Role of genital mycoplasmata and other bacteria in urolithiasis

Rat strains differ in susceptibility to Ureaplasma parvum-induced urinary tract infection and struvite stone formation

Individuals with struvite uroliths are susceptible to recurrent urinary tract infections (UTI), sepsis, and renal disease. Unfortunately, little is known about the host-specific factors that predispose to this disease. In order to develop a rodent model that can address this problem, we inoculated female Fischer 344 (F344), Lewis (LEW), Sprague-Dawley (SD), and Wistar (WIS) rats with a host-adapted strain of Ureaplasma parvum. Animals were necropsied at 2 weeks postinoculation; 100% of F344, 42% of SD, 10% of LEW, and 10% of WIS rats remained infected. Severe bladder lesions and struvite calculi were seen in 64% of F344 rats; in other rat strains, bladder lesions were mild or absent. F344 rats with struvite uroliths had the highest urinary levels of proinflammatory cytokines, such as GRO/KC, interleukin-1alpha (IL-1alpha), and IL-1beta. F344 rats without struvite stones at necropsy had milder bladder lesions and significantly lower urinary levels of proinflammatory cytokines but a more prominent inflammatory response than did other rat strains. Based on our results, struvite stone formation is linked to a robust inflammatory response that does not resolve UTI but instead promotes damage to surrounding tissues.

[Infective lithiasis]

"Infection Lithiasis" refers to calculi that occur with persistent urinary tract infection. Stones composed of magnesium ammonium phosphate (struvite) and carbonate apatite, called "triple phosphate" stones, are the more common type of infection lithiasis. These stones are also called "staghorn" calculi because they may grow rapidly and fill the entire collecting system. They form during urinary infection with urea-splitting micro-organism. They may originate de novo or complicate a lithiasis when pre-existing stones are colonized with urea-splitting bacteria. They represent about 2-3% of stones referred for laboratory analysis. This article reviews the epidemiology, pathogenesis, clinical features, and management of struvite stones. A singular pathologic entity recently described, called "encrusted cystitis or encrusted pyelitis", mainly caused by Corynebacterium urealyticum is also review. Infection lithiases caused by non-urease-producing bacteria may also occur and are examined in this article. Finally, the controversial role of nanobacteria in nephrolithiasis is discussed.