J Reprod Med, 1993 Jul, 38(7), 543 - 8 Microbial invasion of the amniotic cavity during term labor . Prevalence and clinical significance; Romero R et al.; The purpose of this study was to determine the prevalence and clinical significance of microbial invasion of the amniotic cavity during spontaneous parturition at term . Amniotic fluid was retrieved by transabdominal amniocentesis from 90 women in spontaneous term labor with intact membranes . Fluid was cultured for aerobic and anaerobic bacteria, including Mycoplasma . The prevalence of positive amniotic fluid cultures was 18.8% (17/90) . The most common microbial isolates were Ureaplasma urealyticum, Streptococcus agalactiae, Lactobacillus species and Mycoplasma hominis . Clinical signs of chorioamnionitis were present in three patients, and only one of them had a positive amniotic fluid culture . Five patients (5.5%) had puerperal endometritis; three of them had an amniotic fluid culture positive for microorganisms . All neonates were free of clinical signs of infection . The data indicate that microbial invasion of the amniotic cavity occurs frequently during spontaneous labor at term, and it may be both the cause and the consequence of labor. Int J Food Microbiol, 1993 Jul, 19(2), 135 - 43 Microbiological and aromatic characteristics of fermented maize doughs for kenkey production in Ghana; Halm M et al.; A very uniform microflora was demonstrated in 15 samples of fermented maize dough from different larger commercial production sites . At the advanced stage of fermentation, more than 96% of the bacteria present were morphologically and biochemically uniform, obligatively heterofermentative lactobacilli occurring in concentrations about 10(9) cfu/g . Yeast occurred in levels of about 10(6) cfu/g, dominated by Candida and Saccharomyces spp . Studies on microbial successions indicated a selection towards a micropopulation dominated by lactic acid bacteria . The Gram-negative bacteria, catalase-positive Gram-positive bacteria and moulds underwent three to four decimal reductions during the early phase of the process . The aroma components detected were dominated by lactic acid, acetic, butyric and propionic acids . Volatile aroma components demonstrated by gas chromatography and mass spectrometry were characteristic for lactic acid bacteria with acetoin and related products as typical examples. Plasmid, 1993 Jul, 30(1), 14 - 29 Characterization and sequence analysis of a small cryptic plasmid from Lactobacillus curvatus LTH683 and its use for construction of new Lactobacillus cloning vectors; Klein JR et al.; Lactobacillus curvatus LTH683, a strain originally isolated from raw sausage, contains the single cryptic plasmid called pLC2 . The sequence and genetic organization of the complete 2489-bp plasmid pLC2 was determined and used as the basis for construction of a series of vectors useful in Lactobacillus strains . The major parts of pLC2 nucleotide sequence could be aligned with other plasmids from gram-positive bacteria replicating by a rolling circle mechanism of replication (RCR) . Direct evidence for a RCR mechanism was obtained by showing the accumulation of single-stranded plasmid intermediates in the presence of rifampicin . Three protein-coding sequences could be predicted and the corresponding proteins were detected after in vitro transcription/translation of pLC2 plasmid DNA . ORFs 1 and 3 showed minor homologies to plasmids of gram-positive bacteria . The replication protein coded by ORF2 and its corresponding target sequence, the plus origin, were similar to replication regions of other gram-positive bacteria plasmids like pLS1, pWV01, and pE194 . Upstream of the ori+ site, in a noncoding region, which was nonessential for replication, strong homology to other Lactobacillus plasmids like pC30i1, pLP1, pLJ1, and pLAB1000 could be detected . A palindromic sequence predicted to be the minus origin of replication was localized there . Small vectors (3213 bp) suitable for cloning in lactobacilli were constructed based on a 1635-bp DNA fragment of pLC2, containing the region necessary for replication, marked with the chloramphenicol resistance gene and a multiple cloning site. J Gen Microbiol, 1993 Jul, 139 ( Pt 7), 1441 - 8 Two cell-wall-associated aminopeptidases from Lactobacillus helveticus and the purification and characterization of APII from strain ITGL1; Blanc B et al.; Lactobacillus helveticus ITGL1 is able to hydrolyse many amino-acyl and dipeptidyl-p-nitroanilides . Analysis of heat inactivation kinetics, metal ion and protease inhibitor effects, and the subcellular location of aminopeptidase activities in both the parental strain and mutants deficient in lysyl-p-nitroanilide hydrolysis, led to the characterization of two cell-wall-associated aminopeptidases, APII and APIV . APII, which catalysed L-lysine p-nitroanilide hydrolysis, was purified about 28-fold to homogeneity from cell-wall extracts of L . helveticus ITGL1 and characterized . The purified enzyme appeared to be monomeric, with a molecular mass of 97 kDa . Aminopeptidase activity was greatest at pH 6.5 and 50 degrees C . APII was completely inhibited by bestatin, chelating agents such as EDTA or 1,10-phenanthroline and the divalent cations Zn2+ and Cu2+ . The activity of the EDTA-treated enzyme was restored by Co2+, Ca2+ or Mn2+ . Although APII was able to degrade several dipeptides and tripeptides with hydrophobic N-terminal amino acid (Leu, Ala), it was inactive on peptides containing Pro or Gly, and may thus contribute to the development of cheese flavour by processing bitter peptides. Appl Environ Microbiol, 1993 Jul, 59(7), 2326 - 8 Brochocin-C, a new bacteriocin produced by Brochothrix campestris; Siragusa GR et al.; Brochotrix campestris ATCC 43754 produces a bacteriocin inhibitory towards Brochothrix thermosphacta, lactobacilli, Listeria spp., and other gram-positive bacteria . This antimicrobial agent is heat stable, sensitive to proteases, catalase insensitive, and free of organic acids . No phage particles were detected by transmission electron microscopy . Muramidase activity was not detected in the preparations . On the basis of established criteria, the antimicrobial agent was classified as a bacteriocin and named brochocin-C. FEMS Microbiol Lett, 1993 Jul 1, 110(3), 299 - 305 Inhibition of adhesion of enteroinvasive pathogens to human intestinal Caco-2 cells by Lactobacillus acidophilus strain LB decreases bacterial invasion; Coconnier MH et al.; Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC) were found to adhere to the brush border of differentiated human intestinal epithelial Caco-2 cells in culture, whereas Yersinia pseudotuberculosis and Listeria monocytogenes adhered to the periphery of undifferentiated Caco-2 cells . All these enterovirulent strains invaded the Caco-2 cells . Using a heat-killed human Lactobacillus acidophilus (strain LB) which strongly adheres both to undifferentiated and differentiated Caco-2 cells, we have studied inhibition of cell association with and invasion within Caco-2 cells by enterovirulent bacteria . Living and heat-killed Lactobacillus acidophilus strain LB inhibited both cell association and invasion of Caco-2 cells by enterovirulent bacteria in a concentration-dependent manner . The mechanism of inhibition of both adhesion and invasion appears to be due to steric hindrance of human enterocytic pathogen receptors by whole-cell lactobacilli rather than to a specific blockade of receptors. FEMS Microbiol Lett, 1993 Jul 1, 110(3), 249 - 56 Identification and sequence analysis of the replication region of the phage resistance plasmid pCI528 from Lactococcus lactis subsp . cremoris UC503; Lucey M et al.; The replication region of the phage resistance plasmid pCI528 from Lactococcus lactis subsp . cremoris UC503 was localised to within a 10-kb HindIII restriction fragment . A 6.3-kb BglII-HindIII subclone of this fragment, cloned into a replication probe vector, allowed replication in Lactococcus but not in Bacillus or Lactobacillus . Sequence analysis revealed an ORF of 1152 bp preceded by a putative ori region containing a 22-bp sequence tandemly repeated three and three-quarter times, a second smaller direct repeat and two inverted repeats . Extensive homology was observed with the well characterised replication region of the small cryptic plasmid pCI305 (Hayes, F., Vos, P., Fitzgerald, G.F., deVos, W . and Daly, C . Plasmid 25, 16-26). J Dairy Sci, 1993 Jul, 76(7), 1902 - 7 Improving survival of culture bacteria in frozen desserts by microentrapment; Sheu TY et al.; Lactobacillus bulgaricus cells were entrapped in beads of calcium alginate and evaluated for their ability to survive freezing processes . Cells survived freezing (without agitation) in ice milk mix much better than in distilled water, and more entrapped cells survived than did cells that were not entrapped . Glycerol and mannitol were cryoprotective, but glucose was not, when each was added (6%) separately to the beads . Entrapment protected the lactobacilli in batch frozen and continuously frozen ice milk mixes . The percentage of survival for entrapped and unentrapped cells in continuously frozen ice milk approximated 90 and 40%, respectively . Lactobacilli survived better in beads with mean diameters > 30 microns than in those averaging 15 microns . Addition of entrapped lactobacilli had no measurable effect on the sensory characteristics of the ice milk. Plant Foods Hum Nutr, 1993 Jul, 44(1), 45 - 62 The fermentation of trahanas: a milk-wheat flour combination; Lazos ES et al.; The fermented food, trahanas (a milk-wheat flour combination prepared in Greece), was studied to determine the microbiological and chemical changes that occur during fermentation . It is a lactic acid bacterial fermentation in which Streptococcus lactis, Streptococcus diacetylactis, Leuconostoc cremoris, Lactobacillus lactis, Lactobacillus casei, Lactobacillus bulgaricus and Lactobacillus acidophilus play the major acid- and aroma-producing role . The whole fermentation lasts about 50 hours . The pH of the final dried trahanas was 4.07-4.75, the acidity 0.60-1.00%, the moisture content 8.6-11.5% and the protein content 10.4-13.6% . The product offers possibilities as an increased nutritive value or high-protein food. Fiziol Zh, 1993 Jul-Aug, 39(4), 62 - 8 {Protective effect of Lactobacillus acidophilus on development of infection, caused by Klebsiella pneumoniae}; Kostiuk OP et al.; The mechanisms of protective action of Lactobacillus have been studied during development of the generalized infection induced by Klebsiella pneumoniae in CBA mice after weaning . The mice were infected intragastrically during the first day after weaning (1 x 10(9) bacterias per mice) . Suspensions of Lactobacillus were introduced before and after infection during 10 days (1 x 10(6) bacterias per mice) . It has been shown that introduction of Lactobacillus substantially decreased the level of the gut contamination by Klebsiella, prevented generalization of infection and death of animals . Significant higher levels of IgA in the blood serum, IgA and IgM in the gut content, percentage of splenocytes, expressing surface IgM and IgG were observed on the 7th day as compared with those in animals without Lactobacillus . Significantly lower percentage of splenocytes, expressing CD4 antigen was also observed . On the 11th day after infection the mice receiving lactobacillus have shown a tendency to an increase of IgA in the gut content, significantly lower concentrations of IgM in the gut content and a higher level of IgA to the blood serum as compared with the control . Other characteristics were comparable to those of the control group . A conclusion is made that introduction of Lactobacillus prevents development of the Klebsiella infection and protects the immune system from excessive antigenic action. Gen Pharmacol, 1993 Jul, 24(4), 905 - 10 Isolation and characterization of the substance isolated from Streptosporangium species which inhibits lactic acid production by oral bacteria; Ikeda T et al.; 1 . The tentatively named MLI, which inhibits lactic acid production in mutants streptococci, was isolated from Streptosporangium species and purified by solvent extraction followed by chromatography, and then powdered . 2 . MLI greatly inhibited pH-decline and lactic acid production in glucose-containing reaction mixture by mutans streptococci or Lactobacillus species . 3 . These inhibitory mechanisms were not caused by an anti-bacterial effect, since the addition of a sufficient concentration of MLI to inhibit lactic acid production to the culture, recovery of cells in culture was not affected, excluding L . acidophilus . 4 . MLI directly affected lactate dehydrogenase (LDH) activity . 