Occurrence of extended-spectrum beta-lactamase, AmpC and MBLase producers among multidrug-resistant Enterobacteriaceae causing urinary tract infection in a tertiary health-care teaching hospital

Abstract

Introduction: Emerging multidrug resistance continues to be a major concern in healthcare settings. The aim of the study was to determine the resistance pattern of multidrug-resistant (MDR) Enterobacteriaceae causing urinary tract infections in our hospital and to report the occurrence of extended-spectrum beta-lactamase (ESBL), AmpC and metallo-beta-lactamase (MBL) production in them. Materials and Methods: Out of 280 MDR strains collected over a period of one year, 130 strains of Escherichia coli (96), Klebsiella spp. (31) and Enterobacter spp. (3) resistant to the second- and third-generation Cephalosporins were selected for further testing. Cefotaxime, Cefotaxime-Clavulanic acid, Ceftazidime, Ceftazidime-Clavulanic acid and Cefepime, Cefepime-Clavulanic acid Etest strips, Cefoxitin and Cefotetan with Boronic acid and Imipenem/Imipenem-EDTA Etest strips were used to detect ESBLs, AmpC and MBLs. Multiplex polymerase chain reaction (PCR) was done to detect plasmid-mediated AmpC genes. Results: Among 130 Cefoxitin-resistant strains, Cefoxitin-Boronic acid inhibitor method detected AmpC phenotype in 116 (89.2%) isolates. The overall occurrence of AmpC (n = 280) was 116 (41.42%). 92 (32.8%) isolates were found to be ESBL producers by the Clinical and Laboratory Standards Institute confirmatory method. ESBL production was detected in 107 (38.2%) more isolates by Cefepime/Cefepime-Clavulanic acid Etest. MBL producers were relatively low in our study 5 (1.8%). PCR detected CIT genotype (CMY-2) in 13 isolates (4.6%). Conclusion: This study reveals high prevalence of AmpC and ESBL co-carriage suggesting plasmid-mediated spread, indicates the need for surveillance of resistance mechanisms and takes necessary measures to control the emergence of MDR organisms.