Low temperature steam and formaldehyde sterilization.

Area of Science:

• Microbiology
• Sterilization Technology
• Medical Device Engineering

Background:

• Standard low temperature steam/formaldehyde autoclaves are used for sterilization.
• Initial testing revealed failures in eliminating Bacillus stearothermophilus spores, a common challenge organism.

Purpose of the Study:

• To identify reasons for sterilization failures in standard autoclaves.
• To develop and validate modifications for improved autoclave performance.
• To establish reliable sterilization conditions.

Main Methods:

• Testing a standard low temperature steam/formaldehyde autoclave with Bacillus stearothermophilus spore-containing test pieces.
• Analyzing failure modes and implementing autoclave modifications.
• Developing and testing an improved operating cycle.
• Validating performance with a commercially produced prototype autoclave.

Main Results:

• Initial autoclave operation showed failures in killing Bacillus stearothermophilus.
• Modifications and an improved cycle led to greatly improved performance.
• Reliable and consistent sterilization of all test pieces was achieved.
• A similarly modified prototype autoclave also demonstrated effective sterilization.

Conclusions:

• Standard autoclaves require modification for effective sterilization against resistant organisms.
• An improved operating cycle and specific modifications ensure reliable autoclave sterilization.
• The validated modifications are applicable to both standard and prototype autoclaves.