical avirulent M4243A1 did not . Supernatant of virulent M4243 culture decreased the blood B reactivity of salivary mucins by a factor of 32 while the avirulent M4243a1 had no effect . Eleven of 12 colonies of the transconjugant hybrid Escherichia coli K12 (7300-1-5) containing the shigella PWR 110 plasmid and chromosomal markers decreased the blood group B reactivity by a factor of 4-32, and two of four colonies of the E . coli strain 7262 containing only the plasmid reduced the B reactivity by a factor of 4-16 . These findings suggest that blood group B-specific mucinase production may be related to S . flexneri virulence.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Aug, (8), 5 - 9
{The protective properties of the endotoxin protein}; Levenson VI et al.; The isolation and properties of endotoxin protein, or lipid A-associated protein (LAP), from Shigella sonnei were described earlier (Zh . mikrobiol . epidemiol . immunobiol., 1991, No . 4, pp . 11-17, and No . 7) . In this report the data on its protective activity are presented . In experiments on mice one nanogram of LAP injected i . v . protected 50% of the animals against i . p . challenge with 40 LD50 of virulent S . sonnei . Guinea pigs injected s . c . with 10 micrograms of LAP were protected against local (keratoconjunctival) challenge with S . sonnei, the efficiency of immunization being 58% . LAP preparations containing no detectable amounts of O-antigen (less than 0.003%) were found to have a protective effect . Hyperimmune anti-LAP rabbit serum prevented local infection when incubated with S . sonnei challenge inoculum before injection into guinea pigs . Both active and passive protection induced by LAP was specific since no effect was observed in animals challenged with Shigella flexneri . In the homologous system the protective effect of anti-LAP serum was abolished by the addition of protein-free LPS . These results are compatible with the hypothesis that the protective activity of LAP depends on the presence of minute amounts of O-antigen whose immunogenic effect is greatly amplified by the protein component of the natural endotoxin complex.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Aug, (8), 43 - 6
{Shigellosis in the USSR: the biochemical picture of Shigella sonnei}; Solodovnikov IuP; The article deals with original data characterizing the biochemical picture of S . sonnei circulating in the USSR in 1983-1985 . Sub-biovars IIe, IIg and Ia have been shown to prevail practically in all regions, irrespective of the intensity of functioning of the centralized alimentary and chronic water routes of transmission of shigellae . These sub-biovars most frequently cause significant alimentary outbreaks of Sonne dysentery transmitted with milk . Doubts are expressed concerning the importance of the immunological factor in the formation of the biochemical picture of S . sonnei . The necessity of the additional differentiation of strains belonging to the prevalent sub-biovars for epidemiological purposes is emphasized.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Aug, (8), 23 - 7
{The dynamics of the formation of an infection focus in the intestines}; Bondarenko VM et al.; The problem of the stability of the development of Shigella population in the intestine, depending on the dose of the infective agent, is analyzed . The agent is reproduced in the intestinal mucosa in short cycles, starting with adhesion and followed by penetration, intracellular multiplication and, finally, emission of free bacteria and hulled tops of villi with Shigella intracellular microcolonies . This form of emission maintains high concentration of bacteria and ensures, in case of the adhesion of hulled material, high local concentration provoking the repetition of the cycle . Depending on the dose, chains of cycles either progressively develop or maintain a constant level, or become extinct . Stable development of the chains of infectious cycles forms a focus of infection in the body (in the intestine) . The growth of the populations of infective agents in live tissues, following the chain of cycles, produces a new type of microbial culture, differing from the types obtained by batch and flow cultivation . The aggregation and accumulation of infective agents in the hulled material is the particular case of the formation of infections, highly active particles and accumulations of infective agents, ensuring the development of infection with a relatively small number of organisms.

J Clin Pathol, 1991 Aug, 44(8), 667 - 9
Infections in British clinical laboratories, 1988-1989; Grist NR et al.; During 1988-89 this continuing survey showed 18 infections in the staff of laboratories reporting from 166 centres, representing 21,756 person-years of exposure . Shigella and other bowel infections (one caused by S typhi) predominated, affecting 11 microbiology medical laboratory scientific officers . Three shigella infections originated from quality control samples . Pulmonary tuberculosis affected four workers, including two mortuary technicians, but without detected occupational exposure to Mycobacterium tuberculosis . Other infections included one caused by Brucella melitensis . Hepatitis was not reported . The sustained low level of hepatitis is encouraging and suggests a low risk to staff of bloodborne infections such as human immunodeficiency virus.

Infect Immun, 1991 Aug, 59(8), 2706 - 11
Iron uptake in Plesiomonas shigelloides: cloning of the genes for the heme-iron uptake system; Daskaleros PA et al.; The iron uptake systems of Plesiomonas shigelloides strains were determined . Siderophore production was not detected by chemical or biological assays, and the strains tested were unable to use enterobactin, aerobactin, or vibriobactin for growth in low-iron media . Both hemin and hemoglobin supported full growth of the bacteria in media lacking other iron sources, but neither transferrin nor lactoferrin served as a source of iron . Hemolysin was detected, and the production of hemolysin was iron repressible . DNA sequences encoding hemolysin production and DNA sequences encoding the ability to use heme or hemoglobin as a sole source of iron were cloned from P . shigelloides and expressed in Escherichia coli . The abilities to use heme and hemoglobin as iron sources were closely linked, and the cloned sequences encoded the ability to transport the porphyrin, as well as iron, into the cells.

J Infect Dis, 1991 Aug, 164(2), 344 - 52
Evaluation of the role of Shiga and Shiga-like toxins in mediating direct damage to human vascular endothelial cells; Tesh VL et al.; Infection with Shiga toxin- and Shiga-like toxin-producing strains of Shigella dysenteriae and Escherichia coli, respectively, can progress to the hemolytic-uremic syndrome . It has been hypothesized that circulating Shiga toxin, Shiga-like toxins, and endotoxins may contribute to the disease by directly damaging glomerular endothelial cells . The effects of these toxins on HeLa, Vero, and human vascular endothelial cells (EC) were examined . Confluent EC were sensitive to Shiga toxin but were at least 10(6)-fold less sensitive to the toxins than were Vero cells . Shiga toxin was the predominant cytotoxic factor . Lipopolysaccharides were not cytotoxic and did not augment Shiga toxin-mediated toxicity . Lower doses of Shiga toxin caused cytotoxicity when coincubated with tumor necrosis factor . The relative resistance of EC to Shiga toxin and Shiga-like toxins may be due to reduced toxin binding, as low levels of globotriaosylceramide (Gb3), the toxin-specific receptor, were found in EC membranes.

Carbohydr Res, 1991 Jul 30, 214(2), 289 - 97
Structure of the O-antigen of Francisella tularensis strain 15; Vinogradov EV et al.; The O-specific polysaccharide, obtained by mild acid degradation of the lipopolysaccharide of Francisella tularensis strain 15, contained 2-acetamido-2,6-dideoxy-D-glucose (D-QuiNAc), 4,6-dideoxy-4-formamido-D-glucose (D-Qui4NFm), and 2-acetamido-2-deoxy-D-galacturonamide (D-GalNAcAN) in the ratios 1:1:2 . Tri- and tetra-saccharide fragments were obtained on treatment of the polysaccharide with anhydrous hydrogen fluoride and partial hydrolysis with 0.1 M hydrochloric acid, respectively . On the basis of 1H- and 13C-n.m.r . spectroscopy of the polysaccharide and the saccharides, it was concluded that the O-antigen had the structure: ----4)-alpha-D-GalpNAcAN-(1----4)-alpha-D-GalpNAcAN-(1----3) -beta-D-QuipNAc-(1----2)-beta-D-Quip4NFm-(1---- . This O-antigen is related in structure to those of Pseudomonas aeruginosa O6, immunotype 1, and IID 1008, and Shigella dysenteriae type 7.

