Multiplex PCR for detection of bla CTX-M genes among the extended spectrum beta lactamase [ESBL] producing gram-negative isolates

ABSTRACT

Broad spectrum beta-Lactamase producing organisms are a growing world wide problem. Resistance has emerged ever to newer, more potent antimicrobial agents. Although there are several guidelines available for the phenotypic detection of ESBL producing bacteria. This remains a continuous issue. In this study, we used a multiplex PCR as a rapid method to identify bla CTX-M genes and discriminate between its groups that are responsible for ESBL production in members of Enterobacteriacae. Our study includes 250 clinical isolates [23 sputum, 64 urine, 46 from blood, 28 from pus aspirates, 58 from entotracheal secretions, and 31 swabs from cellulitis, impetigo contagiosum [non bullous] and sycosis]. All isolates were biochemically identified, based on colony morphology, and was speciated by standard biochemical tests. ESBL enzyme production was confirmed by double disc synergy test according to CLSI guidelines. Multiplex PCR was performed for bla CTX-M of ESBL +ve isolates for detection and discrimination between groups. Our findings were as follows out of 250 isolates; only 98 were proved to be resistant to different antibiotics by the disc diffusion method according to NCCLS 3 of 53 [5.66%] Enterobacter. All from group [25/26]. 65 of 74 [87.8%] E.coli strains -37 of which from groups [1] [CTX-M 15], 9 from group [1] [CTX-M-3], 8 from group [9] [CTX-M-14], 9 from group [9] [CTX M-9], 2 from group [25/26] [CTX-M 26]. 1 of 50 [2%] non fermenting gram -ve bacilli which is from group [25/26]. 29 of 73 Klebsiella strains [39.7%] 19 from group [9] [CTX-M14] and 10 from group [9] [CTX-M 9]