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Rehab M Abd El-Baky, 1, 2 Salwa M Masoud, 1 Doaa S Mohamed, 2 Nancy GFM Waly, 1 Engy A Shafik, 3 Dina A Mohareb, 4 Azza Elkady, 5 Mohamed M Elbadr, 6 Helal F Hetta 7, 8 1Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, Minia 61519, Egypt; 2Department of Microbiology and Immunology, Faculty of Pharmacy, Deraya University, Minia 11566, Egypt; 3Department of Clinical Pathology, South Egypt Cancer Institute, Assiut University, Assiut, Egypt; 4Department of Clinical Pathology, Faculty of Medicine, Assiut University, Assiut, Egypt; 5Sohag General Hospital, Sohag, Egypt; 6Department of Pharmacology, Faculty of Medicine, Assiut University, Assiut, Egypt; 7Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt; 8Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USACorrespondence: Helal F HettaDepartment of Internal Medicine, University of Cincinnati College of Medicine, PO Box 670595, Cincinnati, OH 45267-0595, USAEmail helal.hetta@uc.eduBackground 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 |
