10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 4 2012(October - December) An extended spectrum beta lactamase (ESBL) production among gram-negative bacilli has emerged as a significant mechanism of resistance to oxyimino-cephalosporin antibiotics during the last 3 decades. Detection of common ESBL genes such as CTX-M and SHV by molecular methods in ESBL-producing bacteria and their pattern of antimicrobial resistance can provide useful information about its epidemiology and aid in rational antimicrobial therapy. A total of 138 multi drug resistant clinical isolates of lessThan i greaterThan Enterobacteriaceae lessThan /i greaterThan family obtained from pyogenic lesions were included in the study. Antibiotic susceptibility test, Phenotypic confirmatory methods, Minimum inhibitory concentration and detection of CTX-M and SHV genes by Polymerase chain reaction were performed. Out of 138 samples, 84 were ESBL producers. Among the 84 isolates CTX-M gene was seen in 55 (65.5%) isolates, SHV was seen in 16 (19%) isolates and both CTX-M and SHV was seen in 14 (16.7%). A strict monitoring mechanism of antimicrobial resistance is necessary because of the high rate of prevalence of CTX-M and SHV genes among gram negative organisms causing clinically significant infections. DHANDAPANY SENTHIL PRAGASH, MANGAIYARKARASI, LATHA RAGUNATHAN, SAGEERA BANOO, VIJAYA RAYAPU AND IVVALA ANAND SHAKER CTX-M, SHV, Extended spectrum beta lactamase, ESBL, Polymerase chain reaction. 782-788