Bacteriological and Molecular Studies on the Enterococcus Species Isolated From Diseased Fish and Its Effect on Fish Farm Profits

The study was carried out on 120 fish samples O. nitoticus collected from Kafir El-Sheikh Governorate (60 diseased and 60 apparently healthy fish). The clinical picture of naturally infected O. niloticus showed haemorrhagic spots on the operculum, base of fins and mouth edges, skin darkening, uni-or bJJateraJ exophthalmia and skeletal deformity in some cases abdominal distension was observed. Postmortum lesions in O. niloticus revealed congested and enlarged liver or pale with grayish nodules in some cases. Spleen and kidneys were enlarged and congested and abdominal cavity contained serous fluid in some cases. Bacteriological examination revealed the isolation of (26) streptococcus isolates with an incidence of (43.3%) from diseased O. niloticus, and isolation of (17) isolates with an incidence of (28.3%) from the 60 apparently healthy . These isolates were biochemically tested. SDS-P AGE analysis of whole cell protein of selected serotyped strains revealed the presence of 7-13 protein bands and the most common characteristic bands were 36.67 KDa, 27.37 KDa and 44.0 KDa. Kb. DNA profile analysis of the 3 streptococcus species showed common band at 321 Serological examination of 37 selected isolates result in differentiation into 17 Enterococcus faecalis, 12 Streptococcus iniae, 5 Streptococcus pneumoniae and 3 untypeable strains. Experimental infection of 8 groups of O. niloticus (each of 10 fish) with bacterial suspension of 8 isolates (2 Enterococcus faecalis, 5 Streptococcus iniae and 1 Streptococcus pneumoniae result in mortality rate of 20%, 10% and 0%, respectively. While, inoculation of the bacterial filtrate of the same isolates result in mortality rate of 30%, 22% and 10%. Our results cleared that the enterococci causes a great economic losses to fish farm production and it differ according to the type of bacteria that infected the fish. In bacterial suspension infection the weight losses for each 100/fish were 450 gm, 262.5 gm and zero losses zero losses for S. fecalis, S. iniae and S. pnumoniae and the return losses reached to 4.5 LE, 2.62 LE and zero losses for S. fecalis, S. iniae and S. pnumoniae. While, in bacterial filtrate the weight losses for each 100/fish were 675 gm, 1237.5 and 112.5 gm for S. fecalis, S. iniae and S. pnumoniae and the return losses reached to 6.75 LE, 12.37 LE and 11.25 losses for S. fecalis, S. iniae and S. pnumoniae. From these results we concluded that: Fish farms should avoid use of polluted water. Fish handlers with cut wounds should avoid fish handling without gloves as Streptococcus soft tissue causing sepsis, infection endocardities, urinary tract infections, labor pneumonia and meningitis. Human should keep water sources away from sewage pollution.