Struvite Urolithiasis and Chronic Urinary Tract Infection in a Murine Model of Urinary Diversion

Abstract

OBJECTIVES To characterize the clinical course following cutaneous vesicostomy (CV) in megabladder (mgb−/−) mice with functional urinary bladder obstruction. MATERIALS AND METHODS Forty-five mgb−/− males underwent CV at a median age of 25 days. The 34 animals that survived longer than 3 days after CV were evaluated by serial observation and renal ultrasound. Moribund animals were euthanized. Urinary bladders and kidneys were analyzed by histopathology, and urine biochemical studies were performed. RESULTS At a median of 11 weeks after CV, 35% (12/34) of mgb−/− males became moribund with pelvic masses, which were identified as bladder stones at necropsy. Urine pH was alkaline and microscopy demonstrated struvite crystals. Urine contained Gram-positive cocci, while urine cultures were polymicrobial. Stone composition was chiefly struvite (88–94%) admixed with calcium phosphate. In 40% (2/5) of cases, retained intravesical polypropylene suture was identified as the presumed nidus. No stones were detected in over 100 males prior to CV or in 25 cases when CV was performed using polydioxanone suture. Kidneys from 33% (4/12) of animals with bladder stones contained staghorn calculi. Histopathology from animals with struvite stones demonstrated active cystitis, pyelitis, and chronic pyelonephritis. CONCLUSIONS These findings attest to the importance of the nidus in lithogenesis and provide a novel murine model for struvite urolithiasis and chronic infection of the diverted urinary tract.

Bacteriological evaluation of the non-struvite nephrolithiasis and its association with urinary tract infections

“…This made us consider that all the CoNS except for the one previously described were external contaminants of the calculi. Nevertheless, there are few studies which found CoNS as real etiological agents in UTI and calculi, especially when prosthetic devices were inserted (25,26). Similar to CoNS, Chryseobacterium indologenes and Leuconostoc pseudomesenteroides were identified only after enrichment, so we also interpreted them as external contaminants.…”

Etiopatogenia Da Urolitíase Em Cães

“…A eliminação incompleta de urina predispõe a infecções urinárias e à formação e precipitação de cristais (TAN et al, 2013;BECKNELL et al, 2013). A atonia de bexiga, o divertículo vesical e divertículos caliceais predispõem à enfermidade devido à estase urinária (OSBORNE et al, 1995;TAN et al, 2013;BECKNELL et al, 2013).…”

“…A ureia é um produto do catabolismo dos aminoácidos. Quando hidrolisada pela urease produz grandes quantidades de íons de amônio e carbonato, alcalinizando a urina progressivamente, o que reduz a solubilidade de estruvita e fosfato de cálcio, favorecendo a precipitação (OSBORNE et al, 1995;ULRICH et al, 2008;BECKNELL et al, 2013). Além de ser fator de predisposição à urolitíase, a infecção bacteriana também pode ocorrer secundariamente ao problema (GATORIA et al, 2006;KOEHLER et al, 2008).…”

“…Nesse caso, a infecção pode ocorrer associada a qualquer tipo de urólito e as bactérias envolvidas podem ou não ser produtoras de urease (GATORIA et al, 2006). A estase urinária, independente da causa, predispõe ao desenvolvimento de infecções urinárias e a formações de urólitos (BECKNELL et al, 2013).…”

“…As bactérias podem também causar degradação de citrato na urina, resultando em hipocitratúria. O citrato é um importante inibidor de deposição de fosfato (BECKNELL et al, 2013). Para que ocorra a deposição de cristais de fosfato de cálcio em cálculos de estruvita é necessária hipercalciúria concomitante .…”