Characterization of Proteus mirabilis isolated from ticks collected in Isiolo and Kilifi Counties, Kenya

Proteus mirabilis is a zoonotic pathogen primarily associated with urinary tract infections but also implicated in systemic infections. While its clinical importance is well-established, its potential reservoirs and transmission routes remain underexplored, particularly in arthropod vectors. This study set out to determine the prevalence of P. mirabilis in the form of viable minimal infectivity rate in ticks collected from Isiolo and Kilifi Counties in Kenya. Ticks were sampled from cattle, camels, sheep, and goats. The collected ticks were surface sterilized and homogenized using zirconia beads. Homogenates were cultured on Sheep Blood, MacConkey, and Cysteine Lactose Electrolyte Deficient agar. Subsequently, isolates were subjected to biochemical and antimicrobial susceptibility testing, followed by whole-genome sequencing. Six (6) P. mirabilis isolates were recovered from pooled ticks (Amblyomma gemma and Hyalomma dromedarii) collected from cattle and camels in Kilifi and Isiolo Counties. The ticks were pooled based on species, host animal, size, site, and county of collection. Kilifi isolates (n = 2) were mucoid and motile, while Isiolo isolates (n = 4) were non-motile. All but one of the isolates had a similar antibiotic resistance profile. The isolates had a diverse resistome with numerous unexpressed resistance genes. Despite having flagellar gene clusters, non-swarming isolates from Isiolo exhibited predicted low activity of motility-related systems. Genomic analysis confirmed the presence of numerous virulence factors, alongside varied profiles of antimicrobial resistance genes, including tetJ, parE, and gyrB. Notably, the MAL_1089a isolate uniquely expressed resistance genes to trimethoprim/sulfamethoxazole. Phylogenetic analysis revealed strong clustering of Isiolo isolates compared to Kilifi isolates. The isolates showed relationships to both human and animal isolates from multiple regions. These findings implicate ticks as potential vectors/reservoirs of P. mirabilis and highlight the need for bacterial pathogen surveillance at the human-animal-environment interface.IMPORTANCEThis research is significant as it provides an expansive characterization of Proteus mirabilis obtained from ticks. The results show that not only is viable P. mirabilis present in ticks, but it also has diverse genetic and physical characteristics. This research provides more information about this important pathogen by also comparing it to already characterized strains and drawing similarities. The study shows the importance of integrated research under One Health surveillance to improve public health preparedness and outcomes. This is especially critical in livestock-keeping communities where the risk of spread of zoonotic pathogens is especially high across human, animal, and environmental interfaces.