Colistin Resistance Profiles, Molecular Investigation of <i>mcr</i>-1 and <i>mcr</i>-2 Plasmid Genes and Investigation of Carbapenemase Production in <i>Pseudomonas</i> and <i>Acinetobacter</i> Strains

Abstract

Background and Purpose: The reintroduction of colistin as a last resort treatment against multi-resistant Gram-negative bacilli, is currently challenged by the emergence of colistin-resistant bacteria. The aim of this study was to assess the susceptibility of Pseudomonas and Acinetobacter strains to colistin, to identify carbapenemase production, and to investigate the plasmid genes involved in colistin resistance and carbapenemase production. Methodology: In order to establish the susceptibility profiles of 17 strains of Pseudomonas and Acinetobacter to colistin, their Minimum Inhibitory Concentrations (MICs) were determined using the liquid microdilution method. The possible production of carbapenemases was investigated with the modified Carbapenem Inactivation Method (mCIM). The search for genes encoding carbapenemases (bla OXA , bla IMP , bla Carba ) and those responsible for plasmid resistance to colistin (mcr-1 and mcr-2) was performed by conventional PCR.Results and Conclusion: Ninety-four percent (94%) (16/17) of the strains were resistant to colistin. Intraspecies distribution was 50% (8/16