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PubMed1998

Comparison of inhibitory and bactericidal activities and postantibiotic effects of LY333328 and ampicillin used singly and in combination against vancomycin-resistant Enterococcus faecium.

One hundred ninety-five individual vancomycin-resistant Enterococcus faecium (VRE) isolates from five upstate New York hospitals were studied for antimicrobial susceptibilities to LY333328, quinupristin-dalfopristin, teicoplanin, ampicillin, and gentamicin. LY333328 was the most active antibiotic against VRE. The effect of media and methods on the antibacterial activity of LY333328, its synergy with ampicillin, and the postantibiotic effects (PAE) of LY333328 and ampicillin were evaluated. In microdilution tests, the MIC of LY333328 at which 90% of the isolates were inhibited (MIC90) was 2 microg/ml in Mueller-Hinton II (MH II) broth and 1 microg/ml in brain heart infusion (BHI) broth. In contrast, on MH II agar the MIC90 was 4 microg/ml and on BHI agar it was >16 microg/ml. Bactericidal activity was observed for most strains at concentrations from 8 to >/=133 times the MIC of the tube macrodilution in MH II broth. A bactericidal effect of LY333328 plus ampicillin was demonstrated in time-kill studies, but there was great strain-to-strain variability. By the MH II agar dilution method, bacteristatic synergy (defined as a fractional inhibitory concentration of <0.5) with LY333328 and ampicillin was demonstrated for 61% of the strains tested. Under similar conditions, there was synergy with LY333328 and quinupristin-dalfopristin or gentamicin for 27 and 15% of the strains tested, respectively. The PAE of LY333328 was prolonged (23.0 h at 10 times the MIC). However, 50% normal pooled human serum decreased the PAE to 12.2 h at 10 times the MIC. Test conditions and media had a considerable effect on VRE susceptibilities to LY333328. The prolonged PAE of LY333328, a potent new bactericidal glycopeptide, and its synergy with ampicillin in a large proportion of strains suggest that further evaluation of this drug in pharmacokinetic studies and experimental infections, including those with VRE, is warranted.

Ampicillin↗

PubMed1995

[Microbial resistance to formaldehyde. III> Dependence of the microbial effect on Staphylococcus aureus, Enterococcus faecium and spores of Bacillus stearothermophilus on temperature].

Temperature dependence of microbicidal efficacy of formaldehyde was examined with suspension tests (pH 7.0). Test germs were Staphylococcus aureus, Enterococcus faecium and spores of Bacillus stearothermophilus. The methodology was nearly the same as in previous investigations (5, 7). At given exposure periods and temperatures formaldehyde concentrations necessary to produce a microbicidal effect of log (N/N0) = -4.0 (concentrations of equal efficacy) were determined. N and N0 represent the numbers of colony-forming units in suspensions with and without formaldehyde, respectively. On rectangular graphic representation with the reciprocal value of absolute temperature on the abscissa and with the logarithm of the formaldehyde concentration on the ordinate, the formaldehyde concentrations of equal efficacy fitted straight lines. Lines referring to different exposure periods nearly paralleled each other. With increasing exposure periods the steepness of the lines decreased slightly. This effect was most pronounced with Staphylococcus aureus as a test germ. The ratio of formaldehyde concentrations of equal efficacy for exposure periods of 120 minutes at 20 degrees C and 30 degrees C, respectively, was 3.1:1 with Staphylococcus aureus, and 2.8:1 with Enterococcus faecium. The corresponding ratio obtained with spores of Bacillus stearothermophilus and referring to 60 degrees C and 70 degrees C, respectively, was 3.6:1. The logarithms of these ratios decreased with temperature in the same measure as the pertinent absolute temperatures increased. On the basis of the previously presented three-dimensional model of the relations between concentration, period of action and efficacy of microbicidal agents, it could be shown that deviations of the results from a linear and parallel course reflect an inconstant concentration exponent. When low formaldehyde concentration, long exposure period and "high" temperature coincide, the efficacy of formaldehyde is lower than calculated for a linear and parallel course of the relation.

Drug Resistance, Microbial↗

PubMed1991

Bactericidal activity of daptomycin against vancomycin-resistant Enterococcus faecium in an in vitro pharmacokinetic model.