5 . These results indicate that MLI may represent a new anti-cariogenic substance. Eur J Biochem, 1993 Jun 15, 214(3), 889 - 96 Purification and characterization of glyoxylate synthetase from greening potato-tuber chloroplasts; Janave MT et al.; Glyoxylate synthetase catalyzing the condensation of two formate molecules into glyoxylate was purified to homogeneity by AcA-34, Sepharose CL-6B and DEAE-Sepharose CL-6B chromatography . A 150-fold purification with a specific activity of 25 mumol . mg protein-1 x 5 min-1 was obtained by this procedure . The reaction product was identified as glyoxylate . The enzyme was a tetramer having a molecular mass of 160 kDa with a subunit molecular mass of 40 kDa . The enzyme could be activated 3-4-fold by the addition of 0.3 mM Fe2+ and 0.4 mM tetrahydrofolic acid to the reaction mixture . The requirement for Fe2+ and tetrahydrofolic acid was confirmed from the inhibition of enzyme by O-phenanthroline and alpha-aminopterin, respectively . The presence of a bound folate in the enzyme was indicated by the fluorescence emission at 450 nm and turbidity development in a Lactobacillus casei growth test . Fluorescence emission at 450 nm upon excitation at 280 nm indicated that the bound folate and the aromatic amino-acid residues of the enzyme were in close vicinity . The enzyme was maximally active at 25 degrees C and exhibited a pH optimum at 7.0 . The concentration of substrate was optimal at 5.0 mM and Km for substrate was found to be 1.4 mM . Activation by Fe2+ did not alter the Km but caused an increase in Vmax . The enzyme contained about 14-16 disulfide linkages, of which two were found to be reduced by treatment with 2-mercaptoethanol . The presence of excess 2-mercaptoethanol in the enzyme was inhibitory, indicating that the two disulfide linkages reduced by 2-mercaptoethanol were essential for activity . This was also confirmed by the inhibition of enzyme activity when reduced enzyme was treated with O-phthalaldehyde, which formed a thioisoindole derivative with reduced thiol groups at the active site. J Med Microbiol, 1993 Jun, 38(6), 401 - 5 Sensitisation of cariogenic bacteria to killing by light from a helium-neon laser; Burns T et al.; Suspensions of the cariogenic bacteria Streptococcus mutans, S . sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a 7.3-mW helium-neon laser in the presence of toluidine blue O . A substantial killing rate (c . 10(6) cfu) of all four species was achieved with a dye concentration of 50 micrograms/ml and a light energy dose of 33.6 J/cm2 . This was achieved in 60 s, an exposure time that is clinically acceptable . Exposure to laser light in the absence of the dye did not significantly affect the viability of any of the organisms . This approach may be useful in dentistry to sterilise a carious lesion prior to its repair. J Virol, 1993 Jun, 67(6), 3061 - 8 Molecular comparison of the structural proteins encoding gene clusters of two related Lactobacillus delbrueckii bacteriophages; Vasala A et al.; Virulent phage LL-H and temperate phage mv4 are two related bacteriophages of Lactobacillus delbrueckii . The gene clusters encoding structural proteins of these two phages have been sequenced and further analyzed . Six open reading frames (ORF-1 to ORF-6) were detected . Protein sequencing and Western immunoblotting experiments confirmed that ORF-3 (g34) encoded the main capsid protein Gp34 . The presence of a putative late promoter in front of the phage LL-H g34 gene was suggested by primer extension experiments . Comparative sequence analysis between phage LL-H and phage mv4 revealed striking similarities in the structure and organization of this gene cluster, suggesting that the genes encoding phage structural proteins belong to a highly conservative module. Pediatr Res, 1993 Jun, 33(6), 548 - 53 Diet during rotavirus enteritis affects jejunal permeability to macromolecules in suckling rats; Isolauri E et al.; We studied the influence of diet during diarrhea on gut mucosal barrier in a suckling rat model . Rat pups were inoculated with IDIR virus (a group B rotavirus) at 10 d of age . Beginning 2 d postinfection, in addition to maternal milk, group CM received a daily gavage of cow milk and group GG received Lactobacillus casei strain GG, a human strain previously shown to survive the passage through the gastrointestinal tract and temporarily colonize the gut . Group CMGG received a combination of these, and control animals were gavaged with tap water . At 21 d of age, jejunal absorption of intact and degraded horseradish peroxidase (HRP) in Ussing chamber was markedly higher in IDIR virus-infected than in noninfected controls . In the two groups gavaged with cow milk, group CM and group CMGG, the numbers of specific antibody-secreting cells (enumerated by the solid-phase enzyme-linked immunospot assay) against beta-lactoglobulin were significantly higher than in the groups that had not received cow milk . In parallel with immune system activation, a statistically significant increase in the absorption of intact HRP (mean and 95% confidence interval, ng x h-1 x cm-2) was detected: group CM, 302 (155, 586); group CMGG, 174 (56, 545); infected controls, 121 (57, 257); and group GG, 44 (8, 254) . A decrease in the uptake of intact HRP (F = 3.64, p = 0.06) and degraded HRP (F = 9.50, p = 0.004) was associated with the introduction of L . casei GG to the diet, irrespective of coexposure to cow milk.(ABSTRACT TRUNCATED AT 250 WORDS) J Appl Bacteriol, 1993 Jun, 74(6), 649 - 51 A note on lactobacilli and beta-glucuronidase activity in the intestinal contents of mice; McConnell MA et al.; A comparison was made of caecal beta-glucuronidase activity in the caecal contents of mice with or without lactobacilli as members of the normal microflora . Male mice that did not have lactobacilli as intestinal inhabitants had approximately 52% more caecal beta-glucuronidase activity than their female counterparts . Colonization of male mice by lactobacilli reduced the beta-glucuronidase activity to that of female mice. Community Dent Oral Epidemiol, 1993 Jun, 21(3), 136 - 42 Transmission of mutans streptococci to infants following short term application of an iodine-NaF solution to mothers' dentition; Dasanayake AP et al.; In a randomized clinical trial, six applications of an I2-NaF or a placebo solution were administered to the mothers' dentition at the time of tooth emergence of her infant, to evaluate its effect on transmission of mutans streptococci (MS) to the infant . MS and other bacterial levels were periodically monitored in 48 mother-infant pairs until the child's third birthday . There were significant reductions in maternal salivary MS (P = 0.04), lactobacilli (P = 0.04), total streptococci (P = 0.002), and total cultivable organisms (P = 0.004) immediately following treatment . In children, 3-yr incidence of MS colonization and the time of acquisition of MS or the caries experience did not differ significantly between the two groups . We conclude that short-term application of I2-NaF to the maternal dentition of predentate infants significantly lowers MS, lactobacilli, total streptococci, and total cultivable bacteria in mothers' saliva, but does not influence the incidence and the time of acquisition of MS or the caries experience in children. Int J Food Microbiol, 1993 Jun 1, 18(4), 321 - 32 Changes in the microflora on commercial beef trimmings during their collection, distribution and preparation for retail sale as ground beef; Gill CO et al.; A commercial process for ground meat production, from the collection of meat plant trimmings to the retailing of consumer packs of ground beef, was examined . The selected process compiled with current concepts of Good Manufacturing Practice . During storage for up to 18 days before grinding, most trimming developed a flora of lactobacilli, of up to 10(7) CFU/g . Numbers of coliforms and of Escherichia coli on stored trimmings increased little and not at all, respectively . Increased total counts, and numbers of both coliforms and E . coli in displayed product indicated loss of control of the temperature of the displayed packaged product . It appears that the need to store a product, taking into account the unpredictable fluctuations in supply and demand, will inevitably result in much ground beef carrying large numbers of spoilage bacteria . Furthermore, currently accepted Good Practice in the retail handling of ground beef does not adequately control either spoilage or the growth of pathogenic bacteria. Int J Food Microbiol, 1993 Jun 1, 18(4), 305 - 20 Characteristics and antagonistic activity of lactic acid bacteria isolated from chilled fish products; Jeppesen VF et al.; In fish products, contrary to other foods, the commercial use of starter cultures is relatively unexploited . In this study, 61 isolates of lactic acid bacteria from lightly preserved, chilled fish products were characterized with special emphasis on their antagonistic activity and their possible use as starter cultures . The strains were phenotypically identified and characterized with regard to gas production, carbohydrate fermentations, production of off odours, H2O2-production, antagonistic activity and growth at 2, 5 and 10 degrees C . Growth at 10 degrees C was detected for all strains within 4 days . At 5 degrees C, 90% of the isolates were growing within 3-9 days . At 2 degrees C only 33% of the strains were growing within 9 days . Fourteen strains were selected for further testing of antagonistic activity against spoilage- and pathogenic bacteria at different pH in a disc assay . Two strains, a Leuconostoc spp . (V 6) and a Lactobacillus plantarum (LKE 5), differed from the other lactic acid bacteria by a very wide inhibitory spectrum for V 6 and by very distinct inhibition zones for LKE 5 . The mechanisms of their inhibitory effects are discussed. Int J Food Microbiol, 1993 Jun 1, 18(4), 279 - 87 Characterization and frequency distribution of species of lactic acid bacteria involved in the processing of mawè, a fermented maize dough from Benin; Hounhouigan DJ et al.; Lactic acid bacteria involved in the natural fermentation of both home-produced and commercial mawe were investigated during a 72 h fermentation period . Lactobacillus spp . constitute the majority (94%) of the strains of the lactic acid bacteria isolated, among which 89% represent the Betabacterium group . They include L . fermentum (biotype cellobiosus) (41%), L . fermentum or L . reuteri (19%), L . brevis (26%), L . confusus (less than 2%), L . curvatus (less than 1%) and L . buchneri (less than 1%) . Other isolated lactic acid bacteria were L . salivarius, Lactococcus lactis, Pediococcus pentosaceus, Pediococcus acidilactici and Leuconostoc mesenteroides . Several species were detected at the early stage of fermentation, but the final stage was dominated by L . fermentum (biotype cellobiosus) and L . fermentum or L . reuteri totalling 90% of the isolated strains . The trend was the same for both home-produced and commercial mawe . No strains of L . plantarum, generally reported as dominating lactic acid bacteria at the final stage of fermentation of most plant foods, were isolated. Antimicrob Agents Chemother, 1993 Jun, 37(6), 1364 - 6 In vitro activity of ramoplanin against vancomycin-resistant gram-positive organisms; Collins LA et al.; In vitro activity of ramoplanin, a cyclic lipoglycopeptide, against 92 vancomycin-resistant gram-positive organisms was evaluated . Ramoplanin demonstrated potent activity against many highly vancomycin-resistant organisms including enterococci (MICs for 90% of strains tested of 0.5 micrograms/ml) and against Lactobacillus spp., Leuconostoc spp., and Pediococcus spp., all of which were inhibited at concentrations of < or = 0.25 micrograms/ml . This drug or a derivative compound merits further investigation as a potential therapeutic agent for infections due to vancomycin-resistant enterococci. J Anim Sci, 1993 Jun, 71(6), 1503 - 9 Effect of galactan on selected microbial populations and pH and volatile fatty acids in the ileum of the weanling pig; Mathew AG et al.; Studies were conducted to determine the effect of galactan on the colonization of E . coli and lactobacilli and ileal pH and volatile fatty acid production in the digestive tract of the weanling pig . In each of two replicate trials, eight 21-d-old nursing pigs were cannulated in the terminal ileum . After a 7-d recovery period, the pigs were weaned and randomly assigned to two test diets: 1) a corn-soybean meal-based control diet and 2) a similar diet containing 1% galactan . On d 1 after weaning, all pigs were orally subjected to K88+ E . coli (2 x 10(9) colony forming units) . Ileal digesta samples were collected on d 0, 2, 4, 6, 8, and 10 after weaning and assayed for total E . coli, K88+ E . coli, lactobacilli, pH, and VFA . At the end of the trials, the pigs were killed and digesta samples were collected from the stomach, duodenum, cecum, and colon . Assays similar to those performed on the digesta samples collected from ileal cannulas were performed . Pigs fed 1% galactan had lower (P < .10) ileal pH, lower (P < .05) total E . coli on d 6 and 8, and lower (P < .05) K88+ E . coli concentrations in the ileum than pigs fed the control diet . There were no differences in ADG or gain:feed ratio between diets . The VFA concentrations were not different in the ileum between diets . The VFA were higher (P < .10) on d 0 than on any other day of the study . Acetate and isobutyrate concentrations were lower (P < .10) in the cecum in pigs fed 1% galactan.