A Comparison of Acetic Acid with a Quaternary Ammonium Compound for Disinfection of Hand-Held Nebulizers

Abstract

Although home care companies routinely recommend the use of acetic acid solutions (white vinegar) and/or quaternary ammonium compounds (QAC) for disinfection of respiratory care equipment, the literature offers little information about the relative effectiveness of these agents. We therefore compared the disinfectant ability of acetic acid solutions prepared from white vinegar, QAC, and detergent. Methods: In Phase I of the study, we compared the ability of fresh preparations of 0.63% acetic acid, 1.25% acetic acid, QAC, and an aqueous detergent alone to disinfect medication nebulizers contaminated with three common pathogens, Pseudomonas aeruginosa (Pa), Pseudomonas cepacia (Pc), and Staphylococcus aureus (Sa). In Phase II, we evaluated the effectiveness of re-used QAC during 14 days of use and re-used 1.25% acetic acid during 4 days. In Phase III, we evaluated the effectiveness of a detergent wash before disinfection by QAC and by 1.25% acetic acid. Results were expressed as a percentage of positive cultures. We used chi-square analysis for multiple comparisons and the Fisher Exact test for pairs. Phase-I results: The 0.63% acetic acid treatment showed 100% positive cultures; the 1.25% acetic acid, 63% positive; the QAC, 37% positive; the detergent, 100% positive. The 1.25% acetic acid and QAC were superior to 0.63% acetic acid and to detergent alone (P=0.007). There was no difference between the results of 1.25% acetic acid and the results of QAC. Phase-II results: Re-used 1.25% acetic acid showed 100% positive cultures on Days 2-4 and was least effective against Sa. The re-used QAC completely disinfected at least one nebulizer each day up to 14 days. It appeared to be least effective against Pa and most effective against Sa. Phase III results: 1.25% acetic acid after detergent pre-wash showed fewer positive cultures than QAC after detergent pre-wash (P=0.021). Conclusions: The combined effectiveness of a detergent pre-wash and 1.25% acetic acid soak was comparable to the effectiveness of a quaternary ammonium compound for disinfection of Sa- or Pc-contaminated equipment and superior for Pa; and a quaternary ammonium compound can be effective after repeated re-use up to 14 days.