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Characterization of glycopeptide-resistant enterococci from a Swiss hospital
1Central Laboratory of Bacteriology, University Hospital, Geneva, Switzerland. Nadia.Liassine@hcuge.ch
Abstract:
Between August 1994 and September 1996, 28 glycopeptide-resistant enterococci (GRE) were isolated from 8 infected patients and 11 intestinal carriers hospitalized at the University Hospital of Geneva. Identification to the species was made by both phenotypic (API 20 STREP and Rapid ID 32 STREP systems, and Vitek Gram Positive Identification Card) and genotypic methods using a multiplex PCR assay developed also for the determination of the genotype of glycopeptide resistance (vanA, vanB, vanC1, and vanC2-C3 genes). Fifteen isolates were identified as Enterococcus faecium, 8 as E. gallinarum, 4 as E. faecalis, and 1 as E. hirae. All of the phenotypic identification methods failed to differentiate some isolates of E. gallinarum from E. faecium, or vice versa. Both vanA (n = 18) and vanB (n = 4) glycopeptide resistance genotypes were found. For the first time, the vanB determinant was found in two isolates of E. gallinarum. Two patients were colonized by two different species containing the vanA gene and one by two different species containing the vanB gene. All vanA isolates were highly resistant to both vancomycin and teicoplanin except for three isolates which were susceptible to teicoplanin. Molecular typing by pulsed-field gel electrophoresis showed identical or similar patterns among E. faecium isolates with the vanA gene in five patients for whom the epidemiological link could not be always elucidated. This study emphasizes the necessity of utilizing both phenotypic and genotypic methods to characterize GRE.
Insights
Glycopeptide-resistant enterococci (GRE) were identified using phenotypic and genotypic methods. The study found vanB in Enterococcus gallinarum for the first time, highlighting the need for combined identification techniques.
Area of Science:
- Microbiology
- Infectious Diseases
- Molecular Biology
Background:
- Glycopeptide-resistant enterococci (GRE) pose a significant threat in hospital settings.
- Accurate identification of GRE species and resistance mechanisms is crucial for effective treatment and infection control.
Purpose of the Study:
- To characterize glycopeptide-resistant enterococci (GRE) isolates from a university hospital.
- To evaluate the performance of phenotypic and genotypic methods for GRE identification and resistance genotyping.
- To investigate the prevalence and distribution of vanA and vanB resistance genes in different Enterococcus species.
Main Methods:
- Isolation and identification of 28 GRE from patients and intestinal carriers.
- Phenotypic identification using API 20 STREP, Rapid ID 32 STREP, and Vitek Gram Positive Identification Card.
- Genotypic identification and resistance gene determination (vanA, vanB, vanC1, vanC2-C3) using a multiplex PCR assay.
- Molecular typing of vanA-positive Enterococcus faecium isolates by pulsed-field gel electrophoresis (PFGE).
Main Results:
- Fifteen Enterococcus faecium, 8 Enterococcus gallinarum, 4 Enterococcus faecalis, and 1 Enterococcus hirae isolates were identified.
- Phenotypic methods showed limitations in differentiating E. gallinarum from E. faecium.
- The vanA genotype was found in 18 isolates, and the vanB genotype in 4 isolates.
- The vanB determinant was identified in E. gallinarum for the first time.
- All vanA isolates exhibited high resistance to vancomycin and teicoplanin, with three exceptions.
- PFGE revealed similar patterns among vanA-positive E. faecium isolates from five patients, suggesting potential transmission.
Conclusions:
- Combined phenotypic and genotypic methods are essential for accurate characterization of GRE.
- The emergence of vanB in E. gallinarum warrants further surveillance.
- Understanding GRE epidemiology and resistance mechanisms is critical for hospital infection control.