Virulence Factors of Bacteria Isolated from Fish Sold at Open Air Market Centre in Okepedi, Itu, Akwa Ibom State, Nigeria

Abstract

The study on the virulence factors of bacteria isolated from fish sold in the open market centre of Okepedi fishing settlement, Itu, Akwa Ibom State was investigated using standard microbiological techniques and analytical procedures. The skin, gills and intestine of Clarias gariepinus, Oreochromis niloticus and Tilapia guinensis were all investigated. The results revealed that all the fishes obtained from the Okepedi open market centre were contaminated with microorganisms. The densities of heterotrophic bacteria accumulated by the fishes exceeded 1.2 x 105 cfu/g recommended  fresh fish samples and the loads of fecal coliform (Escherichia coli) in the fishes. Analysis of variance revealed a significant difference in the mean load of bacteria in the fishes at significance level of p ≤ 0.05. The high faecal coliform load of the fishes has shown that the rivers surrounding the market are highly contaminated with faecal matter. Contaminant bacteria isolated from the fishes included Micrococcus sp, Streptococcus sp, Staphylococcus aureus, Klebsiella pneumonia, Enterobacter aerogene, Salmonella sp, Vibrio cholera, Bacilus subtilis, Escherichia coli, Enterococus sp, Pseudomonas aeruginosa, Proteus vulgaris and Serratia sp. The analysis revealed that the isolates exhibited varying degree of virulence. Salmonella sp, Serratia sp, Enterobacter aerogene, E. coli, Proteus vulgaris, Micrococcus sp, Bacilus subtilis, Staphylococcus aureus and Vibrio cholerae demonstrated α haemolytic activity while Klebsiella pneumonia, Streptococcus sp, Enterococus sp and Pseudomonas aeruginosa showed β haemolytic activity. Salmonella sp, E. coli, Proteus vulgaris, Klebsiella pneumonia, Streptococcus sp, Enterococus sp, Pseudomonas aeruginosa, Bacilus subtilis, Staphylococcus aureus and Vibrio sp were capable of producing lipase while E. coli, Proteus vulgaris, Klebsiella pneumonia, Micrococcus sp, Streptococcus sp and Staphylococcus aureus exhibited gelatinase activity. Proteus vulgaris, Pseudomonas aeruginosa, Enterococus sp, and Vibrio cholera showed urease producing activity. The occurrences of pathogenic bacteria in these fishes lighten the public health concern and therefore, efforts should make maintaining and enforce adequate sanitation practices in the habitats of these produce.