Vaccines against C. perfringens type C necrotic enteritis, pleuropneumonia, atrophic rhinitis, enterotoxic E. coli infections, erysipelas, Streptococcus suis infection, M. hyopneumoniae infection, dysentery, salmonellosis, porcine proliferative enteritis, leptospirosis were classified in relation to high, medium and low efficacy. The differences were referred to properties of the etiological agent and pathogenesis of the disease. The importance for vaccine efficacy of the pathogenicity factors such as adhesions, toxins and resistance to antibacterial activity of the host, was stressed.
The increasing resistance of bacteria to available antibiotics constitutes one of the greatest challenges in intensive fish culture. The growing problem of chemotherapeutic resistance has revived interest in the potential use of bacterial viruses (bacteriophages) for therapy of bacterial diseases in fish. Bacteriophages are viruses specific for bacterial strains and are natural regulators of bacterial populations in waters. In the present study, we determined the influence of specific bacteriophages on mortality percentages after experimental challenges with the pathogenic bacteria Aeromonas hydrophila in rainbow trout. Healthy rainbow trout, weighing 50-100 g were used in the study. Bafador-1 with 1x108 PFU/ml or 1x109 PFU/ml concentrations of bacteriophages were used in immersion or injection at 12,24, or 48 h after experimental infections. The results showed that Bafador-1 reduced mortality after application in immersion or injection at a concentration of 1 LVm3 of water, or 0.2 ml per fish. The three experimental studies presented indicated that Bafador-1 is very effective in reducing mortality after experimental infection with the pathogenic bacteria A. hydrophila. The preliminary study showed that specific bacteriophages are very effective in specific therapy of bacterial diseases in fish.