Nature, 1991 Jul 11, 352(6331), 168 - 72
Structure of the detoxification catalyst mercuric ion reductase from Bacillus sp . strain RC607; Schiering N et al.; Several hundred million tons of toxic mercurials are dispersed in the biosphere . Microbes can detoxify organo-mercurials and mercury salts through sequential action of two enzymes, organomercury lyase and mercuric ion reductase (MerA) . The latter, a homodimer with homology to the FAD-dependent disulphide oxidoreductases, catalyses the reaction NADPH + Hg(II)----NADP+ + H+ + Hg(0), one of the very rare enzymic reactions with metal substrates . Human glutathione reductase serves as a reference molecule for FAD-dependent disulphide reductases and between its primary structure and that of MerA from Tn501 (Pseudomonas), Tn21 (Shigella), p1258 (Staphylococcus) and Bacillus, 25-30% of the residues have been conserved . All MerAs have a C-terminal extension about 15 residues long but have very varied N termini . Although the enzyme from Streptomyces lividans has no addition, from Pseudomonas aeruginosa Tn501 and Bacillus sp . strain RC607 it has one and two copies respectively of a domain of 80-85 residues, highly homologous to MerP, the periplasmic component of proteins encoded by the mer operon . These domains can be proteolytically cleaved off without changing the catalytic efficiency . We report here the crystal structure of MerA from the Gram-positive bacterium Bacillus sp . strain RC607 . Analysis of its complexes with nicotinamide dinucleotide substrates and the inhibitor Cd(II) reveals how limited structural changes enable an enzyme to accept as substrate what used to be a dangerous inhibitor . Knowledge of the mode of mercury ligation is a prerequisite for understanding this unique detoxification mechanism.

South Med J, 1991 Jul, 84(7), 818 - 21
Shigellosis in Kentucky, 1986 through 1989; Pelletier AR et al.; A marked increase in the number of cases of shigellosis was reported in Kentucky in 1988 . To examine reasons for this increase, we reviewed the 389 cases of shigellosis reported from 1986 through 1989 . Ninety-three percent (285/305) of cases due to known species were due to Shigella sonnei . Sixty-two percent (243/389) of cases occurred in children less than 10 years of age . The annual incidence for blacks (6.8 cases per 100,000) was nearly four times that for whites (1.8 per 100,000) . The increased number of cases in 1988 was due to outbreaks in five areas of the state, which accounted for 85% (200/234) of the cases . Three of the five outbreaks involved day-care centers . The primary mode of transmission appeared to be person-to-person; there was no evidence of a common source of infection from food or water . To prevent future outbreaks, cases of shigellosis need to be reported promptly to ensure appropriate investigation and control by local health departments.

Infect Immun, 1991 Jul, 59(7), 2341 - 50
Prospective study of systemic and mucosal immune responses in dysenteric patients to specific Shigella invasion plasmid antigens and lipopolysaccharides; Oberhelman RA et al.; Shigellosis is a major cause of infant morbidity and mortality in developing countries . To find immunological correlates of specific protection against shigellosis, we examined chronological samples of sera, stool extracts, duodenal aspirates, and saliva samples from 39 adults and 22 children with shigellosis from Peru for the presence of specific antibody to invasion plasmid antigens (Ipa) common to all virulent Shigella strains, by using both a whole-organism enzyme-linked immunosorbent assay (ELISA) and a Western blot (immunoblot) assay . Antibody responses to lipopolysaccharide (LPS) from Shigella serotypes both homologous and heterologous to the infecting strain were also determined by ELISA . ELISAs showed that the highest serum immunoglobulin G (IgG) antibody titers to Shigella whole organisms both with and without surface Ipa were found in adults and malnourished children, the two groups with the shortest and longest durations of disease, respectively . Mucosal IgA antibody titers to Shigella strains decreased over time to a much greater extent than serum IgG titers, and IgA to Ipa in mucosal secretions was found in adults and well-nourished children but not in malnourished children . The presence of mucosal antibody to Ipa may limit the spread and severity of the infection, as indicated by the prolonged illness observed in malnourished children who have no significant mucosal antibody to Shigella Ipa . Serum antibody titers to the Ipa antigens were high relative to anti-Shigella LPS antibody titers, especially in pediatric patients . In contrast to the anti-Ipa responses observed, no differences in antibody responses to LPS in children compared by nutritional status were found . High levels of serum and mucosal cross-reacting antibody to heterologous serotype LPS were found between Shigella flexneri serotypes 1a and 2a . Different patterns of immune response to Ipa proteins and LPS that may aid in the definition of Shigella antigens important in host protection were observed in adults, well-nourished children, and malnourished children.

Rev Infect Dis, 1991 Jul-Aug, 13(4), 688 - 96
Houseflies (Musca domestica) as mechanical vectors of shigellosis; Levine OS et al.; Houseflies (Musca domestica) are mechanical vectors of Shigella organisms . Seasons during which both flies and cases of dysentery are prevalent often coincide . Houseflies have an affinity for human excrement and, as documented by bacteriologic culture of trapped flies, become contaminated with Shigella organisms following contact with infected human feces . The inoculum required to transmit shigellosis is only 10-10(2) . Since houseflies cohabit with humans, they can readily contaminate food and eating utensils . With the advent of insecticides in the 1940s, intervention studies in the United States provided evidence of the role of the housefly in transmission of shigellae . In towns that were exposed to fly-control measures, the density of flies and the prevalence of carriage of Shigella organisms, diarrhea, and mortality due to diarrheal disease among young children all markedly diminished as compared with the situation in control towns . Investigations that quantitate the importance of fly-borne transmission of Shigella organisms relative to other modes of transmission and that provide evaluation of measures to diminish fly-borne transmission are warranted in developing areas.

Microbiologica, 1991 Jul, 14(3), 219 - 22
Reemergence of Shigella dysenteriae type 2 in Sicily: an epidemiological evaluation; Nastasi A et al.; Three strains of Shigella dysenteriae type 2 were isolated from a small household outbreak which occurred in Palermo, Sicily, during summer 1990 . Two isolates were recovered from hospitalized patients and one from an asymptomatic carrier . The infection could not be associated with travel to foreign countries or contact with travellers returned from abroad . Since 1953 S . dysenteriae has been never isolated in Southern Italy . The isolates from dysentery cases were susceptible to antibiotics and carried a plasmid of 120 MDa associated with a small cryptic plasmid; in contrast, the strain isolated from the healthy carrier contained an additional plasmid of approximately 40 MDa, which codified for resistance to ampicillin, streptomycin, sulfamethoxazole and trimethoprim . All strains showed some atypical biochemical properties, but their rRNA-DNA patterns of hybridization were closely similar to that of the reference strains of type 2 and easily distinguishable from those of the other types of non-Shiga bacillus reference strains . Epidemiological isolation features of these strains suggest a possible circulation of this Shigella species in Sicily . Genetic characterization of these strains may be useful for surveillance of infections by this organism.

Kansenshogaku Zasshi, 1991 Jul, 65(7), 857 - 63
{Species and serovar distribution, and drug resistance of Shigella strains isolated from imported and domestic cases in 1980-1989 in Tokyo}; Matsushita S et al.; A total of 1,189 Shigella strains consisting 804 imported and 385 domestic strains were examined for their species and serovar distribution, and their drug-resistance . In both imported and domestic strains, S . sonnei was found to be the most prevalent species, followed by S . flexneri, S . boydii and S . dysenteriae in order . In imported strains, however, the isolation frequency of S . flexneri, S . boydii and S . dysenteriae were higher than that of domestic strains, and the serovar of each species was distributed in a wider range than that of the domestic strains . The drug resistance test using chloramphenicol (CP), tetracycline (TC), streptomycin (SM), kanamycin (KM), ampicillin (ABPC), sulfamethoxazole-trimethoprim (ST), nalidixic acid (NA), fosfomycin (FOM) and norfloxacin (NFLX) showed that 80.1% of the imported strains and 82.9% of the domestic strains were resistant to any of drugs examined, although frequency of resistance varied by their species . The frequency of resistance to each drugs were SM (74.0%), TC (68.5%), CP (38.8%), ABPC (35.3%), ST (34.1%), NA (1.5%) and KM (1.0%) in imported strains, and TC (79.2%), SM (55.3%), ABPC (40.3%), CP (38.4%), ST (32.4%), NA (30.5%) and KM (4.2%) in domestic strains . No strain resistant to FOM or NFLX was found in both groups . The resistance patterns varied to 32 types . Among those, a multiple drug-resistance type with CP.TC.SM.ABPC was found most frequently in both groups . Frequency of strains carrying transferable R plasmid was tested for 50 strains isolated in 1989 and three (6%) of them had the plasmid.

