Antibiotic-resistance of Fecal Coliforms at the Bottom of the Tama River, Tokyo

Abstract

We investigated the midstream bottom of the Tama River, which flows through Tokyo, to evaluate the occurrence and degree of antibiotic-resistant fecal coliforms including multidrug-resistant fecal coliforms. The genera Klebsiella and Escherichia were the major isolates among the fecal coliforms. For the genus Klebsiella, the highest antibiotic resistance was observed for ampicillin (100%) , followed by kanamycin, tetracycline, cefotaxime, and cefoxitin. The highest resistance to E. coli was found for kanamycin (44.4%) , followed by ampicillin, tetracycline, chloramphenicol, amoxicillin-clavulanate, cefotaxime, ceftazidime, and aztreonam. Multidrug resistance （MDR） was observed in three E. coli isolates. A double disc synergy test confirmed the production of extended-spectrum β-lactamases by the six-antibiotic-resistant isolate E. coli hfa7, and the strain had CTX-M-1 group gene. Assessments of antibiotic-resistant fecal coliforms at the bottom of the Tama River are important toward the goals of preventing the spread of antibiotic-resistant fecal coliforms in humans, animals, and the environment.