Staphylococcal interference studies²

Bennett, J. V. (Epidemiology Program, NCDC, Atlanta, Ga. 30333) J. A. Shulman, B. J. Rosenstein, B. J. Trembarh, T. C. Eckhoff, and J. R. Boring. Staphybcoccal Interference Studies. Amer. J. Epid, 1968, 88: 410-421.-Artificial colonization with the 502A strain of Staphylococcus aureus was used in an attempt to control endemic staphylococcal infections in an institutional population. After infranasal instillations, 71% of the treated group became colonized with 502A, but nasal carriage declined rapidly. Six weeks after the inoculations, an outbreak of impetigo due to both a S. aureus strain of phage-type 55/71 and Group A streptococci began. Both organisms were sensitive to tetracycline, which was given to about half of the study population. Tetracycline therapy promptly terminated the outbreak of impetigo, and provided an opportunity to observe the effects of tetracycline on nasal carriage of the tetracycline-resistant 502A strain; "recall" of carriage occurred among persons who had previously carried this strain, and 502A was disseminated to exposed susceptibles. However, a concomitant, marked, and unexpected increase in colonization with a tetracycline-resistant, phage-type 80/81 S. aureus occurred in persons receiving this antibiotic, and lesions caused by this strain appeared. Nasal colonization with 502A did not prevent staphylococcal lesions, and the 502A strain itself was associated with lesions in three members of the study population.