Vancomycin-resistant Enterococci, Mexico City

To the Editor: Vancomycin-resistant Enterococcus (VRE) has become an important nosocomial pathogen because of its rapid spread, limited therapy options, mortality, and the possibility of transfer of vancomycin resistance to other pathogens such as Staphylococcus aureus. Vancomycin-resistant E. faecium (VREF) and E. faecalis were fi rst described in 1988 (1,2).They have become major noso-comial pathogens, but their prevalence in Latin America has remained <2% (3). In Mexico, VRE has rarely been reported (4,5). In a recent study in Mexico City, 100% (n = 60) of the isolates of E. faecium and E. faecalis were susceptible to vancomycin (6). rate of vancomycin resistance among all Enterococcus isolates was 0.27%. However, in May 2005 the fi rst fully VREF was isolated at our hospital, and the rate of vancomycin resistance was 6.23% (a 23-fold increase) during the following 12-month period. We performed a retrospective study to describe the isolates and the characteristics of patients with VREF. All VREF isolates from May 2005 through April 2006 were included. We collected demographic and clinical data. For the fi nal identifi cation of the isolates, the VITEK system (bioMéri-eux, Lyon, France) with VITEK GPI cards (bioMérieux, Inc., Durham NC, USA) were used. Antimicrobial drug susceptibility was tested by using the VITEK GPS-111 card and confi rmed by MIC determination that used broth microdilution. Resistance to vancomy-cin and teicoplanin was confi rmed by E-test (AB Biodisk, Solna, Sweden). An isolate was considered vancomy-cin resistant when the MIC was >32 μg/mL and was considered to have high-level resistance when the MIC was ≥256 μg/mL. A PCR for detection of the vanA or vanB genotype was used (7). Isolates were characterized by pulsed-fi eld gel electrophoresis (PFGE) (8,9); a dendrogram was constructed with the GelCompare II 4.0 software (Applied Maths, Kortrijk, Belgium), and the similarity was compared with the Dice coeffi cient. In the study period, VREF was isolated from 27 patients. The median age was 40 years (range 22–84 years). VREF was isolated from the abdomen in 14 patients (51.9%); 11 isolates were from an abscess, 2 from infected surgical sites, and 1 from ascites. An additional 8 isolates were from the urinary tract (29.6%), 2 from the bloodstream (7.4%), 2 from soft-tissue (7.4%), and 1 (3.7%) from bone. Residence in the general medical wards during the isolation of VREF was most common, 17 (63%) cases, followed by 6 (22.2%) in the intensive care unit. The remaining …