J Infect, 1991 Jul, 23(1), 89 - 92
Fatal Plesiomonas shigelloides septicaemia in a splenectomised patient; Clark RB et al.; A case of fatal Plesiomonas shigelloides septicaemia is reported in a splenectomised patient . One week prior to his illness the patient was exposed to river water that was potentially contaminated with plesiomonads . Autopsy findings indicated that the plesiomonad may have invaded the blood stream through the terminal ileum.

Trop Geogr Med, 1991 Jul, 43(3), 266 - 70
Evaluation of indigenous plants in the treatment of acute shigellosis; Haider R et al.; The clinical efficacy of three indigenous plants was compared with that of ampicillin and placebo in a randomized double blind clinical trial . Eighty-two men with shigellosis were studied . Sixteen patients received dried unripe fruit powder of 'bel' (Aegle marmelos), 19 received dried powdered plant of 'thankuni' (Hydrocotyle asiatica), 15 received a similar preparation of 'gandhavadulia' (Paederia foetida), 15 received ampicillin and 17 received a placebo . Treatment with indigenous plants did not show any clinical improvement or bacteriological cure as compared to ampicillin . The natural history of shigellosis was obtained by documenting the response of the indigenous plants and placebo treated groups.

East Afr Med J, 1991 Jul, 68(7), 562 - 6
Occurrence of Plesiomonas shigelloides--associated diarrhoea in Calabar, Nigeria; Eko FO et al.; The prevalence, clinical profiles and virulence factors of Plesiomonas shigelloides were determined in patients attending the University of Calabar Teaching Hospital, Microbiology Laboratory . P . shigelloides was isolated from 12 (1.4%) of 880 patients with diarrhoea and from none of the controls (P less than 0.05) . Isolates were mostly from febrile children less than or equal to 10 years with most of the infections occurring during the rainy months . Although our findings suggest the significance of Plesiomonas in acute diarrhoea in this environment, our isolates did not seem to show any of the proxy indicators of virulence usually associated with other enteric pathogens.

Zhonghua Nei Ke Za Zhi, 1991 Jul, 30(7), 423 - 5, 457
{A study of Kirby-Bauer method of antimicrobial sensitivity test and resistant plasmid assay with 486 strains of Shigella isolated clinically}; Peng ZW et al.; 486 cases of bacillary dysentery admitted to an army hospital during the peak season (July to September) from 1986 to 1988 were studied . The pathogens in 452 cases were tested for antimicrobial sensitivity with 14 kinds of antibiotics by using Kirby-Bauer method recommended by WHO . The results showed that the number of antibiotics to which the dysentery bacteria became resistant had increased . In 1986 the number was 9, while in 1987 and 1988 it increased to 12 and 13 respectively . Among the resistant strains of bacteria, 331 had been assayed for resistant plasmids . 88.8% was positive with more than three resistant plasmids . The result of antimicrobial sensitivity test coincided well with that of resistant plasmid assay.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Jul, (7), 73 - 6
{The immunogenic properties of the endotoxin protein: serum antibodies in animals and man}; Belkin ZP et al.; Endotoxin protein or lipid A-associated protein (LAP) from Shigella sonnei was isolated and characterized earlier (Zh . mikrobiol . epidemiol . immunobiol., 1991, No . 4, pp . 47-50) . In this investigation serum antibodies against LAP were studied in ELISA Anti-LAP antibodies were detected in high titers in the sera of nonimmunized mice, guinea pigs, rabbits, monkeys and healthy adults . We suppose that normal anti-LAP antibodies resulted from interaction between the immune system and environmental endotoxin . Parenteral injections of LAP to different animals induced intensive antibody response with a 100- to 1000-fold increase in the serum anti-LAP antibody level and a significant rise in the serum O-antibody level . The latter is seemingly due to the contamination of LAP with minute amounts of O-antigen (0.12% or less) and to the amplification of its immunogenicity by LAP . Both antigenic and amplifying activity of LAP was destroyed by proteinase K . The biological function of LAP and its possible use as a component of bacterial vaccines are briefly discussed.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Jul, (7), 25 - 9
{The immunogenic and serological properties of the O-specific polysaccharide (L-hapten) in Shigella}; Levenson VI et al.; O-specific polysaccharide (L-hapten) was isolated earlier (Zh . mikrobiol . epidemiol . immunobiol., 1989, No . 11, pp . 8-11) . In this paper L-hapten was shown to be unable, even at high concentrations (up to 2,000 micrograms/ml), to sensitize sheep red blood cells for passive hemagglutination by O-antibodies . At the same time classical LPS and heat-activated LPS were active at concentrations ot 32 and 8 micrograms/ml respectively . The O-antibody-neutralizing activity of L-hapten was lower than that of LPS 10(3)-10(4) times in the passive hemagglutination test and 25-50 times in competitive ELISA . The immunogenicity of isolated L-hapten was very weak: primary response in mice to the i.v . injection of 1-10 micrograms of L-hapten was similar to the effect produced by 10(-3)-10(-4) micrograms of LPS . No protective activity of L-hapten was noted in mice when the challenge dose of virulent shigellae was 16 LD50 or more, and only a weak protective effect was observed with a low challenge dose (8 LD50) . The molecular basis of low serological and biological activity of L-hapten is discussed . The most probable explanation of the results obtained in this study is that L-hapten contains some nonspecific carbohydrates, inserted in or complexed with the O-side chain . Despite its low immunogenicity, L-hapten can be an important component of effective bacterial vaccines provided it is included into a suitable delivery system as is the case with Shigella ribosomal vaccine.

MMWR Morb Mortal Wkly Rep, 1991 Jun 28, 40(25), 421, 427 - 8
Shigella dysenteriae type 1--Guatemala, 1991; Multilocus genetic relationships between clinical and environmental Aeromonas strains; Istituto Cantonale Batteriosierologico, Lugano, Universite de Geneve, SwitzerlandAllelic variations in the chromosomal genome of 120 isolates of motile Aeromonas (A . hydrophila, A . sobria and A . caviae) and eight reference strains with one Plesiomonas shigelloides were assessed by analysis of electrophoretically demonstrable polymorphism in 16 genes encoding metabolic enzymes . The strains were collected from humans (n = 59) and from the aquatic environment (n = 61) in canton Tessin, Switzerland . Clustering of the electrophoretic types (ET) from a matrix of pairwise genetic distances, based on the 16 enzyme loci, confirmed the genetic distinctness of the three species . Furthermore, A . hydrophila and A . sobria were divided in three and two groups respectively . For each species clinical strains were well differentiated from those collected in the environment.

Infect Immun, 1991 Jun, 59(6), 1997 - 2005
Two novel virulence loci, mxiA and mxiB, in Shigella flexneri 2a facilitate excretion of invasion plasmid antigens; Andrews GP et al.; A bank of over 4,200 lacZ protein fusions in Shigella flexneri 2a was screened for fusions to temperature-regulated promoters . One mutant, BS260, was completely noninvasive on HeLa cells and mapped to a region on the 220-kb virulence plasmid in which we had previously localized several avirulent temperature-regulated operon fusions (A.E . Hromockyj and A.T . Maurelli, Infect . Immun . 57:2963-2970, 1989) . The phenotype of BS260 was similar to that of the previously identified mxi (membrane expression of invasion plasmid antigens) mutants, since it made wild-type intracellular levels of the invasion plasmid antigens (Ipa) but was deficient in the surface expression of IpaB and IpaC . Six kilobases of DNA upstream of the BS260 fusion end joint were cloned, but no temperature-regulated promoter was found, whereas the fusion end joint clone of the noninvasive mxi operon fusion mutant BS226 contained a temperature-regulated promoter . The locus defined by BS260 was designated mxiA, and that defined by BS226 was designated mxiB . Closer analysis of the mxiA and mxiB phenotypes by a cell-free enzyme-linked immunosorbent assay revealed that the mutants failed to excrete IpaB and IpaC into the culture medium, whereas wild-type cells actively released these antigens . Excretion of the ipa polypeptides from wild-type bacteria was confirmed by Western blot analysis of culture supernatants . Protease protection experiments revealed that wild-type S . flexneri 2a actually had much lower levels of surface-exposed IpaB and IpaC relative to those in the total antigen pool . In addition, examination of cellular fractions showed that, although there was no IpaB or IpaC in the outer membrane of BS260 and BS226, the antigens did accumulate in the cytoplasmic membrane . A 76-kDa temperature-regulated polypeptide in wild-type S . flexneri was identified as the putative mxiA gene product . These results strongly suggest that IpaB and IpaC represent truly excreted proteins of S . flexneri and that the mxiA and mxiB loci on the plasmid code for accessory proteins required to facilitate their export through the bacterial outer membrane . These data also suggest that mxiA is part of an operon that specifies additional mxi genes . The products of this operon may constitute a unique multicomponent protein secretion apparatus involved in the transport of Shigella virulence determinants.

