RESUMO
Antimicrobial effectiveness of methylparaben and a mixture of methyl- and propylparabens in an oil-in-water cream was studied. How the number of microbes and inclusion of nutrients into the cream affect the effectiveness of these compounds were also investigated, as well as the survival of test microbes in the cream without preservatives. Survival of microbes and antimicrobial effectiveness of parabens against the microbes in the cream were dependent on the species and number of microbes present and also on the amount of nutrients available for the microbes. In spite of the large amount of water, the cream studied did not readily support microbial growth unless the number of microbes was large or nutrients were added. Parabens were not effective antimicrobial agents against the yeast studied. The bacterial species showed different sensitivities to parabens. A mixture of methyl- and propylparabens was more effective than the methylester alone.