title: The influence of penicillin on growth and morphology of Streptococcus pyogenes in vivo.
abstract: The influence of penicillin (pc) on the growth, phagocytosis and killing of Streptococcus pyogenes was studied for an M protein positive (M+) and an M protein negative (M-) strain in vivo as well as in vitro. In vivo studies were based on a tissue cage model and the analyses were performed by CFU determinations and electron microscopic investigations. The M- strain was easily phagocytized with and without pc, but killing only occurred after pc treatment and thus the number of viable bacteria rapidly decreased under the influence of pc. M+ streptococci were not reduced in numbers by pc-treatment in vivo, but morphological changes and at high pc concentrations, phagocytosis could be seen. When this strain (M+) was cultivated in the absence of pc, the phagocytic cells were totally destroyed - a reaction that was prevented by penicillin. Variations in surface morphology of the two strains seem to influence the differences in sensitivity to penicillin, phagocytosis and killing.
mesh_terms: D000818:Animals; D001433:Bacteriolysis; D002473:Cell Wall / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D009504:Neutrophils / Q000382:microbiology / Q000502:physiology*; D010400:Penicillin G / Q000494:pharmacology*; D010587:Phagocytosis; D011817:Rabbits; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D010400:Penicillin G