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Name | Molecular characterisation of β-lactamase producing Escherichia coli and Klebsiella pneumoniae isolates with special attention to blaCTX-M-15 |
Description | Research article:- Microbiology Menezes Priyadharshini S.1,2*, Madhavan Radha1, Arunagiri K.3, Menaka K3, Sekar B3,4. 1Department of Microbiology, SRM Medical College Hospital & Research Institute, Kattankalathur, Tamil Nadu, India. 2Department of Immunology, National Institute of Research in Tuberculosis (ICMR) [previously TRC], Chetpet, Chennai, India. 3Laboratory Division, Central Leprosy Teaching & Research Institute, Chengalpattu, Tamil Nadu, India. 4Pasteur Institute of India, Coonoor, Tamil Nadu, India.
Abstract: Background: ESBLs are mutant; plasmid-mediated β-lactamases that hydrolyses all cephalosporins, penicillins, and aztreonam but are inhibited by beta lactamase inhibitors like clavulanic acid. The CTX-M-3 enzyme, which commonly hydrolyses cephotaxime, is one of the most common and broadly disseminated β- lactamase. A point mutation in CTX-M-3 gives rise to CTX-M-15 which increases the hydrolytic activity against ceftazidime also. Materials & Methods: A total of 319 clinical Gram negative isolates obtained between January 2008 and August 2008 in a tertiary care hospital were included in the study. The isolates were screened for resistance to third generation (ceftazidime, ceftriaxone, cephotaxime) cephalosporins by Kirby Bauer Disc Diffusion test. The third generation cephalosporin resistant strains were confirmed as ESBL producing by MIC phenotypic method. Results: Of 319 isolates tested, 92 were screen positive for ESBL. However, of 92 isolates only 62 (67.4%) were ESBL positive by phenotypic confirmatory method. Molecular characterisation of ESBL positive isolates revealed 12, 4 and 3 isolates being positive for blaCTX-M, blaTEM and blaSHV respectively. All the 12 blaCTX-M positive isolates belonged to Cluster– I, of which 5 isolates were positive for the blaCTX-M-3 variant by PCR using specific primers. BLAST analysis showed that 3 of 5 (60%) and 2 out of 5 (40%) isolates were positive for blaCTX-M-3 and blaCTX-M-15 respectively. Conclusion: This study emphasizes the molecular characterization of the ESBLs and its prevalence in this hospital and also highlights the incidence of blaCTX-M-15 type ESBL.
Keywords:- ESBL, MIC, blaCTX-M-15 Escherichia coli, Klebsiella pneumoniae. |
Filename | Menezes P S et al. (207-211..).pdf |
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Created On: | 12/03/2012 00:00 |
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Last updated on | 09/17/2014 11:55 |
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