Sequence-Specific Gene Silencing of acrA in the Multi-drug Efflux System AcrAB Induces Sensitivity in Drug-Resistant Klebsiella pneumoniae

Multi-drug efflux is one of the resistant determinants in Klebsiella pneumoniae that are encountered in a broad range of clinically relevant antimicrobial agents. An alternative method to strategically induce sensitivity in drug-resistant K. pneumoniae and improve the efficacy of the existing antibiotics is the need of the hour. Hence, an antisense RNA was designed against the acr A gene of the AcrAB-TolC efflux system in a drug-resistant isolate of K. pneumoniae obtained from a blood culture. Minimum inhibitory concentration by E test demonstrated that the antisense RNA could significantly increase the susceptibility of previously resistant K. pneumoniae toward ciprofloxacin (CIP) and co-trimoxazole. Real-time PCR determined the ability of the antisense RNA to inhibit the expression of the acr A-mRNA. The wild-type K. pneumoniae showed increased growth in the presence of CIP, while, under the same condition, the growth of the antisense RNA-treated K. pneumoniae was inhibited up till 12 h. In the presence of co-trimoxazole, delayed growth rate of the antisense RNA-treated K. pneumoniae was seen, in comparison to that of the wild-type K. pneumoniae and also a fourfold reduction was noted in the expression of the efflux gene acr A. Our results underscore the potential of the acr A antisense RNA as an alternative therapeutic against multi-drug-resistant K. pneumoniae.