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PubMed1999

Phenotypic characteristics of Enterococcus faecium variants confirmed by intergenic ribosomal polymerase chain reaction and E. faecium polymerase chain reaction.

Enterococcus faecium has recently emerged as a serious nosocomial pathogen. The emergence of multiple antimicrobial agent-resistant E. faecium has been remarkable; with its strains it is one of the most phenotypically heterogeneous of all enterococcal species. About 15% of enterococcal strains isolated from human clinical specimens were found to have atypical biochemical characteristics. In order to determine if these strains were E. faecium variants, intergenic ribosomal polymerase chain reaction (ITS-PCR) and E. faecium PCR (EfPCR) were performed in 45 atypical strains, and the two PCR results were used to analyze phenotypic characteristics of the strains. As many as 60% (27/45) of the atypical strains were identified as E. faecium. Thus, it is concluded that if an enterococcal strain shows positive reaction to arabinose, arginine, and ribose and negative reaction to methyl-alpha-D-glucopyranoside and pigment, it should be identified as E. faecium.

Bacterial Typing Techniques↗
PubMed2006

[Meningitis caused by Enterococcus faecalis during disseminated anguilluliasis].

INTRODUCTION: Disseminated anguilluliasis is a serious disease requiring early diagnosis and treatment. The occurrence of bacterial complications, especially meningeal, is generally due to Gram-negative bacteria from the gastrointestinal tract. CASE: A 52-year-old man from Guadeloupe, treated for T-lymphoma during the previous year by polychemotherapy, was hospitalized for meningitis. Culture of the cerebrospinal fluid and the bronchoalveolar lavage both showed Enterococcus faecalis. Strongyloides stercoralis were also found in the stool and bronchoalveolar lavage. Outcome under treatment was favorable. DISCUSSION: This case reminds us of the usefulness of presumptive routine ivermectin treatment for all patients exposed to any immunosuppression treatment and ever having lived in a tropical area and thus possibly infected by chronic but silent anguilluliasis, even in the absence of parasitological certainty.

Amoxicillin↗
PubMedDate not supplied

[Vancomycin-resistant Enterococcus in an epidemic situation: screening at admission for patients at risk of carriage].

OBJECTIVES: To evaluate a strategy based on screening and isolation at admission to a department of infectious diseases during an epidemic of vancomycin-resistant Enterococcus (VRE) at the University Hospital of Clermont-Ferrand. METHODS: Systematic screening for VRE by anal swabs began on November 15, 2004. Patients were isolated on admission if (a) they had been hospitalized more than 24 h in an at-risk department of our hospital or (b) they had received a course of wide-spectrum antimicrobial therapy for longer than 48 h in the three months preceding admission. Patients hospitalized in our department were screened weekly if they were treated with wide-spectrum antibiotics, had a urinary catheter left in place for one week, or were neutropenic. RESULTS: Through May 15, 2005, 12 (3.5%) of 341 swabs were found to be positive for VRE: eight were detected on admission and four during hospitalization. In all, 81 patients were isolated on admission. A case-control study confirmed that the criteria for patient isolation were indeed risk factors for VRE. Isolation was well accepted when it was clearly explained. No new case has been detected since March 2005. CONCLUSION: An isolation strategy based on known risk factors for VRE with systematic screening on admission appears to be an effective way to control an outbreak of VRE, perhaps in part because it helps to keep the medical staff alert to this problem. Isolation is well tolerated as long as it is explained clearly.

Aged↗
PubMed2002

In vivo production of hydroxyl radical by Enterococcus faecalis colonizing the intestinal tract using aromatic hydroxylation.

