Abstract
Actual situations concerning the distribution of antibiotic-resistant bacteria in aquatic environments around livestock area in Miyagi prefecture were investigated. Four selective plates to isolate bacteria derived from feces indicating wastewater pollution by livestock farms and indigenous bacteria in the aquatic environments were used to examine the existing ratio of antibiotic-resistant bacteria to ampicillin, kanamycin, oxytetracycline and chloramphenicol. As a result, resistant bacteria to these antibiotics were extensively found in indigenous bacteria as well as intestinal bacteria derived from livestock farm. Their distribution was confirmed not only at down-flow area of livestock farm, but also at up-flow area without livestock farm. The relationships between the ratio of antibiotic-resistant bacteria and wastewater pollution by livestock farms were indicated by correlation with intestinal bacterial number. Although some indigenous antibiotic-resistance was observed, the ratio of antibiotic-resistant bacteria was unusually high at some investigation sites. Potential causes for high ratio of antibiotic-resistant bacteria were discussed.
