Molecular mechanisms of colistin resistance among multi-drug resistant (MDR) Klebsiella pneumoniae and Escherichia coli isolated from ICU patients and their susceptibility towards eravacycline

Abstract

The evolution of colistin-resistant strains is considered a great threat for patients admitted to intensive care unit (ICU). This study focused on screening the existence of mcr-1, mcr-2 and mutation in pmrA gene in Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) isolates collected from patients admitted to ICU in Ain Shams University hospitals. Also, this study evaluated the susceptibility of colistin resistant microorganisms to eravacycline antibiotic. Methods: Isolation and identification of K. pneumonia and E. coli were performed then antimicrobial susceptibility test and VITIC -2 compact system were used. Colistin susceptibility and minimum inhibitory concentrations were determined. The mcr-1, mcr-2 and pmrA genes were detected and then pmrA gene was sequenced. Eravacycline susceptibility against colistin resistant strains was determined via E-test. Results: Colistin resistance appeared in 42.9% (36 out of 84) isolates. Mobilized colistin resistance (mcr-1) revealed in 94.4% (34 out of 36), Mcr-2 revealed in 27.8% (10 out of 36) and pmrA gene revealed in 61.1% (22 out of 36). Sequencing of pmrA gene in eight selected isolates revealed two-point mutation in all isolates. All colistin resistant strains showed sensitivity to eravacycline except two K. pneumoniae isolates. Conclusion: This study revealed a high rate of mcr-1, mcr-2 and pmrA genes among MDR K. pneumoniae and E. coli isolated from ICU. Plasmid mediated mcr is a source of acquired resistance to colistin. So, there was a recommendation for broader surveillance of this resistance pattern. Eravacycline could be used for treatment of infections caused by colistin resistant K. pneumonia and E. coli.

Keywords

• colistin resistance
• e. coli
• k. pneumoniae
• eravacycline