Prevalence, Antimicrobial Patterns and Evaluation Of Different Methods for Controlling Pathogenic Microbes in Water and Fish from Lake Victoria and Its Basin in Kenya

Abstract

Fish is a very important foodstuff in developing countries due to its high protein content and other nutritional value. Fish contamination by microbes, mainly bacteria and fungi, may lead to food poisoning characterized by gastrointestinal diseases, vomiting, diarrhea, acute renal failure and nausea Developing countries are worst affected by food-borne illnesses due to the presence of pathogenic microbes that may grow in fish. Antimicrobial resistant enteric bacteria have been reported in various aquatic environments including lakes, rivers, drinking water and sewage. Food including fish contaminated with antimicrobial-resistant bacteria is a major threat to public health. Prevalence of fungi and moisture content in sun-dried fish have been a concern due to mycotoxins produced by fungi. This study was designed to determine the prevalence and antimicrobial susceptibility patterns of Escherichia coli, Salmonella enterica serovar Typhimurium and Vibrio cholerae 01 Isolated from water and two fish species Rastrineobola argentea (Dagaa) and Oreochromis niloticus (Nile tilapia) in the Lake Victoria basin of western Kenya. It also assessed the levels of infestations of dried fish by fungi and moisture contents and finally compared and evaluated the traditional non-selective methods of brine salting and sanitizing with chlorinated solution with new Moringa oliefera plant extracts and bacteriophage treatments which can be used for preserving Rastrineobola argentea (Dagaa) and Oreochromis niloticus (Tilapia) fish and controlling the spread of fishborne pathogenic microbes. Using a cross-sectional study design, water and fresh or sun-dried fish (Rastrineobola argentea and Oreochromis niloticus) samples were randomly collected from three fish landing beaches (Dunga, Luanda Rombo and Sirongo) and from three markets (Kisumu municipality, Luanda and Bondo), in the Lake Victoria Basin of western Kenya and taken to the laboratory within 4 hours for processing and microbiological analysis using conventional standard procedures. Statistical difference in the prevalence of enteric bacteria in water or fish samples between the beaches or markets, and effectiveness of the different preservatives was determined by two way Analysis of Variance (ANOVA) with p ~0.05 value considered statistically significant. Escherichia coli, S. enterica serovar Typhimurium and V. cholerae a1 were isolated from water and fish. The results showed that water samples from Dunga beach were the most contaminated (282 CFU/ml) and that from Sirongo beach was least contaminated (193 CFU/ml). Fish samples (Rastrineobola argentea and Oreochromis niloticus) from Kisumu market had the highest total viable bacteria count (218 CFU/g) and those from Sirongo beach had the lowest viable count (130 CFU/g). Out of 162 samples analyzed, 133 (82.1%) were contaminated with various enteric bacterial species. S. enterica serovar Typhimurium was the most prevalent with 49.6% among the isolates followed by E. coli, 46.6% and the least was V. cholerae, 2.8%. Dunga beach had the highest number of bacterial species isolates, 33.8% followed by Kisumu market, 15.85% and the least was Sirongo beach with, 11.3%. The difference in prevalence between the enteric bacteria species, and the beaches or markets was statistically significant, (p < 0.01), by two way ANOV A. All the isolates were sensitive to ciprofloxacin. E. coli was resistant to ampicillin, tetracycline, cotrimoxazole, chloramphenical and gentamicin while S. enterica ser. Typhimurium exhibited resistance to ampicillin, tetracycline, and cotrimoxazole. V. cholerae 01 was resistant to tetracycline and ampicillin. Paired two-tail t-test showed that sun-dried R. argentea and 0. niloticus from the markets had significantly higher fungal species isolates compared to fish from the beaches (P = 0.012) sun-dried R. argentea from the markets had significantly higher fungal species isolates compared to sun-dried 0. niloticus from the