Evaluation of antimicrobial agents for veterinary use in the ecotoxicity test using microalgae.
The influence of antimicrobial agents approved as veterinary drugs in Japan on the growth of green algae, Selenastrum capricornutum and Chlorella vulgaris, was studied in accordance with the OECD guidelines for testing chemicals. Among the agents tested, growth inhibitory activity was very varied, i.e. erythromycin showed the strongest activity (EC50, 50% effective concentration, = 0.037 mg/l), sulfa drugs had activity to some extent (EC50s of sulfamethoxazole, sulfadiazine, and sulfadimethoxine were 1.5, 2.2, and 2.3 mg/l, respectively), but ampicillin and cefazolin did not inhibit growth (EC50s>1000 mg/l). We also investigated synergistic effect of combining sulfa drugs with trimethoprim or pyrimethamine, which are commonly used as a combined drug. By adding trimethoprim, the growth inhibitory activity of sulfamethoxazole and sulfadiazine was significantly enhanced. Growth inhibition by sulfa drugs was reduced by the addition of folic acid, indicating that they inhibit folate synthesis in green algae.
Eguchi
Kaoru
K
National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji-shi, Tokyo 185-8511, Japan. eguchi@nval.go.jp
Nagase
Hiroyasu
H
Ozawa
Manao
M
Endoh
Yuuko S
YS
Goto
Kisako
K
Hirata
Kazumasa
K
Miyamoto
Kazuhisa
K
Yoshimura
Haruo
H
D000667:Ampicillin / Q000633:toxicity; D000890:Anti-Infective Agents / Q000633:toxicity*; D001681:Biological Assay / Q000379:methods; D002437:Cefazolin / Q000633:toxicity; D000460:Chlorophyta / Q000187:drug effects* / Q000254:growth & development*; D002851:Chromatography, High Pressure Liquid; D004357:Drug Synergism; D004917:Erythromycin / Q000633:toxicity; D007564:Japan; D007928:Lethal Dose 50; D013424:Sulfanilamides / Q000633:toxicity; D013997:Time Factors; D014295:Trimethoprim; D019155:Veterinary Drugs / Q000633:toxicity*
D000890:Anti-Infective Agents; D013424:Sulfanilamides; D019155:Veterinary Drugs; D004917:Erythromycin; D000667:Ampicillin; D014295:Trimethoprim; D002437:Cefazolin