Genotypic characterisation of endemic VanA Enterococcus faecium strains isolated in a paediatric hospital.
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A total of 36 vancomycin-resistant Enterococcus faecium isolates obtained from 30 patients during a 28-month period in a paediatric university hospital was analysed by pulsed-field gel electrophoresis (PFGE) combined with Southern hybridisation of a vanA-specific DNA probe. All the isolates hybridised with the vanA probe. Seventeen different PFGE patterns and 11 PFGE subtypes were identified among the 36 clinical isolates, and the size of probe-positive bands ranged from c. 30 to 300 kb. These data are consistent with an increase in the overall genomic diversity of vancomycin-resistant E. faecium isolates during the study period. Two periods were distinguished. The prevalence of a single clone in the initial period suggested transmission between patients in three wards. During the following period, multiple genotypes of vancomycin-resistant E. faecium were identified, indicative of multiple introductions or the dissemination of resistance genes by recombinant transposition. (+info)
Outbreak of vancomycin-resistant enterococci in a hospital in Gdask, Poland, due to horizontal transfer of different Tn1546-like transposon variants and clonal spread of several strains.
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Twenty-two vancomycin-resistant enterococcal (VRE) isolates of the VanA phenotype (21 Enterococcus faecium isolates and 1 E. faecalis isolate), representative of a large outbreak that occurred in a hospital in Gdansk, Poland, were studied. All of the isolates demonstrated resistance to a wide variety of other antimicrobial agents in addition to glycopeptides. Several lines of evidence suggested that the outbreak most probably consisted of two epidemics that followed the independent introduction of VanA determinants into two separate hematological wards of the hospital. This hypothesis is supported by the fact that isolates recovered in these wards possessed two different polymorphs of the highly conserved DNA region encompassing the vanRSHAX genes and two distinct polymorph types of Tn1546-like transposons, which contain these genes. According to pulsed-field gel electrophoresis data, the outbreak in the adult hematology ward (HW) was highly polyclonal, which suggested a major role for the horizontal transmission of Tn1546-like elements among nonrelated strains of E. faecium and E. faecalis in this environment. On the other hand, the outbreak in the pediatric hematology ward (PHW) was most probably due to the clonal spread of two epidemic E. faecium strains, which had exchanged a plasmid carrying the Tn1546-like transposon. Restriction fragment length polymorphism studies of transposons and their insertion loci in plasmid DNA have suggested that numerous isolates from both HW and PHW contained two or more copies of Tn1546-like elements that underwent diversification due to various genetic modifications. The reported data demonstrated a very complex epidemiology of the first, and up to now the only, VanA VRE outbreak characterized in Poland. (+info)
In vivo activities of evernimicin (SCH 27899) against vancomycin-susceptible and vancomycin-resistant enterococci in experimental endocarditis.
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To assess the potential efficacy of evernimicin (SCH 27899) against serious enterococcal infections, we used a rat model of aortic valve endocarditis established with either a vancomycin-susceptible Enterococcus faecalis or a vancomycin-resistant Enterococcus faecium strain. Animals infected with either one of the test strains were assigned to receive no treatment (controls) or 5-day therapy with one of the following regimens: evernimicin 60-mg/kg of body weight intravenous (i.v.) bolus once daily, 60-mg/kg i.v. bolus twice daily (b.i.d.), 60 mg/kg/day i.v. by continuous infusion, or 120 mg/kg/day i.v. by continuous infusion. These regimens were compared with vancomycin at 150 mg/kg/day. In animals infected with E. faecalis, evernimicin at 120 mg/kg/day by continuous infusion significantly reduced bacterial counts in vegetations (final density, 5.75+/-3.38 log(10) CFU/g) compared with controls (8.51+/-1.11 log(10) CFU/g). In animals infected with 0.5 ml of an 8 x 10(7)-CFU/ml inoculum of the vancomycin-resistant E. faecium, both 60-mg/kg bolus once a day and b.i.d. dose regimens of evernimicin were very effective (viable counts, 3.45+/-1.44 and 3.81+/-1.98 log(10) CFU/g, respectively). Vancomycin was unexpectedly active against infections induced with that inoculum. In animals infected with a 10(9)-CFU/ml inoculum of the vancomycin-resistant E. faecium, the evernimicin 60-mg/kg i.v. bolus b.i.d. reduced viable counts in vegetations compared with controls (6.27+/-1.63 versus 8.34+/-0.91 log(10) CFU/g; P<0.05), whereas vancomycin was ineffective. Although resistant colonies could be selected in vitro, we were not able to identify evernimicin-resistant clones from cardiac vegetations. An unexplained observation from these experiments was the great variability in final bacterial densities within cardiac vegetations from animals in each of the evernimicin treatment groups. (+info)
Detection of the high-level aminoglycoside resistance gene aph(2")-Ib in Enterococcus faecium.
