, Volume 40, Issue 4, pp 425-429
Date: 25 Apr 2012

Frequency of extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacilli in a 200-bed multi-specialty hospital in Vellore district, Tamil Nadu, India

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Extended-spectrum β-lactamase (ESBL) producers were reported only from hospital settings previously, but, nowadays, its common presence in community settings is evident from reports. Our primary aim was to assess the frequency of ESBL-producing Gram-negative bacteria (GNB) and their antibiogram pattern among the clinical isolates received during an 8-month time period.


The clinical isolates which belonged to the family Enterobacteriaceae from the clinical specimens were included in the study. These clinical isolates were tested for ESBL production using the double-disk synergy test.


In total, 301 patients were included in this study, of which 146 (48.50 %) were found to harbor strains of ESBL producers. The acquisition of ESBL in relation to age, sex, inhabitancy, inpatients, and outpatients was also analyzed. In our study, 50.29 % of inpatients and 45.86 % of outpatients were found to harbor ESBL producers. The difference between the two groups was not statistically significant. We found five meropenem-resistant ESBL-producing strains among the 146 ESBL producers. Rural inhabitants were found to contain more ESBLs when compared to peri-urban inhabitants.


The study showed a high frequency of ESBLs in both community-acquired and hospital-acquired infections. The frequency of ESBLs was higher among isolates from patients who were from rural populations than those from peri-urban populations. The data on ESBL frequency suggests the need for a rational antibiotic use which would reduce the spread of ESBL-producing members of the family Enterobacteriaceae.