title: In vivo germination of Bacillus anthracis spores during murine cutaneous infection.
abstract: BACKGROUND
  Germination is a key step for successful Bacillus anthracis colonization and systemic dissemination. Few data are available on spore germination in vivo, and the necessity of spore and host cell interactions to initiate germination is unclear.
  
  
  METHODS
  To investigate the early interactions between B. anthracis spores and cutaneous tissue, spores were inoculated in an intraperitoneal cell-free device in guinea pigs or into the pinna of mice. Germination and bacterial growth were analyzed through colony-forming unit enumeration and electron microscopy.
  
  
  RESULTS
  In the guinea pig model, germination occurred in vivo in the absence of cell contact. Similarly, in the mouse ear, germination started within 15 minutes after inoculation, and germinating spores were found in the absence of surrounding cells. Germination was not observed in macrophage-rich draining lymph nodes, liver, and spleen. Edema and lethal toxin production were not required for germination, as a toxin-deficient strain was as effective as a Sterne-like strain. B. anthracis growth was locally controlled for 6 hours.
  
  
  CONCLUSIONS
  Spore germination involving no cell interactions can occur in vivo, suggesting that diffusible germinants or other signals appear sufficient. Different host tissues display drastic differences in germination-triggering capacity. Initial control of bacterial growth suggests a therapeutic means to exploit host innate defenses to hinder B. anthracis colonization.
authors.affiliation: Toxines et Pathogénie Bactériennes, Pathogénie des Toxi-Infections Bactériennes, Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Corre
authors.forename: Alejandro
authors.initials: A
authors.lastname: Piris-Gimenez
authors.forename: Marie
authors.initials: M
authors.lastname: Moya-Nilges
authors.forename: Gregory
authors.initials: G
authors.lastname: Jouvion
authors.forename: Agnes
authors.initials: A
authors.lastname: Fouet
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Glomski
authors.forename: Michèle
authors.initials: M
authors.lastname: Mock
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Sirard
authors.forename: Pierre L
authors.initials: PL
authors.lastname: Goossens
mesh_terms: D000818:Animals; D000881:Anthrax / Q000382:microbiology*; D001408:Bacillus anthracis / Q000254:growth & development* / Q000648:ultrastructure; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D054884:Host-Pathogen Interactions; D008099:Liver / Q000382:microbiology; D008221:Lymphoid Tissue / Q000382:microbiology; D051379:Mice; D017192:Skin Diseases, Bacterial / Q000382:microbiology*; D013154:Spleen / Q000382:microbiology; D013171:Spores, Bacterial / Q000254:growth & development* / Q000648:ultrastructure