The skin response of rabbits to non-hemolytic streptococci.

Abstract

A study of the skin reactions in rabbits which were induced by intra-dermal injection of non-hemolytic streptococci demonstrated an unusual phenomenon. Following the injection of these microorganisms a local reaction took place which reached its maximum within 24 to 36 hours. The lesion then diminished until the eighth day, when an exacerbation occurred which at times approached the original lesion in intensity. This persisted for about 2 days and disappeared slowly. The late lesion is referred to as the “secondary reaction.” This reaction was first encountered while studying a green streptococcus isolated from a rheumatic subcutaneous fibroid nodule; with it definite secondary reactions were induced in 50 per cent of normal adult rabbits and doubtful reactions in an additional 13 per cent. On further extending the strains of green streptococci studied, the reaction was found to be incited by 5 out of 10 strains from nodules, blood or heart of rheumatic fever patients; by 1 out of 4 strains from the blood of subacute bacterial endocarditis patients; by 1 strain from the urine of a nephritic patient and by 1 anomalous strain isolated from a rheumatic nodule. It never followed the injection of green streptococci from normal throats, nor of hemolytic streptococci, staphylococci, micrococcus catarrhalis, B. coli, and B. influenza. The material used for intra-cutaneous injection consisted of the centrifuged sediment from 5 cc. of an 18-hour growth of the bacteria in blood broth. It was subsequently found that the reaction could be obtained with heat killed organisms. Lesions were excised daily and studied bacteriologically and histologically. In the early stages an abundant growth of streptococci was obtained, but the number of viable organisms progressively diminished until the 7th day, when none was present, although many could still be seen in the smears.