Effect of Rapid Dehydration by Vacuum Drying on Fungal Viability

Park, So Hyun; Park, Jin Woo; Shin, Dong Hoon; Choi, Jong Soo; Kim, Ki Hong

Abstract

BACKGROUND
Tinea pedis and candidiasis of the feet is the most common type of dermatomycosis. Contaminated shoes may play an important role in spread and relapse of tinea pedis and candidiasis of the feet. However there is no effective method to sterilize contaminated shoes. Since vacuum drying can evaporate water in relatively low temperature, it is thought to be able to dehydrate rapidly and to sterilize shoes without damaging them. OBJECTIVE: This study was designed to evaluate the fungicidal effect of rapid dehydration by vacuum drying. METHODS: The suspension of Trichophyton (T.) rubrum, T. mentagrophytes and Candida (C.) albicans was made with distilled water. Vacuum drying or wet heating of the suspension was conducted in the vacuum dryer at various temperature and time. The treated fungi were rehydrated and were cultured on Sabouraud dextrose agar petri dish. The viability was determined as colony forming unit (CFU) of experimental group divided by that of control group. RESULTS: When C. albicans was dried for one hour by vacuum drying, the viability decreased as temperature increased, but no sterilization was noted even at 80degrees C. Under vacuum drying at 50degrees C for one hour, viability decreased below 3% and there was no difference in the viability between one hour of the treatment and more than one hour. In T. rubrum, T. mentagrophytes, C. albicans, the number of fungi was reduced by 90% under the condition of one hour vacuum drying at 50degrees C. Wet heating was more effective than vacuum drying in reducing and sterilizing C. albicans. Sterilization was done under the condition of wet heating of one hour at 50degrees C or wet heating over 30 minutes at 60degrees C. The higher concentration of C. albicans was, the stronger resistance against the heat and dehydration was observed. Combined teatment with wet heating for one hour followed by vacuum drying for one hour at 50degrees C was effective way to sterilize C. albicans. CONCLUSION: These results suggest combined treatment with wet heating and vacuum drying can effectively sterilize shoes without damage and prevent the feet from spread and relapse of tinea pedia and candidiasis of the feet.