Single or Multiple Antibiotic-Amended Media to Enumerate Yeasts and Molds .

Gentamicin, chloramphenicol and chlortetracycline were evaluated singly and in combination for their ability to control bacteria in media to enumerate yeast and molds. No single antibiotic tested at 50 or 100 ppm was totally effective in controlling bacteria. Chlortetracycline in combination with either chloramphenicol or gentamicin inhibited the contaminating bacteria as long as the antibiotics were added after autoclaving. It is recommended that for routine use, reliance not be placed upon a single antibiotic to control bacteria when enumerating fungi.