Detection of MCR-1 Gene in Multiple Drug Resistant <I>Escherichia coli</I> and <I>Klebsiella pneumoniae</I> in Human Clinical Samples from Peshawar, Pakistan

Background: The presence of plasmid mediated mcr-1 gene in multidrug resistant Gram-negative bacteria poses a serious public health concern in today’s world. Objective: The present study was aimed to detect the presence of plasmid mediated mcr-1 encoding resistance to colistin in multiple drug resistant (MDR) E. coli and K. pneumoniae isolates. Methods: A total of 180 clinical isolates of E. coli (n=120) and K. pneumoniae (n=60) were isolated from different clinical specimens, i.e., urine, blood, stool and pus, from diagnostic labs of two major public sector tertiary care hospitals in Peshawar, Pakistan. MDR profile of these isolates was assessed through Kirby-Baur disc diffusion method. All isolates were screened for colistin resistance by dilution methods. Colistin resistant isolates were subjected to PCR for mcr-1 detection and confirmation was done by Sanger sequencing method. Results: Overall, 83.3% (100/120) E. coli and 93.3% (56/60) K. pneumoniae were detected as MDR. Colistin resistance was found in 23.3% (28/120) E. coli and 40% (24/60) K. pneumoniae isolates, whereas mcr-1 gene was detected in 10 out of 52 colistin resistant isolates, including six E. coli and four K. pneumoniae isolates. Minimum inhibitory concentrations (MICs) of colistin in these ten mcr-1 positive isolates ranged from 4μg/ml to 16μg/ml. All mcr-1 positive isolates showed 99% sequence similarity when compared with other present sequences in GenBank. Conclusion: Hence, our study confirms the presence of mcr-1 mediated colistin resistance in the studied area. Therefore, urgently larger scale surveillance studies are recommended to investigate prevalence of mcr-1 mediated colistin resistance and to prevent its further spread in the area.