A dynamic in vitro model was used to determine the killing kinetics of daptomycin against 15 vancomycin-resistant clinical isolates of Enterococcus faecium. Concentration profiles simulating those observed in serum following administration of both low-dose (2 mg/kg) and high-dose (6 mg/kg) daptomycin were bactericidal within 5.5 and 2.8 h, respectively. In contrast, when albumin was added to the growth medium, the corresponding bacterial killing times were slowed to greater than 24 h and 7 h; these results suggest that in the clinical setting, daptomycin dosages of approximately 6 mg/kg are required to achieve bactericidal activity against vancomycin-resistant Enterococcus faecium.

Albumins↗

PubMed2006

Linezolid treatment of glycopeptide-resistant Enterococcus faecium in very low birth weight premature neonates.

Glycopeptide-resistant Enterococcus faecium has emerged as an important nosocomial pathogen with limited therapeutic options. Here we report the successful treatment of glycopeptide-resistant E. faecium infection in two very low birth weight premature infants with the new oxazolidinone linezolid. Treatment with linezolid at a dosage of 10 mg/kg every 8 h intravenously for a duration of 16 days and 14 days, respectively, was well tolerated and led to complete clinical recovery and clearance of the organism from all body sites. The two cases support the clinical efficacy and safety of linezolid in very low birth weight premature neonates with glycopeptide-resistant E. faecium infections.

Acetamides↗

PubMed1996

Comparative in vitro activity of quinupristin/dalfopristin against multidrug resistant Enterococcus faecium.

The in vitro susceptibilities of 82 strains of vancomycin resistant Enterococcus faecium (VREF), (49 vanA and 33 vanB) from over 13 hospitals in Europe and United States were studied. The MIC for several antibiotics showed high levels of resistance to vancomycin, ampicillin, gentamicin, and imipenem. All VREF strains were highly susceptible to quinupristin/dalfopristin with a MIC 90% of 0.5 microgram/ml for both vanA and vanB phenotypes. Time-kill and synergy studies of VREF for quinupristin/dalfopristin alone and quinupristin/dalfopristin in combination with several antibiotics (ampicillin, gentamicin, ciprofloxacin, rifampin and novobiocin) did not show bactericidal activity. In induction experiments using SF6550, (VREF, a vanA strain), quinupristin/dalforpristin showed a delay in the expression of vancomycin resistance by 2.5 hours. The results of this study show quinupristin/dalfopristin to have excellent in vitro activity versus multiple resistant E. faecium.

Anti-Bacterial Agents↗

PubMed2005

Long-term (56-week) oral administration of probiotic Enterococcus faecium M-74 decreases the expression of sICAM-1 and monocyte CD54, and increases that of lymphocyte CD49d in humans.

OBJECTIVES: To study the effects of long-term probiotic [Enterococcus faecium (EF) M-74 strain] application in humans with respect to adhesion molecules, both soluble forms (sICAM-1, sPECAM-1) and their expression on leukocytes. METHODS: Double-blinded randomized and placebo controlled study lasting for 60 weeks. A single capsule containing either 2x10(9) of bacteria EF M-74 with 50 microg of organically bound selenium (E-group) or placebo (P-group) was given to volunteers. Peripheral blood was analyzed for the expression of particular adhesive molecules. RESULTS AND CONCLUSIONS: We observed significant changes in CAMs expression in terms of a decrease in sICAM-1, CD54 on monocytes and CD11b on lymphocytes after one-year administration of Enterococcus faecium M-74 in humans. Anti-adhesion-aimed therapeutic modalities may provide the future approach to prevention and treatment of cardiovascular diseases. Application of probiotics may be part of such strategies. (Tab. 2, Fig. 6, Ref. 41.)

Administration, Oral↗

PubMed2004

First confirmed case of vancomycin-resistant Enterococcus faecium meningitis in Turkey: case report and literature review.

