Microbial contamination and preservative efficacy of topical creams

Abstract

Nineteen different brands of topical creams were tested in duplicate for microbial growth. The efficacy of their preservation was assessed, when possible, by standard pharmacopoeial procedures. Microbial growth was demonstrated in cultures from all specimens. However, high counts (>104c.f.u./g) were obtained from eight specimens from six different brands. The microbes were found to belong to different species of bacteria and fungi including Pseudomonas aeruginosa. Two samples of each of the seven, easily emulsifiable creams, were challenged with standard strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans to assess the efficacy of the preservatives used in their preparations. With the exception of a single brand, all creams tested were ineffectively preserved. This study highlights the dangers of marketing domestically prepared topical creams and more effective monitoring of the components for all topical creams is recommended. The inclusion of a proper preservative system in these formulas is essential.