Extended spectrum â-lactamase producing multidrug resistant clinical bacterial isolates at National Public Health Laboratory, Nepal.

Extended Spectrum â-lactamase (ESBL) producing multidrug resistant bacteria complicate therapeutic management and limit treatment options. Therefore, detection of ESBL-producing multidrug resistant (MDR) pathogens has a paramount importance. Between April 2009 and January 2010, a prospective study was carried out in National Public Health Laboratory with an objective to determine the status of ESBL producing MDR bacterial isolates from different clinical samples. Identification of the isolates was done by standard microbiological techniques and antibiotic susceptibility testing was done by Kirby Bauer disc diffusion method following Clinical and Laboratory Standard Institute (CLSI) guidelines. ESBL screening among MDR isolates was done using Ceftriaxone, Aztreonam, Cefotaxime, Ceftazidime and Cefpodoxime followed by confirmation using MASTDISCS ID ES2L Detection Discs (CPD10). Data analysis was done by SPSS 16 software. Of the 314 bacterial isolates from 1601 different clinical specimens, 199 (63.4%) were MDR. Cefotaxime was found the reliable screening agent for ESBL detection with sensitivity and positive predictive value of 98.6% and 76.4% respectively. Sixtey nine (62.7%) isolates of the 110 tested MDR isolates were ESBL positive with at least one of the Combined Disk (CD) Assays. Escherichia coli (80%) was the major ESBL producer followed by Klebsiella pneumoniae (5.8%). A statistically significant relationship was found between increasing spectrum of drug resistance and ESBL production (p<0.05). Thus it is concluded that a higher rate of ESBL production prevail among MDR clinical bacterial isolates underscoring the need for routine ESBL detection in clinical laboratories.