Rapid read-out biological indicator

The present invention relates to a rapid method for determining the efficacy of a sterilization cycle. In particular, the present invention employs an enzyme whose activity can be correlated with the viability of at least one microorganism commonly used to monitor sterilization efficacy, hereinafter referred to as a "test microorganism". The enzyme, following a sterilization cycle which is sublethal to the test microorganism, remains sufficiently active to react with an enzyme substrate in a relatively short period of time, e.g., normally eight hours or less. However, the enzyme is inactivated or appreciably reduced in activity following a sterilization cycle which is lethal to the test microorganism. The invention further relates to biological sterility indicators which include such an enzyme. A rapid method of determining the efficacy of a sterilization cycle, and an indicator adapted to perform such method, comprising subjecting to the sterilization cycle a source of active enzyme having activity which correlates with the viability of a microorganism commonly used to monitor sterilization, and incubating the enzyme source, following the completion of the sterilization cycle, with an effective amount of a substrate system capable of reacting with any residual active enzyme to produce a detectable enzyme-modified product.