Three patients with furunculosis due to a pathogenic strain of Staphylococcus aureus became free of furuncles after S aureus strain 502A was purposely substituted. Relapse of furunculosis occurred when 502A was lost and the original strain reacquired. Nine other patients lost their furuncles after replacement of a pathogenic strain by 502A. Abscess formation is a strain-related phenomenon in these patients, and disappearance of furuncles was not a chance event but was related to the implantation of strain 502A.
Strauss WG, Maibach HI, Shinefield HR. Bacterial Interference Treatment of Recurrent Furunculosis2. Demonstration of the Relationship of Strain to Pathogenicity. JAMA. 1969;208(5):861-863. doi:10.1001/jama.1969.03160050115019