MIIM20002 Lecture Notes - Lecture 29: Microorganism, Asepsis, Hand Washing
4 Aug 2018
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Calculate dx value or decimal reduction (decay) time = time to reduce population 10-fold at a particular temperature i. e. from 103 to 102 = 90% reduction at x c. 10-1 doesn"t mean there"s 1/10th of an organism per unit. Out of 10 units, 1 of them will have a microorganism. Sterility assurance: a calculated probability that a micro-organism will survive a sterilization process and thereby render a proportion of treated articles unsterile. Decision about level of sterility assurance: we want to accept depends on intended use (likely risk) e. g. bandaids 10-3 syringes 10-6. Also need to consider cost-effectiveness of procedures, environmental concerns, level of public concern. Relationship between d value, level of contamination and sterility assurance. A and b are the same bacterium except b is at a lower conc. Takes longer to get to our level of sterility assurance if there are more microorganisms. If another organism has a lower d value then you can reach sterility assurance quicker.
