<p>Prevalence and Some Possible Mechanisms of Colistin Resistance Among Multidrug-Resistant and Extensively Drug-Resistant <em>Pseudomonas aeruginosa</em></p>
Rehab Mahmoud Abd El-Baky, Salwa Mahmoud Masoud, Doaa Safwat Mohamed, Nancy G. F. M. Waly, Engy A. Shafik, Dina A. Mohareb, Azza Elkady, Mohamed M. Elbadr, Helal F. Hetta
Abstract
Background and Aim: The 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 ). Methods: Antimicrobial 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. Results: It 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. Conclusion: The 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. Keywords: Pseudomonas aeruginosa , colistin resistance, mcr-1 , mcr-2 , toxA gene, XDR, MDR