Kashi Nath Prasad
Sanjay Gandhi Postgraduate Institute of Medical Sciences, India
Title: Chromosome mediated colistin resistance in clinical isolates of klebsiella pneumoniae
Biography
Biography: Kashi Nath Prasad
Abstract
Multidrug-resistant (MDR) Gram-negative bacteria have emerged as the most dreaded health-care threat worldwide. Increased carbapenem resistance in Gram-negative bacteria has led to frequent use of colistin with risk of emergence of resistance. Recently several studies have reported plasmid (mcr-1 gene) mediated colistin resistance among Enterobacteriaceae isolated from veterinary and human sources. In the present study, we have investigated for the presence of mcr-1 gene in colistin resistant clinical isolates of Klebsiella pneumoniae, one of the most notorious bacteria in the family Enterobacteriaceae. Total 1000 Gram-negative bacteria isolated from clinical samples during January and February 2016 were subjected to antimicrobial susceptibility and 21 colistin resistant K. pneumoniae were detected. All 21 isolates were subjected to PCR for mcr-1 and blaNDM genes. Isolates positive for mcr-1 gene were further analyzed by Southern hybridization for localization of the gene either on plasmid or on chromosome. Clonal-relatedness of mcr-1 positive isolates was studied by pulsed field gel electrophoresis (PFGE). PCR based screening showed that 4 of 21 K. pneumoniae isolates harboured mcr-1 gene; one mcr-1 gene positive isolate also harboured blaNDM. All 3 mcr-1 gene positive isolates were clonally related by PFGE, while one blaNDM positive isolate was unrelated. Southern hybridization analysis showed that the mcr-1 gene was located on chromosome. In contrast to other earlier studies where the mcr-1 gene was plasmid borne, in the present study, it was localized on the chromosome. Further studies are required to know the genetic environment associated with mcr-1 gene to understand the source and its mechanism of transmission.