Comparison of Methods for Measuring Bacillus cereus Contamination of Hospital Towels

Abstract

  Hospital towels must be disinfected by hot water cleaning. However, towels are sometimes contaminated with Bacillus cereus spores resistant to heat. Such contamination can cause healthcare associated infections. Thus, B. cereus contamination of hospital towels should be routinely evaluated to control infections. However, standard methods for the evaluation have not yet been established. In the present study, B. cereus contamination of hospital towels was measured using four methods; the agar contact method, the swab method, the simple shaking method, and the glass bead shaking method. The agar contact method could not quantify the towel contamination. The swab method could detect only a small number of bacteria from hospital towels. Both shaking methods could detect a large number of bacteria from hospital towels. Especially, the glass bead shaking method detected twice as many bacteria as the simple shaking method. These results indicate that the glass bead shaking method is the most suitable method for evaluating B. cereus contamination of hospital towels. In addition, our results demonstrated that B. cereus does not have uniform distribution in towels. Therefore, evaluation of B. cereus contamination must examine several test pieces of the same towel.