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Growth‐inhibiting effects of 12 antibacterial agents and their mixtures on the freshwater microalga Pseudokirchneriella subcapitata
Author(s) -
Yang LiHua,
Ying GuangGuo,
Su HaoChang,
Stauber Jennifer L.,
Adams Merrin S.,
Binet Monique T.
Publication year - 2008
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/07-471.1
Subject(s) - triclosan , tylosin , triclocarban , norfloxacin , chemistry , antibacterial agent , minimum inhibitory concentration , trimethoprim , microbiology and biotechnology , environmental chemistry , ciprofloxacin , biology , antibiotics , biochemistry , medicine , pathology
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.