The Effect of Bacillus cereus Organism on Fish and Its Effect on Human Health
The Effect of Bacillus cereus Organism on Fish and Its Effect on Human Health
Aml M. Ragab1*, Maha R. Basyoni1, Enas A.I. Khoris2, Nadia A. Abd Elghany3
ABSTRACT
Four hundred samples of Tilapia and Mullet, were screened for the frequency of B. cereus. It was identified by molecular methods based on sequencing of genes, the potential of the groEL gene as a phylogenetic marker, and identified (hbl ,(nhe), (cytK), and (ces) enterotoxigenic genes. B. cereus isolates were analyzed for antibiotic susceptibility. A lab trial was conducted for two weeks using 60 Tilapia fish were divided into three equal groups, (1): kept as control negative, (2): infected intraperitoneally with (0.1ml) 8×107 (CFU/ ml/ fish) B. cereus on 1st day, (3) infected I/P intraperitoneally with (0.1ml) 8×107 (CFU/ml/fish) B. cereus on the first day and treated with erythromycin (sensitive antibiotic) on at day 5 (100 mg /kg food) for 10 days. Isolates were (22%) from Tilapia, 16% from Mullet. Gene sequences were determined for the groEL PCR products generated from 28 references B. cereus group strains and our isolates. Comparison of sequences showed that our strain groups were identical to others in nucleotide sequence similarity, ranging from 98% to 100%. The topology of the groEL- based trees was comparable to that of the phylogenetic tree from B. cereus group strains. Three subclusters could be identified, (nhe) and (cytK) could be detected in all of the B. cereus isolates, (hbl) could be detected in 50% , and (ces) gene could be detected only in 25%. During the experimental period, the high mortality rate was (80%) in the group (G2) - Reisolation of B. cereus in G2 was 83.3% and 91.6%, while in G3, it was 16.6% and 8.3% on the first and second week, respectively. The results of selected blood parameters and enzymes proved that B. cereus infection exhibit high levels of AST, ALT, ALP, and creatinine with reduced total protein, albumin, globulin, and albumin: globulin ratio. While in the treated group, reversible changes occurred.
Keywords | B. cereus, Enterotoxigenic genes, PCR, Phylogenetic tree, Fish
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