Speciation and Susceptibility Pattern of Enterococcal Species with Special Reference to High Level Gentamicin and Vancomycin

Abstract

Introduction: Enterococci have emerged as the second most common cause of nosocomial infections in the gastrointestinal tract, oral cavity and genitourinary tract. The common species of Enterococci which cause human infections are E. faecalis and E. faecium, their resistance to common antibiotics is a major obstacle for treatment. Identification to the species level is crucial for the proper treatment, epidemiology and infection control. Aim: To isolate and speciate Enterococcal species obtained from clinical samples, to study their antimicrobial susceptibility pattern with special reference to High Level Gentamicin Resistance (HLGR) and Vancomycin. Materials and Methods: A hospital based cross-sectional study was done using 75 clinical isolates of Enterococci over a period of one year in the Department of Microbiology, Government Medical College, Thrissur, Kerala, India. The isolates were identified, speciated using standard methods and antibiotic susceptibility was determined by Kirby Bauer disc diffusion method; and Vancomycin MIC was determined by E-test method. Statistical analysis was done by counts and percentages using MS Excel version 2010. Results: Out of the 75 Enterococci strains, 50 (66.7%) were E. faecalis, 16 (21.4%) were E. faecium, 6 (8%) were E.raffinosus, 2 (2.6%) were E.durans and 1 (1.3%) was E.avium. The maximum no. of isolates were from male patients, and pus samples yielded more Enterococci. HLGR was found in 25/75 (33.3%) strains and 3/75 (4%) strains showed Vancomycin resistance. Isolates had 100% sensitivity to Linezolid. Conclusion: The study showed more drug resistance to E.faecium isolates, with high rate of resistance to Penicillin, Vancomycin, Ciprofloxacin and Aminoglycosides; which emphasises the urgent need for more rational use of antimicrobials and infection control.

Keywords

• enterococci
• e-test
• minimum inhibitory concentration