[In vitro obtaining stable L forms of group A beta-hemolytic streptococci type 1 and 12]

Stable L-forms of hemolytic streptococcus of group A of the 1st and 12th types were obtained in vitro under the effect of penicillin. L-form strains were passaged over 40 times and failed to reverse to the initial. Stability of the obtained L-cultures of the 1st and 12th types was confirmed by electron microscopy which showed the absence of cell wall in them. Morphology of the colonies on hard nutrient medium showed some difference in the L-form strains of the 1st and 12th type. Phage contrast microscopy demonstrated in the culture of the 12th type a relatively greater number of granular structures; as to the L-form cultures of the 1st type, it was mainly represented by the globular elements. Submicroscopic characteristic of the L-form of streptococcus was revealed on the ultra-thin sections of both L-form strains.