Effectiveness of a peracetic acid-based disinfectant against spores of Bacillus cereus under different environmental conditions

- Concentration of disinfectant and temperature influences efficacy of disinfectant.
- Time of exposure and bacterial strain also influences disinfection efficacy.
- Sterile bovine serum had no significant influence on reductions.
- Spores of Bacillus cereus vary in their susceptibility against the disinfectant.

A peracetic acid based disinfectant was tested for its efficacy against spores of different Bacillus cereus -strains (DSM 318, 4312, 4313 and 4384). To determine the influence of different factors like exposure-time, temperature and presence of protein quantitative and qualitative suspension tests were performed. Spore suspensions of B. cereus were treated with various concentrations of a representative peracetic acid based disinfectant at three temperatures (10, 15 and 20 °C), with protein load and with different exposure times (5, 30 and 60 min). Temperature, level of concentration and exposure-time had a significant influence on reduction of spores of B. cereus (p < 0.05). The susceptibility of spores of different strains greatly differed. A treatment of spores of DSM 4384 with 2.0% for 30 min even at 10 °C inactivated all present spores (initial number 6.18-6.71 log CFU/ml). Spores of B. cereus strain DSM 4313 had only reductions of 0.16-0.97 log CFU/ml at same treatment conditions. The presence of inactivated bovine serum as interfering substance had no significant influence on reduction (p > 0.05).