Prevalence of extended spectrum -lactamase producing Klebsiella pneumoniae in a tertiary care hospital.

PURPOSE: The purpose of this study was to know prevalence of extended spectrum -lactamase (ESBL) in multi drug resistant (MDR) strains of Klebsiella pneumoniae isolated from different clinical samples.

METHODS: A total of 120 MDR strain of K. pneumoniae were selected for the study, 106 of which were resistant to at least one of the third generation cephalosporins (3GC). They were studied for ESBL production by phenotypic confirmatory disc diffusion test (PCDDT) and by double disc synergy test (DDST).

RESULTS: 88.3% (106) of the isolates were found to be resistant to at least one of the 3GC tested (cefotaxime, ceftazidime and ceftriaxone) and 72% of the isolates were resistant to all the 3GC tested. ESBL was detected in 30.18% (32) of the K. pneumoniae by PCDDT and in 27.3% (29) by DDST. Among the ESBL producers 6 (18.75%) were sensitive to cefotaxime, 2 (6.25%) to ceftazidime and 3 (9.37%) to ceftriaxone by disc diffusion test. The minimum inhibitory concentrations (MICs) of 3GC for these strains ranged from 2-8 microg/mL while for non ESBL producer sensitive counterparts it ranged from 0.03-1 microg/mL. Resistance to cefotaxime was transferred to recipient E. coli K12 strains J62-1. All the K. pneumoniae isolates were sensitive to imipenem. Resistance against amoxicillin, gentamicin, ciprofloxacin and amikacin was found in 93.28, 70, 10.37 and 26.14% of the isolates respectively.

CONCLUSIONS: Our study shows presence of ESBL producer K. pneumoniae in clinical isolates. The routine antimicrobial sensitivity test may fail to detect ESBL mediated resistance against 3GC and detection of ESBL production should be carried out as a routine in diagnostic laboratories by PCDDT as it is a simple and cost effective test.