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Molecular epidemiology by ribotyping and PCR-ribotyping of Enterococcus faecium strains isolated from intercontinental areas.

In this study classical ribotyping based on hybridization of an enteroccocal ribosomal operon previously cloned from Enterococcus hirae (Sechi and Daneo-Moore, 1993) with XbaI cut chromosomal DNA and PCR-ribotyping were used to characterize the molecular epidemiology of 131 Enterococcus faecium, with high-level resistance to gentamicin, isolated from different hospitals in Italy and the United States. The ribotyping was able to differentiate all 131 clinical isolates into 96 family patterns. These family patterns appeared to be useful in establishing epidemiological spread. The results obtained were in agreement with those previously published, suggesting the presence of five to six operons in the Enterococcus genus (Sechi et al., 1994). We performed PCR-ribotyping, based on conserved sequences at the 3' end of the enterococcal 16S rrn and the 5' end of the 23S rrn, on 131 clinical isolates as well as on several enterococcal ATCC strains tested. The results were then compared with those obtained with the classical ribotyping method. The results suggest the presence of at least four classes of intergenic spacers among enterococci, but these classes are not helpful in differentiating between Enterococci or among Enterococcal isolates.

DNA, Bacterial↗

Prospective, randomized study comparing quinupristin-dalfopristin with linezolid in the treatment of vancomycin-resistant Enterococcus faecium infections.

OBJECTIVES: Quinupristin-dalfopristin and linezolid have been shown to be efficacious in the treatment of vancomycin-resistant Enterococcus faecium (VREF) infections. However, the two antibiotics have not been compared in terms of safety and efficacy in a prospective randomized study. The objective of this study was to compare the safety and efficacy of the two drugs in the treatment of VREF infections in cancer patients. PATIENTS AND METHODS: Forty cancer patients with VREF infection were randomized to receive linezolid 600 mg every 12 h or quinupristin-dalfopristin 7.5 mg/kg every 8 h. All patients were followed up for 30 days after discontinuation of study drugs. RESULTS: Linezolid and quinupristin-dalfopristin had comparable clinical responses (58% and 43%, respectively, P = 0.6). Myalgias and/or arthralgias occurred at a frequency of 33% in patients who received quinupristin-dalfopristin, but were not observed in the linezolid group (P = 0.03). In contrast, drug-related thrombocytopenia occurred in 11% of patients who received linezolid, but was not observed in the quinupristin-dalfopristin group (P = 0.2). CONCLUSION: In cancer patients, quinupristin-dalfopristin treatment is associated with a relatively high frequency of myalgias/arthralgias; however, profound thrombocytopenia might limit the choice of linezolid in a subpopulation of cancer patients.

Acetamides↗

Molecular typing of ampicillin-resistant, non-beta-lactamase-producing Enterococcus faecium isolates from diverse geographic areas.

Molecular typing methods were compared by using 66 ampicillin-resistant, non-beta-lactamase-producing Enterococcus faecium clinical isolates from diverse geographic areas. Whole-plasmid analysis, restriction enzyme analysis of plasmid DNA with EcoRI and HindIII, and contour-clamped homogeneous electric field electrophoresis with digestion by SmaI and ApaI were performed on all isolates. Whole-plasmid analysis identified 47 different groups. Restriction enzyme analysis of plasmid DNA identified 50 groups when EcoRI was used and 51 groups when HindIII was used. Results with EcoRI and HindIII differed in 9 of 66 isolates. Grouping results with whole-plasmid analysis differed from results of restriction enzyme analysis of plasmid DNA (combining EcoRI and HindIII) in 20 of 66 isolates. Contour-clamped homogeneous electric field electrophoresis identified 46 groups when SmaI was used and 44 groups when ApaI was used. Results with SmaI and ApaI differed in 3 of 66 isolates. Grouping results with contour-clamped homogeneous electric field electrophoresis (combining SmaI and ApaI) differed from results of restriction enzyme analysis of plasmid DNA (combining EcoRI and HindIII) in 17 of 66 isolates. The combined use of whole-plasmid analysis, restriction enzyme analysis of plasmid DNA with two enzymes, and contour-clamped homogeneous electric field electrophoresis with two restriction enzymes should be considered when E. faecium is typed for epidemiologic investigation.