Mol Gen Mikrobiol Virusol, 1991 Jun, (6), 3 - 9
{Virulence plasmids of Shigella bacteria}; Romanova IuM; The contemporary data on the genetical control of invasion process in dysentery causative agent coded by the virulence plasmids of the bacteria are presented . The examples of plasmid genes expression regulated by the genes-regulators located on the chromosome are presented . The mechanism for virulence genes regulation is discussed.

J Assoc Physicians India, 1991 Jun, 39(6), 452 - 3
Blood group and shigellosis; Sinha AK et al.; A study on the distribution of ABO blood groups was carried out on 85 patients with clinically and bacteriologically proven shigellosis . A significant association (P less than 0.01) of blood group B was observed with shigellosis cases in comparison to controls from whom no Shigella species or other enteropathogen could be isolated . Patients with isoagglutinin B or those who possess blood group B antigen may be at a relatively increased risk of shigellosis.

J Diarrhoeal Dis Res, 1991 Jun, 9(2), 94 - 9
The epidemiology of diarrhoeal diseases in southeastern China; Chen KC et al.; In a community survey of 19,410 people for 12 months in southeastern China (Fujian Province), the overall annual incidence rate of diarrhoea was 729.9 episodes/1,000 population . The incidence varied with different age groups; children aged under five years had the highest rate, 2.25 episodes per child per year . A bacterial pathogen was isolated from 883 cases (44.03%), and 147 (14.76%) strains from 996 healthy controls . Enterotoxigenic Escherichia coli, enteropathogenic E . coli, and Shigella species were the most frequently isolated bacterial pathogens . Isolation was highest during the hot summer months . The investigation showed that the diarrhoea incidence was related to the status of economy, education, healthy, hygiene, food, and water.

Int J Epidemiol, 1991 Jun, 20(2), 546 - 50
Sociodemographic factors associated with serum anti-Shigella lipopolysaccharide antibodies and shigellosis; Cohen D et al.; The association between various sociodemographic variables and the presence of anti-Shigella sonnei lipopolysaccharide (LPS) antibodies was examined in a random sample (N = 383) of male Israeli conscripts . Of the male conscripts, 190 (49.6%) had pre-existing antibodies against S . sonnei LPS (defined as HA titres of greater than or equal to 1:10 after treatment of sera with 2-mercaptoethanol) . Univariate analysis revealed a significant positive association between the presence of humoral anti-S . sonnei LPS antibodies and sociodemographic variables including Eastern origin (p = 0.007), low socioeconomic status (p = 0.0016), and the number of siblings (p = 0.023) . When multiple logistic regression was used to control simultaneously for the effects of the other variables, ethnic origin emerged as the strongest correlate of anti-S . sonnei LPS antibodies . On the other hand, the association of the sociodemographic variables in subjects suffering from S . sonnei infection during their military service, was in the opposite direction (p less than 0.001 for both socioeconomic status and ethnicity) . These findings suggest differences between subpopulations in acquired immunity to S . sonnei due to differences in exposure to the homologous organism prior to military service.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Jun, (6), 59 - 62
{The determination in saliva of IgA antibodies to Shigella ribosomes for the diagnosis of dysentery}; Salamatova SA et al.; The levels of antiribosomal antibodies to Shigella ribosomes in serum and saliva samples from 38 dysentery patients (15 S . sonnei cases and 23 S . flexneri cases), 14 patients with salmonellosis and 136 healthy adults were determined in ELISA with ribosomes from S . sonnei R-mutant used as solid-phase antigen . High levels of "normal" antiribosomal IgA, IgG and IgM antibodies were revealed in the sera of healthy persons while the level of salivary IgA antibodies was very low . In dysentery infection no increase in the levels of serum IgG and IgM antibodies and only a slight increase in the level of IgA antibodies were revealed . Local immune response was manifested by the early (on days 2-4 from the onset of infection) and significant augmentation (12- to 16-fold) of salivary antiribosomal IgA antibodies . An increase in the level of these antibodies was registered in 95-100% of dysentery patients but not in patients with salmonellosis, which made it possible to recommend the method for diagnosing shigellosis . Immune response to Shigella ribosomal antigens, in contrast to the response induced by Shigella O-antigen, is almost exclusively local.

Vaccine, 1991 Jun, 9(6), 416 - 22
OmpB (osmo-regulation) and icsA (cell-to-cell spread) mutants of Shigella flexneri: vaccine candidates and probes to study the pathogenesis of shigellosis; Sansonetti PJ et al.; Genetic and molecular data now available on the pathogenic properties of Shigella flexneri allow rational design of live attenuated vaccine strains . The genes required at given steps of the infection process can be selectively mutated to impair the bacterium's capacity to interact with intestinal epithelial cells and/or survive within intestinal tissues in general . We have tested two mutations in S . flexneri serotype 5a (M90T) which, alone or in combination, have yielded promising results when evaluated as vaccine prototypes in orally infected macaque monkeys . The first mutation, icsA, blocks intracellular and cell-to-cell spread of the micro-organism . This mutant (SC560) appeared reasonably well tolerated and elicited protection against homologous challenge . The second mutation, ompB, disconnects the bacterium from one of its major environmental regulatory factors, osmolarity . This mutant (SC433) still caused slight dysenteric symptoms in vaccinees . It was also perfectly protective . When these two mutations were combined, the double mutant (SC445), was perfectly tolerated but failed to protect one out of five animals . These studies bring interesting prospects of the possibility of immunizing against shigellosis . In addition to providing new possibilities for vaccine design, construction and evaluation of these mutants allowed substantial progress in understanding the pathogenesis of shigellosis.

Microbiol Rev, 1991 Jun, 55(2), 206 - 24
Genetic basis of virulence in Shigella species; Hale TL; Shigella species and enteroinvasive strains of Escherichia coli cause disease by invasion of the colonic epithelium, and this invasive phenotype is mediated by genes carried on 180- to 240-kb plasmids . In addition, at least eight loci on the Shigella chromosome are necessary for full expression of virulence . The products of these genes can be classified as (i) virulence determinants that directly affect the ability of shigellae to survive in the intestinal tissues, e.g., the aerobactin siderophore (iucABCD and iutA), superoxide dismutase (sodB), and somatic antigen expression (rfa and rfb); (ii) cytotoxins that contribute to the severity of disease, e.g., the Shiga toxin (stx) and a putative analog of this toxin (flu); and (iii) regulatory loci that affect the expression of plasmid genes, e.g., ompR-envZ, which mediates response to changes in osmolarity, virR (osmZ), which mediates response to changes in temperature, and kcpA, which affects the translation of the plasmid virG (icsA) gene which is associated with intracellular bacterial mobility and intracellular bacterial spread . A single plasmid regulatory gene (virF) controls a virulence-associated plasmid regulon including virG (icsA) and two invasion-related loci, i.e., (i) ipaABCD, encoding invasion plasmid antigens that may be structural components of the Shigella invasion determinant; and (ii) invAKJH (mxi), which is necessary for insertion of invasion plasmid antigens into the outer membrane.

FEMS Microbiol Immunol, 1991 Jun, 3(3), 165 - 70
Potentials of Shigella flexneri Y strain TSF21 as a candidate vaccine against shigellosis: safety, immunogenicity and protective efficacy in Bonnet monkeys; Ashraf MM et al.; A thymine-requiring and temperature-sensitive mutant of Shigella flexneri Y was tested in Bonnet monkeys for safety, immunogenicity and protective efficacy . A dose of 10(11) cells when fed orally mimicked natural infection in having invaded epithelial cells, but was otherwise clinically non-reactogenic . Animals immunized with two oral doses, each dose consisting of 1 x 10(11) mutant bacteria, were fully protected when challenged, with respect to the lack of any clinical symptoms or detectable histological abnormalities in the intestinal mucosa . Unimmunized animals when similarly challenged developed frank dysentery and the intestinal mucosa showed severe histological abnormalities . Titres of serum antibodies increased by about 11-fold of the base level in animals immunized with a dose of 10(11) cells, but not with lower doses . The challenge bacteria appeared to be phagocytised by macrophages . In some monkeys of a particular group, congestive patches were seen in the stomach, but not in any other part of the gut, after the animals were fed with the virulent parent strain . The lesions were relatively severe in the immunized groups of animals.

