Some cultural characteristics ofStaphylococcus aureusstrains from superficial skin infections

Abstract

1. A collection of 1389 strains of Staphylococcus aureus of human origin was examined by the following tests: phage typing, antibiotic resistance, ability to inhibit the growth of Corynebacterium diphtheriae, the egg-yolk reaction and the serum opacity reaction.2. Nearly all strains of Staph. aureus Type 71 were penicillin resistant, inhibited C. diphtheriae, gave a negative egg-yolk reaction, and produced a zone of opacity on horse-serum agar.3. The penicillin resistance of Type 71 strains is unlikely to have arisen as a result of the therapeutic use of penicillin, and is probably a natural characteristic of the type.4. Staph. aureus strains which gave a negative egg-yolk reaction and a positive serum opacity reaction occurred almost exclusively in superficial lesions. The majority of them were members of Type 71, or were penicillin-resistant members of phage-group III. It is suggested that these organisms can cause superficial inflammation, but are usually unable to invade deeper tissues.I wish to thank Dr A. J. H. Tomlinson for valuable information about his unpublished work on impetigo. Thanks are also due to many colleagues who have provided cultures and clinical information, to Dr R. E. O. Williams for typing phages, and to Mr L. E. Simmons for technical assistance.