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Lab Research
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An assessment of the efficacy of expired topical antibiotic ointments First Author: Dyane Tower Authors: SC Wu, JM Vanik Topical antibiotics are traditionally used to help prevent infection in minor cuts, scrapes, and burns and to control or reduce bacterial colonization of infected wounds. Expired antibiotic ointments are commonly kept in medicine cabinets and applied on skin cuts and scrapes. The purpose of this study is to determine the efficacy of expired antibiotics on bacteria. Seven common organisms including, E coli, S. epidermidis, S. Aureus, C. Albicans, B. spizizenii; and P. aeruginosa were individually added to small amounts of expired antibiotic ointments and brand matched new antibiotic ointments. Each combination was incubated for 24 hours at 37°C and then cultured. Each combination was incubated for an additional 24 hours at 37ûC and re-cultured. The cultures were observed for growth after each period of incubation. After the 24 hour incubation period, 9 of 64 (14.1%) cultures had bacterial growth. Six of the 9 (66.7%) cultures that allowed bacterial growth after 24 hours were expired ointments while the remaining three (33.3%) were new tubes of antibiotic ointment. After 48 hours of incubation at 37ûC, 13 of 64 (20.3%) cultures had bacterial growth. Five of the thirteen (38.5%) cultures that allowed bacterial growth after 48 hours were expired ointments while the remaining eight (61.5%) were new tubes of antibiotic ointment. In conclusion, the expiration date labeled on antibiotic ointments may not be as important as ensuring that the ointment is not left on the wound for a long period of time before it is washed off and replaced with a fresh application. |
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