title: Molecular mechanisms of β-lactam resistance in carbapenemase-producing Klebsiella pneumoniae from Sri Lanka.
abstract: Carbapenemases are increasingly important antimicrobial resistance determinants. Little is known about the carbapenem resistance mechanisms in Sri Lanka. We examined 22 carbapenem-resistant Klebsiella pneumoniae from Sri Lanka to determine their β-lactam resistance mechanisms. The predominant resistance mechanisms we detected in this study were OXA-181, NDM-1 carbapenemases and extended-spectrum β-lactamase CTX-M-15. All isolates were then genotyped by pulsed-field gel electrophoresis, variable-number tandem repeat sequence analysis and multilocus sequence typing, and seven distinct genotypes were observed. Five OXA-181-positive Klebsiella pneumoniae isolates were genotypically related to an isolate of Indian origin. Multilocus sequence typing found that these related isolates belong to ST-14, which has been associated with dissemination of OXA-181 from the Indian subcontinent. Other genotypes we discovered were ST-147 and ST-340, also associated with intercontinental spread of carbapenemases of suspected subcontinental origin. The major porin genes ompK35 and ompK36 from these isolates had insertions, deletions and substitutions. Some of these were exclusive to strains within single pulsotypes. We detected one ompK36 variant, ins AA134-135GD, in six ST-14- and six ST-147, blaOXA-181-positive isolates. This porin mutation was an independent predictor of high-level meropenem resistance in our entire Sri Lankan isolate collection (P=0.0030). Analysis of the Sri Lankan ST-14 and ST-147 ins AA134-135GD-positive isolates found ST-14 was more resistant to meropenem than other isolates (mean MIC: 32±0 µg ml(-1) and 20±9.47 µg ml(-1), respectively, P=0.0277). The likely international transmission of these carbapenem resistance determinants highlights the need for regional collaboration and prospective surveillance of carbapenem-resistant Enterobacteriaceae.
authors.affiliation: School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Jarrad M
authors.initials: JM
authors.lastname: Hall
authors.affiliation: Department of Microbiology, University of Colombo, Colombo, Sri Lanka.|School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Enoka
authors.initials: E
authors.lastname: Corea
authors.affiliation: Department of Microbiology, North Colombo Teaching Hospital, Colombo, Sri Lanka.
authors.forename: H D Anusha
authors.initials: HDA
authors.lastname: Sanjeewani
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine WA, Nedlands, Western Australia, Australia.|School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Timothy J J
authors.initials: TJJ
authors.lastname: Inglis
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D013188:Sri Lanka / Q000453:epidemiology; D018440:beta-Lactam Resistance / Q000235:genetics / Q000502:physiology*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases