Evaluation of a new rapid readout biological indicator for use in 132°C and 135°C vacuum-assisted steam sterilization cycles.
BACKGROUND
Sterilization is a process that cannot be inspected or tested in a practical manner to assure that all microorganisms have been inactivated. The process must therefore be validated for all of the specific items processed or monitored on a per cycle basis.


METHODS
A new, faster rapid readout biological indicator (RRBI) has been developed for use in 132°C and 135°C vacuum-assisted steam sterilization cycles. The aim of this study was to evaluate the performance of this new 1-hour readout RRBI at 132°C in side-by-side testing with an existing 3-hour readout RRBI and also evaluate the performance of the new RRBI in 135°C cycles. Readout responses of 1 hour (fluorescent) and 48 hours and 7 days (growth) of the new RRBI were compared with 3-hour, 48-hour, and 7-day readouts of the 3-hour RRBI following exposures in 132°C cycles using a highly controlled test vessel, ie, a steam resistometer. Additional testing of the 1-hour RRBIs was also performed in 135°C cycles.


RESULTS
The number and percentage of fluorescent-positive 1-hour RRBIs were virtually identical to those of the 3-hour RRBIs after 1 and 3 hours of incubation, respectively. Testing of the 1-hour RRBI in 135°C cycles paralleled the results of the testing at 132°C but with the expected shorter exposure times.


CONCLUSIONS
The results of this study suggest that the 1-hour RRBI is equivalent to the 3-hour RRBI and would be suitable for use in monitoring dynamic air removal steam sterilization cycles at both 132°C and 135°C per recommended practice guidelines.
LexaMed, Toledo, OH. Electronic address: pmschneider11@yahoo.com.
Philip M
PM
Schneider
D006801:Humans; D007202:Indicators and Reagents; D013227:Steam; D013242:Sterilization / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014618:Vacuum
D007202:Indicators and Reagents; D013227:Steam
Biological indicators; Rapid readout biological indicators; Reduced test time; Steam sterilization; Sterile processing; Sterility assurance; Sterilization indicators