Genetic Diversity and Antibiotic Resistance of Escherichia Coli Isolated from Human, Cattle, and Buffalo in the Maasai Mara Ecosystem, Kenya
Onyari, Winfridah Bwari
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Antibiotic resistance is an emerging health crisis globally with a significant impact on human and animal populations. The emergence and spread of antibiotic resistance are attributed to the wrong use of antibiotic products in human and animal health care. This is further amplified and complicated in the human-livestock-wildlife interfaces where there is selective pressure and close interaction. This interface and its impact on antibiotic resistance dynamics are inadequately evaluated in Kenya. The study aimed to establish the genetic diversity and prevalence of antibiotic resistance of Escherichia coli isolates from human, cattle, and buffalo populations in the Maasai Mara Ecosystem located in Kenya. E. coli was isolated by phenotypic and biochemical methods from stool samples of humans and fresh dung samples of cattle and buffalo collected from the Maasai Mara Ecosystem. Molecular techniques were used to characterize E. coli isolates. E. coli isolates were tested against tetracycline, gentamicin, ciprofloxacin, ceftriaxone, and amoxicillin-clavulanic acid using the Kirby-Bauer disk diffusion method and then assigned to phylogenetic groups according to chuA, yjaA, and TspE4.C2 genetic markers. E. coli isolates exhibiting resistant strains were genetically characterized based on their 16S rRNA gene region of the gDNA. Phylogenetic analysis established that all the four phylogroups (A, B1, B2, and D) were present in the E. coli isolates from the sympatric hosts except phylogroup B2 which was absent in buffalo population. E. coli isolates from the sympatric hosts were predominant in phylogroup A and B1. Buffalo was predominated by isolates of E. coli in phylogroup B1 and D. Further, the genetic sequence of resistant E. coli isolates recorded 14 unique haplotypes, with haplotype 4 and haplotype 7 being present in all the three sympatric hosts. Humans recorded the highest resistance to the tested antibiotics at 94% followed by buffalo at 50% and cattle at 45%. Humans, cattle, and buffalo recorded the highest antibiotic resistance to tetracycline at 83%, 45%, and 33%, and lowest antibiotic resistance to amoxicillin-clavulanic acid at 46%, 94%, and 100% respectively. Further, antibiotic resistance was prevalent in isolates of E. coli from buffalo with interactions and the resistant pattern exhibited those of humans and cattle against tetracycline 27%, gentamicin 23%, and ciprofloxacin 14% as compared to E. coli isolate from isolated buffalo which only recorded resistance to tetracycline antibiotic at 5%. It was concluded that isolates of E. coli from humans, cattle, and buffalo were genetically diverse. E. coli isolates from the sympatric hosts were resistant to frequently used antibiotics in human medicine and veterinary practices and finally, antibiotic-resistant in buffalo correspond to those antibiotics used in humans and food-producing animals. It was recommended that additional studies using a One-Health approach, are needed to identify the main reservoir of antibiotic resistant strains and to determine the transmission pathway in the multi-host system.