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Efficacy of Oral Ramoplanin for Inhibition of Intestinal Colonization by Vancomycin-Resistant Enterococci in Mice. Usha Stiefel, 2004.Ramoplanin is a glycolipodepsipeptide antibiotic with activity against gram-positive bacteria that is in clinical trials for prevention of vancomycin-resistant Enterococcus (VRE) bloodstream infections and treatment of Clostridium difficile diarrhea . Orally administered ramoplanin suppresses VRE intestinal colonization, but recurrences after discontinuation of treatment have frequently been observed . We used a mouse model to examine the efficacy of ramoplanin for inhibition of VRE colonization and evaluated the etiology of recurrences of colonization . Eight days of treatment with ramoplanin (100 µg/ml) in drinking water suppressed VRE to undetectable levels, but 100% of mice developed recurrent colonization; a higher dose of 500 µg/ml in water was associated with recurrent colonization in 50% of mice . Two of eight (25%) mice treated with the 100-µg/ml dose of ramoplanin had low levels of VRE in their cecal tissues on day 8 despite undetectable levels in stool and cecal contents . Mice that received prior ramoplanin treatment did not develop VRE overgrowth when challenged with 107 CFU of oral VRE 1, 2, or 4 days later . In communal cages, rapid cross-transmission and overgrowth of VRE was observed among clindamycin-treated mice; ramoplanin treatment effectively suppressed VRE overgrowth in such communal cages . Ramoplanin treatment promoted increased density of indigenous Enterobacteriaceae and overgrowth of an exogenously administered Klebsiella pneumoniae isolate . These results demonstrate the efficacy of ramoplanin for inhibition of VRE colonization and suggest that some recurrences occur due to reexpansion of organisms that persist within the lining of the colon . Ramoplanin treatment may be associated with overgrowth of gram-negative bacilli . Nitrite Elimination and Hydrolytic Ring Cleavage in 2,4,6-Trinitrophenol (Picric Acid) Degradation. Klaus W. Hofmann, 2004.Two hydrogenation reactions in the initial steps of degradation of 2,4,6-trinitrophenol produce the dihydride Meisenheimer complex of 2,4,6-trinitrophenol . The npdH gene (contained in the npd gene cluster of the 2,4,6-trinitrophenol-degrading strain Rhodococcus opacus HL PM-1) was shown here to encode a tautomerase, catalyzing a proton shift between the aci-nitro and the nitro forms of the dihydride Meisenheimer complex of 2,4,6-trinitrophenol . An enzyme (which eliminated nitrite from the aci-nitro form but not the nitro form of the dihydride complex of 2,4,6-trinitrophenol) was purified from the 2,4,6-trinitrophenol-degrading strain Nocardioides simplex FJ2-1A . The product of nitrite release was the hydride Meisenheimer complex of 2,4-dinitrophenol, which was hydrogenated to the dihydride Meisenheimer complex of 2,4-dinitrophenol by the hydride transferase I and the NADPH-dependent F420 reductase from strain HL PM-1 . At pH 7.5, the dihydride complex of 2,4-dinitrophenol is protonated to 2,4-dinitrocyclohexanone . A hydrolase was purified from strain FJ2-1A and shown to cleave 2,4-dinitrocyclohexanone hydrolytically to 4,6-dinitrohexanoate . Characterization of PauB, a Novel Broad-Spectrum Plasminogen Activator from Streptococcus uberis. Philip N. Ward, 2002.A bovine plasminogen activator of atypical molecular mass (  45 kDa) from Streptococcus uberis strain SK880 had been identified previously (L . B . Johnsen, K . Poulsen, M . Kilian, and T . E . Petersen . Infect . Immun . 67:1072–1078, 1999) . The strain was isolated from a clinical case of bovine mastitis . The isolate was found not to secrete PauA, a bovine plasminogen activator expressed by the majority of S . uberis strains . Analysis of the locus normally occupied by pauA revealed an absence of the pauA open reading frame . However, an alternative open reading frame was identified within the same locus . Sequence analysis of the putative gene suggested limited but significant homology to other plasminogen activators . A candidate signal peptide sequence and cleavage site were also identified . Expression cloning of DNA encoding the predicted mature protein (lacking signal peptide) confirmed that the open reading frame encoded a plasminogen activator of the expected size, which we have named PauB . Both native and recombinant forms of PauB displayed an unexpectedly broad specificity profile for bovine, ovine, equine, caprine, porcine, rabbit, and human plasminogen . Clinical and nonclinical field isolates from nine United Kingdom sites were screened for the pauB gene and none were identified as carrying it . Similarly, clinical isolates from 20 Danish herds were all found to encode PauA and not PauB . Therefore, PauB represents a novel but rare bacterial plasminogen activator which displays very broad specificity .
Identification and Functional Characterization of Sphingomonas macrogolitabida Strain TFA Genes Involved in the First Two Steps of the Tetralin Catabolic Pathway. Emilia Moreno-Ruiz, 2003.Five genes involved in the two initial steps of the tetralin biodegradation pathway of Sphingomonas macrogolitabida strain TFA have been characterized . ThnA1A2 and ThnA3A4, components of the ring-hydroxylating dioxygenase, were encoded in divergently transcribed operons . ThnA1, ThnA2, and ThnA3 were essential for tetralin ring-hydroxylating dioxygenase activity . ThnB was identified as a dehydrogenase required for tetralin biodegradation . Evaluation of Potential Indicators of Viral Contamination in Shellfish and Their Applicability to Diverse Geographical Areas. M. Formiga-Cruz, 2003.The distribution of the concentration of potential indicators of fecal viral pollution in shellfish was analyzed under diverse conditions over 18 months in diverse geographical areas . These microorganisms have been evaluated in relation to contamination by human viral pathogens detected in parallel in the analyzed shellfish samples . Thus, significant shellfish-growing areas from diverse countries in the north and south of Europe (Greece, Spain, Sweden, and the United Kingdom) were defined and studied by analyzing different physicochemical parameters in the water and the levels of Escherichia coli, F-specific RNA bacteriophages, and phages infecting Bacteroides fragilis strain RYC2056 in the shellfish produced, before and after depuration treatments . A total of 475 shellfish samples were studied, and the results were statistically analyzed . According to statistical analysis, the presence of human viruses seems to be related to the presence of all potential indicators in the heavily contaminated areas, where E . coli would probably be suitable as a fecal indicator . The F-RNA phages, which are present in higher numbers in Northern Europe, seem to be significantly related to the presence of viral contamination in shellfish, with a very weak predictive value for hepatitis A virus, human adenovirus, and enterovirus and a stronger one for Norwalk-like virus . However, it is important to note that shellfish produced in A or clean B areas can sporadically contain human viruses even in the absence of E . coli or F-RNA phages . The data presented here will be useful in defining microbiological parameters for improving the sanitary control of shellfish consumed raw or barely cooked .
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