Biomass colonization and bioconversion of the molecular characterized Oxalobacter formigenes to mitigate calcium oxlate urolithiasis

Calcium oxalate (CaOx) is one of the common causes of kidney stones and accounts for 40 to 50% of all uroliths in cats. Oxalobacter formigenes, an oxalate-degrading intestinal microbiota, has been hypothesized to play a protective role against CaOx urolithiasis due to its capability to degrade oxalate. This study was designed to reveal the association between biomass colonization of O. formigenes and clinical occurrence of CaOx urolithiasis in household tomcats. Fifteen tomcats were allocated into three groups (healthy control (n=5), static chronic kidney disease (static CKD) (n=4), and progressive CKD (n= 6)) based on diagnosis of CaOx urolithiasis and disease progression. Fecal samples were collected from all tomcats, genomic DNA was extracted, and oxc, a gene specific for O. formigenes, was quantified using real-time PCR. Additionally, the clinical association between blood serum urea, creatinine, and relative abundance of oxc gene among different groups was examined. The oxc gene was detected in all cats in various frequency; however, its relative abundance was significantly higher in progressive CKD group compared to static CKD and control groups. In summary, our results suggest a protective role of O. formigenes against calcium oxalate urolithiasis only in static CKD. Further studies are required in a larger group of cats to help illustrate the protective role of O. formigenes in the pathophysiology of calcium oxalate urolithiasis in cats.