title: Increase in the in vitro susceptibility of Staphylococcus aureus to antimicrobial agents in the presence of Candida albicans.
abstract: In experiments with mixed cultures of Staphylococcus aureus and Candida albicans both in the absence and in the presence of 5-fluorocytosine (5-FC), we have observed that (1) there is an inhibition of S. aureus growth in mixed cultures with C. albicans in media supplemented with 1 microgram/mL of 5-fc and that 5-FC has no effect on staphylococci in pure cultures; (2) this inhibition occurred with clinically isolated and laboratory strains and could be reversed by specific metabolites; (3) Staphylococcus aureus was inhibited by filtrates of C. albicans cultures treated with 5-FC and this seemed to be favored by some C. albicans filterable product which can affect the cell wall and the permeability of the staphylococcal cells since they become sensitive to 5-FC; (4) nine other commonly used antimicrobials showed an increased inhibitory activity against S. aureus in mixed cultures with C. albicans; and (5) there is a decrease in the number of precipitating antigens of S. aureus and of the activity of alpha toxin when this species was grown with both C. albicans and 5-FC. Our results indicate that the susceptibility of some species to antimicrobials could be significantly modified in the presence of other species. One cannot exclude that a similar phenomenon could happen in hosts under treatment with antibiotics against infection.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002176:Candida albicans / Q000254:growth & development*; D003030:Coagulase / Q000096:biosynthesis; D003596:Cytosine / Q000031:analogs & derivatives*; D004352:Drug Resistance, Microbial; D005437:Flucytosine / Q000494:pharmacology*; D013045:Species Specificity; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D003030:Coagulase; D003596:Cytosine; D005437:Flucytosine