Bull Acad Natl Med, 1991 Jun-Jul, 175(6), 803 - 9; discussion 809-10
{Molecular and cellular bases of Shigella flexneri virulence}; Sansonetti PJ; Shigella flexneri, a Gram negative bacillus, causes bacillary dysentery, an ulcerative disease of the human colon, by invading intestinal epithelial cells . Entry into epithelial cells occurs via an induced phagocytic process which involves the actino-myosin complex . The host-cell receptor and the transmembrane signal which initiate reorganization of the cytoskeleton are under study . Binding to integrins has recently been demonstrated in related models such as the entry of Yersinia pseudotuberculosis and Bordetella pertussis into cells . Bacterial genes necessary to achieve entry are located on five contiguous loci covering 30 kb on a 220 kb virulence plasmid in S . flexneri . Locus 2 has been particularly studied . Six genes organized as an operon encode highly immunogenic proteins among which IpaB (62 kD) and IpaC (48 kD) are the invasins of this microorganism which subsequently grows very rapidly within infected cells due to its capacity to lyse the membrane bound phagocytic vacuole . Once free within the cytoplasm, bacteria interact again with the cell cytoskeleton . They first express Olm (organelle like movement), a phenotype reflecting intracellular movement along actin stress cables . They subsequently express Ics (intracellular spread), a phenotype by which intracellular bacteria induce nucleation and polymerization of actin followed by accumulation of this material at one end of the bacillus . This process causes rapid random movement leading to the formation of protusions which allow passage to adjacent cells . A combination of these two movements achieves bacterial colonization of the epithelium.

Mol Microbiol, 1991 Jun, 5(6), 1491 - 9
Genetic analysis of the rfb region of Shigella flexneri encoding the Y serotype O-antigen specificity; Macpherson DF et al.; The gene cluster (rfb region) which determines the biosynthesis of the Shigella flexneri O-antigen of the Y serotype specificity was cloned from a S . flexneri serotype 2a strain . Two plasmids, pPM2212 and pPM2213, which conferred O-antigen biosynthesis were generated from separate cosmid clones by deletion with Clal . These plasmids expressed O-antigen in Escherichia coli K12 like that of the parental strain, as assessed by reactions to antisera in colony and Western immunoblots, sensitivity to bacteriophage Sf6, and by silver staining of lipopolysaccharides separated by sodium dodecyl sulphate/polyacrylamide gel electrophoresis . These plasmids also mediated O-antigen expression in an E . coli K12 rfb-delete background, indicating that all the necessary genes have been cloned . A detailed restriction map of the region has been constructed and analysis of various subclones has allowed the limits of the coding region for O-antigen biosynthesis to be defined to a maximum of 11 kb . Expression of these plasmids demonstrates a novel phenotype associated with control of lipopolysaccharide chain length . The gene(s) responsible maps adjacent to, but separate from, those associated with the biosynthesis of the O-antigen unit . Analysis of plasmid-encoded proteins in minicells and maxicells has facilitated the construction of a physical map . Finally, plasmid pPM-2212 was used to probe a collection of S . flexneri serotypes by Southern hybridization . With the exception of serotype 6, which appears to be unrelated, a similar pattern was found in all serotypes.

Jpn J Med Sci Biol, 1991 Jun, 44(3), 141 - 6
Peritrichous flagellation in Plesiomonas shigelloides strains; Inoue K et al.; In total, 131 strains of Plesiomonas shigelloides isolated from various sources were tested for peritrichous flagella by a flagella staining method . When incubated on a solid medium for 18 hr at 25 C, peritrichous flagella were demonstrated in 89 (68%) of them . With an electron microscope, the peritrichous flagella were clearly distinguished from the lophotrichous ones by their wavelength.

Res Microbiol, 1991 Jun, 142(5), 489 - 98
Molecular typing of Shigella strains using pulsed field gel electrophoresis and genome hybridization with insertion sequences; Soldati L et al.; The genomes of 18 independent Shigella isolates (9 Shigella sonnei, 5 Shigella dysenteriae and 4 Shigella flexneri) as well as of 4 epidemic S . flexneri strains were analysed by pulsed field gel electrophoresis (PFGE) and by the distribution of insertion sequences (IS1, IS2 and IS911) . Despite the close relatedness observed among the 9 independent S . sonnei, all of them could be differentiated from each other . The 4 independent S . flexneri isolates showed clearly distinguishable DNA profiles . Nearly complete genetic identity was detected within the 4 epidemic S . flexneri when analysed by PFGE or for IS1 and IS2 patterns . However, IS911 was found to be too mobile in these epidemic S . flexneri to be used as a typing probe . The 5 S . dysenteriae isolates could also be distinguished by the techniques used . The diversity found within this species is striking: of the 5 investigated isolates, 3 completely different DNA profiles were revealed . In conclusion, both PFGE and IS probing demonstrated their potential usefulness in molecular epidemiology and in typing of Shigella strains . The degree of differentiation given by these two methods was generally comparable, although IS probes showed better discrimination of the isolates.

Experientia, 1991 May 15, 47(5), 441 - 4
The role of motile aeromonads in the fish disease, ulcerative disease syndrome (UDS); McGarey DJ et al.; Ulcerative Disease Syndrome (UDS) is an epizootic fish disease characterized by the presence of severe, open dermal ulcers on the head, midbody, and dorsal regions of the fish . Aeromonas hydrophila and A . sobria were recovered more often from UDS fish than other bacteria from the genera Vibrio, Alteromonas and Plesiomonas . Representative isolates of A . hydrophila, A . sobria, V . anguillarum, V . vulnificus, Alteromonas putrefaciens, and P . shigelloides taken from UDS and healthy fish were assayed for virulence-associated factors . The aeromonads produced a wide variety of hydrolytic enzymes and expressed cell surface characteristics linked to virulence whereas the other bacterial species rarely produced the same enzymes or cell surface characteristics . The role of aeromonads in UDS is believed to be opportunistic or secondary and these bacteria are thought to play an important role in this degenerative disease.

Experientia, 1991 May 15, 47(5), 439 - 41
Biochemical characteristics and plasmids of clinical and environmental Plesiomonas shigelloides; Kelly MT et al.; The biochemical characteristics of 68 clinical and 5 environmental Plesiomonas shigelloides isolates were determined . The reactions for ONPG, phenylalanine deaminase, motility, lactose fermentation and salicin fermentation were different from previously published findings . The reactions of the clinical and environmental isolates were very similar . The isolates were also tested for the presence of plasmids, and 40% of the strains were found to harbor between one and seven plasmids . The findings of this study will be useful for the identification and characterization of this recently recognized enteric pathogen.

J Clin Microbiol, 1991 May, 29(5), 1072 - 4
Cellular fatty acid composition of Plesiomonas shigelloides; Chou S et al.; The cellular fatty acid compositions of 29 strains of Plesiomonas shigelloides and 5 strains of Aeromonas hydrophila were studied . The cellular fatty acid compositions of all the Plesiomonas strains were identical and characterized by the presence of hexadecanoate (16:0) (33%), hexadecenoate (16:1) (28%), octadecenoate (18:1) (9%), and octadecanoate (18:0) (6%) . The cellular fatty acid composition of A . hydrophila was similar to that of the Plesiomonas strains, except that the former contained an average of 25% 16:0, 29% 16:1, 12% 18:1, and 2% 18:0 acids compared with 33, 28, 9, and 6%, respectively, for the latter . The percentage ratios of 16:1 to 16:0 and 18:1 to 18:0 could be used to differentiate P . shigelloides from A . hydrophila . These ratios were 0.8 and 1.5 for the former and 1.2 and 6.0 for the latter.