Enterococcus faecalis is an intestinal commensal that produces extracellular superoxide (O(2)(*-)) through autoxidation of membrane-associated demethylmenaquinone. To assess free radical production by E. faecalis in vivo, intestinal tracts of rats were colonized using wild-type E. faecalis or a mutant strain with attenuated O(2)(*-) production. Ex vivo electron paramagnetic resonance spin trapping study of colonic contents (mean +/- SD) showed 1.4 +/- 1.5 and 0.094 +/- 0.24 microM 5,5-dimethyl-1-pyrroline-N-oxide-hydroxyl radical adduct/gm stool for rats colonized with wild-type and mutant strains, respectively (p = .002). In vivo hydroxyl radical production was further assayed by aromatic hydroxylation using phenyl N-tert-butylnitrone (PBN) and D-phenylalanine. Hydroxylated PBN and D-phenylalanine products were recovered from stool (microM/gm colonic contents/10(9) colony forming units) and urine (microM/h/ml), respectively, and quantified using electrochemical detection. Hydroxylated (OH) PBNs and isomeric tyrosines (hydroxylated phenylalanine) were significantly increased (mean +/- SD) for rats colonized with wild-type E. faecalis (2-OH PBN, 63 +/- 58; 3-OH PBN, 63 +/- 84; ortho-tyrosine, 31 +/- 27; meta-tyrosine, 17 +/- 14) compared to the mutant strain (2-OH PBN, 2.5 +/- 7.3 (p < .001); 3-OH PBN, 3.9 +/- 12.3 (p = .01); ortho-tyrosine, 1.9 +/- 6.0 (p < .001); meta-tyrosine, 1.5 +/- 3.4 (p = .03)). Similar differences were observed following in vitro incubations of these bacteria with aromatic targets. These results confirm in vivo production of hydroxyl radical by E. faecalis colonizing the intestine, and indicate this bacterium may be a potent source of oxidative stress on the intestinal epithelium.

Animals↗
PubMedDate not supplied

Sex pheromones and gene transfer in Enterococcus faecalis.

Cell-density-dependent regulatory controls have been recognized in recent years to play major roles with regard to many microorganisms. In gram-negative bacteria very often N-acyl-homoserine lactones act as 'quorum-sensing' regulators, whilst gram-positive bacteria mainly use peptides to monitor their cell density. The so-called sex pheromone system of Enterococcus faecalis is just one example of the latter type of regulation. The system is a complex one; in this communication, I will discuss in particular the potential role of the peptides to also act as virulence factors.

Animals↗
PubMed2002

Differential antimicrobial susceptibility between human and chicken isolates of vancomycin-resistant and sensitive Enterococcus faecium.

To compare the differential antimicrobial susceptibilities of Enterococcus faecium from humans and whole chicken carcasses, MICs of 12 antimicrobial agents were determined for 54 clinical-isolates (31 vancomycin-resistant [VREF]) and 60 chicken-isolates (29 VREF). Chicken VREF were slightly but consistently more resistant to vancomycin, teicoplanin and avoparcin, compared with human VREF (P<0.01). MICs of LY333328 were <or = 2 mg/l. All human VREF were resistant to erythromycin and tylosin, compared with only 58.6% of chicken VREF (P<0.01). Streptogramins were active against all isolates except four chicken strains. MIC(90s) of amoxycillin and gentamicin for human E. faecium were 8-16-fold higher than chicken isolates. Chicken VREF were significantly more resistant to tetracycline but more susceptible to chloramphenicol than human VREF (P<0.001).

Animals↗
PubMed2002

Epidemiology of multiresistant Enterococcus avium isolates in a Greek tertiary care hospital.

A retrospective survey of the isolation rate of Enterococcus avium during the period March 1994-February 2000 conducted in Laikon General Hospital using the WHONET software, revealed a peak in the isolation rates of this species during March 1995-February 1996. The ten strains isolated during this time were studied further. No glycopeptide resistance was detected but resistance to ampicillin, ciprofloxacin, erythromycin, gentamicin (high-level) and streptomycin (high-level) was present in nine, ten, nine, three and seven of the isolates, respectively. The genes aac(6')-Ie+aph(2")-Ia and ant(6)-I, encoding for high-level gentamicin and streptomycin resistance, respectively, were detected only in the isolates with the corresponding phenotypes. Beta-lactamase production and haemolysis were not detected. There was evidence of ward-, floor- and building-specific distribution among the different aminoglycoside resistance phenotypes. DNA fingerprinting by PFGE grouped six of the ten isolates in a single cluster with 83% similarity, even though they expressed various resistance phenotypes. These results suggest dissemination of resistance genes among both genetically related and unrelated strains.

Anti-Bacterial Agents↗
PubMed1999

Interferon-gamma effects on activities of gentamicin and vancomycin against Enterococcus faecalis resistant to the drugs: an in vitro study with human neutrophils.

