Epidemiology, Antimicrobial Resistance, and Molecular Characterisation of Campylobacter Isolates from Diarrheic Patients and Poultry in a Rural Sub-Saharan African Setting
Background: Campylobacteriosis is a leading cause of bacterial gastroenteritis worldwide, with poultry serving as the primary zoonotic reservoir. In sub-Saharan Africa, the burden is compounded by limited sanitation, widespread backyard poultry keeping, and weak antimicrobial resistance (AMR) surveillance. The prevalence, demographic distribution, and homestead risk factors for Campylobacter infection among diarrheic patients at Busia County Hospital, western Kenya, have been documented in a preceding publication from this dataset (Ouko et al.) [1]. Building on those findings, this study extends the analysis to characterize antimicrobial resistance (AMR) profiles and molecular epidemiology of Campylobacter isolates from diarrheic patients and poultry in Busia County, western Kenya. Methods: Antimicrobial susceptibility testing was performed on 114 isolates (98 C. jejuni, 16 C. coli) from human and poultry sources against 11 antibiotics using disc diffusion and broth microdilution methods. Multilocus sequence typing (MLST) was conducted using published seven-locus Campylobacter MLST scheme on 87 representative isolates based on AMR phenotype and resistance marker profiles. Genotypic resistance determinants were identified through whole-genome sequencing (WGS) of 24 selected isolates representing each identified MLST profile. Results: Resistance to tetracycline (100%) and trimethoprim-sulfamethoxazole (95% - 100%) was universal across all isolate groups. Erythromycin resistance was 57.1% in human C. jejuni but absent in poultry C. jejuni (0%). Human C. coli exhibited extensively drug-resistant (XDR) profiles, with resistance exceeding 50% in 10 of 11 antibiotics. MLST identified predominant lineages (ST-353, ST-1036, ST-1932) shared between human and poultry isolates, suggesting a possible zoonotic transmission pathway. Isolates belonging to ST-1038 and ST-7784 were unassigned to known clonal complexes, suggesting the need for further evaluation as potential novel African lineages. Conclusions: This study documents substantial Campylobacter AMR burden in western Kenya. Universal tetracycline and sulfonamide resistance renders these agents therapeutically obsolete for use in clinical scenarios. The emergence of XDR C. coli and evidence of shared ST and clone types between humans and animals suggest a possible zoonotic transmission pathway. These data demand urgent One Health interventions, including an enhanced AMR
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