Evaluation of extended spectrum beta lactamase in urinary isolates

Urinary tract infection (UTI) remain the common infections diagnosed in outpatients as well as in hospitalized patients. Current knowledge on antimicrobial susceptibility pattern of uropathogens is mandatory for appropriate therapy. Extended spectrum beta lactamases (ESBL) hydrolyse expanded spectrum cephalosporins like ceftazidime, cephotaxime which are used in the treatment of UTI. ESBL producing bacteria may not be detectable by routine disk diffusion susceptibility test, leading to inappropriate use of antibiotics and treatment failure. Not much information on ESBL producing organisms causing UTI is available from India. An effort was therefore made to study the ESBL producing uropathogens and also the susceptibility patterns of ESBL and nonESBL producers.

Urinary isolates from symptomatic UTI cases attending or admitted to the Indira Gandhi Medical College and Hospital, Nagpur were identified by conventional methods. Antimicrobial susceptibility testing was done by Kirbey Bauer's disc diffusion method. Isolates resistant to cephotaxime were tested for ESBL production by double disc synergy test method.

Of the 217 isolates, 87 were cephotaxime resistant Gram-negative bacilli. Of these, 42 (48.3%) were found to be ESBL producers. Escherichia coli, Klebsiella pnuemoniae and Acinetobacter were ESBL producing species. Multidrug resistance was found to be significantly (P<0.05) more in ESBL producing isolates (90.5%) than non ESBL producers (68.9%).

In the present study a large number of uropathogens were found to be ESBL producers. Most of the ESBL producing isolates were multidrug resistant. Monitoring of ESBL production and antimicrobial susceptibility testing are necessary to avoid treatment failure in patients with UTI.