L Type Cultures Isolated from Streptococci. ∗,†

Abstract

Summary

L cultures were isolated from two strains of alpha-hemolytic streptococci obtained from the human mouth. The appearance of these cultures and their morphology are similar to those of other bacteria, and they originated in a similar way from the parent streptococci. When exposed to certain influences, especially to penicillin, the cocci grew to large bodies and, on appropriate media, L type colonies developed from these. The L forms of streptococcus are not sensitive to penicillin and, like the L forms of gram-positive spore-bearing bacilli, do not require animal serum for growth. The cocci reappeared several times in cultures of the L form. Thus far, only two strains of streptococci could be induced to produce L forms. However, colonies similar in appearance and growth requirements to the L type colonies of streptococcus often develop on plates inoculated from the human mouth, suggesting that streptococci which produce L forms are often present in the mouth.