The Interaction between Enterobacteriaceae and Calcium Oxalate Deposits

Area of Science:

• Urology
• Microbiology
• Nephrology

Background:

• The role of calcium oxalate (CaOx) crystals in urinary tract infection (UTI) pathogenesis is unclear.
• Investigating CaOx deposits in pediatric urolithiasis and experimental pyelonephritis is crucial.

Purpose of the Study:

• Identify bacteria in pediatric urolithiasis.
• Determine the relevance of CaOx deposits in experimental pyelonephritis using in vitro and in vivo models.

Main Methods:

• Collected pediatric kidney stones and urine for bacterial culture and sequencing.
• Assessed bacterial adhesion to CaOx.
• Induced CaOx deposits in murine kidneys via glyoxalate injection and inoculated with uropathogenic Escherichia coli (E. coli) to model pyelonephritis.

Main Results:

• E. coli (family Enterobacteriaceae) identified in patient stones; Enterobacteriaceae DNA sequenced from stones.
• E. coli selectively aggregated on CaOx monohydrate crystals.
• Mice with glyoxalate and E. coli showed higher bacterial burdens, increased kidney CaOx deposits, and heightened innate immune response.

Conclusions:

• CaOx deposits in a murine model enhance pyelonephritis risk, likely by facilitating bacterial aggregation.
• Co-occurrence of CaOx deposits and E. coli increased CaOx deposit number and renal gene expression of stone matrix proteins.
• Renal CaOx deposits may be a modifiable risk factor for UTIs; bacteria within deposits could contribute to CaOx renal disease.