Bacterial Contamination Levels in Fresh Fish Fillets Sold in Lusaka District of Zambia

Zambia’s aquaculture sector has expanded rapidly, increasing the risk of bacterial zoonotic diseases from fish. This cross-sectional study assessed bacterial contamination in 132 fresh fish fillets—69 hake and 63 tilapias — sold in Lusaka District, Zambia, addressing gaps in local fish contamination and antimicrobial resistance. Bacterial isolates were identified through morphological characteristics and biochemical tests, while antibiotic susceptibility was determined using the Kirby–Bauer disc diffusion method. Total viable count (TVC) and faecal coliform analysis showed that 31% of samples exceeded TVC limits, and 45% contained faecal coliforms. Notably, 93% of tilapia fillets were contaminated, while hake fillets showed no faecal contamination. Escherichia coli (53.8%) was the predominant bacterium, followed by Klebsiella pneumoniae (46.2%), Vibrio parahaemolyticus, and Enterobacter. Antimicrobial susceptibility testing revealed broad-spectrum efficacy of chloramphenicol, while Staphylococcus and Serratia species exhibited resistance to penicillin. Ciprofloxacin and doxycycline were largely effective, though one E. coli strain showed resistance. The high contamination levels, particularly in tilapia fillets, pose serious health risks to vulnerable populations, including children, the elderly, and immunocompromised individuals. Consumption of contaminated fish could lead to gastrointestinal illness or severe infections. These findings highlight the need for improved aquaculture practices, stricter food safety regulations, and enhanced public awareness on proper fish handling and cooking to mitigate health risks.