Anthrax spore germination

In cutaneous and gastrointestinal anthrax, spore germination takes place at or near the inoculation site following uptake by the macrophage or dendritic cell. It is the vegetative form, not the spore, which produces the deadly factors. After transformation to the vegetative bacilli, these bacteria are free to mediate toxicity at the inoculation site in skin and gastrointestinal tract (Beatty et al., 2003). In inhalational... 

The cutaneous infection process initiates as a result of anthrax spores colonizing an abrasion in the skin (Figure 31.3). A small eruption or lesion develops into a painless, black eschar. Eschars usually develop within 2-5 days following exposure. During this stage of infection, low-level spore germination can occur at the primary site of infection, leading to localized edema and necrosis. While this infection often remains localized, some patients experience systemic symptoms. 

Tissue macrophages engulf anthrax spores o by phagocytosis. While many spores will die in the lysosome, others will escape detection inside aixl germinate into vegetative bacilli. 

Huang, C.M., Foster, K.W., DeSilva, T.S., Van Kampen, K.R., Elmets, C.A., Tang, D.C. (2004). Identification of Bacillus anthracis proteins associated with germination and early outgrowth by proteomic profiling of anthrax spores. Proteo-mics 4 2653-61. 

After surviving the initial membrane oxidative burst, the anthrax spores must contend with the acid environment of the phagolysosome to further germinate and multiply. Several pathogens have shown an ability to evade pha-golysosomal activity however, the mechanism by which an rax spores avoid hydrolysis in the phagolysosome is unclear (Guidi-Rontani and Mock, 2002). 

Gastrointestinal Anthrax. Gastrointestinal (GI) anthrax is contracted by germination of ingested spores in the upper or lower GI tract. The GI forms of the disease are generally an upper GI form and a lower GI form. In the upper GI form, oral or esophageal ulcers develop with associated edema, lymphadenopathy, and sepsis. In the lower GI form, partial necrosis of the GI tract can occur with symptoms including bloody diarrhea, acute abdomen, ascites, or sepsis. 

In each case, spore ( 9 germination into mature B. anthracis bacilli takes place in the macrophages at the primary site of infection. In the case of inhalational anthrax, germination occurs later upon arrival at the local lymph node. 

FIGURE 31.3. Spore uptake in cutaneous anthrax disease. The steps involving spore uptake at the primary site of local infection on the skin, germination inside the macrophage, and migration back into lymphatic ducts are illustrated. Illustrations are copyright protected and printed with permission by Alexandre M. Katos. 

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