Molecular characterization of extended-spectrum [beta]-lactamases among clinical isolates of Escherichia coli & Klebsiella pneumoniae: A multi-centric study from tertiary care hospitals in India

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From: Indian Journal of Medical Research(Vol. 149, Issue 2)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Technical report
Length: 4,180 words
Lexile Measure: 1470L

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Byline: Vikas. Gautam, Anjana. Thakur, Megha. Sharma, Avinash. Singh, Shruti. Bansal, Aditi. Sharma, Arti. Kapil, Bimal. Das, Sujatha. Sistla, Subhash. Parija, Balaji. Veeraraghavan, John. Prakash, Kamini. Walia, V. Ohri, Pallab. Ray

Background & objectives: The increasing prevalence of extended-spectrum [sz]-lactamases (ESBLs) has abated therapeutic options worldwide. This study was undertaken to investigate the molecular profile and resistance patterns of ESBLs among clinical isolates of Escherichia coli and Klebsiella pneumoniae at four tertiary care centres in India. Methods: Clinical isolates of E. coli and K. pneumoniae were collected from the All India Institute of Medical Sciences (AIIMS), New Delhi; the Jawaharlal Institute of Postgraduate Medical Education & Research (JIPMER), Puducherry; Postgraduate Institute of Medical Education & Research (PGIMER), Chandigarh and Christian Medical College (CMC), Vellore, over one and a half year period. Antimicrobial susceptibility was determined by Kirby-Bauer disc diffusion method. ESBLs were confirmed phenotypically, and multiplex PCR was performed to identify genes for [sz]-lactamases (bla[sub]TEM, bla[sub]SHV, bla[sub]OXA-1, bla[sub]CTXM-1, bla[sub]CTXM-2, bla[sub]CTXM-9 and bla[sub]CTXM-15). Results: Among 341 E. coli isolates collected during the study period, 171 (50%) harboured bla[sub]TEM, 145 (43%) bla[sub]OXA-1,[sub]70 (21%) bla[sub]CTXM-1, 19 (6%) bla[sub]SHV and four (1%) harboured bla[sub]CTXM-2. Phenotypically, combined disc test detected ESBL production in 98/298 (33%) E. coli. Among 304 K. pneumoniae isolates, 115 (38%), 89 (29%), 83 (27%), 64 (21%) and two (0.6%) harboured bla[sub]TEM, bla[sub]OXA-1, bla[sub]CTXM-1, bla[sub]SHV and bla[sub]CTXM-2, respectively. Combined disc test (CDT) detected ESBL production in 42 per cent K. pneumoniae. Most of the bla[sub]CTXM-1positive isolates were also bla[sub]CTXM-15 positive. The carbapenem susceptibility ranged from 56 to 88 per cent for E. coli and from 20 to 61 per cent for K. pneumoniae. Antibiotic sensitivity patterns showed that colistin (CST) was the most sensitive drug for both E. coli (271/274, 99%) and K. pneumoniae (229/234, 98%). Interpretation & conclusions: The prevalence of ESBL among four study centres varied, and bla[sub]TEM, bla[sub]OXA-1 and bla[sub]CTXM-15 were the most common genotypes in E. coli and K. pneumoniae isolates in India. The growing carbapenem resistance and emerging colistin resistance warrant the judicious use of these antimicrobials.

Extended-spectrum [sz]-lactamases (ESBLs) are often plasmid-encoded [sz]-lactamases that confer resistance to penicillins, narrow- and extended-spectrum cephalosporins and aztreonam. ESBL-producing organisms are also often resistant to quinolones, trimethoprim-sulphamethoxazole and aminoglycosides. Organisms harbouring these enzymes, thus, become multidrug resistant (MDR) and cause nosocomially-acquired infections [1]. ESBLs can be classified into three main types, designated as TEM, SHV and CTX-M. The CTX-M type of ESBL can further be classified into three groups: CTX-M-1, CTX-M-2 and CTX-M-9. Previously, ESBLs were generally found in Klebsiella pneumoniae (TEM or SHV types) and most of the isolates were from nosocomial infections [1]. The prevalence and molecular profile of the ESBL-producing Escherichia coli is substantially different from that of ESBL-producing K. pneumoniae [2]. Further, ESBL-producing Enterobacteriaceae isolates have been reported from community-associated infections leading to higher mortality and treatment cost than their non-ESBL-producing counterparts [3]. There is, thus, a need for geographical surveillance of ESBL production to guide appropriate antimicrobial therapy. The challenge is more in a country...

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Gale Document Number: GALE|A588322704