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Nevine S Fam,1 Doaa Gamal,1 Sara H Mohamed,2 Reham M Wasfy,1 May S Soliman,3 Amani A El-Kholy,3 Paul G Higgins4 1Department of Microbiology, Theodor Bilharz Research Institute, Giza, Egypt; 2Department of Microbiology, National Organization for Drug Control and Research, Giza, Egypt; 3Clinical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt; 4Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne 50935, GermanyCorrespondence: May S SolimanClinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, El Saray Street Manial, El Manial, 11956-Manial, Cairo, EgyptTel +20 21068800242Email dr.maysherif@gmail.comPurpose: The rise of carbapenem-resistant A. baumannii (CRAB) is considered a public health problem limiting the treatment options. Our current work studied the emergence and mechanisms of colistin-resistance among CRAB isolates in Egypt.Materials and Methods: Seventeen clinically recovered A. baumannii were identified and screened for their antimicrobial susceptibilities using VITEK-2 system. Colistin susceptibility was evaluated using broth microdilution, and characterization of carbapenem/colistin resistance determinants was performed using whole-genome sequencing (Illumina MiSeq).Results: About 52.9% (9/17) were colistin-resistant. PCR results revealed that all isolates carried blaOXA-51-like genes, blaOXA-23-like was detected in 82.3% (14/17) and blaNDM in 23.5% (4/17). Two isolates harboured blaGES-35 and blaOXA-23. Furthermore, genome analysis of seven isolates revealed six belonged to international clone 2 (IC2) while the remaining isolate was a singleton (ST158), representing a clone circulating in Mediterranean/Middle Eastern countries.Conclusion: The emergence and high incidence of colistin-resistance among CRAB clinical isolates in Egypt are alarming because it further limits therapy options and requires prudent antimicrobial stewardship and stringent infection control measures. Whole-genome sequence analyses suggest that the resistance to colistin was associated with multiple mutations in the pmrCAB genes. The high incidence of the high-risk lineage IC2 harbouring blaOXA-23-like as well as blaNDM is also of concern.Keywords: colistin resistance, pmrCAB, cgMLST, ST158, WGS |
