Escalating Colistin Resistance in Carbapenem‐Resistant <i>Klebsiella pneumoniae</i>: Evidence of <i>mcr‐1</i> and <i>bla</i>_NDM Co‐Production

Carbapenem resistance among multidrug-resistant pathogens is a growing global concern, particularly in Asia. The increased use of colistin as a final treatment option for carbapenem-resistant Enterobacteriaceae has contributed to the development of colistin resistance. This study sought to identify the prevalence of carbapenemase and colistin resistance genes in carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates from a Malaysian tertiary hospital. A total of 257 different CRKP isolates were obtained from various clinical specimens between January 2017 and November 2020. Antibiotic susceptibility testing and multiplex polymerase chain reaction were performed to detect carbapenemase genes (bla_NDM, bla_KPC, and bla_OXA) and the colistin resistance gene mcr-1. The bla_NDM gene was found in 247 isolates (95.3%), bla_OXA in one (0.4%), and mcr-1 in two (0.8%). Two isolates co-harbored bla_NDM and mcr-1, whereas one had both bla_NDM and bla_OXA. No bla_KPC gene was detected. The highest number of bla_NDM-positive isolates came from endotracheal tubes specimens (21.8%). Males accounted for 65.7% of cases, with the highest prevalence in patients aged 61-80. Ertapenem showed the highest resistance (99.6%) among the carbapenems tested. This study highlights a high prevalence of bla_NDM in CRKP and reports the first detection of mcr-1 in this hospital. These findings underscore the urgent need for the judicious use of colistin in managing infections caused by CRKP.