J Med Microbiol, 1991 May, 34(5), 259 - 64
The association of haemagglutination and adhesion with lipopolysaccharide of Shigella dysenteriae serotype 1; Qadri F et al.; In this study the ability of strains of Shigella dysenteriae serotype 1 to agglutinate mammalian erythrocytes is attributed to the polysaccharide fraction of bacterial-cell lipopolysaccharide (LPS) . LPS obtained from a rough, mutant strain of S . dysenteriae serotype 1, lacking the O-antigen polysaccharide side-chain, did not agglutinate erythrocytes, clearly demonstrating a link between O-antigen polysaccharides and haemagglutinating activity (HA) . Strains of S . dysenteriae serotype 1 adhered well to cultured Henle Intestinal 407 cells, whereas rough strains adhered poorly . Pre-treatment of bacteria with LPS-specific antisera inhibited both HA and binding to cultured human-intestinal cells . The contribution of the polysaccharide side-chain and its associated HA--which appear to facilitate binding to cultured cells--to bacterial attachment to colonocytes and to the pathogenesis of shigellosis in vivo needs to be confirmed in animal studies.

Infect Immun, 1991 May, 59(5), 1723 - 32
Stress fiber-based movement of Shigella flexneri within cells; Vasselon T et al.; icsA (virG), a gene located on pWR100, the virulence plasmid of Shigella flexneri serotype 5 (M90T), encodes a 120-kDa outer membrane protein . This protein promotes a random intracellular movement of the bacteria and leads to the infection of adjacent cells by the formation of protrusions . This movement, which involves the nucleation, polymerization, and subsequent polarization of actin, is referred to as the Ics phenotype (intra/intercellular spread) . Here we present evidence that a second, distinct form of locomotion is also elaborated by S . flexneri in chicken embryo fibroblasts in which the Ics phenotype is not expressed . Using a combination of phase-contrast microcinematography and confocal microscopy, we have demonstrated that bacteria adopt parallel orientations by interacting with stress fibers . This interaction subsequently results in bacterial movement along the stress fibers themselves . This phenomenon occurs independently of the presence of a phagocytic vacuole which is lysed shortly after entry of the bacteria into the cell . It is expressed by M90T and SC560, its icsA mutant . This movement has been termed organelle-like movement (Olm phenotype) and is thought to account for the early accumulation of bacteria seen near the nucleus.

Am J Public Health, 1991 May, 81(5), 637 - 9
Use of a medical center's computerized health care database for notifiable disease surveillance; Watkins M et al.; The sensitivity of a medical center's inpatient and outpatient database to detect notifiable diseases was examined . Only 53 percent of inpatient and 7 percent of outpatient laboratory-confirmed cases of shigellosis, salmonellosis, giardiasis, and hepatitis were identified by an automated search for matching diagnosis codes . Reasons for lack of sensitivity include nonavailability of laboratory results at the time of diagnosis assignment, use of a standardized encounter form with limited preselected diagnosis codes, and pre-emptying of the infectious disease diagnosis by other diagnoses.

J Cell Biol, 1991 May, 113(3), 553 - 62
Endocytosis and intracellular transport of the glycolipid-binding ligand Shiga toxin in polarized MDCK cells; Sandvig K et al.; The glycolipid-binding cytotoxin produced by Shigella dysenteriae 1, Shiga toxin, binds to MDCK cells (strain 1) only after treatment with short-chain fatty acids like butyric acid or with the tumor promoter 12-O-tetradecanoylphorbol 13-acetate . The induced binding sites were found to be functional with respect to endocytosis and translocation of toxin to the cytosol . Glycolipids that bind Shiga toxin appeared at both the apical and the basolateral surface of polarized MDCK cells grown on filters, and Shiga toxin was found to be endocytosed from both sides of the cells . This was demonstrated by EM of cells incubated with Shiga-HRP and by subcellular fractionation of cells incubated with 125I-labeled Shiga toxin . The data indicated that toxin molecules are endocytosed from coated pits, and that some internalized Shiga toxin is transported to the Golgi apparatus . Fractionation of polarized cells incubated with 125I-Shiga toxin showed that the transport of toxin to the Golgi apparatus was equally efficient from both poles of the cells . After 1-h incubation at 37 degrees C approximately 10% of the internalized toxin was found in the Golgi fractions . The results thus suggest that glycolipids can be efficiently transported to the Golgi apparatus from both sides of polarized MDCK cell monolayers.

J Appl Bacteriol, 1991 May, 70(5), 394 - 400
A rapid fluorogenic method for the detection of Escherichia coli by the production of beta-glucuronidase; Sarhan HR et al.; A medium containing the fluorogenic substrate 4-methylumbelliferyl-beta-D-glucuronide was developed for the isolation and identification of Escherichia coli within 7.5 h and was based on the detection of beta-glucuronidase . Optimum conditions for the rapid development of fluorescent colonies were determined . The optimum temperature was 41.5 degrees C . Development of fluorescence was delayed when carbohydrates were incorporated into the medium . Water samples were used to evaluate the medium by surface plating and membrane filtration . The frequency of false-negative results was 6.1% and false-positives were 3.7% for freshwater samples . The false-positive organisms were identified as Klebsiella spp . and Shigella sonnei . The potential applications of the medium are discussed.

Vaccine, 1991 May, 9(5), 358 - 63
Virulence phenotype and genetic characteristics of the T32-ISTRATI Shigella flexneri 2a vaccine strain; Venkatesan M et al.; The T32-ISTRATI strain, which has been used as an oral attenuated Shigella flexneri 2a vaccine, has lost the invasive phenotype due to a spontaneous deletion in the shigella virulence plasmid . This deletion has eliminated three plasmid loci (ipaBCDA, invA and virG) that are necessary for production of a positive Sereny test by Shigella species . Virulence in the Sereny test was reconstituted in the T32-ISTRATI strain by the conjugal transfer of an intact 140 M Da virulence plasmid from S . flexneri 5 . The T32-ISTRATI vaccine is safe when given orally in multiple doses of 50-100 x 10(9) organisms, and both homologous and heterologous protection has been reported in large Romanian and Chinese field trials . Although the protective antigen(s) in this vaccine have not been identified, the potential use of non-invasive plasmid deletion mutants as living shigella vaccines is illustrated by the T32-ISTRATI vaccine.

Can J Microbiol, 1991 May, 37(5), 407 - 10
Comparison of colony and stool blots for detection of enteropathogens by DNA probes; Vieira MA et al.; DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathogens . The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe . The specificity of all probes is higher than 95% . In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E . coli infections than the colony blots.

Zhonghua Yi Xue Za Zhi (Taipei), 1991 May, 47(5), 362 - 8
Plesiomonas shigelloides--associated diarrhea; Yeh TJ et al.; Although Plesiomonas shigelloides is considered to be a cause of diarrhea in the Orient, it has infrequently been noted to be associated with diarrhea in Taiwan . Six cases of various extent of diarrhea were found to be associated with P . shigelloides in stool culture in this department between January 1987 and December 1988 . Only two of them had history of chronic diarrhea and the others had mild or even no symptom . All six strains of this organism were susceptible to most commonly used antibiotics, but resistant to ampicillin, carbenicillin, clindamycin, oxacillin, penicillin, and vancomycin . Those which required least minimal inhibitory concentration (MIC) were cefazolin, ceftazidime, cefuroxime, ciprofloxacin, and trimethoprim/sulfamethoxazole . Our experiences showed that P . shigelloides may cause mild diarrhea in normal hosts . It sometimes is an incidental finding . An oxidase test for this organism should be included as routine culture of the stool specimen, but treatment is not always necessary.

Lancet, 1991 Apr 27, 337(8748), 993 - 7
Reduction of transmission of shigellosis by control of houseflies (Musca domestica)
Cohen D, Green M, Block C, Slepon R, Ambar R, Wasserman SS, Levine MM.
The effect of control of houseflies on the incidence of diarrhoea and shigellosis was evaluated in a prospective crossover intervention study at two military field bases several kilometers apart . In early summer, 1988, intensive fly control measures (mainly bait and trap strategy) were introduced on one base, while the other served as a control . After 11 weeks, as new cohorts arrived, the intervention was abruptly discontinued in the first base and instituted in the second for the next 11 weeks . The study was repeated the next summer . Overall, fly counts were 64% lower on the bases exposed to fly control measures (p = 0.024) . Concomitantly, clinic visits dropped by 42% (p = 0.146) for diarrhoeal diseases and by 85% for shigellosis (p = 0.015), as did rates of seroconversion, by 76% (p = 0.024) for antibodies to Shigella and by 57% (p = 0.006) for antibodies to enterotoxigenic Escherichia coli . The findings indicate that houseflies, acting as mechanical vectors, transmit Shigella (and possibly enterotoxigenic E coli) diarrhoeal infections.