Vancomycin-resistant enterococci are unusual etiologic agents of bacterial meningitis and pose significant therapeutic difficulties. We report the first confirmed case of nosocomial vancomycin-resistant Enterococcus faecium meningitis in Turkey. The patient was treated with chloramphenicol and cerebrospinal fluid cultures became negative, but clinical success was not achieved. We also review the previously reported cases of vancomycin-resistant Enterococcus faecium meningitis.

Adult↗

PubMed1996

Multiplicity of genetic backgrounds among vancomycin-resistant Enterococcus faecium isolates recovered from an outbreak in a New York City hospital.

A total of 182 vancomycin-resistant Enterococcus faecium and 6 Enterococcus faecalis inpatient isolates recovered during a 2-year period (1990-1992) in a New York City hospital were analyzed by molecular fingerprinting techniques, pulsed-field gel electrophoresis (PFGE), of chromosomal SmaI digests combined with Southern hybridization using vanA and vanB2-specific DNA probes. Of the 180 isolates hybridizing with these probes, 153 carried the vanA and 27 the vanB gene. As many as 21 different PFGE types and a total of 54 subtypes were identified among the isolates, and the size of vanA and vanB-hybridizing DNA fragments also showed a wide range of sizes, from about 37 to over 280 kb (in vanA) or 140 kb (in vanB), suggesting extensive recombination, including chromosomal integration, of the resistance genes in the isolates. Close to one-third, 46, of the 148 isolates from 1992 belonged to two closely related PFGE subtype variants, each of which carried a 48 kb vanA hybridizing DNA fragment. Spread of this clone appears to be mainly responsible for the substantial increase in the prevalence of vancomycin-resistant E. faecium in early 1992.

Anti-Bacterial Agents↗

PubMed2000

Evaluation of D-xylose and 1% methyl-alpha-D-glucopyranoside fermentation tests for distinguishing Enterococcus gallinarum from Enterococcus faecium.

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.

Bacterial Proteins↗

PubMed2006

Combination of known and unknown mechanisms confers high-level resistance to fluoroquinolones in Enterococcus faecium.

In order to elucidate the mechanisms of fluoroquinolone resistance in Enterococcus faecium, spontaneous mutants isolated from Ent. faecium ATCC 19434 by stepwise selection with sparfloxacin (SPX) or norfloxacin (NOR) and 13 clinical isolates of Ent. faecium were characterized by analysing quinolone-resistance-determining regions (QRDRs) of the gyrA, gyrB, parC and parE genes and examining changes in MICs of SPX and NOR in the presence of efflux pump inhibitors. The SPX-selected first-step mutant had a point mutation only in gyrA, and the mutants QR7-18 and QR7-39, and clinical isolates that had point mutations in parC, showed NOR resistance. These results indicate that the primary targets of SPX and NOR are DNA gyrase and topoisomerase IV, respectively, and therefore that the primary target of fluoroquinolones in Ent. faecium differs depending on the structure of the compound used. The characterization of the spontaneous mutants and the clinical isolates demonstrates that in addition to the previously reported alterations in GyrA and ParC, an alteration in GyrB, a NorA-like pump, an unknown efflux pump, which excretes both SPX and NOR from bacterial cells, and probably other unknown mechanism(s) all contribute to fluoroquinolone resistance in Ent. faecium.

Anti-Bacterial Agents↗

PubMed1999

A new resistance gene, linB, conferring resistance to lincosamides by nucleotidylation in Enterococcus faecium HM1025.

Resistance to lincomycin and clindamycin in the clinical isolate Enterococcus faecium HM1025 is due to a ribosomal methylase encoded by an ermAM-like gene and the plasmid-mediated inactivation of these antibiotics. We have cloned and determined the nucleotide sequence of the gene responsible for the inactivation of lincosamides, linB. This gene encodes a 267-amino-acid lincosamide nucleotidyltransferase. The enzyme catalyzes 3(5'-adenylation) (the adenylation of the hydroxyl group in position 3 of the molecules) of lincomycin and clindamycin. Expression of linB was observed in both Escherichia coli and Staphylococcus aureus. The deduced amino acid sequence of the enzyme did not display any significant homology with staphylococcal nucleotidyltransferases encoded by linA and linA' genes. Sequences homologous to linB were found in 14 other clinical isolates of E. faecium, indicating the spread of the resistance trait in this species.

