Status of Extended Spectrum Beta-Lactamase Producing Enterobacteriaceae among Bacterial Uropathogens

Abstract

The prevalence of Extended Spectrum Beta Lactamases (ESBL), the main cause of resistance to broad spectrum β-lactams, among uropathogenic bacteria have increased over time raising a global concern in the therapeutic management of infections caused by these organisms. This resistance poses difficulties with the choice of therapeutic options for the treatment of severe infections. The study was carried out in the Alka Hospital, Lalitpur between May to October 2012 with an objective to determine the status of ESBL producing Enterobacteriaceae isolated from the urine sample, collected from patients suspected of urinary tract infection. During the study, the Enterobacteriaceae isolated were tested for the presence of ESBL by double disc synergy test (DDST) and combination disk method and antibiotic susceptibility testing was done by Kirby Bauer disc diffusion method following Clinical and Laboratory Standard Institute (CLSI) guidelines. Among the total 1054 mid-stream urine samples, 267 Enterobacteriaceae were isolated. By screening test using third generation cephalosporins, 81 of the isolates were suspected of ESBL producers. Among 81 isolates, 72 isolates were positive for ESBL test by combination disk method and only 28 isolates were positive by DDST method. Among the 72 (27%) isolates 67 (30.2%) Escherichia coli, 3 (15.8%) of Klebsiella pneumoniae, 1 (25%) of Citrobacter spp. and 1 (14.3%) of Morganella morganii were found to be ESBL producers. Majority of ESBL producer showed resistance to amoxicillin (100%), cotrimoxazole (79.2%) followed by ciprofloxacin (76.4%). Imipenem (100%), tigecycline (98.6%), amikacin (97.2%), piperacillin- tazobactam (98.6%) and nitrofurantoin (91.7%) seemed to be the agent of choice for urinary tract infections when ESBL producers are susceptible to it. Combination disk method was found to be more sensitive than DDST method for the detection of ESBL producing Enterobacteriaceae. The high level of ESBL production found in these Enterobacteriaceae with the resultant microbial resistance to the available cephalosporins and other agents may pose difficulties with the choice of therapeutic options for the treatment of severe infections. Efforts to prevent and/or control outbreaks of infections with ESBL producing strains must emphasize on the judicious use of all antibiotics.