Steam sterilization autoclave: which test to perform to show a sanitization (not sterilization)

Dear all,

We have a non-asceptic process with final filtration, so we must only have a bioburden reduction. For most of the loads, we performed a full sterilization with all EN 285 criteria. Due to the nature of one load (porous, but sensitive to low pressure), we are not able to perform a robust cycle with enough vacuum pulses to have all air-pockets removed. A preliminary test showed that the bioindicator was killed, but the chamber temperature/pressure data shows some irregularities at the bottom of the chamber (potential air layer around drain which fails the saturated steam conditions and temperature distribution tests in the chamber (EN 285)).

If we decide the claim only a sanitization (bioburden reduction) instead of a sterilization. Which test would you still recommend to do?

I was think on only performed the following tests:

  • Bioindicator test in load (to show that no significant air pocket existed in the load).
  • Temperature in chamber must be higher than 121.0 °C during holding time.
  • F0 calculation in load (mathematically support the bioindicator test).

I would not include:

  • temperature band (3 °C), fluctuations (1.0 °C) and difference (2.0 °C) according to EN 285 (during holding time).
  • equilibration time.
  • saturated steam conditions in chamber (i.e. drain (cold spot) temperature corresponds to saturated steam pressure at all time during holding time).


Whoa! The difference between sanitization versus sterilization is;

  1. What you have promised the regulators in your DMF.
  2. Parenteral (injectable) drug dosages are required to be sterilized and the USP has a specific test. Section <61> (if I recall) as well as endotoxins (max. < 0.25 EU/mL).

Having said that, I think you are close to sterilization since multiple cycles are allowed (Tyndalization).