Abstract:
Background: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging antimicrobial resistance threat, yet data on circulating strains and resistance mechanisms remain limited in Africa. In Kenya, data on the prevalence, molecular epidemiology, and resistance mechanisms are scarce, hindering understanding of its contribution to community and health security.
Methods: A cross-sectional study analyzed 228 wound swabs from community-acquired skin and soft tissue infections, collected from 5 AMR surveillance sites in Kenya. S. aureus isolation, identification, and antimicrobial susceptibility tests were carried out using standard bacteriological methods, and whole-genome sequencing (WGS) was done to outline genetic structure of lineages, map resistant genes, and demonstrate genotype-phenotype concordance.
Results: Among the tested isolates, S. aureus isolation rate was 29.4% (67/228), while the prevalence rate for CA-MRSA was 1.8% (4 /228). MRSA was not significantly correlated with gender or age. All CA-MRSA displayed resistance to erythromycin (100 %), clindamycin (75%), gentamycin (75 %), trimethoprim-sulfamethoxazole (75%), rifampicin (50%) and linezolid (25%). Presence of mupirocin resistance gene and discordance between genotype and phenotype of resistance against selected antibiotics were also observed in few isolates. WGS identified mutations within resistance genes, efflux-mediated resistance, and MLSBi resistance. The most prevalent SCCmec type was type IV, while sequence types detected were ST30, ST8, and novel ST7460 and ST7635. IS1272 was found in a mecA regulatory gene whereas only one isolate possessed intact mecA and its regulatory genes, but still exhibited methicillin resistance.
Conclusion: CA-MRSA was detected in almost all community-acquired SSTI surveillance sites, and genomic analysis detected multiple sequence types, including novel lineages and diverse multidrug resistance mechanisms. Evidence for phenotype-genotype discordance showed the limits of defining MRSA resistance with conventional phenotypic screens alone. These results underscore the critical importance of a combined genomic and microbiological AMR surveillance system, establishing it as an integral part of National Public Health Preparedness and assisting NPHIs in identifying emerging resistant strains in a timely manner and informing health-security strategies in Kenya and Africa.
Biography:
Mr. John Njenga Mburu is an upcoming research scientist with over ten years’ experience in clinical microbiology, molecular diagnostics, and health systems strengthening. He has proven expertise in AMR surveillance, PCR-based diagnostics, laboratory quality systems, and capacity building. He has a strong track record in grant writing, scientific research, and policy-relevant reporting. He has supported national diagnostic programmes and contributed to successful grants through roles with the CHAI, KEMRI, and Aga Khan University. He is an active scientific reviewer for international journals and Editorial Advisory Committee member at AJHS-KEMRI and currently serves as an Adjunct Research Scientist at AICAD.
