Abstract
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.
