Effect of penicillin on ultrastructure, growth and multiplication of Leptospira (Russian)

The effect of single doses of penicillin on cultures of L. icterohaemorrhagiae was studied by prolonged observation of their growth and multiplication. It was found that low doses of penicillin stimulated growth and multiplication, and led to selection of individuals more resistant to penicillin. With the help of definite penicillin doses it was possible to show heterogeneity of the Leptospira populations in culture which was confirmed by differences in ultrastructure and presence of colonies differing by their appearance (smooth and rough) on solid medium. Pure cultures isolated from such colonies acquired resistance to penicillin.