cnm-positive Streptococcus mutans is associated with IgA nephropathy: a comparative study among kidney diseases

We previously reported an association between cnm-positive Streptococcus mutans in the oral cavity and IgA nephropathy. However, whether this association is specific to IgA nephropathy among various kidney diseases remains unclear. This study aimed to investigate the presence of cnm-positive S. mutans in patients who underwent a renal biopsy and to evaluate its association with different kidney disease subtypes.

We included 294 patients who underwent a renal biopsy and provided informed consent between May 2017 and March 2024 (renal biopsy group). The healthy control group consisted of 81 individuals with an estimated glomerular filtration rate > 60 mL/min and no proteinuria. Saliva samples were collected from all participants, stored at - 20 °C, and analyzed by polymerase chain reaction to detect S. mutans and cnm-positive S. mutans. Associations between cnm-positive S. mutans and the histopathological diagnosis were subsequently assessed.

The prevalence of cnm-positive S. mutans was significantly higher in the renal biopsy group than in the control group (21.8% vs. 11.1%, p < 0.05). Among kidney disease subtypes in the renal biopsy group, a higher prevalence of cnm-positive S. mutans was observed in patients with lupus nephritis (31.6%), membranous nephropathy (29.2%), and IgA nephropathy (23.6%). However, a logistic regression analysis identified a significant association only between cnm-positive S. mutans and IgA nephropathy (p < 0.05).

This study suggests that cnm-positive S. mutans is significantly associated with IgA nephropathy.