Molecular mechanisms of colistin resistance in Africa: A systematic review of literature

Updated and comprehensive data on the mechanism underlying colistin resistance is lacking in Africa. Herein, we aimed to review available literature on the molecular mechanisms of colistin resistance in Africa. PubMed, Google Scholar, and African Journal online databases were searched on the 15th of January 2020 for original research articles that reported mechanisms of colistin resistance in any of the 54 African countries. Of the 1473 studies identified through initial database search, 36 met the inclusion criteria. Colistin resistance was mostly observed in isolated from human clinical samples. Plasmid-mediated colistin resistance mechanism (26; 72.2%) was the most frequently reported resistance mechanism. About three-quarters (27; 75.0%) of the 36 studies were done in North Africa. In this zone, the mobilized colistin resistance ( ) genes were mostly detected in harboring three plasmid types, , , and , from animal samples (n=9; 42.8%). Of the six studies performed in Southern Africa, four reported mostly detected from human samples (n=2; 50.0%) in isolates carrying , , and with diverse range of STs. One hitherto unknown mutation, the mutation in the gene was detected in colistin resistant isolates in this region, which was absent in colistin susceptible isolates. In West and Central Africa, two and one studies, respectively, reported gene exclusively in isolates. Transferable plasmid mediated colistin resistance is rapidly emerging in Africa with as the predominant genetic variant in human, animals, and environmental samples.