(ABSTRACT TRUNCATED AT 250 WORDS) Clin Infect Dis, 1993 Jun, 16 Suppl 4, S273 - 81 The normal vaginal flora, H2O2-producing lactobacilli, and bacterial vaginosis in pregnant women; Hillier SL et al.; In this study of the vaginal flora of 171 pregnant women in labor at term, the flora was categorized as normal (Lactobacillus predominant), intermediate, or representative of bacterial vaginosis (BV) on the basis of a vaginal smear . BV was diagnosed in 39 women (23%); the vaginal flora was classified as normal in 50% of cases and as intermediate in 27% . H2O2-producing lactobacilli were recovered from 5% of women with BV, 37% of those with an intermediate flora, and 61% of those with a normal flora . H2O2-negative lactobacilli were equally frequent (57%-65%) in all three groups . The microorganisms most frequently recovered from women with BV included Gardnerella vaginalis, Prevotella bivia/disiens, Bacteroides ureolyticus, Prevotella corporis/Bacteroides levii, Fusobacterium nucleatum, Mobiluncus species, Peptostreptococcus prevotii, Peptostreptococcus tetradius, Peptostreptococcus anaerobius, viridans streptococci, Ureaplasma urealyticum, and Mycoplasma hominis (P < .05 for each) . The presence of all but three of these organisms was inversely related to vaginal colonization by H2O2-producing lactobacilli; the exceptions were B . ureolyticus, F . nucleatum, and P . prevotii . Other microorganisms were equally frequent among women with and without BV . We conclude that specific groups of anaerobes are associated with BV in this population and that a strong association exists between species associated with BV and those inhibited by H2O2-producing lactobacilli. Clin Infect Dis, 1993 Jun, 16 Suppl 4, S181 - 7 Lactobacilli and the normal human anaerobic microflora; Lidbeck A et al.; The normal human microflora is a complex and usually stable ecosystem . The intestinal microflora is important to the host with regard to many metabolic functions and in resistance to bacterial infections . Administration of antimicrobial agents may disrupt the normal microflora, leading to a decrease in colonization resistance and alterations in metabolic activities of the intestinal bacteria . Antimicrobial therapy may also be accompanied by gastrointestinal disturbances and a reduction or elimination of lactobacilli in the intestinal microflora . Lactobacilli are part of the normal gram-positive anaerobic microflora . Through the production of lactic and acetic acids, hydrogen peroxide, and antimicrobial substances, these microorganisms possibly contribute to the maintenance of colonization resistance . Several studies have indicated a protective effect of lactobacilli against potential pathogens in the gastrointestinal tract . In view of these beneficial properties, it is considered important to maintain or increase the levels of lactobacilli in the intestinal microflora. Biosci Biotechnol Biochem, 1993 Jun, 57(6), 978 - 81 Mechanism for the antihypertensive effect of a polysaccharide-glycopeptide complex from Lactobacillus casei in spontaneously hypertensive rats (SHR); Furushiro M et al.; Pharmacological studies on the antihypertensive effect of a polysaccharide-glycopeptide complex (SG-1) isolated from Lactobacillus casei were carried out by using spontaneously hypertensive rats (SHR) . An antihypertensive effect of SG-1 was observed by oral, but not by intravenous or intraperitoneal administration, and the effect was attenuated by orally pre-treating with indomethacin . A single oral administration of SG-1 (20 mg/kg) decreased the peripheral vascular resistance (PR) . The daily oral administration of SG-1 (10 mg/kg) for 14 days had no effect on either the urine volume or urinary electrolytes (Na+, K+, and Cl-), but it did increase the excretion of 6-keto-PGF1 alpha, a metabolite of PGI2, in the urine . Moreover, a single oral administration of SG-1 (20 mg/kg) also increased the biliary 6-keto-PGF1 alpha excretion . These results suggest that the antihypertensive effect of orally administered SG-1 resulted from an enhancement of PGI2 biosynthesis and the subsequent decrease in PR. J Biol Chem, 1993 May 15, 268(14), 10102 - 8 Studies of 5-fluorodeoxyuridine 5'-monophosphate binding to carboxypeptidase A-inactivated thymidylate synthase from Lactobacillus casei; Cisneros RJ et al.; The binding of 5-fluorodeoxyuridylate (FdUMP) to carboxypeptidase-inactivated thymidylate synthase obtained from methotrexate-resistant Lactobacillus casei was investigated using {3H}FdUMP in a trichloroacetic acid precipitation assay and by 19F nuclear magnetic resonance spectroscopy . The cleavage of 1 valine residue from the carboxyl terminus of one of the identical subunits of the enzyme dimer correlates with complete loss of thymidylate synthesis (Aull, J . L., Loeble, R . B., and Dunlap, R . B . (1974) J . Biol . Chem . 249, 1167-1172) . We have further investigated the phenomenon of carboxypeptidase A-dependent inactivation of thymidylate synthase by employing immobilized carboxypeptidase A in order to facilitate the isolation and characterization of the inactivated enzyme . The time course of carboxypeptidase treatment of thymidylate synthase has been profiled by the spectrophotometric assay, tritium release assay, trichloroacetic acid precipitation assay (covalent adduct analysis), 19F nuclear magnetic resonance spectroscopy, and amino acid analysis . The techniques utilized in this study yielded results which showed that the completely inactivated enzyme (failure to catalyze thymidylate formation) continued to catalyze both covalent FdUMP-enzyme interactions and the formation of the covalent inhibitory ternary complex with the cofactor, 5,1O-methylenetetrahydrofolate, although to a reduced extent, thus effectively uncoupling these processes from thymidylate synthesis activity. Biochim Biophys Acta, 1993 May 13, 1163(2), 165 - 75 Characterization of the covalent chromatography of thymidylate synthase on thiopropyl-Sepharose 6B; Bradshaw TP et al.; We have examined the covalent chromatography of Lactobacillus casei thymidylate synthase on thiopropyl-Sepharose 6B resin . This enzyme is a dimer of identical subunits, each of which contains one active site that features a catalytic sulfhydryl group (Cys-198) . Reversible coupling was achieved via the attack of one of the enzyme's two catalytic cysteine residues, causing displacement of 2-thiopyridone, the reactive moiety of the resin . To establish the usefulness of this matrix for immobilization and the conditions required for chromatography, model studies were conducted with 2,2'-dithiodipyridine . The chemical modification of thymidylate synthase with 2,2'-dithiodipyridine was shown to be specific for the catalytic sulfhydryl groups of the native dimer, titrating 1.51 sulfhydryl groups, while 2.93 cysteines were modified in the GnHCl-denatured protein . The former reaction, which resulted in total loss of enzyme activity, was reversible with complete recovery of control activity within 30 min after addition of 100 mM 2-mercaptoethanol . Characterization of the protein pools generated in the covalent chromatography procedure indicated that the enzyme fraction washing through the column without attachment had substantially lower catalytic and ligand binding activities than the original protein stock; conversely, the enzyme fraction eluted from the column by 2-mercaptoethanol exhibited higher levels of these activities . Gel electrophoresis studies further illustrated that the unique application of the covalent chromatography technique described herein fractionated homogeneous thymidylate synthase protein into enzyme pools exhibiting distinct biochemical properties . As immobilization reaction times were increased beyond 6 h, the coupling of thymidylate synthase was demonstrated to occur through more than one enzymic sulfhydryl group . Interestingly, no covalent coupling was detected in attempts using activated thiol-Sepharose 4B, a result underlining the importance of the structure of the resin linker arm in enzyme immobilization. Biochemistry, 1993 May 11, 32(18), 4943 - 8 Site-directed alteration of three active-site residues of a pyruvoyl-dependent histidine decarboxylase; Pishko EJ et al.; The active site of histidine decarboxylase (HDC) from Lactobacillus 30a contains a pyruvoyl cofactor sitting at the interface of two molecules in a trimer . Although exhibiting hyperbolic kinetics at pH 4.8, near its optimum, HDC is cooperative at pH 7.6, indicating that the units of the trimer communicate . A Hill plot analysis shows that HDC, at pH 7.6, can be described by a two-state model . The tense (T) state has an apparent Km for histidine of 50 mM, while the relaxed (R) state has a Km of 5 mM . To explore the catalytic mechanism, three of the cross-boundary active-site residues were altered by site-directed mutagenesis and their effects observed . Ile-59 is known to act as lid on the substrate binding pocket; it was converted to Ala (I59A) and to Val (I59V) . The former was inactive, attesting to the importance of this residue in the mechanism . The I59V mutant showed a decrease in Km and in kcat at pHs 4.8 and 7.6 . Ile-59 appears to help orient substrate properly for catalysis; decreasing its size expands the binding site . This may allow the substrate to bind more readily, but in a number of conformations which are not optimal for catalysis . Conversion of Tyr-62 to Phe (Y62F) had no effect on catalysis but raised the Km 7-fold at pH 4.8 . Asp-63 appears to form an ion pair to the substrate imidazolium . Conversion to the neutral amide (D63N) had no effect on the kcat, but raised the Km 240-fold at pH 4.8 . This is consistent with the notion that the ion pair is up to 3 kcal/mol stronger than a simple hydrogen bond with the substrate . The mutant had no detectable activity at pH 7.6. Mol Gen Genet, 1993 May, 239(1-2), 33 - 40 Cloning and expression of the manganese superoxide dismutase gene of Escherichia coli in Lactococcus lactis and Lactobacillus gasseri; Roy DG et al.; The Escherichia coli sodA gene encoding the antioxidant enzyme Mn-containing superoxide dismutase (MnSOD), was cloned in the expression vector pMG36e . This vector has a multiple cloning site downstream of a promoter and Shine-Dalgarno sequences derived from Lactococcus . The protein-coding region of sodA from E . coli was amplified by the polymerase chain reaction, using a thermocycler and Taq DNA polymerase before cloning into pMG36e . When introduced into E . coli, the recombinant plasmid expressed the predicted fusion protein, both in the presence and absence of oxygen . The expression of the fusion protein in E . coli was verified by SOD assays, activity gels and Western blots . The recombinant plasmid was also introduced into Lactococcus lactis, which contains a resident SOD, and into Lactobacillus gasseri, which is devoid of SOD . Transformed lactococci expressed an active SodA fusion protein plus an active hybrid protein composed of subunits of the Lactococcus and the recombinant E . coli enzymes . Transformants of L . gasseri expressed only the fusion SodA protein, which was enzymatically active. Mol Gen Genet, 1993 May, 239(1-2), 269 - 72 Gene disruption in Lactobacillus plantarum strain 80 by site-specific recombination: isolation of a mutant strain deficient in conjugated bile salt hydrolase activity; Leer RJ et al.; A chloramphenicol-resistance gene (cml) was introduced into the Lactobacillus plantarum gene encoding conjugated bile acid hydrolase (cbh) on a ColE1 replicon . This plasmid which is nonreplicative in Lactobacillus was used to transform L . plantarum strain 80 . A homologous double cross-over recombination event resulted in replacement of the chromosomal cbh gene by the cml-containing cbh gene . The transformants obtained were unable to synthesize active conjugated bile acid hydrolase (Cbh) . The Cbh- CmlR phenotype was stably maintained for more than 100 generations under nonselective conditions. Plant Foods Hum Nutr, 1993 May, 43(3), 273 - 8 Alcohol production in submerged cashew pomace; Aderiye BI et al.; The variations in the total titratable acidity, hydrogen ion concentration, reducing sugar, soluble solids and alcohol contents of the supernatant of the submerged cashew pomace in a non-aseptic condition were investigated . The crude fibre content of the pomace was also determined during fermentation . At intervals, the changes in microbial load in both the pomace and its supernatant were examined during the 14-day study . Fifty four percent of the total soluble solids (TSS) was utilised within 7 days of degradation while an increase of about 91% in the total titratable acidity occurred in the cashew pomace within the same period bringing its pH to 3.24 . Acid hydrolysis of the pomace accounted for the relative high value of 2.15% TSS on the 8th day . Isolates of the genera Leuconostoc, Lactobacillus, Pediococcus, Aspergillus, Rhizopus and some yeast strains were obtained from the fresh pomace . The fungal colonies constituted about 76% of the population in the cashew pomace . The 86% drop in microbial population of the 8th day biodegraded pomace could be attributed to a decrease in nutrients of the substrate and the inhibitory effect of the organic acids produced during fermentation. J Dairy Sci, 1993 May, 76(5), 1253 - 9 Influence of bile on cellular integrity and beta-galactosidase activity of Lactobacillus acidophilus; Noh DO et al.; The influence of bile on beta-galactosidase activity, cellular integrity, cellular retention of beta-galactosidase, and cellular permeability of five strains of Lactobacillus acidophilus was investigated . The five strains were also compared for bile tolerance . Two strains, 223 and 4356, were significantly less resistant to bile than the others (107, NCFM, and 606) . beta-Galactosidase activity of all five strains was significantly higher in the presence of .3% oxgall than in its absence . Strain 107 showed the highest increase of enzyme activity in the presence of oxgall . Cells were not lysed in the presence of .3% oxgall, and beta-galactosidase was retained inside the cell even after extended incubation (60 min) in the presence of .3% oxgall . However, material that absorbed light at 260 nm leaked from the cells in the presence of oxgall . We concluded that, in the presence of bile, the permeability of cells of L . acidophilus increased, permitting more substrate to enter the cells, thus increasing the beta-galactosidase activity of whole cells. FASEB J, 1993 May, 7(8), 662 - 70 Lysine 2,3-aminomutase: is adenosylmethionine a poor man's adenosylcobalamin? Frey PA. The interconversion of lysine and beta-lysine, which is catalyzed by lysine 2,3-aminomutase, is formally similar to the isomerization reactions catalyzed by adenosylcobalamin-dependent aminomutases . However, lysine 2,3-aminomutase is activated by S-adensoylmethionine and not by adenosylcobalamin . Lysine 2,3-aminomutase also contains {FeS} clusters, Co(II), and pyridoxal 5'-phosphate, all of which are required for maximum activity . Lysine 2,3-aminomutase acts through a mechanism akin to that of the adenosylcobalamin-dependent enzymes in which substrate radicals are intermediates . However, the 5'-deoxyadenosyl moiety of S-adenosylmethionine mediates hydrogen transfer in place of the 5'-deoxyadenosyl moiety of adenosylcobalamin . 