Impetigo Contagiosa. The Association of Certain Types of <i>Staphylococcus Aureus</i> and of <i>Streptococcus Pyogenes</i> with Superficial Skin Infections

<jats:title>Summary</jats:title><jats:p>In an investigation of impetigo among troops, carried out in 1941, nearly half of the strains of <jats:italic>Staphylococcus aureus</jats:italic> isolated from the lesions had the ability to inhibit the growth of corynebacteria on solid media. A much smaller proportion of strains from other superficial lesions and from nose and throat swabs had this ability, and strains from deep suppurative lesions were uniformly negative.</jats:p><jats:p>Three-quarters of <jats:italic>Staph. aureus</jats:italic> strains isolated from schoolchildren with impetigo in Lancashire in 1953 and early 1954 were of one variety, which could be denned by its susceptibility to typing phages (‘type 71’).</jats:p><jats:p>Nearly 90 % of ‘type 71’ staphylococci, and very few others, produced a narrow, sharp zone of inhibition of <jats:italic>Corynebacterium diphtheriae mitis</jats:italic> on solid media.</jats:p><jats:p>A small number of other staphylococci, mainly non-typable or unclassifiable strains, produced a wider, hazy zone of inhibition.</jats:p><jats:p>The majority of the impetigo staphylococci were penicillin-resistant, and most of the resistant strains were members of ‘type 71’. However, ‘type 71’ gave rise to only a small proportion of the penicillin-resistant hospital infections occurring in the same district at the same time.</jats:p><jats:p>Three-quarters of the <jats:italic>Str. pyogenes</jats:italic> strains from impetigo lesions belonged to one of two groups of closely related serological types, one of which was rarely encountered in other situations.</jats:p>