Anti-Bacterial Agents↗

PubMed1994

Growth and adhesion of Enterococcus faecium L-forms.

Comparisons of growth and surface colonisation of Enterococcus faecium L-forms and their cell-walled forms were undertaken to produce information about their ability to form sessile cells. The growth of L-forms in liquid culture was slower than that of the parent. This was reflected in their longer lag phase and slower specific growth rates: 0.16 h-1 for the L-form and 0.81 h-1 for the parent. Although E. faecium L-forms attached to a silastic rubber surface, the attached population density was 10-100-fold less than that of the parent. Confluent biofilms on the silastic surfaces were not observed for either bacterial form. Comparison of the attachment of E. faecium L-form and parent may provide important information on how bacteria overcome host defence mechanisms and antibiotic treatment.

Bacterial Adhesion↗

PubMed2000

Purification and some characteristics of enterocin ON-157, a bacteriocin produced by Enterococcus faecium NIAI 157.

Bacteriocin-like activity (BLA) was screened in 690 strains of lactic acid bacteria isolated from plant materials such as silages and fermented vegetables. Among them, a strain identified as Enterococcus faecium NIAI 157 showed a clear BLA against the indicator strain, Ent. faecium IFO 13712. The proteinaceous nature and antimicrobial activity against closely related species strongly indicated that this BLA was a bacteriocin and was designated enterocin ON-157. The bacteriocin activity of this strain was extracellularly produced in the logarithmic growth phase in MRS broth and purified by ultrafiltration, ammonium sulphate precipitation and cation-exchange chromatography. Purified enterocin ON-157 had a molecular weight of approximately 2500 Da in SDS-PAGE analysis and was easily inhibited by treatment with alpha-amylase and proteolytic enzymes. Enterocin ON-157 had a bactericidal mode of action and inhibited the growth of the enterococci, Lactobacillus sake and Listeria monocytogenes. Enterococcus faecium NIAI 157 harboured two plasmids, 49.0 kb and 43.7 kb, and a variant missing a larger plasmid by curing with novobiocin lost the bactriocin activity.

Anti-Bacterial Agents↗

PubMed2003

Growth and energy generation by Enterococcus faecium FAIR-E 198 during citrate metabolism.

Citrate metabolism by Enterococcus faecium FAIR-E 198, isolated from Greek Feta cheese, was studied in various growth media containing citrate either in the presence of glucose, or as the sole carbon source, both under aerobic and anaerobic conditions. In de Man-Rogosa-Sharpe (MRS) broth with increasing citrate concentrations, cometabolism of citrate and glucose took place. Glucose was stoichiometrically converted into lactate, while citrate into acetate. Glucose consumption and biomass yield were enhanced with increasing initial citrate concentrations, even though maximum specific growth rate was not. When citrate was used as the sole carbon source in increasing initial concentrations, the main end product was acetate. Small amounts of lactate, formate, ethanol, and acetoin were also produced. In all cases, no significant differences were observed between aerobic and anaerobic conditions. However, when citrate was used as sole carbon source, formate production was favored in the absence of oxygen. The present work shows that E. faecium is able to utilize citrate in synthetic media, either in the presence of glucose or as the sole carbon source, resulting in energy production and the formation of aroma compounds.

Cheese↗

PubMed2002

Multilocus sequence typing scheme for Enterococcus faecium.

A multilocus sequence typing (MLST) scheme has been developed for Enterococcus faecium. Internal fragments from seven housekeeping genes of 123 epidemiologically unlinked isolates from humans and livestock and 16 human-derived isolates from several outbreaks in the United States, the United Kingdom, Australia, and The Netherlands were analyzed. A total of 62 sequence types were detected in vancomycin-sensitive E. faecium (VSEF) and vancomycin-resistant E. faecium (VREF) isolates. VSEF isolates were genetically more diverse than VREF isolates. Both VSEF and VREF isolates clustered in host-specific lineages that were similar to the host-specific clustering obtained by amplified fragment length polymorphism analysis. Outbreak isolates from hospitalized humans clustered in a subgroup that was defined by the presence of a unique allele from the housekeeping gene purK and the surface protein gene esp. The MLST results suggest that epidemic lineages of E. faecium emerged recently worldwide, while genetic variation in both VREF and VSEF was created by longer-term recombination. The results show that MLST of E. faecium provides an excellent tool for isolate characterization and long-term epidemiologic analysis.

