title: Atypical behaviour and survival of Streptococcus pyogenes L forms during intraperitoneal infection in rats.
abstract: Groups of rats were injected intraperitoneally with cell wall-deficient (L) forms of Streptococcus pyogenes, with their parental (S) forms, as well as with a combined inoculum of both forms (S+L). Peritoneal exudate samples were harvested on days 1, 3, 7, 15 and 30 after challenge and were investigated by microbiological, electron microscopic, cytometric and biochemical methods. Parental S forms were isolated from peritoneal exudate samples up to day 15 post infection, while L form cultures were isolated until the end of the examined interval. Electron microscopic examination revealed continuous adhesion of L forms on the macrophage surface as well as intracellular persistence inside them. It was demonstrated that the intraperitoneal inflammatory response to L form infection was higher than to the other infections and the monocyte-macrophage populations were predominant. The established atypical behaviour and long survival of S. pyogenes L forms in the rat's peritoneum could explain some of the mechanisms of the pathogens' persistence as well as the reasons for chronic streptococcal infections.
authors.affiliation: Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. 26, 1113, Sofia, Bulgaria. michail@bas.bg
authors.forename: L
authors.initials: L
authors.lastname: Michailova
authors.forename: N
authors.initials: N
authors.lastname: Markova
authors.forename: T
authors.initials: T
authors.lastname: Radoucheva
authors.forename: S
authors.initials: S
authors.lastname: Stoitsova
authors.forename: V
authors.initials: V
authors.lastname: Kussovski
authors.forename: M
authors.initials: M
authors.lastname: Jordanova
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D005260:Female; D007740:L Forms / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000382:microbiology; D008297:Male; D008854:Microscopy, Electron; D010529:Peritoneal Cavity / Q000166:cytology / Q000382:microbiology*; D010538:Peritonitis / Q000276:immunology / Q000382:microbiology*; D010587:Phagocytosis; D051381:Rats; D017208:Rats, Wistar; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000502:physiology*