Genomic characterization of two Staphylococcus aureus isolates from a Tanzanian orthopaedics ward: a fomite-associated ST152 MSSA isolate and a rectal-swab ST8 mecA-positive isolate

Staphylococcus aureus is an important cause of healthcare- and community-associated infections and can acquire antimicrobial resistance (AMR), virulence determinants, and mobile genetic elements that influence colonization, persistence, and disease potential. Whole-genome sequencing (WGS) enables integrated isolate-level characterization of these features, including in resource-constrained hospital settings where genomic surveillance data remain limited. We performed a descriptive WGS-based characterization of two S. aureus isolates collected from the orthopaedics ward at Bugando Medical Centre, Mwanza, Tanzania, in 2020. A55934 was recovered from a wheelchair handle on 16 January 2020 and is described as a fomite-associated isolate. A55935 was recovered from a rectal swab collected from a 43-year-old male patient 24 h after admission for a patella fracture on 6 April 2020 and is described as a patient-associated rectal-swab isolate. The two isolates were collected approximately 11 weeks apart and were not used to infer transmission or contemporaneous circulation. Genomes were analysed using the rMAP 2.0 bioinformatics pipeline for lineage assignment, AMR determinants, virulence-associated genes, and mobile genetic elements. The isolates were also placed within a contextual core-genome phylogeny of publicly available Tanzanian S. aureus genomes. The two isolates belonged to distinct lineages: A55934 was assigned to ST152, while A55935 was assigned to ST8. The patient-associated rectal-swab ST8 isolate carried mecA, consistent with an MRSA genotype, together with additional predicted AMR determinants including erm(C) , tet(K) , and dfrG , and multiple plasmid replicons. A bla OXA−60 -like hit was also detected but is interpreted cautiously because OXA-type beta-lactamases are atypical in S. aureus and require further validation. In contrast, the fomite-associated ST152 isolate had no acquired AMR genes detected at the reporting thresholds and was consistent with an MSSA genotype. Both isolates carried genes associated with adhesion, biofilm formation, immune evasion, and other virulence-related functions, while leukocidin-associated genes were detected only in the ST8 isolate at the applied thresholds. In the contextual phylogeny, the two study isolates occupied distinct positions within broader Tanzanian S. aureus diversity. This two-isolate analysis provides a descriptive, proof-of-concept genomic characterization of source-distinct S. aureus isolates from a Tanzanian orthopaedics ward. The findings show that WGS can resolve lineage, AMR genotype, virulence-gene content, and mobile-element profiles from both fomite-associated and patient-associated isolates. However, because the isolates were few, non-contemporaneous, and not epidemiologically linked, these data cannot establish transmission, ward-level circulation, environmental reservoirs, or representativeness of the broader S. aureus population. Larger longitudinal studies integrating patient and environmental sampling, phenotypic antimicrobial susceptibility testing, and detailed epidemiological metadata are needed to define transmission dynamics and the contribution of high-touch surfaces to S. aureus persistence and AMR dissemination in this setting. Not applicable.