Changes in the activity of antifungals in mixed cultures of bacteria and yeasts

When Candida cells were grown in mixed cultures with Escherichia coli, Salmonella typhimurium, or Pseudomonas aeruginosa, their sensitivity to antifungal agents affecting sterol metabolism or functioning (polyenes and miconazole) was increased by several log units. This phenomenon was overcome by the addition to the culture medium of sugars utilized either by the bacteria or the yeast. Antifungals without direct effect on sterol metabolism (5-fluorocytosine, methylparaben, and 4-hydroxyquinazoline) were not more active in mixed than in pure cultures.