A clinico-microbiological study of extended spectrum β-lactamases in the intensive care unit

Introduction

Extended spectrum β-lactamase (ESBL) producing organisms are emerging as common nosocomial pathogens in the ICU worldwide. Early detection and prevention of spread is the primary measure to overcome the challenge posed by these difficult to treat ESBL infections. The aim of this study was to find the incidence, risk factors and microbiological and clinical outcome of patients infected with ESBL producing Escherichia coli and Klebsiellae in the ICU of a tertiary care cardiac center in India.

Methods

A prospective, observational, case–control study of 150 patients was conducted from August 2004 to July 2005. ESBL testing was performed by the phenotypic confirmatory disc diffusion method. Clinical data and risk factors for ESBL acquisition were analysed as well as the antimicrobial therapy, and clinical and microbiological outcomes were studied.

Results

A high incidence of ESBL producing E. coli and Klebsiellae was observed (85.8%). Meropenem (9.3%) and imipenem (2.8%) resistance in the ESBL producers was seen. On multivariate analysis with logistic regression, a central venous catheter was an independent risk factor for ESBL acquisition (P = 0.01, OR 3.55, 95% CI 1.4–9.02). The median ICU length of stay was 3.5 days and 3 days in the ESBL and non-ESBL groups, respectively. The overall mortality was 13.28% and 13.6% in the two groups, respectively. Microbiological outcomes were similar to clinical outcome, with 83.6% microbiologic success rate among ESBL producers.

Conclusion

ESBL producing E. coli and Klebsiellae are problematic pathogens in our ICUs. Emergence of carbapenem resistance is of serious concern. Stringent infection control practices such as aseptic insertion and proper handling of central lines within the ICU should be followed by all.