Ampicillin Resistance↗

Linezolid treatment of vancomycin-resistant Enterococcus faecium ventriculitis.

The successful treatment of a 7-month-old infant with shunt-associated ventriculitis caused by vancomycin-resistant Enterococcus faecium is presented. Linezolid was administered intravenously every 8 h; children have a greater volume of distribution and total body clearance than adults and therefore require more frequent dosing. The patient tolerated the therapy without adverse effects.

Acetamides↗

Isolation of streptogramin-resistant Enterococcus faecium from human and non-human sources in a rural community.

OBJECTIVES: To detect quinupristin-dalfopristin and virginiamycin M1 resistance in Enterococcus faecium from human, food and environmental sources. MATERIALS AND METHODS: Enterococcal isolates derived from human faeces and urine, meat and seawater were screened for resistance to quinupristin-dalfopristin and virginiamycin M1 by an agar dilution method. Identification of all E. faecium strains and the presence of streptogramin acetyltransferase genes were confirmed using a PCR method. RESULTS: No high-level quinupristin-dalfopristin-resistant strains were isolated. Two isolates from faeces and five from seawater were confirmed to be high-level virginiamycin M1-resistant E. faecium (MIC 32 mg/L); none of these carried the vat(D) or vat(E) acetyltransferase genes that mediate high-level resistance to streptogramin A compounds. CONCLUSION: High-level quinupristin-dalfopristin-resistant strains of E. faecium are uncommon in Cornwall. However streptogramin A-resistant strains were detected from human and animal sources.

Animals↗

Inconsistent bactericidal activity of triple-combination therapy with vancomycin, ampicillin, and gentamicin against vancomycin-resistant, highly ampicillin-resistant Enterococcus faecium.

Combination therapy with ampicillin, vancomycin, and gentamicin in vitro against several clinical isolates of vancomycin-resistant, highly ampicillin-resistant Enterococcus faecium, including VanA and VanB strains, was evaluated. The MICs of ampicillin were not significantly decreased by induction with vancomycin, and the combination of ampicillin and vancomycin was not inhibitory for any strain. Triple-combination therapy was least active against highly resistant VanA isolates, achieving a reduction of less than 1 log CFU at 24 h, but demonstrated slightly more activity against VanB strains.

Ampicillin↗

Variation within the vat(E) allele of Enterococcus faecium isolates from retail poultry samples.

In a survey of retail meat samples, twelve quinupristin-dalfopristin-resistant (MICs, > or =4 mg/liter) Enterococcus faecium isolates that carried a vat(E) gene were recovered. DNA sequence comparison revealed five new variations in the vat(E) allele among 12 isolates, which were designated vat(E-4) through vat(E-8); two isolates had vat(E-1). There was no correlation between the number of base changes and the quinupristin-dalfopristin MIC.

Acetyltransferases↗

Effects of the movement of insertion sequences on the structure of VanA glycopeptide resistance elements in Enterococcus faecium.

A Tn1546-related element with IS1216V at position 8839 underwent a structural change after storage of the host strain of Enterococcus faecium at 4 degrees C. The element acquired IS1542 at position 3932, nucleotides 8732 to 8831 were deleted, and the first 3417 nucleotides were lost and replaced by an inverted copy of the IS1216V-vanY-vanZ-inverted-repeat block from the 3' end. Insertion sequence movement is likely to play a key role in the evolution of VanA resistance elements.

Anti-Bacterial Agents↗

[1st isolation of vancomycin-resistant Enterococcus faecium with the vanB genotype in Argentina: presentation of 2 cases].

We describe the first isolate of van B vancomycin-resistant Enterococcus faecium in Argentina. The strains were recovered from ambulatory patients admitted to a hospital of Buenos Aires city in July 2000. They were not high-risk patients, they had not received previous antibiotic therapy, and they were assisted in different services. MICs for vancomycin were 32 micrograms/ml for both strains, whereas MICs for teicoplanin were 0.12 microgram/ml in case 1 and 0.25 microgram/ml in case 2. PCR was performed to confirm the vanB genotype. The molecular fingerprints of the isolations by PFGE revealed that they were identical. No further VanB strains were isolated in the hospital.

