The use of doxycycline, mezlocillin and clotrimazole in cell culture media as contamination prophylaxis.

The antibiotics Doxycycline (Vibramycin) and Mezlocillin (Baypen) have been compared with the commonly used bacteriostatic substance Neomycin, Streptomycin and Penicillin (NSP), and the broad-spectrum antifungal agent Clotrimazole (Canesten) has been tested in relation to the antimycotic Nystatin (Moronal) in different mammalian cell cultures for cytotoxicity and its influence of increasing concentration in the media on the growth of diploid and heteroploid cell population over several subcultures. Numerous experiments over the last years showed that small amounts of the tested substances were effective against contamination without noteworthy inhibition of cell growth. As suitable levels for the tested antibiotics we would recommend: Doxycycline at 1-2 micrograms/ml (2-5 micrograms/ml), Mezlocillin at 100-200 micrograms/ml (200-1000 micrograms/ml) and Clotrimazole at 0.5-1 microgram/ml (1-2 micrograms/ml) medium for diploid, fibroblastlike cell strains (for continuous epithelial-like cells.