Simultaneous Presence of <b><i>Campylobacter rectus</i></b> and <b><i>Cnm</i></b>-Positive <b><i>Streptococcus mutans</i></b> in the Oral Cavity Is Associated with Renal Dysfunction in IgA Nephropathy Patients: 5-Year Follow-Up Analysis

Abstract

<b><i>Background:</i></b> The simultaneous presence of <i>Streptococcus mutans</i> expressing the Cnm protein encoded by <i>cnm</i> (i.e., <i>cnm</i>-positive <i>S. mutans</i>) and <i>Campylobacter rectus</i> in the oral cavity has been associated with proteinuria in patients with IgA nephropathy (IgAN). <b><i>Objectives:</i></b> The present study evaluated the relationship between renal function and oral bacteria in patients with IgAN over 5 years of follow-up. <b><i>Methods:</i></b> The presence of <i>C. rectus</i> and <i>cnm</i>-positive <i>S. mutans</i> in saliva samples of 117 patients with IgAN was initially evaluated by polymerase chain reaction. Patients were then divided into four groups according to the results of <i>C. rectus</i> and <i>cnm</i>-positive <i>S. mutans</i> detection: group A: <i>C. rectus</i> (−), <i>cnm</i>-positive <i>S. mutans</i> (−); group B: <i>C. rectus</i> (+), <i>cnm</i>-positive <i>S. mutans</i> (−); group C: <i>C. rectus</i> (−), <i>cnm</i>-positive <i>S. mutans</i> (+); and group D: <i>C. rectus</i> (+), <i>cnm</i>-positive <i>S. mutans</i> (+). Clinical characteristics were prospectively followed for 5 years. <b><i>Results:</i></b> Serum creatinine levels were significantly higher in group D than in group A over 5 years of follow-up. Additionally, the proportion of patients with an estimated glomerular filtration rate &#x3c;45 mL/min increased over time; it was significantly greater in group D than in group A over 5 years of follow-up. <b><i>Conclusion:</i></b> These results suggest that the simultaneous presence of <i>C. rectus</i> and <i>cnm</i>-positive <i>S. mutans</i> in the oral cavity is associated with renal dysfunction in IgAN patients.