The prevalence and the characterization of the enterococcus species from various clinical samples in a tertiary care hospital

Background: Enterococci form a part of the normal flora of the intestinal tract, the oral cavity, and the vagina, but in recent times, they have become emerging nosocomial pathogens. Their increasing importance is largely due to their resistance to antimicrobials. The therapeutic failures in enterococcal infections are mainly due to the intrinsic as well as transferable drug resistance. The main aim of our study was to estimate the prevalence of the Enterococcus infection and to determine the antibiogram in a tertiary care hospital.

Method: Enterococcus was isolated from a total of 5555 clinical samples like urine , pus, tissue, blood and body fluids during the period from January to December 2008. The isolates were speciated by using conventional biochemical tests (Facklam and Collins). The antibiotic susceptibility testing was done by the Kirby Bauer disc diffusion method. Confirmation of vancomycin susceptibility was done by the Epsilometer test (E test) to determine the Minimum Inhibitory Concentration (MIC).

Result: From various clinical samples, 128 Enterococcus species were isolated in a period of one year and the rate of the infection was estimated to be 2.3%. Among the isolates, those of Enterococcus faecalis (E.faecalis) were 97(76%) and the remaining 31(24%) were of Enterococcus faecium (E.faecium). The maximum number of isolates were from pus 55(43%), followed by the isolates from urine 40(31%). The sensitivity pattern of these isolates showed an increased resistance to penicillin, ampicillin and ciprofloxacin. A High Level of Gentamicin Resistance (HLGR) was present in 60 (47% ) isolates of Enterococcus and 35(27%) isolates were intermediately sensitive to vancomycin by the Kirby Bauer disc diffusion method. All the intermediately sensitive isolates to vancomycin were further tested by the E test and they were found to be vancomycin sensitive.

Conclusion: Various studies have shown an increase in the rate of infection and the antibiotic resistance in the Enterococcus species. There is also a change in the pattern of the Enterococcus infection, with an increase in the isolation rate of E. faecium and other non faecalis Enterococcus species. The Kirby Bauer disc diffusion method is not an accurate method for detecting the Vancomycin Resistant Enterococci (VRE).