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

Abstract

The instruments and materials used in healthestablishments are frequently exposed to microorganismcontamination, and chemical products are used before sterilizationto reduce occupational infection. We evaluated the antimicrobialeffectiveness, physical stability, and corrosiveness of twocommercial formulations of peracetic acid on experimentallycontaminated specimens. Stainless steel specimens werecontaminated with Staphylococcus aureus, Escherichia coli, Candidaalbicans, blood, and saliva and then immersed in a ready peraceticacid solution: 2% Sekusept Aktiv (SA) or 0.25% Proxitane Alpha(PA), for different times. Then, washes of these instruments wereplated in culture medium and colony-forming units counted. Thisprocedure was repeated six times per day over 24 non-consecutivedays. The corrosion capacity was assessed with the mass loss test,and the concentration of peracetic acid and pH of the solutionswere measured with indicator tapes. Both SA and PA significantlyeliminated microorganisms; however, the SA solution was stablefor only 4 days, whereas PA remained stable throughout theexperiment. The concentration of peracetic acid in the SA solutionsdecreased over time until the chemical was undetectable, althoughthe pH remained at 5. The PA solution had a concentration of500-400 mg/L and a pH of 2-3. Neither formulation inducedcorrosion and both reduced the number of microorganisms(p = 0.0001). However, the differences observed in the performanceof each product highlight the necessity of establishing a protocolfor optimizing the use of each one