BACTERIAL LOAD AND ENTEROTOXIN PRODUCTION BY ESCHERICHIA COLI, IN FISH SAMPLES SOLD IN NSUKKA, NIGERIA.
This study was carried out to determine the level of bacterial contamination of fish retailed in Nsukka Local Government Area of Enugu State, during the period of September 2010 to March 2011. A total number of 120 fish samples comprising of 90 frozen fishes bought from retailers at different retailing joint and 30 fresh fish bought from different fish ponds in Nsukka were collected. After collection, bacteriological analysis of the fish samples was performed by carrying out Total Bacterial Count (TVC), Total Coliform Count (TCC) in fish of different sources by using Nutrient agar, MacConkey agar and Eosin Methylene Blue (EMB) agar respectively. The mean log Total Plate Count for frozen fish ranged from 7.7 log10 cfu/g in TCC to 8.2 log10 cfu/g in TVC while the mean log Total Plate Count for fresh fish ranged from 6.6 log10 cfu/g in TEC to 7.8 log10 cfu/g in TVC, the statistical analysis showed that there was no significant correlation (P>0.05) between TBC and TCC obtained from fish samples bought from different market. Enterotoxin production was assayed using suckling mouse assay. Among the E.coli isolates from both frozen and fresh fish, none was found positive for their ability to produce enterotoxin. High bacterial contamination was associated with the skin, intestine and the gut of the retailed fish. It may be concluded from the results of this study that the presence of high diversity of bacteria in the fish tissues presents health hazards to consumers, fish farmers as well as fish retailers.