Did granny know best? Evaluating the antibacterial, antifungal and antiviral efficacy of acetic acid for home care procedures

BACKGROUND: Acetic acid has been used to clean and disinfect surfaces in the household for many decades. The antimicrobial efficacy of cleaning procedures can be considered particularly important for young, old, pregnant, immunocompromised people, but may also concern other groups, particularly with regards to the COVID-19 pandemics. This study aimed to show that acetic acid exhibit an antibacterial and antifungal activity when used for cleaning purposes and is able to destroy certain viruses. Furthermore, a disinfecting effect of laundry in a simulated washing cycle has been investigated. RESULTS: At a concentration of 10% and in presence of 1.5% citric acid, acetic acid showed a reduction of > 5-log steps according to the specifications of DIN EN 1040 and DIN EN 1275 for the following microorganisms: P. aeruginosa, E. coli, S. aureus, L. monocytogenes, K. pneumoniae, E. hirae and A. brasiliensis. For MRSA a logarithmic reduction of 3.19 was obtained. Tests on surfaces according to DIN EN 13697 showed a complete reduction (> 5-log steps) for P. aeruginosa, E. coli, S. aureus, E. hirae, A. brasiliensis and C. albicans at an acetic acid concentration of already 5%. Virucidal efficacy tests according to DIN EN 14476 and DIN EN 16777 showed a reduction of ≥4-log-steps against the Modified Vaccinia virus Ankara (MVA) for acetic acid concentrations of 5% or higher. The results suggest that acetic acid does not have a disinfecting effect on microorganisms in a dosage that is commonly used for cleaning. However, this can be achieved by increasing the concentration of acetic acid used, especially when combined with citric acid. CONCLUSIONS: Our results show a disinfecting effect of acetic acid in a concentration of 10% and in presence of 1.5% citric acid against a variety of microorganisms. A virucidal effect against enveloped viruses could also be proven. Furthermore, the results showed a considerable antimicrobial effect of acetic acid when used in domestic laundry procedures.