A total of 200 samples of fresh water fish including; Oreochromis niloticus (Nile Tilapia), Mugil cephalus, Clarias lazera (catfish) and Bagrus bajad (50 of each) were randomly collected from different markets in Kafr El Sheikh Province. Samples were subjected to microbiological evaluation including, Enterobacteriaceae (EC) and coliform (CC) counts then isolation and identification of some enteropathogens including E. coli, Salmonella and Shigella were attempted. Firstly, organoleptic examination of the collected samples revealed apparently normal fish. It was found that the mean values of EC for Oreochromis niloticus, Mugil cephalus, Claries lazera and Bagrus bajad were 3.50×103 ± 0.24×103, 3.68×103 ± 0.42×103, 2.45×104 ± 1.96 × 103 and 2.83×103 ± 0.17×103 CFU/g, respectively. In addition, it was recorded that mean values of CC for Oreochromis niloticus, Mugil cephalus, Claries lazera and Bagrus bajad were 1.77×103 ± 0.15×103, 2.0×103 ± 0.32×103, 1.45×104 ± 3.29×103 and 1.1×103 to 4.00×103 CFU/g, respectively. It was clear that the mean values of EC and CC of Claries lazera samples scored the highest counts among the investigated species. Moreover, it was observed that all of the examined samples had coliforms count exceed the permissible limits recommended by EOS. On the other side, detection of enteropathogens revealed that the overall incidence of E. coli was 17% and the highest incidence was observed in Oreochromis niloticus (24%) followed by Claries lazera (22%) then Bagrus bajad (12%) and lastly, Mugil cephalus (10%). Also, the overall incidence of Salmonella was 16.5 % and the highest incidence was observed in Claries lazera (24%) followed by Oreochromis niloticus (16%) then Mugil cephalus (14%) and lastly, Bagrus bajad (12%). Finally, the overall incidence of Shigella was 12.5 % and the highest incidence of Shigella was observed in Oreochromis niloticus (16%) followed by Bagrus bajad (14%) then Claries lazera (12%) and lastly, Mugil cephalus (8%). From the results of the present study, it was cleared that most of freshwater fish samples showed contamination with enteropathogens indicating bad sanitary conditions under which fish were exposed from rearing, catching till reach the markets, resulting in both public health hazards and economic losses. Moreover, catfish appeared more contaminated with investigated bacteria reflecting the sanitary condition of the environment where they reared
Key words: freshwater, fish, enteropathogens, counting, isolation
|