5'-Deoxyadenosine is an intermediate in adenosylcobalamin-dependent reactions and in the reaction of lysine 2,3-aminomutase . The 5'-deoxyadenosyl radical, derived either from adenosylcobalamin or S-adenosylmethionine, appears to participate in these reactions . Similarly, the ribonucleotide reductase from Lactobacillus leichmanii is activated by adenosylcobalamin, whereas the ribonucleotide reductase from anaerobically grown Escherichia coli is activated by S-adenosylmethionine and an activating enzyme . The 5'-deoxyadenosyl radical seems to participate in the activation of both reductases . Therefore, both adenosylcobalamin and S-adenosylmethionine appear to serve as sources of 5'-deoxyadenosyl radicals in nature . S-Adenosylmethionine is not as chemically elegant a molecule as adenosylcobalamin, so it may be regarded as "a poor man's adenosylcobalamin." Int J Food Microbiol, 1993 May, 18(3), 191 - 200 Sugar uptake and involved enzymatic activities by yeasts and lactic acid bacteria: their relationship with breadmaking quality; Antuna B et al.; The uptake kinetics of sugars present in wheat doughs and alpha-glucosidase as well as beta-fructosidase activities were determined in different strains of yeasts and lactic acid bacteria . These strains were previously selected according to their breadmaking quality . Saccharomyces cerevisiae (P6), Candida guilliermondii (P40), Lactobacillus plantarum (B31 and La18) and L . brevis (B21) showed good performance, while Sacch . fructuum (P43), L . cellobiosus (B37) and Enterococcus faecium (B11) yielded bread of lower quality . Leuconostoc mesenteroides (B10), when used in combination with other strains led also to high quality starters . All yeast strains used assimilated glucose, fructose and maltose, exhibiting saturable kinetics . Lactic acid bacteria showed saturable kinetics only for hexoses, whereas disaccharide uptake was linear . Sacch . cerevisiae, Leuconostoc mesenteroides, L . brevis and L . plantarum (B31) displayed better sugar uptake properties . For all the strains used alpha-glucosidase and beta-fructosidase activities were detected . The highest specific activities were found for Sacch . cerevisiae, C . guilliermondii and L . plantarum (B31) . These results indicate good correlation between the parameters evaluated and the breadmaking potential of the microorganisms. J Prosthet Dent, 1993 May, 69(5), 524 - 8 Influence of salivary levels of mutans streptococci on colonization of crown margins: a longitudinal study; Kohler B et al.; Initial colonization of mutans streptococci in 36 crown margins of 21 patients was studied . Before cementation, salivary concentrations of mutans streptococci and Lactobacillus sp, microorganisms associated with dental caries, were determined . Within 1 week 25% of the selected crown margins in subjects with low salivary levels of mutans streptococci and 89% in subjects with high salivary levels were colonized . High salivary counts of lactobacilli seemed to reflect conditions that enhanced the risk of colonization of mutans streptococci . The results suggest that, before cementation of fixed prosthodontics, measures should be taken to control the salivary concentrations of these organisms to reduce the susceptibility to recurrent caries. J Bacteriol, 1993 May, 175(10), 2864 - 70 Generation of a proton motive force by histidine decarboxylation and electrogenic histidine/histamine antiport in Lactobacillus buchneri; Molenaar D et al.; Lactobacillus buchneri ST2A vigorously decarboxylates histidine to the biogenic amine histamine, which is excreted into the medium . Cells grown in the presence of histidine generate both a transmembrane pH gradient, inside alkaline, and an electrical potential (delta psi), inside negative, upon addition of histidine . Studies of the mechanism of histidine uptake and histamine excretion in membrane vesicles and proteoliposomes devoid of cytosolic histidine decarboxylase activity demonstrate that histidine uptake, histamine efflux, and histidine/histamine exchange are electrogenic processes . Histidine/histamine exchange is much faster than the unidirectional fluxes of these substrates, is inhibited by an inside-negative delta psi and is stimulated by an inside positive delta psi . These data suggest that the generation of metabolic energy from histidine decarboxylation results from an electrogenic histidine/histamine exchange and indirect proton extrusion due to the combined action of the decarboxylase and carrier-mediated exchange . The abundance of amino acid decarboxylation reactions among bacteria suggests that this mechanism of metabolic energy generation and/or pH regulation is widespread. Clin Exp Rheumatol, 1993 May-Jun, 11 Suppl 9, S3 - 6 Can we prevent long term cardiac damage in Kawasaki disease? Lessons from Lactobacillus casei cell wall-induced arteritis in mice; Lehman TJ; A single intraperitoneal injection of sonicated cell walls from group B Lactobacillus casei (LC) produces an acute inflammatory coronary arteritis in mice that closely resembles the coronary arteritis found in children with Kawasaki Disease (KD) . The coronary arteritis is accompanied in its early stages by pancarditis and valvulitis, and in its later stages by coronary artery aneurysms, stenoses, and myocardial infarctions . The importance of this model is two-fold . First, it provides the opportunity to study the natural history of coronary artery disease over a relatively short life span . Second, it provides a model system in which the effects of immunological and pharmacological interventions may be tested without putting human life at risk . Studies to date indicate that inflammatory coronary arteritis such as occurs in this model and in children with KD is associated with the accelerated development of coronary artery insufficiency and premature death from cardiovascular disease . The use of immunomodulators or other agents early in the disease course to reduce the frequency and severity of the coronary arteritis appears to reduce the incidence of premature death in this mouse model and may reduce the consequences of KD as well. J Nurse Midwifery, 1993 May-Jun, 38(3), 146 - 51 The vagina as an ecologic system . Current understanding and clinical applications; Overman BA; Recent advances in understanding the mechanisms of dominance of the healthful microecology by Lactobacillus acidophilus through microbicidal enzyme systems has led to renewed interest in ecologic approaches to vaginal health maintenance and treatment of vaginosis and vaginitis . Review of pertinent research suggests that due to inadequate adherence of lactobacilli from dairy sources, contaminants in commercial sources, and lack of evidence of effectiveness in sparse clinical trials, intravaginal applications of L . acidophilus cannot be recommended . Bacterial vaginosis is described in this article as a microecologic shift in the dominant organism of the microecology from L . acidophilus to Gardnerella vaginalis . This results in conditions favorable to vaginal establishment of many anaerobic organisms . The ability to identify and nurture healthful lactobacilli in the vaginal microflora is suggested as a future direction for health-enhancement-oriented research, practice, and screening. Arzneimittelforschung, 1993 May, 43(5), 622 - 5 In vitro anti-human immunodeficiency virus activity of 2',3'-dideoxynucleosides and their effect on clonal growth of hemopoietic cells from human bone marrow; Cinatl J Jr et al.; Seven 2',3'-dideoxynucleosides synthesized by substitution of nucleosides using nucleoside deoxyribosyltransferase from Lactobacillus leichmanii were tested for their anti-human immunodeficiency virus (HIV) activity . Two of them, including 2,6-diaminopurine-2',3'-dideoxyriboside (DAPDDR) and 6-chlorpurine-2',3'-dideoxyriboside (CPDDR) demonstrated high antiviral activity against several strains of HIV-1 and one strain of HIV-2 . The selectivity index of the drugs (SI; ratio of the drug concentration required for 50% of cell killing to drug concentration required to inhibit 50% of virus-induced cell killing) was established by application of tetrazolium (MTT) colorimetric assay . SI ranged for different HIV strains from 501 to 850 and from 60 to 118 for DAPDDR and CPDDR, respectively . Both DAPDDR and CPDDR retained their antiviral activity against HIV-1 strain D148/88 which was resistant to Zidovudine (3'-azido-3'-deoxythymidine, AZT) . Assays for clonal growth of human bone marrow cells in semisolid fibrin clot culture medium demonstrated that DAPDDR possesses significantly lower inhibitory activity for erythroid (BFU-E), multipotent (GEMM-CFC) and granulocyte-monocyte (GM-CFC) bone marrow progenitor cells than CPDDR or AZT . These results suggest that DAPDDR is a nucleoside analog which should be further tested as an anti-HIV compound especially in combination with other anti-retroviral drugs. J AOAC Int, 1993 May-Jun, 76(3), 682 - 90 Potential application of LASER/microbe bioassay technology for determining water-soluble vitamins in foods; Anderson EM et al.; A microbiological technique was developed for quantitating niacin by determining microbial growth rates in response to the amount of vitamin available . Unlike the current official AOAC method, the new procedure for niacin measured the growth rates during the early exponential growth phase rather than during the stationary phase . Lactobacillus plantarum was used to determine niacin to a lower limit of 100 pg/mL . The assay time was approximately 6 h, compared with 16-24 h for the current AOAC method . The extent of microbial growth was determined by differential light scattering of a LASER beam . Multiple photodetectors were integrated with a computer system to collect and analyze the data . The use of differential light scattering to determine 8 water-soluble vitamins under stationary phase conditions demonstrated the potential application of the new technology for microorganisms and foods. J Appl Bacteriol, 1993 May, 74(5), 549 - 56 Strain characterization, genome size and plasmid content in the Lactobacillus acidophilus group (Hansen and Mocquot); Roussel Y et al.; Chromosomal DNA of nine strains of the Lactobacillus acidophilus (Hansen and Mocquot) group in which heterogeneity had previously been revealed by biochemical characteristics and DNA-DNA hybridization studies were further investigated by restriction analysis, Southern hybridization, conventional and pulsed-field gel electrophoresis (PFGE) analyses . Industrial strains were characterized and identified as Lact . acidophilus . For this species, the number of rRNA gene clusters was estimated to be at least four from analyses of rRNA gene restriction patterns . The chromosome size of type-strains of Lact . acidophilus and Lact . gasseri was estimated from PFGE analysis to be 1.85 and 2.02 Mb respectively and Lact . gasseri strains were found to contain large-sized linear plasmids. J Biotechnol, 1993 May, 29(1-2), 157 - 75 Shear stress effects on growth and activity of Lactobacillus delbrueckii subsp . bulgaricus; Arnaud JP et al.; Cells are frequently submitted to shear stresses during industrial processes . Shear stress can be either beneficial or detrimental to the cells depending on the organism and on the level of intensity . The present work was designed to study the effect of shear stress on cell activity of a widely used lactic acid bacterium, Lactobacillus delbrueckii subsp . bulgaricus (L . bulgaricus) . A constant shear stress bioreactor, based on Couette device, was developed and used to control shear stress from 0 to 72 Pa during a 4-h cultivation of a supplemented whey permeate medium with L . bulgaricus at 42 degrees C . In order to reach high shear stresses and to perform experiments within the laminar flow range where hydrodynamic conditions are accurately defined, the medium was thickened with carboxymethylcellulose (CMC) . pH, cell counts, optical density, lactose and lactic acid concentrations were monitored during culture, and cell activity was evaluated after culture and after a freezing treatment at -80 degrees C, using a standardized activity test based on optical density measurement . Cell metabolism was significantly improved by intermediate shear stress levels (36 and 54 Pa) during culture . Furthermore, biomass concentration, evaluated by optical density, was clearly higher at 36 Pa . Cell lengthening was observed, which was mainly related to the presence of CMC and partly to shear stress level, especially at 36 Pa . Hydrodynamic conditions during culture could affect the membrane permeability of the cell and its resistance to freezing . Cells cultivated at 72 Pa were certainly weakened by shearing forces, and these cultures exhibited lag times twice as long after freezing as those grown at 36 Pa . Furthermore, after freezing, cultures grown at 36 Pa had shorter lag times than at 0 Pa (1.1 and 1.3 h, respectively) and higher specific growth rates (1.24 and 0.99 h-1, respectively). J Appl Bacteriol, 1993 May, 74(5), 532 - 41 Phylogenetic analysis of some leuconostocs and related organisms as determined from large-subunit rRNA gene sequences: assessment of congruence of small- and large-subunit rRNA derived trees; Martinez-Murcia AJ et