Molecular Characterization of Carbapenem/Colistin-Resistant Acinetobacter baumannii Clinical Isolates from Egypt by Whole-Genome Sequencing

Nevine S Fam; Doaa Gamal; Sara H Mohamed; Reham M Wasfy; May S Soliman; Amani A El-Kholy; Paul G Higgins

doi:10.2147/IDR.S288865

Molecular Characterization of Carbapenem/Colistin-Resistant Acinetobacter baumannii Clinical Isolates from Egypt by Whole-Genome Sequencing

Infect Drug Resist. 2020 Dec 16:13:4487-4493. doi: 10.2147/IDR.S288865. eCollection 2020.

Authors

Nevine S Fam¹, Doaa Gamal¹, Sara H Mohamed², Reham M Wasfy¹, May S Soliman³, Amani A El-Kholy³, Paul G Higgins⁴

Affiliations

¹ Department of Microbiology, Theodor Bilharz Research Institute, Giza, Egypt.
² Department of Microbiology, National Organization for Drug Control and Research, Giza, Egypt.
³ Clinical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt.
⁴ Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne 50935, Germany.

Abstract

Purpose: 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 bla _{OXA-51-like genes}, bla _OXA-23-like was detected in 82.3% (14/17) and bla _NDM in 23.5% (4/17). Two isolates harboured bla _GES-35 and bla _OXA-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 bla _OXA-23-like as well as bla _NDM is also of concern.

Keywords: ST158; WGS; cgMLST; colistin resistance; pmrCAB.