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A new high-level gentamicin resistance gene, designated aph(2")-Ib, was cloned from Enterococcus faecium SF11770. The deduced amino acid sequence of the 897-bp open reading frame of aph(2")-Ib shares homology with the aminoglycoside-modifying enzymes AAC(6')-APH(2"), APH(2")-Ic, and APH(2")-Id. The observed phosphotransferase activity is designated APH(2")-Ib. (+info)
Antibacterial activity of chaff vinegar and its practical application.
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Since enterohemorrhagic Escherichia coli O157, Salmonella, etc., sometimes contaminate animal feces and may cause infectious diseases to humans, it is important to remove pathogenic bacteria from domestic animal waste. For the purpose, we examined the antibacterial activity of chaff vinegar. We found that the chaff vinegar inhibited the growth of pathogenic bacteria immediately in vitro but not efficiently spores and lactic acid bacteria. Further, it removes bacteria, especially Enterobacteriaceae, from animal feces and the surface of the concrete-floor in the cattle barn. Chaff vinegar is advertised as a natural chemical substance for a soil conditioner, to promote the composting and to deodorize their smell. Chaff vinegar may be useful for organic agriculture without enteric pathogenic bacteria. (+info)
A strain of Enterococcus faecium (18C23) inhibits adhesion of enterotoxigenic Escherichia coli K88 to porcine small intestine mucus.
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Few studies, if any, have addressed the adhesion of enterococci to the intestinal mucosa and their interference with the adhesion of pathogens, although more than 60% of probiotic preparations in the market contain strains of enterococci. The objective of this study was to investigate if Enterococcus faecium 18C23 has the ability to inhibit the adhesion of Escherichia coli K88ac and K88MB to the small intestine mucus of piglets. Approximately 9% of E. faecium 18C23 organisms adhered to the small intestine mucus, and the adhesion was found to be specific. Living E. faecium 18C23 culture efficiently inhibited the adhesion of E. coli K88ac and K88MB to the piglet intestine mucus. Inhibition of the adhesion of E. coli K88ac to the small intestine mucus was found to be dose dependent. Inhibition of >90% was observed when 10(9) CFU or more of living E. faecium 18C23 culture per ml was added simultaneously with E. coli to immobilized mucus. The substances from both the 18C23 cells and the spent culture supernatant contributed to the inhibition of adhesion of E. coli K88 to the small intestine mucus receptors. The inhibiting effect was not solely a pH effect since considerable inhibitory action was demonstrated after neutralizing the mixture or spent culture supernatant to pH 7.0. Part of the inhibition of adhesion of E. coli K88ac by E. faecium 18C23 or its supernatant might occur through steric hindrance. (+info)
Evaluation of D-xylose and 1% methyl-alpha-D-glucopyranoside fermentation tests for distinguishing Enterococcus gallinarum from Enterococcus faecium.
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To determine the validity of the rapid xylose and methyl-alpha-D-glucopyranoside (MDG) fermentation tests in distinguishing Enterococcus gallinarum from Enterococcus faecium, 156 well-characterized clinical isolates of enterococci (55 E. gallinarum, 91 E. faecium, and 10 Enterococcus faecalis isolates) known to be of different clones were examined in a blinded fashion. Species identification was confirmed by PCR of the ddl ligase genes of E. faecium and E. faecalis and the vanC1 gene of E. gallinarum. Xylose tests were performed with D-xylose tablets by using a heavy bacterial suspension and were interpreted after 2 h of incubation. Standard MDG fermentation tests were read after 24 h of incubation. The xylose fermentation test had a sensitivity of 98% (54 of 55) and a specificity of 99% (100 of 101) in distinguishing E. gallinarum from E. faecium and E. faecalis. The standard MDG test had a sensitivity of 100% (55 of 55) and a specificity of 95% (96 of 101) after 24 h. The xylose fermentation test is a simple method, easily incorporated into laboratory protocols, that distinguishes E. gallinarum from E. faecium with high sensitivity and specificity in 2 h. The standard MDG test has high sensitivity and can be useful in ruling out the presence of E. gallinarum but requires overnight incubation. (+info)
Impact of flavophospholipol and vancomycin on conjugational transfer of vancomycin resistance plasmids.
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The influence of vancomycin and flavophospholipol (FPL) on the transfer rate of conjugative plasmids harboring the vancomycin resistance operon vanA was determined in several clinical and animal isolates of Enterococcus faecium. FPL significantly inhibited the frequency of transfer of conjugative VanA plasmids up to 70-fold. Vancomycin had no significant effect on the transfer rate of VanA plasmids. (+info)