Extended spectrum --lactamase mediated resistance in Escherichia coli in a tertiary care hospital in Kashmir, India

To study the prevalence of extended spectrum β–lactamase (ESBL) producing Escherichia coliisolated from different clinical specimens received in the Department of Microbiology, Sher-i-Kashmir institute of Medical sciences (SKIMS) Kashmir, India and to observe the drug resistance pattern of these ESBL producing E. coli. Various isolates of E. coli were obtained from patients admitted or attending Out Patient Department (OPD) over a period of 2 years from 1st August, 2005 to 31st July, 2007. In this study, 221 E. coli were subjected to screening by using cefotaxime, ceftazidime and ceftriaxone 30 μg discs. Among them, 211 were screen positive for potential ESBL productions which were further subjected to confirmatory tests by phenotypic methods: Double Disc Synergy Test (DDST), Phenotypic Confirmatory Disc Diffusion Test (PCDDT) and E-test. 55.9% (118/211) of E. coli isolates were positive for ESBL production from different clinical specimens, maximum number being from urine (72.9%).The maximum number of ESBL producing isolates were from inpatients (71.2%) followed by outpatient (28.8%). Resistance pattern of ESBL positive isolates showed resistance to 3rd and 4th generation cephalosporins (97.5 to 99.2%), quinolones (93.1 to 100%) and aminoglycosides (65.2%) in that order respectively. They showed high degree of sensitivity to imipenam (98.3%), nitrofurantoin (91.5%), gatifloxacin (64.1%) and amikacin (78.2%). Higher prevalence of ESBL production in E. coli of almost 55.9% should alert the physicians. Presence of ESBL producing isolates in outpatients is of main concern as it shows fast spreading ESBL problem in our community. Multidrug resistance pattern of ESBL isolates was studied in detail.   Key words: Escherichia coli, double disc synergy test, phenotypic confirmatory disc diffusion test, extended spectrum βeta-lactamase.