Prevalence and Some Possible Mechanisms of Colistin Resistance Among Multidrug-Resistant and Extensively Drug-Resistant Pseudomonas aeruginosa.

Abstract

Background and AimThe emergence of colistin-resistant strains is considered a great threat for patients with severe infections. Here, we investigate the prevalence and some possible mechanisms of colistin resistance among multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa (P. aeruginosa).MethodsAntimicrobial susceptibility was performed using disc diffusion methods while colistin resistance was detected by agar dilution method. Possible mechanisms for colistin resistance were studied by detection of mcr-1 and mcr-2 genes by conventional PCR, detection of efflux mechanisms using Carbonyl Cyanide 3-Chlorophenylhydrazone (CCCP), studying outer membrane protein profile and Lipopolysaccharide (LPS) profile of resistant isolates.ResultsIt was found that MDR and XDR represented 96% and 87% of the isolated P. aeruginosa, respectively, and colistin resistance represented 21.3%. No isolates were positive for mcr-2 gene while 50% of colistin-resistant isolates were positive for mcr-1. Efflux mechanisms were detected in 3 isolates. Protein profile showed the presence of a band of 21.4 KDa in the resistant strains which may represent OprH while LPS profile showed differences among colistin-resistant mcr-1 negative strains, colistin-resistant mcr-1 positive strains and susceptible strains.ConclusionThe current study reports a high prevalence of colistin resistance and mcr-1 gene in P. aeruginosa strains isolated from Egypt that may result in untreatable infections. Our finding makes it urgent to avoid unnecessary clinical use of colistin.