Carbapenem resistance in gram-negative bacteria in south-western Nigeria: The role of extended-spectrum β-lactamase CTX-M-15

D. O. Ogbolu, M. A. Webber

Research output: Contribution to journalArticle

Abstract

Objective: To determine the role of extended-spectrum β-lactamases in carbapenem-resistant Gram-negative bacteria from south-western Nigeria. Methods: Twenty-seven carbapenem-resistant isolates that were found to be non-carbapenemase producers (15 Escherichia coli, 9 Klebsiella pneumoniae and 3 Pseudomonas aeruginosa) were further studied. These isolates were subjected to analysis including phenotypic and genotypic detection of various β-lactamases, efflux activity, outer membrane protein, plasmids replicon typing, detection of transferable genes and resistances and typing using random amplified polymorphic DNA tests. Results: No isolates demonstrated de-repression of efflux, but all showed either complete loss or reduced production of outer membrane proteins. Transconjugants from these strains contained various genes including plasmid-mediated quinolone resistance and extended-spectrum beta-lactamases. All the transconjugants carried the blaCTX-M-15 gene. The transconjugants had varying minimum inhibitory concentrations of carbapenems ranging from 0.03 µg/ml to 8 µg/ml. Varying resistances to other antimicrobial agents were also transferred with the plasmids. The donor isolates were not clonally related by molecular typing. Conclusion: Resistance to carbapenem antibiotics in this sample was not mediated only by carbapenemases but also by production of extended-spectrum β-lactamases (largely CTX-M-15), accompanied by protein loss. This was an important mechanism underpinning carbapenem resistance in these clinical isolates of various species.

Original languageEnglish
Pages (from-to)344-349
Number of pages6
JournalWest Indian Medical Journal
Volume67
Issue number4
Early online date18 Dec 2017
DOIs
Publication statusPublished - 31 Dec 2018
Externally publishedYes

Keywords

  • Carbapenem
  • Extended-spectrum beta-lactamase
  • Gram-negative bacteria
  • Nigeria
  • Resistance

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