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PubMed1993

Molecular investigation of clinical Enterococcus faecium isolates highly resistant to gentamicin.

Over a 10-month period, 22 beta-lactamase negative E. faecium strains resistant to ampicillin were isolated from severely compromised hospitalized patients. Most isolates were clinically significant. Twenty of these strains were also resistant to extraordinarily high levels of gentamicin, a finding described rarely in E. faecium. By whole-cell DNA restriction endonuclease digestion, the 20 strains with both ampicillin and high-level gentamicin resistance segregated into only 3 different groups, suggesting introduction of limited clones into this population of patients. Plasmid DNA profiles and plasmid DNA restriction enzyme analysis supported this grouping for 18 of these 20 strains, the two remaining isolates had slightly different profiles. Both strains lacking high-level gentamicin resistance had clearly different molecular profiles. The results of hybridization experiments strongly suggested the presence of a similar genetic determinant of high-level gentamicin resistance in E. faecalis and E. faecium. High-level gentamicin resistance in E. faecium was shown to be transferable on conjugative plasmids, so that further dissemination of this resistance trait may be anticipated. Our data indicate that the use of a nucleic acid probe is a promising diagnostic tool for screening both E. faecium and E. faecalis for high-level gentamicin resistance.

Adult↗
PubMed1994

Bactericidal activities of antibiotics against vancomycin-resistant Enterococcus faecium blood isolates and synergistic activities of combinations.

The effects of teicoplanin (8 micrograms/ml), ampicillin (64 micrograms/ml), imipenem (32 micrograms/ml), and gentamicin (4 micrograms/ml), alone and in combination, against 13 unique blood isolates of vancomycin-resistance (MIC for 90% of isolates tested [MIC90], 512 micrograms/ml), teicoplanin-susceptible (MIC90, 2.0 micrograms/ml), ampicillin-resistant (MIC90, 128 micrograms/ml), and non-beta-lactamase-producing Enterococcus facium (vancomycin-resistant enterococci [VRE] isolates) were evaluated by time-kill studies. All 13 isolates exhibited high-level resistance to streptomycin; 7 isolates exhibited high-level gentamicin resistance (HLGR). After 24 h of incubation, ampicillin (64 micrograms/ml) combined with gentamicin (4 micrograms/ml) was bactericidal against three of the VRE isolates that did not display HLGR. Synergy between ampicillin and gentamicin was not observed against these isolates. Teicoplanin (8 micrograms/ml) alone was bactericidal at 24 h against five of six VRE isolates that lacked HLGR, but was not bactericidal against any HLGR VRE isolate at that time point. The addition of ampicillin (64 micrograms/ml) or imipenem (32 micrograms/ml) to teicoplanin did not significantly enhance the killing of HLGR VRE isolates as a group (P = 0.335). However, there was a trend toward improved killing of some HLGR VRE isolates by teicoplanin plus imipenem. Vancomycin (32 micrograms/ml) combined with ampicillin (64 micrograms/ml) was neither bactericidal nor synergistic against HLGR VRE isolates. Overall, bactericidal activity was attainable against 7 of 13 VRE isolates at 24 h.

Ampicillin↗
PubMed2003

Purification of bacteriocin AS-48 from an Enterococcus faecium strain and analysis of the gene cluster involved in its production.

The cyclic bacteriocin AS-48 has previously been shown to be produced by Enterococcus faecalis strains. A bacteriocin has been purified from an E. faecium strain (E. faecium 7C5), and it has been found to possess molecular mass, cyclization and amino acid sequence typical of bacteriocin AS-48. In addition to the structural gene as-48A, the sequence analysis of the AS-48 gene cluster present in E. faecium 7C5 has revealed the presence of several putative coding regions presumably involved in bacteriocin production and immunity. The results of DNA hybridization assays have indicated that the AS-48 gene cluster and the gene pd78 are present on the same plasmid, possibly the pPD1 plasmid, in E. faecium 7C5.

Amino Acid Sequence↗
PubMed2001

Persistence of a vancomycin-resistant Enterococcus faecium in an anaerobic continuous-flow culture of porcine microflora in the presence of subtherapeutic concentrations of vancomycin.

Recombined porcine continuous-flow culture (RPCF) maintained in a continuous-flow fermentation system is effective in protecting neonatal and weaned pigs against infection by enteropathogens. In the current study, we demonstrate the effect of RPCF on vancomycin-resistant enterococci (VRE) in the presence and absence of subtherapeutic levels of vancomycin. Also examined was the ability of VRE to transfer vancomycin resistance to endogenous Enterococcus faecalis 137.1. When RPCF was challenged with VRE, the rate of VRE clearance was dependent on the method of challenge. In the control experiment, RPCF was challenged with 7.0 log10/CFU/ml VRE. Clearance of VRE from the culture was observed within 7 days at a rate of 1.44 log10/day. RPCF containing 0.001 microg/ml vancomycin cleared VRE at a slightly lower rate of 0.94 log10/day. RPCF containing 0.01 microg/ml or 0.1 microg/ml vancomycin reduced the level of VRE from 7.0 log10/CFU/ml to 2.0 log10/CFU/ml within 9 days, but failed to clear the VRE after 24 days. During the period of decline, the VRE clearance rate for the 0.01 microg/ml and 0.1 microg/ml vancomycin-treated cultures was 0.52 log10/day, and 0.53 log10/day, respectively. E. faecalis 137.1 endogenous to RPCF did not acquire the vancomycin resistance genes throughout the experiment as evidenced by direct selection, ribotyping, and pulsed-field gel electrophoresis.

Anaerobiosis↗
PubMed2003

Epidemic and nonepidemic multidrug-resistant Enterococcus faecium.

The epidemiology of vancomycin-resistant Entero- coccus faecium (VREF) in Europe is characterized by a large community reservoir. In contrast, nosocomial outbreaks and infections (without a community reservoir) characterize VREF in the United States. Previous studies demonstrated host-specific genogroups and a distinct genetic lineage of VREF associated with hospital outbreaks, characterized by the variant esp-gene and a specific allele-type of the purK housekeeping gene (purK1). We investigated the genetic relatedness of vanA VREF (n=108) and vancomycin-susceptible E. faecium (VSEF) (n=92) from different epidemiologic sources by genotyping, susceptibility testing for ampicillin, sequencing of purK1, and testing for presence of esp. Clusters of VSEF fit well into previously described VREF genogroups, and strong associations were found between VSEF and VREF isolates with resistance to ampicillin, presence of esp, and purK1. Genotypes characterized by presence of esp, purK1, and ampicillin resistance were most frequent among outbreak-associated isolates and almost absent among community surveillance isolates. Vancomycin-resistance was not specifically linked to genogroups. VREF and VSEF from different epidemiologic sources are genetically related; evidence exists for nosocomial selection of a subtype of E. faecium, which has acquired vancomycin-resistance through horizontal transfer.

Ampicillin Resistance↗
PubMed1993

Characterization of bacteriocins from Enterococcus faecium with activity against Listeria monocytogenes.

Laboratory cultures and environmental isolates of bacteria were screened for antagonism towards Listeria monocytogenes using an agar spot test. Seven of the 163 strains that were tested, one Streptococcus bovis, one Enterococcus casseliflavus, two E. avium and three E. faecium, consistently displayed antilisterial activity. Cell-free, pH-neutralized supernatants prepared from the three E. faecium strains (JBL1061, JBL1083 and JBL1351) exhibited strong antilisterial activity against L. monocytogenes, and were subjected to more detailed analyses. The antagonistic factors produced by these three strains were sensitive to chloroform and several proteolytic enzymes, resistant to heat (121 degrees C, 20 min), and stable over a wide pH range (3.0-10.0). Moreover, they were listericidal without causing cell lysis. These data suggest that a bacteriocin(s) is involved in the inhibition of L. monocytogenes by E. faecium JBL1061, JBL1083 and JBL1351.

Bacteriocins↗
PubMed2003

A pseudo-outbreak of vancomycin-resistant Enterococcus faecium.

Five VRE isolates were reported from sterile samples. No infections were diagnosed among the patients, who were on different wards. PFGE showed that all five isolates were clonal. All samples were manipulated by the same worker, but the source could not be found. Contamination was probably related to manipulation of a source specimen in the laboratory.

Adult↗
PubMed1998

Disinfection of hospital rooms contaminated with vancomycin-resistant Enterococcus faecium.

Sixteen percent of hospital room surfaces remained colonized by vancomycin-resistant enterococci (VRE) after routine terminal disinfection. Disinfection with a new "bucket method" resulted in uniformly negative cultures. Conventional cleaning took an average of 2.8 disinfections to eradicate VRE from a hospital room, while only one cleaning was required with the bucket method.

Anti-Bacterial Agents↗
PubMed2025

Hospital Enterococcus faecium demonstrates distinct environmental and patient reservoirs: a genomic point prevalence survey.

We assessed the hospital environment as a reservoir of vancomycin-resistant E. faecium (VRE) and compared environmental VRE isolates to bloodstream infection E. faecium isolates. We identified distinct environmental and patient reservoirs, with the environment dominated by vanB VRE. Environment-clinical reservoir spillover accounted for 292/895 (33%) of putative transmission links.

Enterococcus faecium↗
PubMed2006

Comparative DNA analysis of two vanA plasmids from Enterococcus faecium strains isolated from poultry and a poultry farmer in Norway.

The DNA sequences of two plasmids carrying vanA, pVEF1 (39,626 bp) and pVEF2 (39,714 bp), were determined. Forty-three shared coding sequences were identified, and the only nucleotide difference was an 88-bp indel. A postsegregational killing system was identified. This system possibly explains the persistence of the vanA gene cluster in Norwegian poultry farms.

Animals↗
PubMed1992

Sequence of the vanY gene required for production of a vancomycin-inducible D,D-carboxypeptidase in Enterococcus faecium BM4147.

Cloning and nucleotide sequencing identified the vanY gene as a member of the vancomycin-resistance van gene cluster of enterococcal plasmid, pIP816. The vanY gene was necessary for synthesis of the vancomycin-inducible D,D-carboxypeptidase activity previously proposed to be responsible for glycopeptide resistance. However, this activity was not required for peptidoglycan synthesis in the presence of glycopeptides. The deduced product of vanY did not display significant similarity with other D,D-carboxypeptidases.

Amino Acid Sequence↗