Campylobacter rectus in the Oral Cavity Correlates with Proteinuria in Immunoglobulin A Nephropathy Patients.

Background: Periodontitis-related pathogens, such as Campylobacter or Treponema species, have recently been shown to be associated with immunoglobulin A nephropathy (IgAN). Some strains of Streptococcus mutans, a major pathogen of dental caries, harbour the cnm gene that encodes a collagen-binding protein (Cnm). This has also been demonstrated to be associated with urinary protein levels in IgAN patients.

Objectives: The purpose of the present study was to analyse the association of IgAN with C. rectus, Treponema denticola and cnm-positive S. mutans in the oral cavity of humans.

Methods: The presence of C. rectus, T. denticola and cnm-positive S. mutans strains in saliva samples of 117 IgAN patients and 56 healthy controls was evaluated by PCR, and the subjects' clinical parameters were analysed.

Results: C. rectus was significantly more prevalent in the IgAN group than in the control group (p < 0.05). The C. rectus-positive group was significantly associated with proteinuria in the IgAN group (p < 0.05). In addition, the C. rectus-positive and cnm-positive S. mutans group was shown to be more closely associated with urinary protein levels than the other groups (p < 0.0083).

Conclusion: Our results suggest that harbouring C. rectus in the oral cavity could be associated with proteinuria in IgAN patients.