Phenotypic and genotypic characterization of clinical and intestinal enterococci isolated from inpatients and outpatients in two Brazilian hospitals

The phenotypic and genotypic characteristics of clinical and intestinal enterococcal isolates recovered from inpatients and outpatients of two Brazilian hospitals, located in Niteroi city, Rio de Janeiro, Brazil, were compared. A total of 601 strains were studied, including 253 isolated from different clinical sources and 348 intestinal strains (205 isolated from inpatients and 143 from outpatients) recovered from fecal specimens. Isolates. were identified by using conventional physiological tests and evaluated for high-level resistance to aminoglycosides (HLR-A) and resistance to vancomycin and ampicillin by the agar screening technique. Susceptibility to several antimicrobial agents was evaluated by the disk diffusion method. The genetic diversity of Enterococcus faecalis strains presenting HLR-A was assessed by pulsed-field gel electrophoresis of chromosomal DNA after SmaI digestion. E. faecalis was the most frequent species among clinical isolates (90.1%) and intestinal strains from inpatients (53.6%). E. casseliflavus was the prevalent species among intestinal isolates from outpatients (35.0%). Clinical isolates were shown to be resistant to erythromycin (53.0%), tetracycline (52.2%), ciprofloxacin (36.4%), gentamicin (36.4%), streptomycin (30.4%), chloramphenicol (34.4%), norfloxacin (32.0%), imipenem (3.2%), and ampicillin (2.8%). Vancomycin resistance was only detected in intrinsic vancomycin-resistant enterococcal species. The overall prevalence of HLR-A was 52.2% among clinical isolates and 40.5% among intestinal strains. However, HLR-A was significantly more frequent among intestinal strains obtained from inpatients (56.6%) than among strains from outpatients (17.5%). Three major clonal groups were found among E. faecalis strains exhibiting HLR-GE or HLR-GE/ST (clonal groups GE-A and GE-B), and strains exhibiting HLR-ST (clonal group ST-A). HLR-A, particularly HLR-GE, was most frequently associated with enterococcal strains of nosocomial origin. Isolates included in the. major clonal groups were recovered from clinical and intestinal sources from patients in both hospitals, indicating both intrahospital and interhospital spread of strains.