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 blaTEM gene (92.3%), followed by blaSHV (69.23%), blaCTXM-1 (38.46%), and blaMCR-1 (23.08%). All three colistin-resistant strains had transferable plasmids and the colistin resistance gene blaMCR-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.
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.