title: Distribution of CTX-M group I and group III β-lactamases produced by Escherichia coli and klebsiella pneumoniae in Lahore, Pakistan.
abstract: Extended-spectrum-lactamases (ESBLs) of the CTX-M type is worrisome issue in many countries of the world from past decade. But little is known about CTX-M beta-lactamase producing bacteria in Pakistan. Therefore, this study was carried out to investigate the distribution of CTX-M beta-lactamase producing E. coli and Klebsiella pneumoniae using phenotypic and molecular techniques. A total of 638 E. coli and 338 Klebsiella pneumoniae were isolated from patients attending two hospitals and one diagnostic Centre in Pakistan during 2013-2015. ESBL production was screened by double disc synergism, combination disc (cefotaxime and ceftazidime with clavulanic acid) and E-test. These strains were further characterized by PCR (CTX-M I, CTX-M III) and sequencing. After ribotyping of strains accession numbers were obtained. These isolates were highly resistant to cephalosporins, ceftazidime, cefotaxime, aztreonam, and cefuroxime but susceptible to carbapenems, sulfzone, amikacin and tazocin. Multiple antibiotic resistances index (MAR) revealed that 51% of E. coli strains fell in the range of 0.61-0.7 and 39% of Klebsiella pneumoniae strains fell in the range of 0.71-0.8. 64% Double disc synergism (DDS), 76.4% combination disc (CD), 74% E-test showed ESBL positivity in strains. In E. coli ESBL genes blaCTX-M-Iand blaCTX-M-IIIwere detected in 212 (72.1%) and 25 (8.5%) respectively. In Klebsiella pneumoniae ESBL genes blaCTX-M-Iand blaCTX-M-IIIwere detected in 89 (82.4%) and 10 (9.2%). Combination of both genes blaCTX-M-Iand blaCTX-M-IIIwere found in 16 (5.4%) of E. coli strains and 5 (4.6%) of Klebsiella pneumoniae strains. Sequencing revealed that CTXM-15 was predominately present in the CTX-M-I group. The prevalence of ESBL producing E. coli and Klebsiella pneumoniae isolates was high and the majority of them positive for blaCTX-M-Ias compared to blaCTX-M-III.These findings highlight the need to further investigate the epidemiology of other CTX-M beta-lactamases in Pakistan.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of the Punjab Lahore, Pakistan.
authors.forename: Samyyia
authors.initials: S
authors.lastname: Abrar
authors.affiliation: Department of Microbiology and Molecular Genetics, University of the Punjab Lahore, Pakistan.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Vajeeha
authors.affiliation: Department of Microbiology and Molecular Genetics, University of the Punjab Lahore, Pakistan.
authors.forename: Noor
authors.initials: N
authors.lastname: Ul-Ain
authors.affiliation: Department of Microbiology and Molecular Genetics, University of the Punjab Lahore, Pakistan. Electronic address: saba.mmg@pu.edu.pk.
authors.forename: Saba
authors.initials: S
authors.lastname: Riaz
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010154:Pakistan / Q000453:epidemiology; D010641:Phenotype; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D001618:beta-Lactamases; C000602253:beta-lactamase CTX-M, E coli
keywords: Beta-lactamases; CTX-M; ESBLs; Escherichia coli; Klebsiella pneumoniae; Pakistan