Different inflammatory responses are associated with <it>Ureaplasma parvum</it>-induced UTI and urolith formation

• Main Authors: Brown Mary B, Reinhard Mary, Reyes Leticia
• Format: Article
• Language: English
• Published: BMC 2009-01-01
• Series: BMC Infectious Diseases
• Online Access: http://www.biomedcentral.com/1471-2334/9/9

<p>Abstract</p> <p>Background</p> <p>Epidemiologic studies show a strong association between <it>Ureaplasmas </it>and urogenital tract disease in humans. Since healthy humans can be colonized with <it>Ureaplasmas</it>, its role as a pathogen remains controversial. In order to begin to define the role of the host in disease, we developed a rodent model of urinary tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 10¹, 10³, 10⁵, 10⁷, or 10⁹log CFU of a rat-adapted strain of <it>Ureaplasma parvum</it>.</p> <p>Results</p> <p>Infected animals exhibited two distinct profiles, asymptomatic UTI and UTI complicated with struvite urolithiasis. Inoculum dose of <it>U. parvum </it>affected the incidence of UTI, and 50% to 57% of animals inoculated with ≥ 10⁷CFU of <it>U. parvum </it>remained infected (p < 0.04). However, inoculum dose did not influence immune response to <it>U. parvum</it>. Asymptomatic UTI was characterized by a minimal immune response that was predominantly monocytic and lymphocytic, with limited lesions, and elevated urinary levels of IFN-γ, IL-18 and MCP-1 (P ≤ 0.02). UTI complicated with struvite formation was characterized by an exaggerated immune response that was mostly neutrophilic (P ≤ 0.0001), with lesions that showed extensive uroepithelial hyperplasia (P ≤ 0.0001), and a predominance of IL-1α, IL-1β, and GRO/KC in the urine (P ≤ 0.02). Animals with asymptomatic UTI also had a significantly high rate of kidney infection (P ≤ 0.0005).</p> <p>Conclusion</p> <p>Complications associated with <it>U. parvum </it>infection are primarily dependent upon host-specific factors rather than <it>Ureaplasma </it>microbial load. The immune response in F344 rats is similar to that which occurs in humans with ureaplasmal associated disease. Therefore, this model of infection is a useful tool for elucidating <it>U. parvum</it>-host interactions that confer UTI and disease.</p>