Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Fri, 02 Aug 2019 00:26:17 Epidemiology of bacterial colonization at intensive care unit admission with emphasis on extended- spectrum b-lactamase- and metallo-b-lactamase- producing Gram-negative bacteria – an Indian experience Afzal Azim, 1 Mayank Dwivedi, 2 P. Bhaskar Rao, 1 A. K. Baronia, 1 R. K. Singh, 1 K. N. Prasad, 2 Banani Poddar, 1 Anshuman Mishra, 2 Mohan Gurjar 1 and T. N. Dhole 2 Correspondence Afzal Azim afzala@sgpgi.ac.in Received 11 December 2009 Accepted 21 April 2010 1 Department of Critical Care Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGIMS), Lucknow, India 2 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGIMS), Lucknow, India An important risk factor for nosocomial infection in an intensive care unit (ICU) is prior colonization. This study was undertaken to determine the spectrum of bacterial colonization and predisposing risk factors in patients being admitted to an ICU in India, with special emphasis on extended-spectrum b-lactamase (ESBL)- and metallo-b-lactamase (MBL)-producing Gram- negative bacteria. Nasal, oral and rectal swab samples were collected and processed for isolation of ESBL-producing Gram-negative bacteria and MBL-producing Pseudomonas aeruginosa and Acinetobacter species. Bacterial colonization (of one or more sites) on admission was detected in 51 out of 96 patients included in the study. Non-fermenters, i.e. P. aeruginosa and Acinetobacter baumannii, were the most common colonizers, present in 37 patients, with simultaneous colonization in 12 patients. A total of 16 patients were colonized with MBL-producing members of the family Enterobacteriaceae, out of which 11 isolates (from 5 patients) were also carrying ESBL-encoding genes. As for MBLs, most of our patients have shown colonization with ESBL-producing bacteria. On admission, 47 of 51 patients (92 %) have been colonized by ESBL-producing members of the family Enterobacteriaceae, at one or more of the three anatomical sites. The most common MBL subtype was bla IMP (51.56 %), whereas bla CTX was the most common gene (84.9 %) identified among ESBL producers. Risk factors for colonization on admission to the ICU were hospitalization for more than 48 h, use of ¢3 groups of antibiotics, co-morbidities and mechanical ventilation for more than 48 h prior to ICU admission. There is an increasing incidence of MBLs and ESBLs in the Indian population. The identified risk factors can be used as a guide for empiric antibiotic therapy targeted to these resistant bacteria. INTRODUCTION The incidence of nosocomial infections in critically ill patients is much higher than in general ward patients despite the immense advancement in therapeutic tech- nologies (Bryan-Brown, 1992; Brawley et al., 1989). Severe nosocomial infections contribute to prolonged intensive care unit (ICU) stays, increased morbidity and mortality, and of course increased resource utilization (Heyland et al., 1999; Inan et al., 2005). An important risk factor for nosocomial infection is prior colonization (Bonten & Weinstein, 1996). The Indian literature lacks evidence about the incidence and patterns of colonization of multidrug-resistant bacteria [especially the metallo-b- lactamase (MBL)- or extended-spectrum b-lactamase (ESBL)-producing bacteria] amongst critically ill patients. This study was undertaken to determine the spectrum of bacterial colonization in patients admitted to an ICU and to assess the predisposing risk factors for colonization. Emphasis was laid on ESBL- and MBL-producing Gram- negative bacteria. Abbreviations: ESBL, extended-spectrum b-lactamase; ICU, intensive care unit; MBL, metallo-b-lactamase. Journal of Medical Microbiology (2010), 59, 955–960 DOI 10.1099/jmm.0.018085-0 018085 G 2010 SGM Printed in Great Britain 955