The emergence of multidrug-resistant enterococci presents a major therapeutic challenge since there is currently no clearly effective antimicrobial therapy for these infections. The combinatorial effects of interferon-gamma (IFN-gamma) with gentamicin and/or vancomycin against a clinical isolate of drug-resistant Enterococcus faecalis, were evaluated in an in vitro system with human neutrophils. Following inoculation of cultures of human neutrophils with the organism, treatments were initiated immediately after the infection and the number of viable bacteria was determined at 12, 18 and 24 h. Antibiotics were applied at concentrations close to their clinically achievable serum trough and peak levels. Treatment with IFN-gamma alone induced a maximal growth inhibition of up to 40% at a concentration of 100 U/ml. Addition of the cytokine to either therapeutic trough or peak concentrations of gentamicin and vancomycin, or a combination of both antimicrobials, was associated with a significant (P < 0.01) enhancement of anti-enterococcal activity compared with the effects of the agents alone. Investigation of a potential underlying mechanism of anti-enterococcal action of IFN-gamma reveals that it is, most probably, largely due to an activated secretion of the microbicidal reactive oxygen intermediates by neutrophils. The results of this study show that there is a possibility that IFN-gamma could be a useful adjunct in the treatment of multidrug-resistant E. faecalis.

Combined Modality Therapy↗
PubMed1999

Influence of adjunctive interferon-gamma on treatment of gentamicin- and vancomycin-resistant Enterococcus faecalis infection in mice.

Increasing antibiotic resistance and the development of multidrug-resistance in the enterococci has complicated the treatment of serious enterococcal infections. It has been demonstrated in vitro that interferon-gamma (IFN-gamma) significantly augments the activities of gentamicin and vancomycin against Enterococcus faecalis resistant to these antibiotics. The present study was aimed at determining whether this beneficial effect of IFN-gamma on antienterococcal antibiotic activity can be validated in vivo. Following intraperitoneal inoculation in mice with a gentamicin- and vancomycin-resistant E. faecalis clinical isolate, the animals received IFN-gamma, antibiotic or a combination of both agents, subcutaneously, at determined dosing regimens. Treatment with IFN-gamma alone significantly improved survival of infected animals in a dose-dependent manner. High dose IFN-gamma was not beneficial and the level of enterococcal infectious burden influenced the effectiveness of the cytokine. The addition of IFN-gamma to therapy with gentamicin or vancomycin, or a combination of both antibiotics was associated with a marked increase in survival of infected non-neutropenic mice compared to treatments with the agents alone. However, the same treatments made in infected neutropenic mice did not show an enhancement effect by IFN-gamma after a combination therapy with antibiotics. In a study to examine pharmacokinetic interactions, concurrent administration with IFN-gamma significantly modified the disposition of gentamicin but not that of vancomycin. The results of this study suggest that the use of IFN-gamma in combination with vancomycin or gentamicin is a new treatment option that might improve the outcome of therapy of multidrug-resistant E. faecalis infections.

Animals↗
PubMed2004

Comparative analysis of amplified fragment length polymorphism and pulsed field gel electrophoresis in a hospital outbreak and subsequent endemicity of ampicillin-resistant Enterococcus faecium.

Reliable molecular methods for determination of relatedness between bacterial isolates have become increasingly important to evaluate outbreaks and endemic situations with nosocomial pathogens. In the present study Simpson's index of diversity with calculated confidence intervals was used to compare amplified fragment length polymorphism (AFLP) and pulsed field gel electrophoresis (PFGE) analysis of a hospital outbreak of ampicillin-resistant Enterococcus faecium and subsequent endemicity. The outbreak, in a Norwegian tertiary hospital, of infections caused by these enterococci started in 1995 and increased in 1996 after which the situation turned endemic. The purpose of this study was to compare the two methods in this setting and to determine the length of time during an outbreak that these methods are sufficiently valid to be of value for hospital infection control efforts. One hundred and sixty clinical isolates from urine specimens collected during the period 1995-1999 were included. The findings indicate that PFGE and AFLP are equally discriminative and could in this setting be used for typing purposes over the whole 5-year period.

Ampicillin↗
PubMed2000

Characteristics of polyarthritis in rabbits by hyperimmunization with attenuated Enterococcus faecalis.

