Do Infection-Associated Stone Subtypes Behave the Same Clinically? A Retrospective Bicenter Study.

Area of Science:

• Urology
• Nephrology
• Infectious Diseases

Background:

• Infection-associated renal stones, commonly magnesium-ammonium-phosphate (MAP) and carbonate apatite (CA), have unknown clinical implications.
• Understanding differences between MAP and CA stones is crucial for patient management.

Purpose of the Study:

• To compare clinical, microbiologic, and metabolic characteristics of patients with MAP versus CA infection stones.
• To identify potential differences in risk factors and outcomes between these stone types.

Main Methods:

• Retrospective review of 154 patients (79 MAP, 75 CA) from two centers (US and Israel) undergoing stone removal (2012-2020).
• Analysis included demographics, medical history, postoperative fever, stone/urinary microbiology, and 24-hour urine studies.

Main Results:

• Both MAP and CA stone formers showed female predominance and similar demographics/comorbidities.
• Hypercalciuria was prevalent in both groups (38% MAP, 32% CA).
• MAP stones were associated with more postoperative fever (14.7% vs 3.8%) and higher rates of gram-negative bacteria in stone cultures.

Conclusions:

• MAP and CA stone formers share demographic traits, with a notable female predominance.
• MAP stones may increase the risk of postoperative fever, potentially due to increased gram-negative bacterial presence.
• Hypercalciuria is common in both stone types, though its clinical significance requires further investigation.