Effective Sterilization Method of the Bacteria-inducing Offensive Odor of Shoes

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

Abstract

BACKGROUND: It is known that the offensive odor of shoes is due to contaminated bacteria. Therefore, the foul odor can be eliminated if these bacteria are sterilized. There is an effective method to sterilize contaminated shoes, which involves vacuum drying evaporate water at a relatively low temperature. This dehydrates the bacteria rapidly, and sterilizes shoes without damage.
OBJECTIVE
This study was undertaken to analyse the contaminated bacteria of shoes and to evaluate the bactericidal effect and rapid dehydration by heating and vacuum drying.
METHODS
Contaminated bacteria were isolated from the soles and foul odor shoes of 15 volunteers by swab sampling method. Three strains of Staphylococcus (S.) aureus and S. epidermidis were used to find an effective sterilization method. Vacuum drying or wet heating of bacterial suspension was conducted by a vacuum dryer at various temperatures and exposure times. The treated bacteria were rehydrated and were cultured on nutrient agar petri dishes. The viability was expressed as colony forming unit (CFU) of experimental group divided by that of control group.
RESULTS
S. aureus was isolated from the soles and shoes of 7 volunteers, and S. epidermidis from 5 volunteers. In 3 volunteers, both S. epidermidis and S. aureus were isolated. When S. epidermidis and S. aureus were dried for one hour by vacuum drying, the viability decreased as temperature increased, however, no sterilization was noted even at 90 degrees C for 8 hours. Moreover, under vacuum drying at 90 degrees C for 15 minutes, viability was reduced by 10%. The number of bacteria was reduced by 90% after 30 minutes of wet heating at 60 degrees C, or 15 minutes wet heating at 65 degrees C. However, sterilization was only accomplished by wet heating at 60 degrees C for one hour. Therefore, wet heating appears to be effective in reducing and sterilizing S. aureus and S. epidermidis, compared to vacuum drying. Sterilization was not obtained by vacuum drying at a moderate temperature.
CONCLUSION
These results indicate that wet heating for one hour at 60 degrees C, followed by vacuum drying at a moderate temperature would be an effective way to sterilize contaminated bacteria, dry shoes and inhibit the offensive odor within shoes.