Chapter <51> Background Material

USP chapter <51> Antimicrobial Effectiveness Testing is designed to determine whether a product containing an antimicrobial agent is adequately preserved. Given the toxic nature of such agents, the lowest amount possible that achieves this level of antimicrobial efficacy should be used.

Each categoryof product, injections, oral products, antacids and others are inoculated with a separate culture of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis. Only aqueous products are considered.

The procedure requires the demonstration of method suitability in part by determining the adequacy of growth promotion for each strain of microorganism used. The recovery of microorganisms is determined by counting the number of colony forming units (cfu) after a set period of incubation.