Bactericidal activity of ammonia and monoethanolamine on Pseudomonas aeruginosa and Staphylococcus aureus strains of various origins.

ObjectiveMicrobiological risk of cosmetic products has to be assessed by the manufacturers to determine whether microbiological testing is required, according to the composition of a given product. The use of certain ingredients in cosmetic formulations will help to create a hostile environment towards microbial growth. In this study, the influence of some cosmetic ingredients on bacterial survival was evaluated. MethodsStrains of Pseudomonas aeruginosa and Staphylococcus aureus, which are relevant to cosmetic products given their ability to cause skin infection, were exposed to various concentrations of ammonia or monoethanolamine in culture medium. Microbial strains obtained from collection, clinical or industrial sources were included to assess the possible influence of strain origin. ResultsIncreased concentrations of ammonia or monoethanolamine led to faster and larger reductions in bacterial populations. Staphylococcus aureus proved being more resistant than P.aeruginosa, and ammonia had a stronger impact than monoethanolamine. Strain origin showed a marginal influence on survival. ConclusionConcentrations higher than or equal to 0.5% (v/v) ammonia or 1% (v/v) monoethanolamine were able to completely inactivate bacterial populations (more than 5-log reduction) in just a few days.