The colour carp with the so-called Epistylis Disease which were sent from Niigata Colour-Carp Research Institute to our laboratory were submitted to study the causative organism and the way of treatment. Red spots and / or supprative wounds amounted to 5 or more per fish were present on the body surface of the diseased fish. The red spots showing haemorrhagic swelling were 5-20 mm in diameter size. A large number of rod bacteria was present in all of the wounds, and also water molds and Epistylis like bell animalcula were found in several wounds, occasionally. Two strains of gram-negative bacteria (strain A and B) which were virulent to goldfish were isolated from the wounds. The strain A, Aeromonas like, was a major bacterium, and the strain B of a minor bacterium differed from the member of Aeromonas or Vibrio. Both strains were sensitive to nifurpirinol, and rather resistant to tetracycline and malachite green. The majority of red spots and wounds disappeared within 7 days following the continued bathing in 0.05 ppm of nifurpirinol. From the results obtained, it was considered that Aeromonas like bacterium participated as a causative organism in this case.
Histopathological observations were made on granuloma caused byAcanthocephalain the cultured rainbow trout(Salmo gairdnerii irideus).Acanthocephalawere found to be parasitic on the most part of the lumen of the pyloric ceacum and intestine except the stomach. These parasites intruded into the mucosa of the both organs by their hooks of proboscis, and consequently chronic catarrhal enteritis was demonstrated on the digestive organs mentioned above. Acanthocephalan infections were characterized by granulomatous proliferation. The granuloma was formed in the submucosa of the pyloric ceacum and intestine in which the parasite had already invaded, and granulomatous reaction was evidently recognized to be carried out only around the worm. In the present observation, the granuloma appeared to consist of three zones, epithelioid cells, fibroblasts, and fibrous tissue in which acidophilic granular cells were recognized to be mainly interspersed. Acidophilic granular cells infiltrated not only in the granuloma but also in the epithelial layer of the pyloric ceacum and intestine. These cells were considered as the wandering cells derived from the tissue.
1) Minimal inhibitory concentrations (MIC) of Moenomycin1) (so called Flavophospholipol) for various fish-pathogenic bacteria isolated from different cultured fishes in Japan and effects of Moenomycin for R factors of gram negative-bacilli isolated from the cultured fishes were examined in vitro. 2) MIC levels of Moenomycin for various fish-pathogenic bacteria except Chondrococcus columnaris were within a range from 0.2 to 3.1 μg/ml. MIC level for C. columnaris was 50.0 μg/ml. Especially the MIC levels of Moenomycin for Vibrio anguillarum and the pathogenic agent of bacteria-tuberculoidosis2) (Pasteurella piscicida3)) were almost the same as the levels of Chloramphenicol, Thiamphenicol and Chlortetracycline or showed a little stronger. 3) MIC levels of Moenomycin for the R- and R+ strains of Aeromonas liquefaciens 67-P-24 were examined. Eleven strains of gram negative-bacilli carrying R factors isolated from intestines of cultured eels (Anguilla japonica) were used as donors and Escherchia coli CSH-24) as the recipient. The R factors transferred to E. coli CSH-2 were then each transferred to a R- strain, Aeromonas liquefaciens 67-P-24. MIC level of Moenomycin for the R- strain was 3.1 μg/ml, while those for R+ strains were all 1.6 μg/ml. This suggested that Moenomycin has a stronger anti-bacterial effect for drug resistant bacteria carrying R factors than for bacteria not carrying it. 4) A comparative study of the growth curves of R- and R+ strains of Aeromonas liquefaciens incubated at 30°C in Penassay broth (Difco) containing various amounts of Moenomycin revealed that antibacterial effect of Moenomycin is stronger against the R+ strain than the R- strain.
1) It was reported in the previous paper1) that antibacterial effect of Moenomycin was stronger for R+ strain than R- strain. In this study, the effect of Moenomycin to bacteria carrying R factor in the intestinal tracts of eels (Anguilla japonica) was investigated. 2) Experimental animals were fed with a test diet containing various amounts of Flavocorm-5G (containing 0.5% of Moenomycin) for successive 80 days. Gram negative-bacilli were isolated on drug-free nutrient agar or nutrient agar containing drugs (25 μg/ml of TC or CM) from intestinal tracts of the animals at the end of the experiment. 3) Among 90 strains of CM-resistant gram negative-bacilli isolated, 2 strains carried R factors. Among 100 strains isolated on drug-free nutrient agar, 6 carried R factors. However, among 100 strains of TC-resistant gram negative-bacilli isolated, the number of R factorcarrying strains were 64 (Table 2). 4) When comparing Moenomycin-free eel-group with Moenomycin-additive groups as regard the 64 R+ strains, it became clear that the number of bacteria carrying R factor decreased as the additive amounts of Moenomycin increased. Particularly the number of bacteria carrying R factor was remarkably small in the experimental group fed with a diet containing 50 ppm of Moenomycin. 5) From the above, it may be suggested that feeding of eels with a diet containing 50 ppm of Moenomycin decreases drug resistant bacteria carrying R factors from the intestinal tracts of the fish.