Adult↗

Synergic activity of selenium and probiotic bacterium Enterococcus faecium M-74 against selected mutagens in Salmonella assay.

Concentrated extracts of MRS (De Man-Rogosa-Sharpe) media in which probiotic bacterium Enterococcus faecium strain M-74 was grown exerted different antimutagenic activity against ofloxacin-, N-methyl, N'-nitro-N-nitrosoguanidine- and sodium 5-nitro-2-furylacrylate-induced mutagenicity in Salmonella typhimurium assay depending on the presence (+Se) or absence of disodium selenite pentahydrate (-Se). The antimutagenicity of MRS(+Se) extract was higher than that of MRS(-Se) extract. Selenium enhanced also the antimutagenic effect of both live and killed cells of E. faecium M-74, respectively. The live bacteria decreased the mutagenicity of selected substances more than killed cells. Synergic activity of selenium with the bacterium was also manifested.

Antimutagenic Agents↗

Isolation of an 1,3-1,4-beta-glucan degrading Enterococcus faecium strain from the intestinal tract of chicken and partial characterization of its novel 1,3-1,4-beta-glucanase.

An Enterococcus faecium strain with a novel endo 1,3-1,4-endo-beta-glucanase (lichenase, E.C. 3.2.1.73) was isolated from the intestinal tract of broiler chicken. The enzyme was secreted into the culture medium and acted exclusively on mixed linked 1,3-1,4-beta-glucans as determined with a reducing sugar assay. The purified enzyme has its isoelectric point at pI 4.8, maximum activity was determined at pH 6.5 and 40 degrees C. Thermal stability of the enzyme was low, but high pH stability and high residual activity was observed after incubation in digesta samples from the chicken intestine. Multiple lichenase activities were obtained from culture supernatants on SDS/PAGE and native zymograms, but it is concluded that the lichenase consists of one active protein at 30.5 kD and additional polypeptides of unknown function.

Animals↗

Intracellular activities of RP 59500 (quinupristin-dalfopristin) and sparfloxacin against Enterococcus faecium.

RP 59500, a combination of the streptogramins quinupristin and dalfopristin, and sparfloxacin are new antibiotics with good in vitro activities against Enterococcus faecium, which is an increasingly important nosocomial pathogen with resistance to multiple antimicrobials. Since fluoroquinolones and related macrolides have displayed high intracellular concentrations inside host cells, we evaluated the intracellular activities of these agents inside neutrophils against three strains each of vancomycin-susceptible E. faecium (VSEF) and vancomycin-resistant E. faecium (VREF). At concentrations equal to four times the MIC, RP 59500 and sparfloxacin decreased the number of intracellular VSEF organisms, while both antibiotics were at best bacteriostatic against intracellular VREF strains. At concentrations equal to one-fourth of the MIC, both antibiotics were bacteriostatic against intracellular VSEF strains but were ineffective in inhibiting the growth of VREF strains. Despite their anticipated markedly higher intracellular human neutrophil (PMN) concentrations, RP 59500 and sparfloxacin activities in medium alone were equal to or greater than those inside PMNs against almost all strains. We conclude that the intracellular PMN concentrations of these antibiotics may not be directly related to their intracellular activities in our assay. The reason for the differences in their activities against VSEF versus VREF remains undefined.

Ampicillin↗

Treatment of experimental endocarditis caused by multidrug resistant Enterococcus faecium with ramoplanin and penicillin.

