Streptococcus mitis Peritonitis in a Peritoneal Dialysis Patient: A Case Report Highlighting the Importance of Dental Hygiene.

Viridans-group streptococci, including the Streptococcus mitis/oralis subgroup, can cause peritoneal dialysis (PD)-related peritonitis. The link between dental pathology and PD-related peritonitis remains to be fully elucidated. We report a case of an 83-year-old man undergoing nocturnal intermittent PD due to kidney failure from diabetic nephropathy who developed S. mitis peritonitis and septicemia traced back to a periodontal abscess. Despite having no prior history of peritonitis and maintaining good nutritional status, the patient presented with generalized abdominal pain and a low-grade fever. The initial treatment included intraperitoneal antibiotics. Root cause analysis identified multiple periodontitis and dental abscesses as the primary source of infection, confirmed by DNA sequencing of cultures from the abscesses and blood, which matched S. mitis. This case highlights the critical role of oral flora in causing invasive diseases in immunocompromised individuals, including PD patients, and illustrates how dental infections can lead to PD-related peritonitis through hematogenous spread. Our case also stresses the importance of meticulous dental care and regular dental examinations to prevent such infections in PD patients.