Penicillin-Induced Unstable Intracellular Formation of Spheroplasts by Rickettsiae

• Published in: The Journal of infectious diseases 1982-08, Vol.146 (2), p.147-158
• Main Authors: Wisseman, C. L., Silverman, D. J., Waddell, A., Brown, D. T.
• Format: Article
• Language: English
• Subjects: Animals; Antimicrobial Agents and Therapeutics; Cell culture techniques; Cell growth; Cell Membrane - ultrastructure; Cell Wall - ultrastructure; Cells, Cultured; Chick Embryo; Cultured cells; Dose-Response Relationship, Drug; Embryonic cells; Embryos; Kinetics; Orientia tsutsugamushi - drug effects; Penicillin; Penicillin G - pharmacology; Rickettsia; Rickettsia - cytology; Rickettsia - drug effects; Rickettsia prowazekii; Rickettsia prowazekii - cytology; Rickettsia prowazekii - drug effects; Rickettsia rickettsii - drug effects; Spheroplasts; Spheroplasts - drug effects; Yolk sac
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/146.2.147

Penicillin G (≥20 µg/ml) is rapidly rickettsiacidal for intracellular Rickettsia prowazekii. Light and electron microscopic examinations revealed that penicillin G in culture medium induced a predictable transformation into typical enlarging spheroplasts deficient in the internal, putative peptidoglycan layer of the outer membrane. Under certain conditions, spheroplasts ruptured to discharge contents into host cell cytoplasm and to leave empty shells of defective outer membrane and diffuse amorphous intracytoplasmic antigen. Host cell destruction often accompanied spheroplast rupture. Penicillin G (100 µg/ml) caused similar spheroplast formation by Rickettsia rickettsii, but 1,000 µg/ml caused neither growth inhibition nor spheroplast formation in Rickettsia tsutsugamushi. The clinical and epidemiological significance of a practical rickettsiacidal drug for the treatment of louse-borne typhus fever is discussed. Practical pharmacologic considerations preclude the use of penicillin for the treatment of typhus or spotted fever.