[Studies on motile-Aeromonas infection: incidence of motile-Aeromonas in river mud, river water and fresh-water fish].

During the period from October 1982 to July 1984, a total of 1,157 specimens that consisted of 132 river and lake water, 514 river and lake muds, and 511 fresh-water fish caught in both Tama River and Sagami River were examined the presence of the organisms. Of them, 132 (100%) river and lake waters, 304 (59.1%) river and lake muds, and 462 (90.4%) intestinal contents of fresh-water fish were found to have harbor a mean concentration of 1.3 x 10(3)/l, 1.6 x 10(6)/g, and 1.1 x 10(6)/g of motile-Aeromonas respectively. However, nonseasonal variation was observed in the incidence of the organisms throughout the period of investigation. When attempts were made to classify the isolates by the method described Popoff et al., 17 (14.2%) of 120 water-isolates were typed as A. hydrophila, 33 (27.5%) as A. sobria and 35 (29.2%) as A. caviae respectively. And the rest of the 35 (29.2%) remained untypable. As for the 176 mud-isolates, 38 (21.6%) were typed as A. hydrophila 23 (13.1%) as A. sobria and 41 (23.3%) as A. caviae respectively. And the rest of 74 (42.0%) remained untypable. Some efforts were made on the 1,056 strains obtained from fresh-water fish, and 182 (17.2%) were typed as A. hydrophila, 332 (31.4%) as A. sobria and 206 (19.5%) as A. caviae respectively. And the rest of the 336 (31.8%) remained untypable.