Could you tell me which is recommended frequency of sterilization process monitoring by biological indicators?
Liliana Denic

Dear,

A few of my thoughts on biological indicators (BI) you can read on our Discussion page under: "Can chemical indicators replace biological ones in routine control of sterilization processes".
As a consequence we don't use in our hospital BI in the routine control of steam sterilization processes. But every low temperature process we do - Ethylene oxide or Gasplasma - is controlled by a biological indicator.

Best regards,
Wim Renders

Hi Liliana

i would like to give you an answer to the frequency of BIs, what is very common in many countries is to use them at least every week What's more, World Health Organisation in december 2002 published a Practical guide on Prevention of Hospital Acquired Infections in which it is recommended you use Biological indicators at least weekly or more frequently.
You can find it in WHO site

Ciao
Pierfranco Mirabile
Professional Service Sterilizzazione

Hello Liliana,

Firstly, there are different practises and recommendations in European countries, here are some of them.

STEAM STERILISING: Some European countries, the UK for instance, do not recommend routine monitoring with biological indicators (BI)at all. Monitoring of the programme parameters is prefered. BI's are therefore only used in certain validation processes. In Norway BI's are commonly used, they are regarded as a suppliment to parametric monitoring. Frequency varies between hospitals but intervals of 4, 8 or 12 weeks are usual. Older sterilisers are normally tested more frequently than newer models.

LTSF: BI's testing frequency is normally every 7-10 days in Norway. In the UK however, BI's are required for every LTSF production load. I agree completely with this, as the efficacy of the process relies upon a chemical reaction combined with low temperature steam, therefore the safety margins are smaller.

ETHYLENE OXIDE: BI's are essential for every EO load.

Kind regards
Linda Ashurst

Dear Liliana!

As already mentioned, the actual use of BI (biological indicators) varies quite a bit in Europe. Besides normative and regulatory specifications, the decision needs to be based on the circumstances of the individual case. Some of the influencing factors are: sterilization method, hardware status (i.e. sterilizer age, quality of pressure and temperature sensors, calibration, ...), cycle type, load and load configuration, personal (e.g. level of expertise) etc..
Bear in mind that each type of monitors (biological indicators, chemical indicators and physical measurements) has advantages and limitations. A combination of each three types should give you the necessary information to judge the quality of a sterilization process.

Best regards/Mit freundlichen Grüßen
Klaus Hahnen
3M Laboratories (Europe)

Dear Liliana!

The frequency of using BI's is one question, which has been discussed already.

Which way to use BI's during sterilization monitoring is a second question. The best BI can monitor only sterile conditions at the place the BI is located in the sterilization chamber. The BI cannot monitor in a distance away from the BI. Please keep in mind, that inside a sterilization chamber there are no homogenous conditions. The BI's has to be placed into most difficult places where the sterilant has problems to reach all the surfaces of complex instruments.

Quite often BI's are placed in areas where the sterilant can easily reach the BI, but necessarily not all the difficult surfaces. In this case the BI shows a pass, but this pass is no guaranty, that all instruments are sterilized successfully. Therefore the answer of BI monitoring in that case would be false positive. A false positive monitoring is worse, that no monitoring at all.

Therefore the most difficult penetration characteristic of load in a given sterilization process must be known, to make a BI monitoring meaningful. To know the places, where to put the BI's in, is not always easy to determine. A validation procedure for each process should answer this question and should give the user information, which way to monitor their sterilization processes correctly.

This information is not only valid, how to use BI's, but the same applies for chemical indicators as well.

Sterilant = condensed steam on surfaces, EtO-gas, Formaldehyde-water solution on the surface, Hydrogen peroxid, etc depending on the sterilization process.

Ulrich Kaiser

gke-mbH,