Methicillin-resistant Staphylococcus aureus and Candida albicans on denture surfaces

Infectious diseases caused by methicillin-resistant Staphylococcus aureus, MRSA, and Candida albicans are often serious in compromised hosts. We enumerated MRSA and C. albicans on denture surfaces and in saliva samples from 29 adults. Staphylococcus species, MRSA, and methicillin-resistant Staphylococcus epidermidis, MRSE, were detected on 17, 3, and 1 of the 29 denture surfaces, respectively. C. albicans were detected on 22 denture surfaces. All saliva samples from patients whose dentures carried Staphylococcus species and C. albicans were also found to contain both microorganisms. Adherence of isolated 3H labeled cells of MRSA and C. albicans to resin beads and saliva-coated resin beads was examined. Cells of both microorganisms adhered in significantly higher numbers to saliva-coated resin beads than to resin beads. The hydrophobicity of the MRSA isolated from denture surfaces varied from strain to strain; that of C. albicans strains was moderately high. The zeta potentials of MRSA isolates and of C. albicans isolates determined in KCI buffer were significantly low. The potential of the resin beads decreased after treatment with saliva. Two out of 5 MRSA strains were found to be inhibited in growth by oral Streptococcus, Actinomyces, and gram-negative bacterial strains, suggesting that some oral bacterial species play a role in inhibiting the colonization of Staphylococcus species. No isolates of C. albicans were inhibited in their growth by any of the oral bacteria tested. Isolates of MRSA and C. albicans coaggregated with Porphyromonas gingivalis and Fusobacterium nucleatum strains. Using denture cleaners every night for 2 weeks did not reduce numbers of Staphylococcus species or C. albicans organisms in saliva.