Growth-inhibiting effects of 12 antibacterial agents and their mixtures on the freshwater microalga Pseudokirchneriella subcapitata.
The growth-inhibiting and binary joint effects of 12 antibacterial agents on the freshwater green alga Pseudokirchneriella subcapitata (Korschikov) Hindák were investigated over 72-h exposures. The toxicity values (the median inhibitory concentration value, in micromoles) in decreasing order of sensitivity were triclosan (0.0018)>triclocarban (0.054)>roxithromycin (0.056)>clarithromycin (0.062)>tylosin (0.20)>tetracycline (2.25)>chlortetracycline (3.49)>norfloxacin (5.64)>sulfamethoxazole (7.50)>ciprofloxacin (20.22)>sulfamethazine (31.26)>trimethoprim (137.78). Several of these antibacterial compounds would be toxic at the micrograms per liter concentrations reported in surface waters and sewage effluents. Simple additive effects were observed in binary mixtures of sulfonamides, and most tylosin, triclosan, or triclocarban combinations. Potentially synergistic effects were observed in binary mixtures of the same class, such as macrolides, tetracyclines, and fluoroquinolones, as well as in some combined drugs, such as trimethoprim and sulfonamides or tylosin and tetracyclines. Potentially antagonistic effects were only observed between tylosin and triclocarban, triclosan and norfloxacin, and triclocarban and norfloxacin. Although present at low concentrations in the aquatic environment, mixtures of these antibacterial agents can potentially affect algal growth in freshwater systems due to their combined action.
Yang
Li-Hua
LH
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.
Ying
Guang-Guo
GG
Su
Hao-Chang
HC
Stauber
Jennifer L
JL
Adams
Merrin S
MS
Binet
Monique T
MT
D000900:Anti-Bacterial Agents / Q000633:toxicity*; D001681:Biological Assay; D056890:Eukaryota / Q000187:drug effects* / Q000254:growth & development; D005618:Fresh Water
D000900:Anti-Bacterial Agents