The factors of biological indicator resistance

Biological indicator(BI)is the gold standard in verifying the effectiveness of the sterilization processes.The resistance of biological indicators generally means the population of viable organism and D value.The population and the D value are all not intrinsic,which will vary according to the lot,the manufacturer.Spores,carrier,recovery medium and the packaging compose the self-contained biological indicators.And all of the component will affect BI resistance.Different kinds of carrier spore inoculated on exhibit different manners to attach different D-values.Another factor that affects the resistance of BI is spore production methods.The sporulation conditions including temperature,p H,humidity,nutrient and ions content,largely influence the spore resistance to heat.Furthermore,resistometer performance and the different test method are also the major source of the D value variation.All the factors affect the resistance of biological in an comprehensive manner,and when a resistance variation occur,all the factors above should be taken into consideration.