Medical device SALs and surgical site infections: a mathematical model

It is commonly accepted that terminally sterilized healthcare products are rarely the source of a hospital-acquired infection (HAI). The vast majority of HAIs arise from human-borne contamination from the workforce, the clinical environment, less-than-aseptic handling techniques, and the patients themselves. Nonetheless, the requirement for a maximal sterility assurance level (SAL) of a terminally sterilized product has remained at 10(-6), which is the probability of one in one million that a single viable microorganism will be on a product after sterilization. This paper presents a probabilistic model that predicts choosing an SAL greater than 10(-6) (e.g. 10(-5) or 10(-4), and in some examples even 10(-3) or 10(-2)) does not have a statistically significant impact on the incidence of surgical site infections (SSIs). The use of a greater SAL might allow new, potentially life-saving products that cannot withstand sterilization to achieve a 10(-6) SAL to be terminally sterilized instead of being aseptically manufactured.