al.; The large-subunit ribosomal RNA gene sequences of Leuconostoc carnosum, Leuc . mesenteroides, Leuc . oenos, Leuc . paramesenteroides and Lactobacillus confusus were determined by direct sequencing of enzymatically-amplified DNA . Comparative analysis of the large-subunit rDNA sequences revealed that the leuconostocs form three distinct lines of descent: Leuconostoc sensu stricto, Leuc . paramesenteroides group of organisms, and Leuc . oenos . The distance matrix tree constructed from the large-subunit sequence data was in excellent agreement with that derived from small-subunit sequences, and demonstrates the 'synchrony' of the two chronometers . The results of the present and earlier sequence analyses indicate the taxonomy of the genus Leuconostoc is in need of revision, and that the Leuc . paramesenteroides group of organisms and the species Leuc . oenos represent distinct phylogenetic units, separate from Leuconostoc sensu stricto. Biochemistry, 1993 Apr 20, 32(15), 3998 - 4006 Isotope effects and the identification of catalytic residues in the reaction catalyzed by glutamate racemase; Tanner ME et al.; Primary kinetic isotope effects on Vmax were observed in both reaction directions upon racemizing samples of {2-2H}glutamate with the cofactor-independent glutamate racemase from Lactobacillus . This supports a deprotonation/protonation mechanism for racemization in which the breaking of the carbon-hydrogen bond at C-2 is partially rate-determining . Substantial "overshoots" were observed when the time course of racemization of either enantiomer of glutamate was monitored using circular dichroism spectroscopy . This is consistent with a "two-base" mechanism accompanied by a kinetic isotope effect . "Competitive deuterium washout" experiments were used to measure kinetic isotope effects on Vmax/Km of 2.5 for (S)-glutamate and 3.4 for (R)-glutamate . The ratio of the notably different isotope effects was confirmed by "double competitive deuterium washout" experiments . Site-directed mutagenesis was used to generate the mutant C73A and C184A enzymes . In each case the mutant enzymes were inactive as racemases . The two mutant enzymes are, however, capable of catalyzing the elimination of HCl from opposite enantiomers of threo-3-chloroglutamic acid, a process that presumably requires only one enzymic base . This finding indicates that the active sites of the mutant enzymes are intact and that the two cysteines flank the bound substrate molecule . It appears that cysteine-73 is responsible for the abstraction of the C-2 hydrogen from (R)-glutamate and cysteine-184 abstracts the proton from (S)-glutamate in the racemization reaction of the wild-type enzyme. Biochemistry, 1993 Apr 20, 32(15), 3991 - 7 Mechanism of the reaction catalyzed by glutamate racemase; Gallo KA et al.; The mechanism of the cofactor-independent glutamate racemase from Lactobacillus has been studied . The possible formation of an acylenzyme intermediate during catalysis has been investigated using 18O-carboxyl labeled glutamate . The absence of any washout of label during racemization argues against intermediate formation . The observation of the enzyme-catalyzed incorporation of deuterium at the C-2 position of glutamate upon racemization in D2O provides evidence for a deprotonation/protonation mechanism . Further experiments have been performed in order to determine the number of enzymic bases responsible for racemization . Solvent deuterium is efficiently incorporated into the product enantiomer but not into the recovered substrate enantiomer in each reaction direction . This finding is consistent with a "two-base" mechanism in which one enzymic base deprotonates the substrate, and the conjugate acid of a second enzymic base protonates the resulting intermediate from the opposite face . It also suggests that the two bases are monoprotic . The possibility that the two enzymic forms, which differ at the very least by the protonation states of the active-site bases, are kinetically significant has been examined by measuring the entire time course of the approach to equilibrium at various concentrations of glutamate . An "oversaturated" regime {Fisher, L . M., Albery, W . J., & Knowles, J . R . (1986) Biochemistry 25, 2529-2537} was not observed using glutamate concentrations as high as 100 mM, indicating that the two enzyme forms are rapidly interconverting under physiological conditions. Gene, 1993 Apr 15, 126(1), 61 - 6 Genetic organization and sequence of the region encoding integrative functions from Lactobacillus gasseri temperate bacteriophage phi adh; Fremaux C et al.; A 2.0-kb fragment from the Lactobacillus gasseri temperate bacteriophage phi adh contained the essential genetic determinants for site-specific integration . The nucleotide sequence of this fragment was determined . An open reading frame (intG), which adjoined the phage attachment site (attP), encoded a deduced protein related to the integrase family . The organization of this region was comparable to other phage site-specific recombination systems. New Microbiol, 1993 Apr, 16(2), 177 - 80 Isolation and partial characterization of three rumen Lactobacillus plantarum bacteriophages; Nemcova R et al.; The first isolation of Lactobacillus plantarum bacteriophages from ruminal fluid is reported . Three bacteriophages were characterized on the basis of plaque morphology, host ranges, stability, electron microscopic morphology and DNA restriction endonuclease digestion patterns . They formed clear plaques and are placed in group A of Bradley's scheme and have identical host ranges . Bacteriophages were stable to urea and chloroform . They were relatively thermostable but partially inactivated by rumen fluid and by acetate . DNA restriction analysis showed that phage L20 had different numbers of cleavage sites in comparison with the next two phages. Int J Food Microbiol, 1993 Apr, 18(2), 107 - 13 Biochemical characterization of lactobacilli from dry fermented sausages; Hugas M et al.; The characterization of 254 strains of lactobacilli isolated from dry spontaneously fermented sausages from 15 different producers at two different stages of ripening time is reported . The species identified were Lactobacillus sake 55%, L . curvatus 26%, L . bavaricus 11% and L . plantarum 8% . The main criteria for the identification of isolates to species level were: production of lactic acid isomers, presence of mDpm acid in cell walls, deamination of arginine and fermentation of mannitol and melibiose . The composition of the populations of lactobacilli were the same for the two stages of ripening . The deamination of arginine was tested in aerobic and anaerobic cultures and in different media by checking the production of ammonia and detecting the production of citrulline . In 94% of strains tested both methods gave identical results . In two L . sake strains arginine catabolism was dependent on culture media; for two other L . sake strains the deamination of arginine only occurred when oxygen was scarce. J Dairy Sci, 1993 Apr, 76(4), 956 - 61 Relationship among bile tolerance, bile salt deconjugation, and assimilation of cholesterol by Lactobacillus acidophilus; Walker DK et al.; The relationships among growth in the presence of bile, deconjugation of sodium taurocholate, and assimilation of cholesterol by 19 cultures of Lactobacillus acidophilus were examined . Cultures of L . acidophilus were grown at 37 degrees C in lactobacilli MRS broth supplemented with sodium thioglycollate, sodium taurocholate, and cholesterol (cholesterol phosphatidyl choline micelles) . Deconjugation activity was maximum in the late exponential phase of growth, which also coincided with maximum assimilation of cholesterol . Considerable variation existed among cultures in their ability to grow in the presence of bile, to deconjugate sodium taurocholate, and to assimilate cholesterol . However, statistical analyses revealed no significant correlations. J Dairy Sci, 1993 Apr, 76(4), 1083 - 90 In vitro effects of a thiopeptide and monensin on ruminal fermentation of soluble carbohydrates; Tung RS et al.; Using a purified diet and a mixed culture of ruminal microorganisms, we studied the in vitro effects of a sulfur-containing peptide (A10255) and monensin on ruminal VFA and lactic acid concentrations . After 22 h of fermentation, total VFA concentration was greater in cultures with A10255 and monensin (2.5 ppm each) than in untreated controls (84.1, 91.9, and 65.2 mM for cultures with A10255, monensin, and control, respectively) . The molar proportions of propionate were more than 40% greater, and the molar proportions of acetate were about 15% less, in treated than in untreated cultures . The molar proportions of the remaining VFA were lowest in monensin-treated cultures, intermediate in A10255-treated cultures, and greatest in untreated cultures . Addition of A10255 or monensin also prevented the accumulation of lactate and maintained higher pH than in untreated cultures . In pure culture, growth of Streptococcus bovis was slowed by A10255 at pH 5.5 and 6.5 . Growth of S . bovis was reduced markedly with addition of monensin at pH 6.5 and inhibited at pH 5.5 . Growth of Lactobacillus acidophilus was inhibited more at pH 5.5 than 6.5 with monensin but was unaffected by A10255 . The thiopeptide A10255 and monensin inhibited ruminal lactate production, but sensitivities of lactate-producing bacteria differed between compounds. J Appl Bacteriol, 1993 Apr, 74(4), 372 - 9 Mesenterocin 52, a bacteriocin produced by Leuconostoc mesenteroides ssp . mesenteroides FR 52; Mathieu F et al.; One hundred and sixty-five isolates of Leuconostoc spp . were tested for bacteriocin production . Only one strain, Leuc . mesenteroides ssp . mesenteroides FR 52, isolated from a raw milk, produced a bacteriocin which was named Mesenterocin 52 . This bacteriocin inhibited other Leuconostoc strains and several strains of Enterococcus and Listeria spp . No activity was found against lactococci and lactobacilli . The antibacterial spectrum differed from that of previously described Leuconostoc bacteriocins . Mesenterocin 52 was secreted into the medium during the growth phase . It was inactivated with protease treatments . At pH 7.0 it had a relative stability after heating at 100 degrees C (15 min), but it had a greater stability at pH 4.5 than at pH 7.0 after 6 h at 80 degrees C . The apparent molecular mass was estimated to be less than 10 kDa by ultrafiltration . Mesenterocin 52 showed a bactericidal effect on Leuconostoc paramesenteroides DSM 20288. J Bacteriol, 1993 Apr, 175(8), 2475 - 8 Cloning and sequence determination of the valS gene, encoding valyl-tRNA synthetase in Lactobacillus casei; Taylor BV et al.; The DNA sequence of the valS gene from Lactobacillus casei and the predicted amino acid sequence of its valyl-tRNA synthetase product have been determined . An open reading frame coding for a protein of 901 amino acids was found . A clone containing the intact L . casei valS gene functionally complemented the temperature-sensitive growth of the valS mutant strain 236c of Escherichia coli . The valS gene and the downstream folylpolyglutamate synthetase gene are transcribed in the same direction but are separated by a putative transcription terminator. Scand J Dent Res, 1993 Apr, 101(2), 87 - 91 Periodontopathic bacteria and salivary microbes before and after extraction of partly erupted third molars; Rajasuo A et al.; This study examines the effect of extraction of third molars on suspected periodontopathogenic microbes, salivary acidogenic bacteria, and yeasts . The subjects were 39 healthy conscripts aged 20.2 yr, with symptom-free, partly erupted mandibular third molars . Microbial samples were taken from the mandibular third molar pericoronal space and from the adjacent gingival pocket of the second molar . The samples were stained by Gram's and Giemsa's methods and studied under a light microscope . Stimulated saliva was collected for assessing mutans streptococci, lactobacilli, and yeast counts by chair-side kits . All partly erupted third molars were extracted from 20 test subjects; 19 control subjects were left untreated . Microbial samplings were repeated 2 and 5 months postoperatively . Results showed that at base line the total number of Gram-negative bacteria, Gram-negative rods, and spirochetes was significantly higher at the third molar than at the second molar sites . The extraction of the third molars caused a significant decrease in the percentage of these bacteria at the second molar sites . High counts of salivary mutans streptococci (CFU > or = 10(6)) and lactobacilli (CFU > or = 10(5)) were also significantly less frequent after the operations . Yeast counts were not affected by the extractions . Thus, partly erupted third molars may harbor a periodontally pathogenic microflora and increase the number of salivary acidogenic microbes. Indian J Biochem Biophys, 1993 Apr, 30(2), 89 - 97 Studies on cinnamic acid-4-hydroxylase from wounded potato tissue: isolation and characterization of cinnamic acid-4-hydroxylase activation factor; Pendharkar MB et al.; Cinnamic acid-4-hydroxylase activation factor has been found to be located in the supernatant fraction of wounded potato tissue homogenate in phosphate buffer . The factor has been purified to homogeneity as judged by SDS polyacrylamide gel electrophoresis, by heat treatment on boiling water-bath for 7.5 min followed by dialysis with cut off limit of 8 kDa and final separation by gel filtration on Sephadex G-50 column . Gel filtration resolved this into three active fractions of molecular mass 12500, 10000 and 8500 Da conjugated to a fluorescent compound and subsequently identified as a folate derivative . The amino acid analysis of polypeptide chains of these fractions revealed that the polypeptides were rich in glutamic and aspartic acids . The fluorescent moiety of the complex released from polypeptide chain of molecular weight 10000 by mild acid hydrolysis was able to support the growth of Lactobacillus casei ATCC 7469 which requires folic acid for its growth . On storage, this compound degraded into a number of fluorescent products identified as p-amino benzoic acid, p-amino benzoyl glutamic acid, pteroic acid and 6-methyl pterin indicating that the activation factor is a folic acid derivative conjugated with the polypeptide chain. Indian J Biochem Biophys, 1993 Apr, 30(2), 103 - 10 Ternary complex formation with 5-fluoro-2'-deoxyuridylate and the kinetic properties of thymidylate synthase from Lactobacillus leichmannii; Rao KN; Lactobacillus leichmannii thymidylate synthase (5,10-CH2-H4PteGlu:dUMP C-methyltransferase, EC 2.1.1.45) forms a tight and stable covalently bonded ternary complex with the inhibitor 5-FdUMP in the presence of the cofactor 5,10-CH2-H4-PteGlu . 