Zhonghua Liu Xing Bing Xue Za Zhi, 1991 Apr, 12(2), 95 - 8
{A report of surveillance on acute diarrhoeal diseases in Wuwei Prefecture from 1987 to 1988}; Feng J; Surveillance on acute diarrhoeal diseases in Jinta County, Wuwei City for two successive years from January 1987 to December 1988 showed that the annual average incidence of diarrhoeal diseases was 0.079-0.124 . The total detection rate of the etiologic agent was 58.95% . Bacterial infection was predominant . Ten species of pathogenic bacteria were detected, of which shigella remained the prevalent bacteria among which flexneri appeared as the predominant species after a decline for several years since early 1980s . The percentage of rotavirus was rather low . Diarrhoea was related to multiple factors . Children under 5 years old should be regarded as the target population for the prevention . Early detection of carriers has great significance in the prevention and control of diarrhoea.

J Appl Bacteriol, 1991 Apr, 70(4), 291 - 3
Evaluation of the antimicrobial activity of methylglyoxal bis(guanylhydrazone) analogues, the inhibitors for polyamine biosynthetic pathway; Midorikawa Y et al.; Metabolic and antiproliferative effects of methylglyoxal bis(butylamidinohydrazone) (MGBB) and methylglyoxal bis(cyclopentylamidinohydrazone) (MGBCP), inhibitors for polyamine biosynthetic pathway, on Escherichia coli, Shigella sonnei, Aeromonas sobria, Aeromonas hydrophila and Vibrio cholerae were investigated . MGBB at the concentration of 100 mumol/l depleted intracellular putrescine and spermidine concentrations of E . coli to 25 and 20% of the controls, respectively, while MGBCP depressed their concentrations to 38 and 24%, respectively . In these polyamine-depleted E . coli cells the syntheses of RNA, DNA and protein decreased to 13, 54 and 29% of the control, respectively, with MGBB and to 23, 71 and 55%, respectively, with MGBCP . The minimum inhibitory concentrations (MIC) of MGBB for the growth of A . sobria, E . coli, A . hydrophila, V . cholerae and Sh . sonnei were estimated to be 50, 160, 240, 285 and 320 mumol/l, respectively, whereas those of MGBCP were slightly higher for respective bacteria.

J Pediatr, 1991 Apr, 118(4 ( Pt 1)), 627 - 32
Comparative efficacy of ceftriaxone and ampicillin for treatment of severe shigellosis in children; Varsano I et al.; In a prospective randomized open study, ceftriaxone, 50 mg/kg per day, was compared with ampicillin, 100 mg/kg per day, both given for a period of 5 days, for the treatment of 40 children whose mean (+/- SD) age was 4.5 +/- 3.2 years and who had severe dysentery caused by Shigella organisms . Twenty patients were treated with ceftriaxone and 20 with ampicillin . Both drugs were initially given intravenously for a period of 1 to 2 days and were continued intramuscularly, in the case of ceftriaxone, or orally, in the patients receiving ampicillin . All Shigella organisms isolated were susceptible to ceftriaxone; 28% were resistant to ampicillin . The diarrhea persisted for a mean (+/- SD) period of 2.5 +/- 1.0 days in the ceftriaxone-treated patients versus 6.8 +/- 6.3 days in the ampicillin-treated patients (p less than 0.005) . At the end of the 5 days of therapy, stool cultures for Shigella organisms were negative in 12 (60%) of the 20 patients from the ampicillin group and in all the children (100%) from the ceftriaxone group (p less than 0.001) . Bacteriologic relapses were observed in eight (40%) of the patients treated with ampicillin but in none of the children treated with ceftriaxone (p less than 0.001) . In instances of clinical or bacteriologic failure in the ampicillin group, retreatment was instituted in most of the cases with ceftriaxone; persistent clearing of the Shigella organisms from the stool was finally achieved after a mean (+/- SD) period of 11.75 +/- 9.4 days after therapy was started, as compared with 1.85 +/- 0.6 days in the ceftriaxone-treated patients (p less than 0.001) . We conclude that in children with severe shigellosis, treatment with ceftriaxone for 5 days is effective and better than use of ampicillin for clinical cure and eradication of the Shigella organisms from the stool.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Apr, (4), 47 - 50
{The action of ribosomal preparations on nonspecific resistance to bacterial infection and on early tolerance to endotoxic shock}; Belkin ZP et al.; Ribosomal preparations from Shigella flexneri and Shigella sonnei, introduced parenterally into mice, enhance their resistance to infection with the causative agents of typhoid fever and staphylococci . This effect is considerably less pronounced than that produced by the preparation of homologous lipopolysaccharide isolated by Boivin's method . After the administration of ribosomes nonspecific resistance to bacterial infective agents lasts for a short time . Ribosomal preparations do not enhance the resistance of mice to the lethal action of endotoxin.

Zh Mikrobiol Epidemiol Immunobiol, 1991 Apr, (4), 11 - 3
{Shigella endotoxin protein--its isolation and physicochemical characteristics}; Egorova TP et al.; The scheme of the isolation of endotoxic protein from S . sonnei 9090 is presented . The isolation procedure includes the 10-minute hot (at 68 degrees C) extraction of protein from endotoxin with 45% aqueous phenol, the precipitation of protein from phenolic extract with 9.5 volumes of 95% ethanol, the purification of protein from lipid material and pigments by multiple extraction with the mixture of chloroform and ethanol in the proportion 2:1 by volume . The yield of protein obtained with the use of this isolation scheme is about 3% of the initial endotoxin preparation . Protein preparations obtained in accordance with this scheme contain 92-95% of protein (determined by Lowry's method), 2.3-3.0% of saccharides (determined by the phenol-sulfate method) and 0.02% of hexose amine, its presence indicating that the preparations contain lipid A (or its fragments) which is firmly bound with endotoxic protein and cannot be extracted with chloroform . As shown in the passive hemagglutination inhibition test, the content of endotoxin in the preparations is less than 0.003% . Out of 7-11 bands revealed by electrophoresis in 15% polyacrylamide gel in the presence of sodium dodecyl sulfate, 3 main bands have molecular weights of 43, 38 and 18 KD . Three antigens differing in their electrophoretic mobility and diffusion rate in 1% agarose gel can be detected in the preparations by the method of immunoelectrophoresis with the use of antisera to both endotoxin and endotoxic protein.

J Pak Med Assoc, 1991 Apr, 41(4), 78 - 80
Haemolytic uraemic syndrome in children; Maqbool S et al.; Of the 4070 children admitted in the department of paediatrics, 830 (24%) presented with diarrhoea . Eleven of these had haemolytic ureamic syndrome (HUS) characterised by microangiopathic haemolytic anaemia, thrombocytopenia and acute renal failure . Only 3 had positive stool cultures (E . Coli 2, shigella dysenteriae 1) . Two children expired while the rest recovered with conservative management and peritoneal dialysis . Thus HUS should be remembered as a complication of diarrhoea and a cause of acute renal failure in children.

J Pak Med Assoc, 1991 Apr, 41(4), 75 - 8
Surveillance of shigellosis in rural Bangladesh: a 10 years review; Zaman K et al.; Over a period of 10 years 35,620 patients, admitted from a defined surveillance area, had a rectal swab culture done at a rural diarrhoea treatment centre in Bangladesh . Shigella spp . were isolated from 3,440 (9.7%) cases . Marked year to year variations were observed in isolation rates of Shigella spp . ranging from 5.7% to 16.7% . Sh . flexneri was the predominant isolate between 1978 to 1982 (56%-67%), Sh . dysenteriae type 1 predominated from 1983 to 1985 (45%-50%), and again Sh . flexneri became predominant in 1986 (55%) and 1987 (61%) . Shigella were most commonly isolated from children aged 1-4 years followed by children 5-9 years and elderly people aged 45+ years . Sh . flexneri was isolated most frequently during August - January and Sh.dysenteriae type 1 during June to July . The overall case fatality rate in patients with shigellosis was 0.96% . It was 1.10% in children under 5 years of age . Prevalence of multiple antibiotic resistant strains increased over the years and at present most strains are resistant to commonly used antibiotics such as ampicillin and cotrimoxazole . Nalidixic acid is currently the drug of choice for Shigella infection in this area.

