Description of a nosocomial outbreak of infection caused by a vanA-containing strain of Enterococcus faecalis in La Coruña, Spain

David Velasco1, Sonia Perez1, M. Angeles Domínguez2, Rosa Villanueva1 and German Bou1,*

1 Servicio de Microbiologia, Complejo Hospitalario Universitario Juan Canalejo, La Coruña; 2 Servicio de Microbiologia, Hospital de Bellvitge, Barcelona, Spain

Keywords: enterococci, hospital infections, glycopeptide resistance

Sir,

Between May and September 2001, six glycopeptide (vancomycin and teicoplanin)-resistant (GRE) strains of Enterococcus faecalis were isolated from six patients admitted to hospital (Complejo Hospitalario Universitario Juan Canalejo, La Coruña) for treatment of different diseases. Microbiological identification was performed by MicroScan and confirmed by PCR, with specific primers to ddI of E. faecalis. The antibiotic resistance phenotype was determined by microdilution following NCCLS criteria,1 and the MICs of glycopeptides were confirmed by Etest. Clonal identity was performed by analysis of the genomic DNA of the E. faecalis isolates digested with SmaI, by PFGE, as described previously.2 The isolates were classified epidemiologically, according to published criteria.3 The putative presence of vanA and vanB were analysed in the E. faecalis GRE strains. The six patients, who were either infected or colonized by the GRE strains, had been admitted to four different wards in the hospital complex (Table 1). The enterococci strains were isolated from urine (n = 4), abdominal abscess (n = 1) and ulcer exudate (n = 1). The index case was patient no. 1 (Table 1). All of the patients had severe underlying diseases and received antibiotic treatment prior to GRE isolation. The outbreak was controlled by implementation of certain measures, such as isolation of patients in single wards and strengthening of the standard precautions for the prevention of infection by contact. All surfaces in the wards were also cleaned. Healthcare personnel were reminded to wash their hands carefully before and after contact with patients and to wear disposable gloves and gowns.


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Table 1. Patients included in this study from whom the different strains of E. faecalis were isolated
 
According to the results of the PFGE, the GRE strains were classified as indistinguishable (data not shown).

All GRE strains were resistant to vancomycin and teicoplanin (MIC > 128 mg/L), as well as to erythromycin (MIC > 4 mg/L), ciprofloxacin (MIC > 2 mg/L) and ofloxacin (MIC > 4 mg/L), and they remained susceptible to ampicillin, piperacillin–tazobactam, imipenem, meropenem, rifampicin and tetracycline. The patients were treated with ampicillin with good resolution of clinical symptoms.

The six GRE strains of E. faecalis harboured the vanA gene and yielded a negative PCR result with vanB primers.

Overall, the results showed that high levels of glycopeptide resistance were associated with the presence of the vanA gene in the strains under study.

A single clone of E. faecalis carrying the vanA gene has recently been detected in hospitals in different areas of Spain.4 However, to our knowledge the present report is the first description of a nosocomial outbreak of infection in Spain caused by a GRE strain of E. faecalis harbouring the vanA gene and in addition several virulence factors (data not shown). Fortunately, although the presence of the vanA gene was associated with a high level of resistance to glycopeptides, the patients were treated with ampicillin and the GRE strains were eradicated and infectious clinical symptoms resolved.

Acknowledgements

We thank P. Llinares for critical reading. This work was supported by Direccion Xeral de I+D, Xunta de Galicia (PGIDT01PXI90101PR and PGIDT03SAN91601PR).

Footnotes

* Corresponding author. Tel: +34-981-178000; Fax: +34-981-178216; E-mail: germanbou{at}canalejo.org Back

References

1 . National Committee for Clinical Laboratory Standards. (2003). Methods for Dilution Antimicrobial Susceptibility Testing for Bacteria that Grow Aerobically: Approved Standard M7-A6. NCCLS, Wayne, PA, USA.

2 . Murray, B. E., Singh, K. V., Heath, J. D. et al. (1990). Comparison of genomic DNAs of different enterococcal isolates using restriction endonucleases with infrequent recognition sites. Journal of Clinical Microbiology 28, 2059–63.[ISI][Medline]

3 . Tenover, F. C., Arbeit, R. D., Goering, R. V. et al. (1995). Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing. Journal of Clinical Microbiology 33, 2233–9.[Free Full Text]

4 . del Campo, R., Tenorio, C., Zarazaga, M. et al. (2001). Detection of a single vanA-containing Enterococcus faecalis clone in hospitals in different regions in Spain. Journal of Antimicrobial Chemotherapy 48, 746–7.[Free Full Text]





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