Proteus infection pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Pathophysiology
Following transmission, Proteus colonizes the urinary tract of the human host and is capable of evading the human immune.
Colonization
- Proteus is part of the normal human GI tract. Following self-contamination, Proteus accesses the urinary tract through the urethra and uses flagella to ascend in a retrograde manner to the upper urinary tract.
- During the motility process, the production of flagella markedly increases, and the organism changes from a single-cell, rod-shaped form (swimmer) to a multi-cell, elongated-form (swarmer).
- In the bladder, Proteus uses fimbriae and adhesins to bind to mucosal surfaces:
- Mannose-resistant fimbriae (MRF)
- P. mirabilis fimbriae (PMF)
- Ambient temperature fimbiae
- Non-agglutinating fimbiae
- P-like pilus
Evasion of Host Defenses
- There are four mechanisms by which Proteus can use to evade the host defenses.
- Production of an IgA-degrading protease which functions to cleave the secretory IgA.
- Expression of flagellin to synthesize flagella that provides the characteristic swarming motility of Proteus.
- Expression of the MR/P fimbriae
- Production of urease (increases pH) to provide an adequate medium for bacterial growth. Urease production is also associated with stone formation in the kidneys and the bladder.
- Production of hemolysin, a cytotoxin involved in injury of host epithelial cells are known to cause damage to host epithelial cells. As mentioned above, urease can damage host epithelial cells through the formation of stones. Hemolysin damages cells