eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2021-09-30 14 3 1189 1196 10.13005/bpj/2221 40049 article Reena Rajan 1 D Karthikeyan 2 Department of Microbiology ,Vinayaka Mission’s Kirupananda Variyar Medical College Salem,Tamil Nadu-636308. Department of Microbiology,Vinayaka Mission’s Medical College Karaikal,Tamil Nadu-609609. 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. https://biomedpharmajournal.org/vol14no3/a-study-on-high-and-low-level-drug-resistance-pattern-among-clinical-isolates-of-enterococci/ High Level  Drug Resistance Low Level Drug Resistance  Minimum Inhibitory Concentration Phenotype Genotype