Antibiotic resistant strains of enterococci are being isolated with increasing frequency. Effective treatment of infections caused by Enterococcus faecium resistant to ampicillin, vancomycin and aminoglycosides has not been established. We studied the activity of ramoplanin, a new lipoglycopeptide antibiotic, against two strains of multidrug resistant E. faecium. In time kill studies, ramoplanin was bactericidal against both strains, but not in the presence of 50% serum. The combination of ramoplanin and penicillin was bactericidal even in the presence of serum. In rabbits with experimental endocarditis neither penicillin nor ramoplanin significantly reduced vegetation colony counts when given alone, although ramoplanin significantly reduced spleen and kidney bacterial counts of both strains. The combination of ramoplanin plus penicillin resulted in a significant reduction of vegetation bacterial counts (-3.2 and -3.7 log10 cfu/g for strains VA3 and MMC3, respectively, P < 0.01). All spleen cultures and 9 out of 10 kidney cultures from each strain were sterile following combination therapy. While ramoplanin will not be available for parenteral therapy, further research into the development of other lipoglycopeptide antibiotics is warranted.

Animals↗

Clinical and molecular epidemiology of hospital Enterococcus faecium isolates in eastern France. Members of Réseau Franc-Comtois de Lutte contr les Infections Nosocomiales.

We carried out a surveillance study of Enterococcus faecium isolates in the Franche-Comtéregion of France over three years. Clinical and epidemiological strains were characterized by antibiotype and genotype (pulsed field gel electrophoresis, PFGE). Three case-control studies were performed to identify risk factors for colonization/infection with three defined resistant phenotypes (amoxycillin, high-level gentamicin and high-level kanamycin). The crude incidence of colonization/infection was 0.156%, and 68.8% of cases were classified as hospital-acquired. Incidence did not differ according to the type of hospitalization (middle term or acute care). The urinary tract was the major site of infection. Resistance rates were: 45.8% (amoxycillin), 18.7% (high-level gentamicin), 61.4% (high-level kanamycin) and 3.1% (vancomycin). No isolate produced b-lactamase and one isolate carried the vanA gene. PFGE revealed two major epidemic patterns each including resistant strains isolated in different hospitals and during different periods in the study. Previous antimicrobial treatment was not identified as a risk factor for colonization/infection with any resistant phenotype. Despite the low frequency of vancomycin-resistant isolates in this study, resistant strains were widely disseminated and had characteristics enabling them to persist and spread. If these strains acquired the vanA gene, the risk of an outbreak would be large. So, the prevalence of vancomycin-resistant E. faecium in hospitals should be carefully monitored in the future.

Adult↗

Outbreak of vancomycin-resistant Enterococcus faecium in a haematology unit: risk factor assessment and successful control of the epidemic.

We describe an outbreak of vancomycin-resistant Enterococcus faecium (VRE) on the haematology ward of a Dutch university hospital. After the occurrence of three consecutive cases of bacteraemia with VRE, strains were genotyped and found to be identical. During the next 4 months an intensive surveillance programme identified 21 additional patients to be colonized with VRE, while two more patients developed bacteraemia. A case-control study was carried out to identify risk factors for VRE acquisition. In comparison with VRE-negative control patients (n=49), cases (n=24) had a longer stay on the ward during the year preceding the outbreak (25.8 versus 10.1 d, P=0.02), more cases with acute myeloid leukaemia [11 versus 4, odds ratio (OR) 9.5, 95% confidence interval (CI95) 2.4-32.2] and higher grades of mucositis (P=0.03). Logistic regression analysis identified antibiotic use within 1 month before admission (OR 13.0, CI95 2.1-80.5, P=0.006) and low albumin levels at baseline (OR 1.2, CI95 1.1-1.3, P=0.02) to be independent risk factors. Four patients with VRE-bacteraemia were successfully treated with quinupristin/dalfopristin (Synercid). Control of the outbreak was achieved by step-wise implementation of intensive infection control measures, which included the cohorting of patients, allocation of nurses and reinforcement of hand hygiene.

Adult↗

Treatment of central nervous system infection by vancomycin-resistant enterococcus faecium.

Enterococci are uncommon causes of CNS infection. We describe a case of ventriculitis and Ommaya reservoir infection due to vancomycin-resistant Enterococcus faecium successfully treated with the combination of i.v. quinupristin/dalfopristin and i.v. linezolid. The patient deteriorated after receiving three dosages of intraventricular quinupristin/dalfopristin. He recovered after discontinuation of intraventricular quinupristin/dalfopristin.

Aged↗