Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a major global clinical threat, particularly in low- and middle-income countries where treatment options remain limited. This study investigated the genomic characteristics and clonal relatedness of CRAB clinical isolates recovered during the implementation of the National Action Plan on Antimicrobial Resistance (NAP-AMR) in Mwanza, Tanzania. Methods Whole-Genome Sequencing was performed on six phenotypically carbapenem-resistant A. baumannii isolates obtained from blood (n = 3), urine (n = 2) and pus (n = 1) samples collected at Bugando Medical Centre, a tertiary referral hospital in northwestern Tanzania. Genomic analyses included sequence typing, antimicrobial resistance gene identification and virulence profiling using web-based bioinformatics tools. Phylogenetic relationships were inferred using core-genome MLST (cgMLST). Results Three STs were identified, with a predominance of ST-1325 (Oxford scheme)/ST-374 (Pasteur scheme), (66.7%; n = 4). Other STs included ST-2822OX/ST-374PAS (n = 1) and ST-2323OX/ST-1PAS (n = 1). The internationally recognized high-risk lineage, ST-1PAS, carried blaOXA-69 and mercury-resistance genes (merA/D/E/T). All isolates exhibited multidrug-resistant phenotypes fully consistent with their genotypic profiles. Carbapenem resistance was driven by blaOXA-259 (66.7%; n = 4) in ST-1325OX/ST-374PAS isolates. Virulence determinants associated with adhesion, biofilm formation, immune evasion and iron acquisition were detected in all isolates. Mobile genetic elements, including transposons (83.3%), integrons (83.3%) and insertion sequences (100%), were common, predominantly Tn6292, In2-10 and ISAba26, respectively. Phylogenetic analysis revealed clonal relatedness among the four ST-1325 isolates recovered from urine and blood samples. Conclusion CRAB isolates in our setting were dominated by ST-1325OX/ST-374PAS carrying blaOXA-259, with evidence of clonal relatedness suggesting possible transmission, underscoring the importance of strengthening infection prevention and genomic surveillance.
Silago et al. (Wed,) studied this question.