Identification and characterization of colistin-resistant E. coli and K. pneumoniae isolated from Lower Himalayan Region of India

Abstract

Multidrug resistance is one of the worldwide public health concerns. Water represents the most suitable environment, for the exchange of antibiotic resistance genes among pathogenic to non-pathogenic bacteria. Therefore, we aimed to screen the presence of blaNDM-1, blaTEM, blaSHV, blaCTX-M and mcr1–5 genes among water samples from different locations of Lower Himachal Pradesh. We examined the genotypic incidences of blaNDM-1, blaTEM, blaSHV, blaCTXM and mcr1–5 by polymerase chain reaction. Survivability assay, fitness cost assay and biofilm assay were performed for phenotypic characterization. The presence of blaNDM-1 and its related variants were analysed and confirmed by sequencing-based approaches. A total of 73 bacterial strains were identified on M-lauryl sulphate agar medium. Out of 73 colistin-resistant isolates, 34 were E. coli and 39 were K. pneumoniae. Out of 34 samples, 2 (5.8%), 2 (5.8%), 5 (14.7%), 5 (14.7%) and 4 (11.76%) E. coli were blaTEM, blaSHV,blaCTXM-1, blaCTXM-2 and blaCTXM-15 positive, respectively. Among 39 K. pneumoniae, 15 (38.4%), 6 (15.3%), 10 (25.6%), 9 (23.07%) and 10 (25.6%) were blaTEM, blaSHV, blaCTXM-1, blaCTXM-2 and blaCTXM-15 positive, respectively. Interestingly, we observed one E. coli (HG4) isolate with both blaNDM-1 and mcr-1 gene. Further analysis showed HG4 isolate has lesser survivability on the cotton swab, long lag phase and less biofilm production compared to colistin-sensitive isolates. Detection of E. coli with blaNDM-1 and mcr-1 in this geographical region is an alarming signal for tourists, community, health workers and policymakers. Hence, it is utmost important to take appropriate measures to control the dissemination of antibiotic resistance gene in such pristine locations.