To analyze the relationship between nanobacterial infection and the risk factors for stone formation in patients with kidney stones.

A total of 1210 patients with unilateral kidney stones treated at our hospital from January 2016 to February 2019 were recruited in this study. Urine nanobacteria were detected, and the patients were divided into three groups according to the count of nanobacteria: group 1 (0/field), group 2 (1-2/field), and group 3 (≥3/field). 24-hour urine was collected to detect the risk factors for stone formation. Urine calcium, oxalic acid, uric acid, citric acid, and magnesium concentrations were compared between groups.

The urinary calcium concentration in groups 1-3 was (74.959±21.664), (94.354±28.579), and (92.998±23.26) mg/24 h, respectively, and it was significantly higher in group 2 or 3 than in group 1 (P=0.021 and P=0.015, respectively). In groups 1-3, the concentration of magnesium was (69.349±22.086), (68.645±26.699), and (65.887±21.126) mg/24 h, the concentration of citric acid was (224.512±102.675), (228.283±88.409), and (234.905±95.226) mg/24 h, the concentration of oxalic acid was (36.714±11.131), (38.735±12.416), and (37.561±15.182) mg/24 h, and the concentration of uric acid was (35.691±11.891), (37.958±15.889), and (36.902±13.606) mg/24 h, respectively, and there was no significant difference among the three groups with regard to magnesium, citric acid, oxalic acid, and uric acid concentrations (P>0.05 for all).

Nanobacterial infection is closely associated with the risk factors for stone formation in patients with kidney stones. Nanobacterial infection increases the risk of stone formation by increasing urinary calcium concentration.