Molecular characterization and epidemiological investigation of colistin resistance in carbapenem-resistant Klebsiella pneumoniae in a tertiary care hospital in Tehran, Iran

Carbapenemase-producing Klebsiella pneumoniae (CRKP) presents a significant challenge to antimicrobial therapy, especially when compounded by resistance to colistin. The objective of this study was to explore molecular epidemiological insights into strains of clinical K. pneumoniae that produce carbapenemases and exhibit resistance to colistin. Eighty clinical isolates of CRKP were obtained from Milad Hospital in Tehran, Iran. Antimicrobial susceptibility and colistin broth disk elution were determined. PCR assays were conducted to examine the prevalence of resistance-associated genes, including bla_KPC, bla_IMP, bla_VIM, bla_OXA−48, bla_NDM and mcr-1 to -10. Molecular typing (PFGE) was used to assess their spread.

Colistin resistance was observed in 27 isolates (33.7%) using the Broth Disk Elution method. Among positive isolates for carbapenemase genes, the most frequent gene was bla_OXA−48, identified in 36 strains (45%). The mcr-1 gene was detected in 3.7% of the obtained isolates, with none of the other of the other mcr genes detected in the studied isolates.

To stop the spread of resistant K. pneumoniae and prevent the evolution of mcr genes, it is imperative to enhance surveillance, adhere rigorously to infection prevention protocols, and implement antibiotic stewardship practices.