In vitro Temocillin efficacy against extended spectrum β-lactamase producing multidrug resistant gram negative bacterial isolates from Nepal.

Temocillin is relatively more stable against most β-lactamases and requires re-evaluation to include it in common clinical practice as a therapeutic alternative. At the National Reference Laboratory of Nepal, we evaluated multidrug resistance (MDR) and extended spectrum β-lactamase (ESBL) phenotypes among 292 gram-negative clinical bacterial isolates of 18 different genera during 2009/2010 by Kirby-Bauer disc diffusion method following CLSI guidelines. ESBL screen positive isolates were tested for Temocillin efficacy by disc diffusion method following British Society of Antimicrobial Chemotherapy (BSAC) guidelines and other antibiotics following Clinical and Laboratory Standards Institute (CLSI) guidelines. Of the 292 isolates, 75.0% isolates were MDR, among which 61.6% were primarily screened positive for ESBL production but only 38.8% were confirmed as ESBL producers. We report relatively lower Temocillin resistance of 28.9% and 15.6% among MDR and ESBL positive populations, respectively. Among ESBL positive isolates, no Proteus mirabilis, 19.7% Escherichia coli and 33.3% Klebsiella oxytoca showed resistance to Temocillin, although such resistance was higher among Acinetobacter spp. (66.7%) and K. pneumoniae 50.0%. Among ESBL negative isolates, none of the K. oxytoca and few (13.3%) Acinetobacter spp. were resistant to Temocillin, while all Citrobacter freundii, Pseudomonas aeruginosa (85.7%) and K. pneumoniae (66.7%) showed Temocillin resistance. Only 14.8% and 3.0% of total MDR isolates were resistant to Imipenem and Meropenem, respectively. However, Imipenem resistance was remarkably high (86.7%) among ESBL negative Acinetobacter spp. than Meropenem (13.3%). Temocillin showed comparable efficacy against MDR and ESBL producing bacterial isolates and could be a next therapeutic option.