Stability of antimicrobial activity of peracetic acid solutions used in the final disinfection process

Area of Science:

• Healthcare-associated infection control
• Microbiology
• Materials science

Background:

• Medical instruments require effective decontamination to prevent microorganism contamination.
• Chemical disinfectants are crucial for reducing occupational infections before sterilization.
• Peracetic acid is a common disinfectant used in healthcare settings.

Purpose of the Study:

• To evaluate the antimicrobial effectiveness, physical stability, and corrosiveness of two commercial peracetic acid formulations.
• To compare the performance of Sekusept Aktiv (SA) and Proxitane Alpha (PA) on contaminated stainless steel specimens.
• To determine the optimal usage protocols for peracetic acid disinfectants.

Main Methods:

• Stainless steel specimens were experimentally contaminated with bacteria (Staphylococcus aureus, Escherichia coli), yeast (Candida albicans), blood, and saliva.
• Contaminated specimens were immersed in ready-to-use SA (2%) or PA (0.25%) solutions for varying durations.
• Antimicrobial effectiveness was assessed by plating instrument washes and counting colony-forming units.
• Solution stability was monitored over 24 non-consecutive days by measuring peracetic acid concentration and pH.
• Corrosiveness was evaluated using the mass loss test.

Main Results:

• Both SA and PA significantly reduced microbial load (p = 0.0001).
• PA solution maintained a stable concentration (500-400 mg/L) and acidic pH (2-3) throughout the experiment.
• SA solution's peracetic acid concentration decreased over time, becoming undetectable within 4 days, despite a stable pH of 5.
• Neither formulation induced corrosion on stainless steel specimens.

Conclusions:

• Both peracetic acid formulations exhibit antimicrobial properties and are non-corrosive to stainless steel.
• Proxitane Alpha (PA) offers superior chemical stability and sustained antimicrobial efficacy compared to Sekusept Aktiv (SA).
• The distinct performance characteristics necessitate the development of specific usage protocols for each peracetic acid product to ensure optimal disinfection outcomes.