Prevalence of extended spectrum beta-lactamases producing clinical isolates from patients of urinary tract infection in a tertiary care hospital in Delhi.

A total of 250 urinary isolates (188 Escherichia coli and 62 Klebsiella pneumoniae) were studied for ESBL production by double disc approximation test and disc diffusion confirmatory test (NCCLS). ESBL production was found to be 56% in E. coli and 52% in K. pneumoniae. The double disc approximation test showed false ESBL production in five (2.6%) isolates of E. coli and one (1.6%) K. pneumoniae. The susceptibility of ESBL producers to imipenem, amikacin, nitrofurantion was found to be 100%, 86% and 84% respectively. A high degree of co-resistance to co- trimaxazole and norfloxacin was found in strains of ESBL producers. Seventy five per cent of ESBL producers detected were from hospitalized patients admitted in ICU or undergoing surgery.