Bactericidal Property of an Ultra-Violet Irradiated Petrolatum-Lanolin Mixture

Abstract

Remarkable results on purulent wounds following the use of ultra-violet irradiated petrolatum, reported by Eising, 1 prompted us to determine whether such petrolatum had any bactericidal effect in vitro. We used a mixture of 2 parts petrolatum molle and one part lanolin, the latter being added to increase tissue absorption of the irradiated petrolatum.

Technic. A 2:1 petrolatum-lanolin mixture was melted and rendered sterile by infra-red heat. Twenty cc. of the mixture were placed in sterile petri dishes and irradiated directly for varying periods of time by a Burdick ultra-violet lamp at a distance of 12 inches. At the end of the time allotted for exposure 1 cc. of a normal saline suspension of organisms was thoroughly mixed with the petrolatum-lanolin. At varying intervals thereafter one loopful of the inoculated mixture was seeded on agar plates and the growth noted. For control we used: (1) Non-irradiated petrolatum-lanolin to which organisms had been added; (2) Petrolatum-lanolin to which organisms had been added before irradiation; (3) Petrolatum-lanolin which was irradiated for the same varying periods of time as the directly irradiated samples but with the petri dish covers left on to filter out the shorter ultra-violet rays as much as possible. The organisms used were Staphylococcus aureus and Bacillus pyocyaneus.

Staph. aureus was practically always killed within 24 hours by a 2-hour directly irradiated mixture. B. pyocyaneus gave less consistent results, but was usually killed within 24 hours by the 4-hour directly irradiated mixture. The plates irradiated with their covers on showed no bactericidal property except those exposed for 4 hours, which consistently killed Staph. aureus within 24 hours, thus suggesting that over the prolonged exposure time sufficient rays passed through the glass to irradiate the mixture.