Microbiological quality of topical drug formulations: Efficacy of antimicrobial preservation against Paecilomyces lilacinus

Background: Microbiological quality of topical products comprises both, the microbiological purity of the unopened product and the efficacy of the ant imicrobial preservation system. Objective: Subsequent to an outbreak of inv asive Paecilomyces lilacinus mycosis among patients of an isolation ward, p robably caused by a contaminated skin care product, the microbiological qua lity of different skin care products from the market was investigated. Meth ods: The different products were investigated for their efficacy of antimic robial preservation in general and especially against P. lilacinus accordin g to a pharmacopoeial routine method slightly adopted for the purpose of th is investigation. Results: The products did partially not comply with the B ritish Pharmacopoeia 1993 test for efficacy of antimicrobial preservation. The antimicrobial preservation systems were less effective against P. lilac inus than against the pharmacopoeial reference germs. The antimicrobial pre servation efficacy decreased towards the end of the shelf-life of the produ ct. A decreased P. lilacinus inoculum dose was related to an increased grow th of the micro-organisms. Conclusion: Topical products are, unless not lab elled otherwise, non-sterile preparations and their preservation systems ar e only tested against pharmacopoeial key micro-organisms. The microbiologic al behaviour following contamination with other germs remains unknown. Copy right (C) 2001 S. Karger AG, Basel.