'Filter assay' employing the radioactive nucleotide ligand showed that 2 moles of FdUMP are bound per mole enzyme during the ternary complex formation with the L . leichmannii dTMP synthase . This is in line with our earlier observation on the Streptococcus faecium thymidylate synthase {Narasimha Rao, K & Kisliuk R L (1983), Proc Natl Acad Sci USA, 80, 916-920} . The enzyme has Km values of 6.3 x 10(-6) M, 8.2 x 10(-5) M and 1.0 x 10(-4) M for dUMP, (dl)-L-H4PteGlu and Mg2+ respectively; Vmax for dUMP, (dl)-L-H4PteGlu and Mg2+ are; 0.55, 0.5 and 1.1 respectively . It has K(i) values of 6.7 x 10(-6) M, 2.2 x 10(-6) M, 5.0 x 10(-5) M and 2.0 x 10(-4) M for FdUMP, dTMP, MTX and Ca2+ respectively . The type of enzyme inhibition with FdUMP, dTMP, MTX and Ca2+ was competitive . dTMP Studies clearly show the 'end product' inhibition of the enzyme. Biotechnol Appl Biochem, 1993 Apr, 17 ( Pt 2), 139 - 53 Microbial reduction of 1-(4-fluorophenyl)-4-{4-(5-fluoro-2-pyrimidinyl)-1- piperazinyl}butan-1-one; Patel RN et al.; Among various micro-organisms screened for the stereoselective reduction of 4-chloro-1-(4-fluorophenyl)butan-1-one (1), Hansenula polymorpha {American Type Culture Collection (A.T.C.C.) 26012 and 86014}, Nocardia salmonicolor {Squibb Culture (S.C.) 6370}, Arthobacter simplex (A.T.C.C . 6949), Mycobacterium vaccae (A.T.C.C . 29678), Candida boidinii (A.T.C.C . 13821) and Saccharomyces cerevisiae (A.T.C.C . 13792) reduced compound 1 to the corresponding (R)-(+)-alcohol (2) . In contrast, Lactobacillus kefir (A.T.C.C . 35411), Pullularia pullulans (A.T.C.C . 16623), Trigonopsis variabilis (A.T.C.C . 10679) and Cunninghamella echinulata (A.T.C.C . 26269) reduced compound 1 to the (S)-(-)-alcohol (2) . When 1-(4-fluorophenyl)-4-(1-piperazinyl)butan-1-one (3) was used as substrate for the reduction, only Nocardia globerula (A.T.C.C . 12505) and Saccharomyces cerevisiae (A.T.C.C . 13792) converted compound 3 into the corresponding (R)-(+)-alcohol (4) . Organisms which reduced compound 1 were inactive for the reduction of compound 3 . 1-(4-Fluorophenyl)-4-{4-(5-fluoro-2- pyrimidinyl)butan-1-one (5) was reduced to the corresponding (R)-(+)-alcohol (6) by Mortierella ramanniana (A.T.C.C . 38191) and to the (S)-(-)-alcohol (6) by Pullularia pullulans (A.T.C.C . 16623) . (R)-(+)-compound 2 and compound 4 are key chiral intermediates in the total chemical synthesis of (R)-(+)-compound 6, an effective antipsychotic agent under development at Bristol-Myers Squibb . A single-stage (fermentation/biotransformation) process and two-stage (fermentation and subsequent biotransformation by cell suspensions) process were developed for the stereoselective reduction of compound 5 to (R)-(+)-compound 6 by Mortierella ramanniana (A.T.C.C . 38191) . In both processes, the reaction yield of 98% and the optical purity of 99.4% were obtained for (R)-(+)-compound 6 . The enzyme which catalysed the reduction of compound 5 to (R)-(+)-compound 6 was purified to homogeneity . The purified protein consisted of a single polypeptide of 29 kDa. Antibiot Khimioter, 1993 Apr-May, 38(4-5), 40 - 2 {Various approaches to treatment of dysentery in children}; Iushkevich SB et al.; The clinical process, etiological pattern and results of antibacterial therapy of dysentery in 1105 children were analyzed by hospital records for the last 25 years . Significant changes in the etiology of dysentery were revealed . In the 1960s Shigella flexneri prevailed (56.3 per cent) and in the 1970-1990s Shigella sonnei prevailed (69.9 to 74.6 per cent) whereas the percentage of Newcastle dysentery was low and stable (1.5 to 8.7 per cent) . Simultaneously, there were changes in antibiotic sensitivity of the Shigella strains . In the 1960s the Shigella strains were mainly sensitive to tetracyclines, in the 1970s they were mainly sensitive to levomycetin and polymyxin and in the 1980-1990s they were mainly sensitive to gentamicin, polymyxin, carbenicillin and ampicillin . Accordingly, the antibacterial therapy allowed for the sensitivity of the pathogen at the particular period . Biological preparations such as bifidum bacterin, bificol, lactobacterin, etc . should be used in the complex therapy of Shigella infection due to frequent affection of intestinal biocenosis. J Mol Biol, 1993 Mar 20, 230(2), 516 - 28 Refined structure of the pyruvoyl-dependent histidine decarboxylase from Lactobacillus 30a; Gallagher T et al.; The crystal structure of the pyruvoyl-dependent histidine decarboxylase from Lactobacillus 30a has been refined to an R-value of 0.15 (for the 5.0 to 2.5 A resolution shell) and 0.17 (for the 10.0 to 2.5 A resolution shell) . A description of the overall structure is presented, focusing on secondary structure and subunit association . The enzyme is a hexamer of alpha beta subunits . Separate alpha and beta-chains arise from an autocatalytic cleavage reaction between two serine residues, which results in the pyruvoyl cofactor . The central core of the alpha beta subunit is a beta-sandwich which consists of two face-to-face three-stranded antiparallel beta-sheets, flanked by alpha-helices on each side . The beta-sandwich creates a stable fold that allows conformational strain to be introduced across an internal cleavage region between the alpha and beta chains and places the pyruvoyl cofactor in a position for efficient electron withdrawal from the substrate . Three alpha beta subunits are related by a molecular three-fold symmetry axis to form a trimer whose interfaces have complementary surfaces and extensive molecular interactions . Each of the interfaces contains an active site and a solvent channel that leads from the active site to the exterior of the molecule . The trimers are related by a crystallographic two-fold symmetry axis to form the hexamer with an overall dumbbell shape . The interface between trimers has few molecular interactions. Science, 1993 Mar 5, 259(5100), 1445 - 50 Structure-based discovery of inhibitors of thymidylate synthase; Shoichet BK et al.; A molecular docking computer program (DOCK) was used to screen the Fine Chemical Directory, a database of commercially available compounds, for molecules that are complementary to thymidylate synthase (TS), a chemotherapeutic target . Besides retrieving the substrate and several known inhibitors, DOCK proposed putative inhibitors previously unknown to bind to the enzyme . Three of these compounds inhibited Lactobacillus casei TS at submillimolar concentrations . One of these inhibitors, sulisobenzone, crystallized with TS in two configurations that differed from the DOCK-favored geometry: a counterion was bound in the substrate site, which resulted in a 6 to 9 angstrom displacement of the inhibitor . The structure of the complexes suggested another binding region in the active site that could be exploited . This region was probed with molecules sterically similar to sulisobenzone, which led to the identification of a family of phenolphthalein analogs that inhibit TS in the 1 to 30 micromolar range . These inhibitors do not resemble the substrates of the enzyme . A crystal structure of phenolphthalein with TS shows that it binds in the target site in a configuration that resembles the one suggested by DOCK. J Antimicrob Chemother, 1993 Mar, 31(3), 363 - 72 Comparative susceptibility of the Bacteroides fragilis group species and other anaerobic bacteria to meropenem, imipenem, piperacillin, cefoxitin, ampicillin/sulbactam, clindamycin and metronidazole; Goldstein EJ et al.; The in-vitro activity of meropenem, imipenem, piperacillin, cefoxitin, ampicillin/sulbactam, clindamycin and metronidazole was determined against 395 strains of strict and facultative anaerobes, including Gardnerella vaginalis, Lactobacillus spp . and Mobiluncus spp . The activities of meropenem and imipenem were within one dilution of their MIC50 and MIC90 values . One isolate of Bacteroides fragilis, two of Bacteroides distasonis, and two of Bacteroides ovatus showed resistance or diminished susceptibility to meropenem and imipenem . Metronidazole was active against almost all obligate anaerobic isolates . Some non-spore-forming Gram-positive bacilli and lactobacilli were resistant . Ampicillin/sulbactam inhibited almost all isolates at < or = 16/8 mg/L . The activity of clindamycin and cefoxitin was relatively good, but some strains of non-fragilis B . fragilis group species were resistant . Piperacillin was the least active agent tested. Rev Fr Gynecol Obstet, 1993 Mar, 88(3 Pt 2), 211 - 4 {Bacterial vaginosis: what risks for the mother and child?}; Zana J; Bacterial vaginosis are characterized by a polymicrobial proliferation of anaerobic organisms and the disappearance of the commensal lactobacilli, which can cause ascending utero-adnexitis and endanger ongoing pregnancy . The role of anaerobes in utero-adnexitis and tubal abscess was first raised in 1973 par Eschenbach . Several authors have since established correlations between bacterial vaginosis and both pain from the uterine appendages and gynecologic infections, particularly post-abortum . Bacterial vaginosis is a major problem in pregnant women, given its high prevalence (15-20 p . cent) and significant relationship with premature delivery and premature rupture of the membranes (at less than 37 weeks of amenorrhea) in epidemiological case-control and cohort studies taking into account demographic and concomitant obstetric characteristics . In particular, histological lesions indicative of chorioamniotitis have been correlated with prematurity and with the presence of bacteria (usually those involved in vaginosis) in the amniochorial space . Bacterial vaginosis can give rise to ascending infections which reach the amniochorial space and cause uterine contractions or alter the amniochorial membrane, leading to premature rupture of the membranes . These epidemiological data must, however, be confirmed by controlled trials of antibiotics active in bacterial vaginosis and their preventive effect on prematurity and premature rupture of the membranes . Finally, bacterial vaginosis can play a role in endometritis following both natural and caesarean delivery; this has been shown in multivariate analyses with adjustment for maternal age, duration of labor and rupture of the membranes, and isolation of bacteria associated with bacterial vaginosis from the endometrium. Rev Fr Gynecol Obstet, 1993 Mar, 88(3 Pt 2), 207 - 10 {Recent bacteriologic data: from physiopathology to treatment}; Lefevre JC; Bacterial vaginosis is characterized by a change in the vaginal ecosystem in which Lactobacillus spp, the dominant members of the normal flora, are replaced by an association of various bacterial species including Gardnerella vaginalis, anaerobes (Bacteroides spp, Prevotella spp, Porphyromonas spp, Peptostreptococcus spp and Mobiluncus spp) and Mycoplasma hominis . The reasons for this imbalance are unknown, although the loss of lactobacilli that produce hydrogen peroxide (which is toxic for G . vaginalis and numerous anaerobes) may be an essential element . The introduction of one or several of these species into the vagina (they can occasionally be isolated in small numbers even in the absence of vaginosis) following intercourse or from the intestinal tract may also play a role . G . vaginalis itself is not considered to cause vaginosis, but is almost always present and multiplies rapidly; in addition, it has a high capacity for adherence to epithelial cells both in vivo and in vitro . It is now agreed that the concomitant growth of one or several anaerobic species is required for bacterial vaginosis to develop . Our knowledge of the bacteriology of bacterial vaginosis has implications for diagnosis and treatment . It is now possible to obtain a precise bacteriologic diagnosis, not by culturing G . vaginalis (a costly and low-yield procedure), but by direct examination of the vaginal flora after Gram staining, which shows the replacement of lactobacilli by a characteristic polymorphic flora . Therapy is based on the use of antibiotics such as the imidazoles, which are active against G . vaginalis and anaerobes, but not against the commensal lactobacilli.