Mol Microbiol, 1991 Apr, 5(4), 887 - 93
Temperature-regulated expression of invasion genes in Shigella flexneri is controlled through the transcriptional activation of the virB gene on the large plasmid; Tobe T et al.; The invasion phenotype of shigellae is subject to thermoregulation that is known to be expressed through activation of some invasion (inv) genes such as ipaB, ipaC, and ipaD encoded by the large virulence plasmid of Shigella flexneri . The expression of ipa genes is regulated positively by virF through the activation of virB on the plasmid . To identify the mediator for the thermoregulation of the large plasmid, we have studied the effect of temperature on the transcription of virF and virB genes and ipa and the other two inv operons . The results showed that transcription of virB was affected by temperature more strictly than that of virF . Analysis of the mRNA level of virB at different levels of virF transcription indicated that virB transcription depended upon both temperature and virF . On the other hand, transcriptions of ipa and the other two inv operons depended on the activation of virB transcription but not on temperature . By inducing virB transcription from a tac promoter fused with the virB region, invasion ability was restored to a virF-deletion mutant at 30 degrees C as well as at 37 degrees C . By using conditions in which the temperature-dependent expression of the invasion phenotype was circumvented by the induction of virB transcription, intercellular spreading ability in a virF+, virB::Tn5 strain was shown to be expressed even at 30 degrees C . These results suggest that the virB transcription stage is the main target for the thermoregulation.

Int J Food Microbiol, 1991 Apr, 12(4), 303 - 11
Aeromonas and Plesiomonas as food- and waterborne pathogens; Wadstrom T et al.; Aeromonas and Plesiomonas have become increasingly recognized as human enteropathogens . Plesiomonas shigelloides has mainly been recovered from various sea foods, whereas Aeromonas sp . have also been cultured from pigs, broilers, eggs, milk and vegetables . Aeromonas sp . also multiply rapidly at +4 degrees C which is a significant risk in food storage . Aeromonas sp . have furthermore been recovered from fresh water sources, and some isolates are resistant to chlorination which makes it a further risk factor . No large food- or waterborne outbreaks have been reported so far with Aeromonas sp . Various virulence factors involved in intestinal infections are described such as enterotoxins, cytotoxins, and adhesins.

J Gen Microbiol, 1991 Apr, 137 ( Pt 4), 867 - 74
Molecular cloning and characterization of form I antigen genes of Shigella sonnei; Yoshida Y et al.; Sau3AI-generated DNA fragments of the Shigella sonnei large plasmid encoding the form I antigen were cloned into Escherichia coli with cosmid vector pHSG262 . One resulting plasmid, designated pJK1137, was studied further . Restriction endonuclease mapping and analysis of transposon Tn3 insertion mutants demonstrated that the form I antigen genes were located within a region of about 12.6 kb consisting of the two contiguous HindIII fragments of 1.26 kb and 12.4 kb . The results of complementation studies between Tn3 insertion mutants of pJK1137 and recombinant plasmids carrying different parts of the form I antigen genes indicated that the 12.6 kb DNA sequence contained at least four gene clusters, regions A, B, C and D . Analysis of radioactively labelled proteins in minicells demonstrated that the DNA sequence of about 12.6 kb coded for at least four specific proteins of 42, 23, 48 and 39 kDa . The former two were coded by region A, the latter two by region D.

Am J Epidemiol, 1991 Mar 15, 133(6), 608 - 15
An outbreak of shigellosis at an outdoor music festival; Lee LA et al.; In August 1988, an estimated 3,175 women who attended a 5-day outdoor music festival in Michigan became ill with gastroenteritis caused by Shigella sonnei . Onset of illness peaked 2 days after the festival ended, and patients were spread throughout the United States by the time the outbreak was recognized . An uncooked tofu salad served on the last day was implicated as the outbreak vehicle (odds ratio = 3.4, p less than 0.0001) . Over 2,000 volunteer food handlers prepared the communal meals served during the festival . This large foodborne outbreak had been heralded by a smaller outbreak of shigellosis among staff shortly before the festival began and by continued transmission of shigellosis from staff to attendees during the festival . S . sonnei isolated from women who became ill before, during, and after the festival had identical antimicrobial susceptibility patterns and plasmid profiles . Limited access to soap and running water for handwashing was one of the few sanitary deficits noted at this gathering . This investigation demonstrates the need for surveillance and prompt public health intervention when Shigella infections are recognized in persons attending mass outdoor gatherings, the singular importance of handwashing in reducing secondary transmission of shigellosis, and the potential for explosive outbreaks when communal meals are prepared by large numbers of food handlers.

Rev Infect Dis, 1991 Mar-Apr, 13 Suppl 4, S362 - 5
O-specific side-chain toxin-protein conjugates as parenteral vaccines for the prevention of shigellosis and related diseases; Robbins JB et al.; Only indirect evidence has been cited to document that lipopolysaccharide-mediated virulence at the bacterial level and serum antibodies to the O-specific side chain of the lipopolysaccharide molecule may prevent shigellosis . Our proposed use of the B subunit of Shiga toxin as a carrier protein is based upon evidence (even more indirect) that serum antitoxin may reduce the severity of dysentery and diarrhea . Because animal models of disease may provide information inapplicable to the prediction of vaccine-induced protective immunity, we suggest that clinical trials in the population at risk should be started after successful completion of the safety and immunogenicity phases of vaccine development in laboratory animals and in the target population . Clinical studies of shigella vaccines are difficult because of the many causes of dysentery in a population with a high rate of intestinal disease.

Rev Infect Dis, 1991 Mar-Apr, 13 Suppl 4, S357 - 61
An auxotrophic live oral Shigella flexneri vaccine: development and testing; Karnell A et al.; Through transduction, a wild-type strain of Shigella flexneri serotype Y (SFL1) was rendered auxotrophic and dependent on aromatic metabolites that are not available in mammalian tissues . Monkeys that were orally vaccinated with 10(11) bacteria of the transductant strain SFL114 remained healthy when challenged with 10(11) bacteria of wild-type strains of S . flexneri serotypes Y, 1b, and 2a . The safety and immunogenicity of SFL114 were next studied in volunteers who were given either 10(9) or 10(10) SFL114 bacteria orally . Mild intestinal discomfort that lasted for 1-2 days was reported by three (12%) of 25 volunteers given 10(9) live SFL114 bacteria and by 13 (54%) of 24 volunteers given 10(10) live SFL114 bacteria . A local intestinal secretory IgA response to the S . flexneri O-antigen was recorded . The in vitro and in vivo results suggest that the aroD transductant SFL114 possesses properties that are desirable in an oral live candidate vaccine.

Rev Infect Dis, 1991 Mar-Apr, 13 Suppl 4, S347 - 50
Effect of antibiotics on food intake and absorption of nutrients for children with diarrhea due to Shigella; Molla AM et al.; The effect of antibiotic therapy on intake of food and absorption of nutrients for 19 male children aged 1-5 years with suspected shigella infection was studied . The children were admitted to the hospital with acute diarrhea, high fever, abdominal pain, and greater than or equal to 25 red blood cells and white blood cells per high-power field in the stool . Microbiologic diagnosis was made within 48 hours of admission . On the basis of clinical and microbiologic criteria, children were classified as having mild or severe infection . Ten children with mild infection did not receive antibiotics, whereas nine children with severe infection were treated with ampicillin . After the children were rehydrated, a 72-hour balance study was carried out during the acute stage of infection with Shigella and was repeated 2 weeks after recovery . The levels of consumption of food and absorption of nutrients were estimated . During the acute stage of infection, such levels were higher for the children treated with antibiotics than for the untreated group . During the recovery phase, the levels of intake of food and absorption of nutrients were equal for both groups . Thus, children who are treated with appropriate antibiotics not only may recover from infection with Shigella more rapidly, but they also may be able to absorb nutrients more efficiently.

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