The emergence of colistin-resistant Klebsiella pneumoniae strains from swine in Malaysia

Abstract

Objective: Colistin is the last line of therapy for infections caused by multidrug-resistant Gram-negative bacteria. The objective of this study was to determine the phenotypic and genotypic characteristics of colistin-resistant Klebsiella pneumoniae (K. pneumoniae) isolated from swine samples in Malaysia.

Methods: A total of 46 swine K. pneumoniae strains isolated from 2013-2015 in Malaysia were analysed for the production of extended-spectrum β-lactamases and carbapenemase. The resistance traits and genetic diversity of these strains were characterised by polymerase chain reaction, conjugation, plasmid analysis, and pulsed-field gel electrophoresis.

Results: Nineteen of 46 strains were multidrug resistant while 13 were resistant to colistin. The majority of colistin-resistant strains harboured bla_TEM gene (92.3%), followed by bla_SHV (69.23%), bla_CTXM-1 (38.46%), and bla_MCR-1 (23.08%). All three colistin-resistant strains had transferable plasmids and the colistin resistance gene bla_MCR-1. Genotyping by pulsed-field gel electrophoresis showed high genetic diversity among the K. pneumoniae and that the colistin-resistant K. pneumoniae strains were heterogenous.

Conclusion: It is believed that this is the first report of colistin-resistant K. pneumoniae among swine strains associated with mcr-1 plasmid in Malaysia. Due to the emergence of β-lactam, carbapenem and colistin resistance, the use of colistin in animal husbandry and agriculture should be avoided to prevent treatment failure.

Keywords: Colistin; Genetic diversity; Klebsiella pneumoniae; Multidrug resistance; Swine.