Microwave sterilization of dentures contaminated with fluconazole-resistant Candida ssp

OBJECTIVES: the aim of this study was to evaluate the effectiveness of microwave irradiation on the sterilization of complete dentures contaminated with fluconazole-resistant isolates of C. albicans (Ca), C. glabrata (Cg) and C. krusei (Ck). One ATCC and three isolates from HIV-infected patients were used. METHODS: forty simulated dentures were fabricated and subjected to ethylene oxide sterilization. Dentures were individually inoculated with the tested microorganisms and, after incubation (37°C/48h), submitted to microwave irradiation at 650W for 3 minutes. Non–irradiated dentures were used as positive controls. Replicate aliquots of suspensions were plated at dilutions 10^-1–10^-4. All plates were incubated at 37°C for 48h and colonies counts of each plate were quantified (cfu/mL). To verify the long-term effectiveness of microwave sterilization, the beakers were incubated at 37°C for 7 days. Data were statistically analyzed with Kruskal-Wallis and Dunn¢s multiple comparison tests (p≤.05). RESULTS: simulated complete dentures contaminated with individual suspensions of all Candida yeasts showed consistent sterilization after 3 minutes of irradiation at 650 W (48h and 7 days). All control dentures showed microbial growth on the plates. There were no significant differences in cfu/mL between ATCC yeasts and clinical isolates from HIV-infected patients resistant to fluconazole (p=.0548). The cfu/mL for Ck was significantly lower than those of Ca and Cg (p<.05). CONCLUSION: Microwave irradiation for 3 minutes at 650W resulted in sterilization of all complete dentures contaminated with Ca, Cg and Ck (ATCC and clinical isolates from HIV-infected patients resistant to fluconazole). Post-graduate scholarship granted by the CNPq—Research and Development National Concil, Brazil.