(ABSTRACT TRUNCATED AT 250 WORDS) Rev Fr Gynecol Obstet, 1993 Mar, 88(3 Pt 2), 203 - 6 {The bacteriologic diagnosis of bacterial vaginosis in an urban practice}; Askienazy-Elbhar M; The term "bacterial vaginosis" carries both bacteriologic and clinical connotations . Indeed, it implies that the vagina is uninflamed (as shown by the absence of polymorphonuclear neutrophils), but that potential pathogens (particularly Gardnerella vaginalis) are present . Many studies conducted over the last 10 years have shown that a tentative diagnosis is simple to make, based on the sniff test, the aspect of the vaginal discharge, the presence of clue cells, and the absence of polymorphonuclear cells and lactobacilli on fresh smears . However, classical treatment with metronidazole can be insufficient given the innumerable microbial associations, and a more thorough bacteriological diagnosis is required . The presence of anaerobes is suggested by a positive sniff test . Direct examination reveals small Gram-negative rods in clue cells, but cannot differentiate between commensal atypical lactobacilli and Gram-positive anaerobes . Culture with CO2 supplementation or in anaerobic conditions yields Bacteroides and Mobiluncus spp, frequently associated with Gardnerella vaginalis and pathogenic Fusobacterium spp . Culture in appropriate conditions will detect metronidazole-resistant Propionibacteria and pathogenic anaerobic cocci . Antibiotic susceptibility testing of these organisms is costly and time-consuming, but can avoid therapeutic failures . Gardnerella vaginalis is also frequently associated in bacterial vaginosis with endogenous (mainly E . coli and group B streptococci) and Ureaplasma . Antibiotic susceptibility testing is useful if the predominant members of the flora are Gram-negative aerobes, group D streptococci or pathogenic anaerobes . Bacterial vaginosis is simple to diagnose but poses a real therapeutic problem since some cases call for a simple readjustment of the commensal flora while others require full chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS) Rev Fr Gynecol Obstet, 1993 Mar, 88(3 Pt 2), 195 - 7 {The definition and epidemiology of bacterial vaginosis}; Mardh PA; Bacterial vaginosis is a condition with a flora change in the vaginal where a lactobacilli-dominated flora is exchanged with an abundant complex flora dominated by strict and facultative anaerobic bacteria . The condition seldom occurs in prepubertal girls and post-menopausal women, suggesting an hormonal component in its etiology . Recurrent episodes of bacterial vaginosis are frequent . Three out of four criteria should be fulfilled for establishing the diagnosis of bacterial vaginosis, i.e., an increased (often homogeneous) vaginal discharge, a positive amine test, the presence of a great number of clue cells, a vaginal pH > or = 4.5 . There are no hard data supporting that bacterial vaginosis is a sexually transmitted disease . Cytological changes (CIN I, II, III) have been found more often in women with bacterial vaginosis than in those without this condition . It has been proposed that nitrosamines from the abundant vaginal bacterial flora may be oncogenic, a correlation which, however, needs to be proved . The reservoir for one or more of the bacterial vaginosis-associated organism, e.g., some Bacteroides and Mobiluncus spp., Gardnerella vaginalis and Mycoplasma hominis, is probably the distal intestinal tract and the mouth . Sparse or even a moderate number of clue cells are present in many women who do not have bacterial vaginosis . A vaginal pH of 4.7 seems to be a better cut-off level than 4.5 . There is a statistical correlation between bacterial vaginosis and obstetrical complications. J Appl Bacteriol, 1993 Mar, 74(3), 314 - 23 Numerical taxonomy of Lactobacillus spp . associated with healthy and diseased mucosa of the human intestines; Molin G et al.; Two-hundred and fifty Lactobacillus strains isolated from healthy and diseased mucosa of human intestines of 75 individuals and 49 reference strains were phenotypically classified using 49 unit characters . Data were processed by the Jaccard (SJ) and Simple Matching (SSM) coefficients, and unweighted pair group algorithm with arithmetic averages . Seventeen major clusters were defined at the 76% SJ-similarity level which approximately correspond to the SSM-level of 91% . Seven clusters could be identified: Lactobacillus plantarum (isolates recovered from 5% of the patients), Lact . casei subsp . rhamnosus (17% of the patients), Lact . casei subsp . pseudoplantarum (5% of the patients), Leuconostoc mesenteroides subsp . mesenteroides (3% of the patients), Lact . buchneri (4% of patients), Lact . reuteri (4% of the patients) and Lact . salivarius subsp . salivarius (9% of the patients) . Unassigned clusters 1 and 3 both contained homofermentative Lactobacillus strains . Cluster 1 included the type strains of Lact . crispatus, Lact . acidophilus, Lact . jensenii and Lact . gasseri, and cluster 3, the type strains of Lact . delbrueckii subsp . lactis, Lact . agilis and Lact . casei subsp . tolerans . Clusters 1 and 3 were found in 15% and 25% of the patients, respectively . Unassigned clusters 2, 6, 7, 8 and 10 contained homofermentative Lactobacillus strains but no reference strains . Clusters 11, 12, 15 and 17 were made up of heterofermentative Lactobacillus strains but no reference strains . Phenotypical characteristics of the clusters are given . No obvious trends in species (cluster) composition between different intestinal locations could be noted . Most clusters contained isolates from both diseased and healthy mucosa . Exceptions were cluster 15 and cluster 17 which only included isolates from healthy mucosa, and cluster 11 which only included isolates from diseased mucosa . Cluster 15 was isolated in 12% of the patients, and cluster 11 in 8%. J Appl Bacteriol, 1993 Mar, 74(3), 295 - 300 Molecular characterization of Lactobacillus curvatus and Lact . sake isolated from sauerkraut and their application in sausage fermentations; Vogel RF et al.; Lactobacillus curvatus and Lact . sake are best adapted to meat fermentations and dominate the flora during the whole process . In fermenting sauerkraut, Leuconostoc mesenteroides subsp . mesenteroides is the major organism only during the early phase . In this environment Lact . curvatus and Lact . sake provide up to 50% of the microbial flora especially of the later phase, depending on the process conditions . Strains of Lact . curvatus and Lact . sake isolated from fermenting sauerkraut were identified by hybridization with species specific 23S rRNA-targeted oligonucleotide probes and further characterized . In 59 of 72 strains, plasmid DNA was detected . Small cryptic plasmids of 20 strains were found to be homologous with pLc2, a 2.6 kb plasmid from Lact . curvatus LTH683, which was originally isolated from meat . The ability to compete was investigated in fermenting sausages of two strains each of Lact . curvatus and Lact . sake isolated from sauerkraut . One strain each of Lact . curvatus and Lact . sake was found to outnumber the meat-borne flora and govern the process. J Appl Bacteriol, 1993 Mar, 74(3), 290 - 4 Adhesion of Lactobacillus acidophilus to avian intestinal epithelial cells mediated by the crystalline bacterial cell surface layer (S-layer); Schneitz C et al.; Lactobacillus acidophilus was isolated from washed and homogenized walls of the crop and caecum of an adult fowl . A strain that adhered well in the Fuller adhesion test was subcultured until colonies on Lactobacillus Selective agar changed from rough to smooth . This coincided with a change from aggregate to planktonic growth in liquid medium and a marked loss of ability to adhere . ultrastructure of cells from both types of culture was studied by electron microscopy . An S-layer formed the outermost part of the cell wall in the strongly-adherent strain, whereas this layer was covered with polymerized material or was absent in strains that lacked the ability to adhere, or those with reduced adherence. J Dent Res, 1993 Mar, 72(3), 623 - 9 A microbiological study of primary root-caries lesions with different treatment needs; Beighton D et al.; Samples of altered or carious dentin for microbiological culture were obtained from 301 primary root-caries lesions in 59 patients by means of a standardized sampling procedure . This involved the cleansing of each root surface of extraneous supragingival plaque by means of a hand-held toothbrush and distilled water and the collection of the sample with a sterile dental excavator passed through the entire vertical dimension of each lesion . The total number of colony-forming units (cfu) in each sample and the numbers of mutans streptococci (primarily Streptococcus mutans), lactobacilli, yeasts, and Gram-positive pleomorphic rods (GPPR) were determined . Individual bacterial counts were expressed as log10 (cfu per sample), as a percentage of the total number of bacteria per sample, and as a frequency of isolation from lesions with different clinical diagnostic criteria . Clinical measurements of each lesion were made for color, texture, position relative to the gingival margin, and treatment need . Lesions classified as soft yielded significantly more bacteria, mutans streptococci, lactobacilli, and GPPR than leathery lesions, which yielded more bacteria than hard lesions . Lesions were classified into 5 treatment categories: soft and restore, leathery and restore, leathery and debride of caries; leathery and treat therapeutically; and hard no treatment . The total numbers of bacteria, mutans streptococci, lactobacilli, GPPR, and yeasts decreased significantly with decreasing treatment need . The frequency of isolation of mutans streptococci, lactobacilli, and yeasts was significantly greater from lesions requiring restoration and from lesions situated within 1 mm of the gingival margin . We suggest that the majority of root caries is initiated adjacent to the gingival margin. FEBS Lett, 1993 Mar 1, 318(2), 177 - 80 Stereospecific assignments of the leucine methyl resonances in the 1H NMR spectrum of Lactobacillus casei dihydrofolate reductase; Ostler G et al.; A general method is described for the stereospecific assignment of methyl resonances in protein NMR spectra based on selective deuteration procedures . A selectively deuterated dihydrofolate reductase from L . casei was prepared by incorporating stereoselectively deuterated L-leucine, (2S,4R){5,5,5-2H3}leucine . By comparing the COSY spectra of the dihydrofolate reductase-methotrexate complexes formed using deuterated and non-deuterated enzyme the stereospecific assignments for resonances of all 13 leucine residues were obtained by noting the absence of cross-peaks in spectra from the deuterated proteins. J Clin Microbiol, 1993 Mar, 31(3), 689 - 91 Biochemical characteristics and fatty acid composition of Gilardi rod group 1 bacteria; Moss CW et al.; Fifteen strains of eugonic, nonoxidative, gram-negative rods isolated primarily from human wounds of the extremities and blood formed a distinct group which was designated Gilardi rod group 1 . The phenotypic characteristics of Gilardi rod group 1 were most similar to those of CDC group M-5, with the major difference that nitrite reduction was observed with CDC group M-5 . All 15 strains of Gilardi rod group 1 possessed a distinct fatty acid profile which was characterized by large amounts (> 15%) of cis-vaccenic (18:1 omega 7c), palmitic (16:0), myristic (14:0), and lactobacillic (19:0 cyc11,12) acids and moderate amounts (3 to 5%) of lauric (12:0), 3-hydroxylauric (3-OH-12:0), and palmitoleic (16:1 omega 7c) acids . This fatty acid profile is unique compared with the profiles of CDC group M-5 and other bacteria we have tested and is useful for the rapid identification of Gilardi rod group 1 isolates. Int J Paediatr Dent, 1993 Mar, 3(1), 17 - 21 The use of a concentrated oral rinse culture technique to sample oral candida and lactobacilli in children, and the relationship between candida and lactobacilli levels and dental caries experience: a pilot study; Coulter WA et al.; The purpose of this study was to test the suitability of a concentrated rinse culture technique, previously applied to adults, as a method for sampling the oral cavity of children on a community basis . The technique was used to assess the levels of oral candida and lactobacilli in the mouths of a group of 32 14- to 15-year-old children and to relate this to their past caries experience . Caries experience was assessed by means of a DMFS count . Each subject rinsed with 10 ml of buffered saline for 1 minute for microbial sampling . The oral rinse was concentrated by centrifugation and cultured on to selective media for candida and lactobacilli . The rinse technique proved simple and effective as a means of sampling the oral flora in children . The level of candida was more easily assessed and appeared to be a more useful indicator of microbial risk factors in caries than the lactobacilli count. J Gen Microbiol, 1993 Mar, 139 ( Pt 3), 513 - 7 Identification and classification of Lactobacillus acidophilus, L . gasseri and L . johnsonii strains by SDS-PAGE and rRNA-targeted oligonucleotide probe hybridization; Pot B et al.; Thirty-two strains originally identified as Lactobacillus acidophilus and L . gasseri were screened for their taxonomic homogeneity by SDS-PAGE of whole-cell proteins . After numerical comparison of the resulting protein electrophoretic fingerprints, two well-delineated clusters were detected . The majority of the strains grouped in one electrophoretic cluster, which contained the type strain of L . acidophilus and corresponds to DNA group A1 of Johnson, J . L., Phelps, C . F., Cummins, C . S., London, J . & Gasser, F . (1980; International Journal of Systematic Bacteriology 30, 53-68) . Another cluster corresponded to DNA group B . It contained two subclusters, which agreed perfectly with DNA subgroups B1 (L . gasseri) and B2 (L . johnsonii), respectively . The 23S rRNA genes were partially sequenced and 23S-rRNA-targeted oligonucleotide probes were designed for identification of DNA groups A1, B1 and B2 . Probe Lbg reacted with all strains of