To produce polyarthritis and rheumatoid factor like substance (RFLS), rabbits were hyperimmunized intravenously with 0.02% thimelosal (TMS)-treated Enterococcus faecalis (E. faecalis) as a persistent bacterial flora. Swelling of knee joints occurred at a rate of 41% (27/66), and of shoulder joints at a rate of 25% (17/66) while that of elbow joints occurred at a rate of 4.5% (3/66). On culturing of knee joint fluids, no colonies appeared while 2/4 fluid specimens from the shoulder joints gave positive colonies for 78 days after the first immunization; thereafter, no colonies appeared. On histological examination, in early stages, acute inflammatory reactions with degenerative changes of synovial tissue was observed. In later stages, chronic inflammatory changes, proliferation of synovial cells with pannus formation, destruction of articular cartilage and subchondral bone were observed. RFLS titer showed bi-phasic peaks at 11 days and 41 days after the first immunization. A high incidence of polyarthritis, particularly knee joints, occurred. Thus, hyperimmunization with attenuated E. faecalis as a normal intestinal flora may provide an animal model of chronic polyarthritis.

Agglutinins↗
PubMed1994

The effect of some antibiotics on Enterococcus faecium SF 68 inoculated in germ-free mice.

A strain of Enterococcus faecium SF 68 (sensitive to penicillin, tetracycline, virginiamicin and tylosin, but resistant to streptomycin) was administered to five groups of germ-free mice. Each group was subsequently given 40 micrograms/ml and then 80 micrograms/ml of a single antibiotic. The following determinations were made: a) colonization of the bacterial strain before and after administration of the antibiotic and b) the MICs in the original strain and after administration of the antibiotic (80 micrograms Iml). The results show that in the mice treated with streptomycin, colonization is not influenced by the antibiotic treatment; in mice treated with antibiotics to which the strain is sensitive, the colonization increases in proportion to the level of the antibiotic resistance (tylosin and tetracycline).

Animals↗
PubMed1998

A bacteriocin-mediated antagonism by Enterococcus faecium BC25 against ruminal Streptococcus bovis.

A bacteriocin-like activity produced by Enterococcus faecium BC25, isolated from the the rumen of a cow, was partially purified and characterized. The active substance was prepared by ammonium sulfate and chloroform/methanol precipitation of culture supernatant. The bacteriocin was a protein of molecular mass 17.5 kDa. Activity was inactivated by trypsin and proteinase K. The bacteriocin BC25 inhibited growth of amylolytic ruminal strains of Streptococcus bovis, including S. bovis AO 24/85. Results showed that bacteriocine substance BC25 has a bacteriostatic effect when present in concentrations exceeding 125 AU/ml. Agar overlays and batch culture growth experiments proved that E. faecium BC25 was producing bacteriocin that inhibited the growth of S. bovis.

Ammonium Sulfate↗
PubMed2003

Efficacy of chlorhexidine- and calcium hydroxide-containing medicaments against Enterococcus faecalis in vitro.

OBJECTIVE: We sought to assess the efficacy of chlorhexidine (CHX) and calcium hydroxide, Ca(OH)(2), against Enterococcus faecalis in vitro. STUDY DESIGN: The effect of CHX (0.2% and 2% in gel or solution) and Ca(OH)(2) (alone or with 0.2% CHX gel) was evaluated by using the agar diffusion test and an in vitro human root inoculation method, to measure zone of inhibition or bacterial growth with optical density analysis, respectively. For optical density analysis, samples from infected root canals were collected after 7 days of medication and were cultured for 24 hours in brain-heart infusion to detect viable bacteria. RESULTS: In the agar diffusion test, CHX was effective against E faecalis in a concentration-dependent fashion, but Ca(OH)(2) alone had no effect. In the root canal inoculation test, CHX was significantly more effective against E faecalis than Ca(OH)(2) was (P < .05), but there were no significant differences between the modes of medication or concentrations of CHX. CONCLUSIONS: CHX is effective against E faecalis in vitro. Further in vivo studies are needed to confirm the value of CHX in clinical treatment.

Anti-Infective Agents, Local↗
PubMed2000

Linkage of determinants for streptogramin A, macrolide-lincosamide-streptogramin B, and chloramphenicol resistance on a conjugative plasmid in Enterococcus faecium and dissemination of this cluster among streptogramin-resistant enterococci.