Alleles↗

PubMed1993

Nosocomial outbreak due to Enterococcus faecium highly resistant to vancomycin, penicillin, and gentamicin.

In October 1990, Enterococcus faecium that was highly resistant to glycopeptides, penicillins, and aminoglycosides was isolated from the peritoneal dialysis fluid from a patient in an intensive care unit. Over the following 6 months, multiresistant E. faecium organisms were isolated from cultures of blood, urine, or surgical wound specimens from eight additional patients. Surveillance cultures of groin and/or rectal swabs were positive for eight of 37 patients and four of 62 employees at risk. Restriction endonuclease digestion of chromosomal DNA from outbreak isolates was consistent with dissemination of a single strain throughout the intensive care unit. Strict infection control interventions contained the outbreak after several weeks. Review of patient charts suggested that renal insufficiency, length of hospital stay, duration of antibiotic treatment, and prior treatment with vancomycin were risks for infection due to multiresistant E. faecium. The emergence of multiple-drug-resistant enterococci presents serious infection control and therapeutic dilemmas.

Aged↗

PubMed2002

Intraspecies genomic groups in Enterococcus faecium and their correlation with origin and pathogenicity.

Seventy-eight Enterococcus faecium strains from various sources were characterized by random amplified polymorphic DNA (RAPD)-PCR, amplified fragment length polymorphism (AFLP), and pulsed-field gel electrophoresis (PFGE) analysis of SmaI restriction patterns. Two main genomic groups (I and II) were obtained in both RAPD-PCR and AFLP analyses. DNA-DNA hybridization values between representative strains of both groups demonstrated a mean DNA-DNA reassociation level of 71%. PFGE analysis revealed high genetic strain diversity within the two genomic groups. Only group I contained strains originating from human clinical samples or strains that were vancomycin-resistant or beta-hemolytic. No differentiating phenotypic features between groups I and II were found using the rapid ID 32 STREP system. The two groups could be further subdivided into, respectively, four and three subclusters in both RAPD-PCR and AFLP analyses, and a high correlation was seen between the subclusters generated by these two methods. Subclusters of group I were to some extent correlated with origin, pathogenicity, and bacteriocinogeny of the strains. Host specificity of E. faecium strains was not confirmed.

Animals↗

PubMed2003

Relations between the occurrence of resistance to antimicrobial growth promoters among Enterococcus faecium isolated from broilers and broiler meat.

From 1995 to 2001, Enterococcus faecium isolates were collected from broiler flocks at slaughter and broiler meat products at retail outlets and were tested for susceptibility to classes of antimicrobials used for growth promotion in broilers in Denmark, namely: evernimicin, glycopeptide, macrolide and streptogramin. By February 1998, all antimicrobial growth promoters (AGPs) were withdrawn from the Danish broiler production. The present study investigates, by logistic regression analyses, the (1) changes in the occurrence of AGP resistance among E. faecium from broilers and broiler meat from the fourth quarter of 1995 to the fourth quarter of 2001 and (2) relations between the occurrence of AGP resistance among E. faecium isolates from Danish broilers and AGP resistance among E. faecium isolates from the broiler meat of Danish and unknown origin collected in the same quarter within the year. In the present study, we showed that after the AGP withdrawal, a significant decline in resistance to avilamycin, erythromycin, vancomycin and virginiamycin was observed among E. faecium from broilers and broiler meat. In addition, a decline in the occurrence of AGP resistance among E. faecium from Danish broilers was associated with a decrease in the predicted probability of isolating an AGP-resistant E. faecium isolate from a randomly selected broiler meat product. In the analyses "relations between the occurrence of AGP resistance among E. faecium isolated from broilers and broiler meat collected in the same quarter" errors in the explanatory variable were expected. Therefore, a simulation study was performed to validate the results from logistic regression analyses. The results obtained by the two methods were similar.

Animals↗