electrophoretic cluster B1 (L . gasseri), probe Lbj hybridized with strains of cluster B2 (L . johnsonii) and probe Lba with strains of cluster A1 (authentic L . acidophilus) . The probes were successfully used for the identification of strains belonging to the respective species . The phylogenetic relationship of a representative of L . johnsonii was determined by comparative sequence analysis of the 16S rRNA genes . It is very closely related to L . gasseri. Science, 1993 Feb 12, 259(5097), 965 - 7 Structure of the thiamine- and flavin-dependent enzyme pyruvate oxidase; Muller YA et al.; Pyruvate oxidase from Lactobacillus plantarum is a tetrameric enzyme that decarboxylates pyruvate, producing hydrogen peroxide and the energy-storage metabolite acetylphosphate . Structure determination at 2.1 angstroms showed that the cofactors thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD) are bound at the carboxyl termini of six-stranded parallel beta sheets . The pyrophosphate moiety of TPP is bound to a metal ion and to a beta alpha alpha beta unit corresponding to an established sequence fingerprint . The spatial arrangement of TPP and FAD suggests that the oxidation of the oxyethyl intermediate does not occur by hydride displacement but rather by a two-step transfer of two electrons. Microbiologia, 1993 Feb, 9 Spec No, 37 - 48 {Utilization of lactic bacteria in the control of pathogenic microorganisms in food}; Hernandez PE et al.; The lactic acid bacteria have the potential to inhibit the growth of pathogenic and spoilage bacteria and the possibility exists of using them to improve the hygienic quality and to extend the shelf-life of different foods . Among the many inhibitory substances produced by the lactic acid bacteria, the bacteriocins are of particular interest . It has been the objective of this work to review the bacteriocins produced by lactic acid bacteria from the genera Lactococcus, Lactobacillus and Pediococcus, as well as Leuconostoc and Carnobacterium to understand their relevant biochemical, immunological and genetic characteristics . The lactic acid bacteria may also express foreign genes codifying metabolites with antimicrobial activities against foodborne pathogens of interest, and this will also permit hypothesize about theoretical and experimental models of microbial antagonism mediated by the lactic acid bacteria. Int J Food Microbiol, 1993 Feb, 17(4), 311 - 20 Inhibition of the growth of yeasts in fermented salads; Bonestroo MH et al.; Salads composed of vegetables and/or meat in an oil-in-water emulsion were prepared by fermentation for 7 h at 42 degrees C or 45 degrees C with strains of Lactobacillus spp . Their stability towards spoilage yeasts was studied using Saccharomyces cerevisiae, Saccharomyces exiguus and Torulaspora delbrueckii, isolated from salads, as well as Pichia membranaefaciens and Zygosaccharomyces bailii . Salads fermented with good lactic starters usually had pH values of < or = 4.2 and lactic acid concentrations of 0.28 to 0.43% (w/w) . High numbers of spoilage yeasts (and production of large volumes of CO2) were not attained in these salads, provided the initial concentration of spoilage yeasts was sufficiently low (< or = 100 CFU/g) . Inhibition of spoilage yeasts in lactic fermented salads is probably due to lactic acid, the low storage temperature and the low residual oxygen concentration. Int J Food Microbiol, 1993 Feb, 17(4), 303 - 9 Effects of gluconodeltalactone and Lactobacillus plantarum on the production of histamine and tyramine in fermented sausages; Buncic S et al.; Fermented sausages were made experimentally with addition of 0.3% (w/w) gluconodeltalactone (GDL) or a starter culture of Lactobacillus plantarum, unable to produce histamine or tyramine . Controls were produced without GDL and starter culture . During 15 days preparation and storage periods, number of bacteria and lactobacilli, pH, and levels of histamine, tyrosine and tyramine were monitored, and organoleptic evaluations were carried out . Maximal histamine levels were 19.41 micrograms/g of dry matter in the GDL-added sausages, 18.64 micrograms/g in the control, and 17.20 micrograms/g in the starter sausages . Maximal tyramine levels were 1249.16 micrograms/g in the GDL sausages, 1101.16 micrograms/g in the control, and 906.35 micrograms/g in the starter sausages . Sausages produced with GDL proved less acceptable in organoleptic evaluation due to an unpleasant sour flavour. Antimicrob Agents Chemother, 1993 Feb, 37(2), 366 - 70 In vitro activity of CP-99,219, a new fluoroquinolone, against clinical isolates of gram-positive bacteria; Eliopoulos GM et al.; The in vitro activity of the fluoroquinolone CP-99,219 against gram-positive bacteria was compared with those of five other antimicrobial agents . Against ciprofloxacin-susceptible staphylococci and against streptococci, MICs were < or = 0.12 and < or = 0.5 microgram/ml, respectively . CP-99,219 was also more active than ciprofloxacin against ciprofloxacin-resistant staphylococci, most enterococci, Leuconostoc spp., and lactobacilli. Acta Odontol Scand, 1993 Feb, 51(1), 31 - 7 Intra- and inter-individual variation in salivary flow rate, buffer effect, lactobacilli, and mutans streptococci among 11- to 12-year-old schoolchildren; Tukia-Kulmala H et al.; Both intra- and inter-individual variation in salivary flow rate, buffer effect, and the levels of salivary mutans streptococci and lactobacilli were analyzed in 128 11-year-old children . The follow-up period was 9 months, with six saliva samplings done at regular intervals . Inter-individual variation was relatively large in paraffin-stimulated salivary flow rate: low (< 1.0 ml/min) and high (> or = 2.0 ml/min) flow rates were measured in 18% and 13% of the children, respectively . Intraindividual variation during the follow-up period was found in 63% of the boys and in 73% of the girls . The buffer effect stayed stable in all samplings in 59% of the boys and in 42% of the girls . Buffer effect was significantly (p < 0.001) lower in girls than in boys . Mutans streptococci were analyzed by a chair-side method (Strip mutans test) and by cultivation on mitis-salivarius-bacitracin (MSB) agar plates . The results of the two methods correlated highly significantly (r = 0.79, p < 0.001) . With the Strip mutans test no variation in test scores occurred in 49% of all subjects in all six samplings, whereas the respective percentage for MSB scores was only 19% . No variation in salivary lactobacilli occurred in only 18% of the subjects, and in 13% the intraindividual variation was as high as > or = 3 logs . These results show that in young teenagers with a developing dentition, simultaneous changes in behavioral, hormonal, and dietary factors make single-point measurements of salivary factors too unreliable for caries-diagnostic or predictive purposes. Scand J Dent Res, 1993 Feb, 101(1), 40 - 3 Salivary stimulation by chewing gum and lozenges in rheumatic patients with xerostomia; Risheim H et al.; The effect of chewing gum and lozenges in relieving the signs and symptoms of xerostomia was studied in a 2-wk cross-over clinical trial in 18 rheumatic patients with dry mouth symptoms and low salivary flow rates . Resting flow was measured before (PRESTIM) a chewing stimulated flow rate test (STIM), and also 5 min after (POSTSTIM) . STIM flow (mean 1.0 ml/min) was not affected by the test regimens . In the lozenge regimen, mean PRESTIM flow in the group increased from 0.11 to 0.14 ml/min and POSTSTIM from 0.10 to 0.13 . In the chewing gum regimen, PRESTIM flow (mean 0.13 ml/min) did not change, whereas POSTSTIM flow increased from 0.13 to 0.16 ml/min . In terms of patients' preferences, chewing gum and lozenges were ranked equal . Both these physiologic stimuli had few side-effects . Subjective symptoms were relieved in about one-third of the subjects, but relief was not always verified by improved flow rates . The regimens were not found to influence buffering capacity; salivary counts of mutans streptococci, lactobacilli, and candida; or oral sugar clearance time. J Clin Periodontol, 1993 Feb, 20(2), 124 - 9 Root caries susceptibility in periodontally treated patients . Results after 12 years; Ravald N et al.; The aim of the investigation was to study the individual susceptibility to root caries in periodontally treated patients in a long-term follow-up of 12 years . Age, plaque score, salivary counts of lactobacilli and mutans streptococci, salivary secretion rate and buffer effect, oral sugar clearance time and dietary habit index were tested as possible predictors for root caries incidence . During the whole observation period of 12 years, new root caries lesions were recorded in 24 of a total of 27 patients . In 8 of these, the root caries incidence was between 1 and 5, in 7 between 6 and 9 and in 9, 12 or more new DFS . However, the annual mean number of new DFS was rather low . 13 patients with > 5 new DFS% during the 3rd 4-year period (years 9-12) differed significantly from 14 patients with < or = 5 new DFS% in salivary mutans streptococcus counts (p < 0.01), plaque scores (p < 0.001) and new DFS% during the 2nd 4-year period (years 5-8) (p < 0.001) . Simultaneously, risk values among the variables tested at the 8-year examination were about 3 x more prevalent in patients that developed > 5 new DFS% in years 9-12 than in those with < or = 5 new DFS% . During the whole 12-year observation period, smokers had significantly more root caries than non-smokers (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) J Dent Res, 1993 Feb, 72(2), 529 - 37 Caries risk assessment by a cross-sectional discrimination model; Leverett DH et al.; Although the prevalence of dental caries is continuing to decline, it still affects a majority of the US population and can be a serious problem for those afflicted . The objective of this project was to develop and perfect a model for assessment of risk of dental caries onset in children . In the first study, reported herein, a set of clinical, microbiological, biochemical, and socio-demographic variables was identified that distinguished, with an acceptable level of sensitivity and specificity, between children who had no previous caries experience and children who had high caries levels . A total of 313 children--age 12-15 years, 140 from a fluoridated community and 173 from a fluoride-deficient community--was selected on the basis of previous caries experience, either zero DMFS or high DMFS (> or = 6 in the fluoridated or > or = 8 in the fluoride-deficient community) . Clinical exams for DMFS, dental fluorosis, and plaque were conducted . Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride concentration . A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices . By means of discriminant analyses, with use of seven key clinical and laboratory variables, it was possible for zero-DMFS subjects to e classified correctly (specificity) in 77.6% of cases in the fluoridated community and in 86.1% of cases in the fluoride-deficient community . High-caries subjects were classified as such (sensitivity) in 79.3% and 88.1% of cases, respectively. J Dent Res, 1993 Feb, 72(2), 508 - 16 The association of mutans streptococci and non-mutans streptococci capable of acidogenesis at a low pH with dental caries on enamel and root surfaces; Sansone C et al.; Coronal dental plaque from each of 12 caries-positive subjects (Group I) was pooled from "white spot" tooth surface areas and, separately, from sound surface areas; sound surface areas in each of 18 caries-free subjects (Group II) were sampled similarly . Two samples, one consisting of material from a root-surface lesion and another of plaque from a sound root-surface area, were obtained from each of another 10 subjects (Group III) . The samples from Groups I and II were evaluated for: (1) pH-lowering potential in vitro with dispersed plaque suspensions, excess glucose supply, and a 60-minute test; (2) the levels of mutans streptococci (MS) and lactobacilli; and (3) the distribution of the predominant non-mutans streptococci (non-MS) according to their final pH in glucose broth; only microbial analysis was done for the Group III samples . The levels of the MS were generally positively associated with caries . A weaker positive association was found for the levels of those non-MS capable of acidogenesis at low pH (final pH < 4.4) . The latter generally far outnumbered the MS in all types of samples . The levels of lactobacilli were nearly always very low . The pH-lowering potential (final pH and pH drop rate) was higher for plaque from "white spot" areas than for plaque from sound surface areas (Group I) . The samples from caries-free subjects (Group II), however, exhibited a pH-lowering potential which was not significantly different from that of both types of samples from the caries-active subjects (Group I).(ABSTRACT TRUNCATED AT 250 WORDS) Diagn Microbiol Infect Dis, 1993 Feb, 16(2), 111 - 8 Antimicrobial activity and spectrum of rifaximin, a new topical rifamycin derivative; Hoover WW et al.; Rifaximin, a rifamycin derivative, was evaluated in vitro to assess its spectrum and potency against a wide variety of bacteria, yeasts, viruses, and parasites . High concentrations of rifaximin were often used to reflect topically achieved levels since this compound is poorly absorbed by oral route . Like rifampin, rifaximin possessed best activity against Staphylococcus spp . (MIC50 < or = 0.015 microgram/ml), Streptococcus spp . (MIC50s, < or = 0.03-0.12 microgram/ml), Enterococcus spp . (MIC50s, 0.25-2 micrograms/ml), Bacillus cereus (MIC50, 0.06 microgram/ml), Moraxella catarrhalis (MIC50, < or = 0.03 microgram/ml), and Haemophilus influenzae (MIC50, 0.25 mic