Isolation and identification of prevalent bacterial pathogens from an exotic fish Tilapia zillii and Oreochromis mossambicus

Abstract

Aim: Fishes are susceptible to a wide variety of bacterial pathogens which are part of the natural microflora of the environment. The aim of the present study was to isolate the pathogenic bacteria in gills, liver, gut, and skin of Tilapia zillii and Oreochromis mossambicus from the lake near Perumbakkam in Chennai. Materials and Methods: The experimental fish T. zillii and O. mossambicus were collected from large lake 2 km length which starts from Perumbakkam through Vengaivasal Chithalapakkam in Chennai. Results and Discussion: Based on the differentiation and characterization of isolates on specific culture media, human bacterial pathogen such as Escherichia coli, Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa, Enterococcus faecalis, and Shigella dysenteriae was isolated. In this study, the total plate count in the tissues of T. zillii ranged between 7.14 × 105 and 23.2 105 cfu/g. Similarly, in O. mossambicus, the total cell count in the tissue ranged between 6.21 × 105 and 21.16 × 105, respectively. The isolation of enteric bacteria in fish serves as indicator organisms of fecal contamination and/or water pollution. Their presences are also hazardous to humans. Conclusion: The association of pathogenic bacteria among the fishes suggests that if fish are handled or prepared improperly it could lead to food safety hazards for consumers.