2.5. Establishment of a model to estimate the probability of residual
bacterial contamination after the cleaning and sanitization process
The probabilities for detecting residual replication competent
E. coli and enterococci on the transfer conveyor surfaces were calculated
by multiplying the probabilities of each bacterium surviving
in situ after each of the three cleaning and sanitizing steps, as
shown in Eq. (1).
PS ¼ PI PQ PA PC ð1Þ
where PS is the probability of the microorganism surviving on the
conveyor after the cleaning and sanitizing process, PI is the initial
prevalence of the microorganism on conveyor before it was cleaned
and sanitized, and PQ, PA and PC are the probability of the microorganism
surviving after the conveyor had been treated with Quorum
Pink II HF detergent, acetic acid and chlorine, respectively.
In addition, a sensitivity analysis was conducted by using the
@Risk program (Palisade Corp., Ithaca, NY) to consider the importance