A new streptogramin A resistance gene, satG (= vatE), has been recently identified in Enterococcus faecium UW1965 (Werner and Witte 1999. Antimicrob. Agents Chemother. 43: 1813-1814). Further sequence analysis of this plasmid revealed that vatE is in a cluster together with other resistance genes. The identified ORFs were nearly identical with the already known genes ermB and cat. The ermB fragment exhibited more than 99% identity with a resistance region from the streptococcal plasmid pIP501, whereas the cat fragment also contained a truncated rep gene homologue with more than 99% identity to sequences in small staphylococcal plasmids. The cat-rep and the ermB-vatE segments were linked by an IS1216V insertion sequence widely distributed among enterococci. PCR analysis of additional 76 streptogramin-resistant isolates possessing vatE and ermB revealed a linkage of both genes in 45 isolates (59%); 15 of them with a gene arrangement, cat-repU-IS1216V-ermB-vatE, identical to the reference strain UW1965. An identical linkage of IS1216V-ermB-vatE was found among isolates from poultry manure, poultry meat, stool samples of humans, and hospital patients indicating a possible spread of the resistance gene cluster via the food chain to humans.

Anti-Bacterial Agents↗
PubMed2003

Assessing risks for a pre-emergent pathogen: virginiamycin use and the emergence of streptogramin resistance in Enterococcus faecium.

Vancomycin-resistant enterococci (VRE) are an important cause of hospital-acquired infections and an emerging infectious disease. VRE infections were resistant to standard antibiotics until quinupristin/dalfopristin (QD), a streptogramin antibiotic, was approved in 1999 for the treatment of vancomycin-resistant Enterococcus faecium infections in people. After that decision, the practice of using virginiamycin in agriculture for animal growth promotion came under intense scrutiny. Virginiamycin, another streptogramin, threatens the efficacy of QD in medicine because streptogramin resistance in enterococci associated with food animals may be transferred to E faecium in hospitalised patients. Policy makers face an unavoidable conundrum when assessing risks for pre-emergent pathogens; good policies that prevent or delay adverse outcomes may leave little evidence that they had an effect. To provide a sound basis for policy, we have reviewed the epidemiology of E faecium and streptogramin resistance and present qualitative results from mathematical models. These models are based on simple assumptions consistent with evidence, and they establish reasonable expectations about the population-genetic and population-dynamic processes underlying the emergence of streptogramin-resistant E faecium (SREF). Using the model, we have identified critical aspects of SREF emergence. We conclude that the emergence of SREF is likely to be the result of an interaction between QD use in medicine and the long-term use of virginiamycin for animal growth promotion. Virginiamycin use has created a credible threat to the efficacy of QD by increasing the mobility and frequency of high-level resistance genes. The potential effects are greatest for intermediate rates of human-to-human transmission (R0 approximately equal 1).

Anti-Bacterial Agents↗
PubMed1994

Thermal inactivation of gamma-glutamyltranspeptidase and Enterococcus faecium in milk-based systems.

Untreated whole milk, skim milk, sweetened milks, sweetened and unsweetened creams and ice-cream mixes were preincubated with a culture of Enterococcus faecium, then subjected to heat treatment in a pilot-scale plate heat exchanger using a hold of 15 s at 76 degrees C. The liquids were examined for gamma-glutamyltranspeptidase (GGTP) activity and total streptococcal count before and after heat treatment and the results plotted against water activity (aW). There was a good correlation between reduction in GGTP activity, destruction of streptococci and aW, demonstrating the potential of the enzymic assay for assessing the severity of HTST heat treatments above the minimum for pasteurization.

Animals↗
PubMed2002

Nucleotide substitutions in vanC-2 gene of Enterococcus casseliflavus isolates obtained from chickens.

DNA sequencing of the vanC-2 gene was partially carried out on 10 isolates of Enterococcus casseliflavus obtained from 8 samples of imported chickens in Japan between July 1999 and June 2001 to evaluate the variation in the gene. Forty nucleotide substitutions in 36 codons were identified within 345 base pairs when compared with the vanC-2 sequence of the reference strain E. casseliflavus ATCC25788. Identical nucleotide substitutions were commonly found in the isolates recovered from chickens imported from both Brazil and China. Pulsed-field gel electrophoresis (PFGE) patterns of NotI-digested chromosomal DNA of these strains were distinguished by two, or more than six, band differences. These observations suggest that sequencing of the vanC-2 gene may be helpful for epidemiological investigation in combination with the PFGE analyses of the isolates, although particular genotypes are unlikely to be restricted to each of the countries that exported chickens.

Animals↗