Phenotypic and Genotypic Study of Klebsiella species with Reference to Extended Spectrum Beta-Lactamase

Abstract

Introduction: Klebsiella species is an important nosocomial pathogen with the emergence of Multi Drug Resistance (MDR). MDR in Klebsiella species is increasing worldwide with the production Extended Spectrum Beta-Lactamase (ESBL). The emergence of ESBL is a critical concern in Klebsiella species due to resistance to ceftazidime and other cephalosporins which compromise the efficacy of life saving antibiotics against these infections. Aim: To know the factors responsible for antimicrobial drug resistance in Klebsiella species with respect to ESBL and their responsible genes. Materials and Methods: A prospective and experimental study was carried out over a period of three years (August 2013 to July 2016). Total 200 isolates of Klebsiella species were screened for cefotaxime and ceftazidime. The resistant strains (cefotaxime/ ceftazidime) were subjected to ESBL agar, Phenotypic Confirmatory Disc Diffusion Test (PCDDT) and Modified Three Dimensional Test (M3DT). Genetic analysis by Polymerase Chain Reaction (PCR) was done for the detection of beta-lactamase (bla) genes i.e., blaTEM, blaSHV & blaCTX-M in 58 isolates of Klebsiella species. The data was presented using frequency and percentage. The proportion was compared using Z-test for the proportions. Results: Out of 200 isolates, 135 (67.5%) were found resistant to cefotaxime and 125 (62.5%) were resistant to ceftazidime. Among which 110 (55%), 75 (37.5%) and 95 (47.5%) Klebsiella species were found positive for production of ESBL by ESBL agar, PCDDT and M3DT respectively. PCR analysis in 48 isolates were positive by PCDDT/M3DT or both were also positive for beta- lactamase genes i.e., 43 (89.58%) blaTEM; 44 (91.67%) blaSHV and 48 (100%) blaCTX-M. Ten negative isolates either by PCDDT/M3DT or both were also negative by PCR. Co-existence of (blaTEM+blaSHV +blaCTX-M), (blaTEM+blaSHV), (blaTEM+blaCTX-M) and (blaSHV+blaCTX-M) were found 81.25%, 0%, 8.33% and 10.42%, respectively. Conclusion: The M3DT is the best phenotypic method for the confirmation of ESBL producer in Klebsiella species which is not included by CLSI while inclusion with PCDDT enhances the detection of ESBL producers. Co-existence of all three genes (blaTEM, blaSHV and blaCTX-M) in a single strain is a serious concern for us. So it is important to include M3DT and PCDDT in routine basis for the detection and management of ESBL producers which will help clinician to prescribe proper antibiotics.