Enterobacteriaceae in Some Marine Fish Fillet

A total of 100 random samples of marine fish fillet represented by Epinephelus alexandrinus fillet, Dicentrachus labrax fillet, Stingray fish fillet and Scomberomorus commerson fillet (25 of each) were collected from different fish markets in Alexandria city. The sample weight was 100 grams. Each sample was kept in a separate sterile plastic bag and transferred in an ice box to the laboratory under complete aseptic conditions without undue delay. All collected samples were subjected to bacteriological examination for isolation and identification of Enterobacteriaceae. The results revealed that the total Enterobacteriaceae count in the examined samples of marine fish fillet were varied from 1.6 x 10² to 6.3 x 10^4 with an average of 2.1 x 10^4 + 3.1 x 10³ cfu/g for Epinephelus alexandrinus fillet, 2.1 x 10² to 4.3 x 10^4 with an average of 9.1 x 10³ + 1.1 x 10³ cfu/g for Dicentrachus labrax fillet, 3.1 x 10² to 6.7 x 10^4 with an average of 1.3 x 10^4 + 7.3 x 10³ cfu/g for Stingray fish fillet and 2.3 x 10² to 1.1 x 10^5 with an average of 6.3 x 10^4 + 5.2 x 10³ cfu/g for Scomberomorus commerson fillet, respectively. Accurately, all examined samples (100%) out of Epinephelus alexandrinus fillet, Dicentrachus labrax fillet, Stingray fish fillet and Scomberomorus commerson fillet were contaminated with Enterobacteriaceae. Also, the total coliform count in the examined samples of marine fish fillet were ranged from 1.3 x 10 to 2.1 x 10³ with a mean value of 9 x 10² + 7.5 x 10 cfu/g for Epinephelus alexandrinus fillet, 3.1 x 10 to 3.2 x 10³ with a mean value of 1.1 x 10³ + 2.3 x 10² cfu/g for Dicentrachus labrax fillet, 1.9 x 10 to 7 x 10³ with a mean value of 2.6 x 10³ + 1.6 x 10² cfu/g for Stingray fish fillet and 6 x 10 to 1.3 x 10^4 with a mean value of 6.4 x 10³ + 7.1 x 10² cfu/g for Scomberomorus commerson fillet. The enteric bacteria isolated were Enterobacter aerogenes (44 %) was the most frequent bacterial species isolated from Epinephelus alexandrinus fillet samples, followed by Proteus vulgaris (28 %), Citrobacter diversus and Shigella species (20 % of each) then Klebsiella ozanae and Provedencia spp (16 % of each). In regard to Dicentrachus labrax fillet samples, the most frequent bacterial species isolated was Enterobacter aerogens (40 %), followed by Klebsiella peumoniae (32 %), Citrobacter diversus(28 %), Proteus vulgaris and Provedencia species (20 % of each), Citrobacter freundii (16 %) then Enterobacter cloacae, Klebsiella ozanae and Shigella species (12 % of each). Concerning Stingray fish fillet samples, Serratia liquifaciens (44 %) represented the highest rate of isolation followed by Enterobacter aerogens and Enterobacter cloacae (36 % of each), Citrobacter freundii (28 %), Citrobacter diversus and Enterobacter cloacae (24 % of each), Shigella species (20 %) and Proteus vulgaris (16 %).On the other hand, Citrobacter freundii (28 %), Enterobacter aerogens (24 %), Proteus vulgaris (20 %) then Klebsiella ozanae, Proteus rettgeri and Shigella species (12 % of each) were isolated from the examined samples of Scomberomorus commerson fillet The Enteropathogenic Escherichia coli was isolated from 8 % , 16 % , 20 % and 28 % of the examined samples of Epinephelus alexandrinus fillet, Dicentrachus labrax fillet, Stingray fish fillet and Scomberomorus commerson fillet, respectively. Also, Salmonella species were recovered from 8 %, 12 % and 8 % of the examined samples of Dicentrachus labrax fillet, Stingray fish fillet and Scomberomorus commerson fillet, respectively. The serotypes of Salmonella organisms isolated from Dicentrachus labrax fillet, Stingray fish fillet and Scomberomorus commerson fillet were S. enteritidis (4 % for each) and S. Haifa (4 % for each). However, only one strain (4 %) isolated from Stingray fish fillet were serologically identified as S. typhimurium. Enterobacteriaceae count, Coliform count, the isolated enteric bacteria, the isolated enteropathogenic E.coli and the isolated Salmonella organisms as well as the public health significance were discussed and the prophylactic measures to reduce the counts and the isolates in marine fish fillet were recommended.