Molecular and epidemiological investigation of a colistin-resistant OXA-23-/NDM-1-producing Acinetobacter baumannii outbreak in the Southwest Indian Ocean Area

•Outbreak caused by extensively-drug-resistant colistin-resistant Acinetobacter baumannii co-producing NDM-1 and OXA-23.•Overall mortality of affected patients was 46.2%.•Environmental persistence of the outbreak strain.•Single nucleotide polymorphism analysis is a powerful tool for providing hints about transmission events.•Early recognition and appropriate infection control measures are crucial for containment of the dissemination of multi-drug-resistant bacteria.