Occurrence of antimicrobial resistant bacteria isolated from farmed Nile Tilapia (Oreochromis niloticus) in Zanzibar, Tanzania

Abstract

Antibiotic resistance is an increasingly significant problem and a serious threat to both public and animal health. Overuse and misuse are key driving factors behind the development of resistance. Antibiotic resistance can occur in fish farming due to the antibiotic treatment of fish, or contamination from the environment or humans. This study investigated the occurrence of antibiotic resistant bacteria in Nile tilapia farming in Zanzibar. Samples were collected from three different sites. A total of 30 fish were examined, and samples were taken from skin/mucus, the gut, and the head kidney. Antibiotic susceptibility testing (AST) was conducted using a disk diffusion method on Muller-Hinton agar. Bacteria were identified through 16S sequencing. Overall, the occurrence of antibiotic resistance was low to moderate. The bacteria samples from one of the three sites showed no resistance to the antibiotics tested for. Within the Enterobacteriaceae family, the highest level of resistance was observed against tetracyclines and sulfonamides. Examining the prevalence of resistance for each antibiotic in relation to the overall resistance, the highest levels of AMR were observed against tetracycline, amoxicillin, and sulfonamides.