A Study on High and Low level Drug Resistance Pattern Among Clinical Isolates of Enterococci .

Abstract

Introduction: The combined abilities of colonisation and both inherent and acquired resistance have made Enterococci a significant human pathogen. Aims and Objectives: This study was done to determine the Minimum Inhibitory Concentration of various antibiotics against Enterococci and to correlate the phenotypic and genotypic characteristics of Enterococci with low level and high level drug resistance. Materials and Methods: A total of 774 isolates of Enterococci obtained from various clinical samples were subjected to antimicrobial susceptibility testing by Kirby Bauer Disk Diffusion method. The Minimum Inhibitory Concentration of various antibiotics were determined by Vitek 2 automated system, agar dilution and E test. Results: 15 out of 774 isolates showed the presence of vancomycin resistant genes by Multiplex PCR. 10 (90.91 %) isolates out of 11 E. faecalis with van A gene showed high level resistance to Penicillin (16-64 µg/ml). 8 (72.73 %) out of 11 isolates showed high level resistance to Gentamicin (512-1024 µg/ml). 6 (54.55 %) , out of 11 isolates were resistant to β lactams. One isolate of E. faecalis from urine with van B gene showed showed high level resistance to Penicillin (32 µg/ml), Linezolid (≥ 8µg/ml), high level resistance to Gentamicin (1024 µg/ml), Fluoroquinolones (≥ 8µg/ml) and Macrolides (≥ 8µg/ml). Conclusion: Isolates of Enterococci resistant to glycopeptides, penicillin, Betalactams and aminoglycosides have important clinical implications in the treatment for infection.