Peritonitis Due to Streptococcus anginosus in Patients Treated with CAPD: A Report of Two Cases

Editor: Streptococcus anginosus is a member of the Streptococcus anginosus group (SAG), which includes S. anginosus, S. intermedius, and S. constellatus. The SAG pathogens, which are found in the oral cavity, gastrointestinal tract, and urogenital tract (1,2), are the cause of significant infections such as various abdominal or hepatobiliary diseases, abscess formation, and endocarditis (3,4). However, to our knowledge, there is no case report of a S. anginosus peritonitis that developed during continuous ambulatory peritoneal dialysis (CAPD) therapy. We present 2 patients with peritonitis caused by S. anginosus. The first patient was a 74-year-old man with chronic renal failure of 15 years’ duration. He was admitted to our unit with a 2-day history of cloudy dialysate effluent, mild abdominal pain, and fever. His medical history was significant for a marked swelling in the left cervical region that developed 5 days before his admission. This patient had no history of invasive dental procedures or pharyngotonsillitis but he had poor dental health, with six tooth caries. On physical examination, a non-elastic non-tender lymphadenitis in the left cervical region was noted. Ultrasonographic examination of the left cervical region showed lymphadenitis in an area approximately 1.3 cm in diameter. The results of the examinations of other organ systems and the peritoneal catheter were within normal limits. The white blood cell (WBC) count in the peritoneal fluid was 17 900/μL (95% neutrophils). Gram stain of the peritoneal fluid revealed no bacteria. Peritoneal fluid samples that had been inoculated into BACTEC bottles for culture (Becton Dickinson, Franklin Lakes, New Jersey, USA) grew S. anginosus, which was identified by conventional methods and automated BBL Crystal (Becton Dickinson) identification kits. The second patient was a 58-year-old woman with chronic renal failure of 11 years’ duration. She had been receiving CAPD therapy for 4 years when she was admitted to our hospital with moderate abdominal pain, vomiting, nausea, and cloudy dialysate ef fluent. Her symptoms had developed about 24 hours before her admission. On physical examination, she had poor dental health; examinations of other organ systems and the peritoneal catheter were within normal limits. The WBC count in the peritoneal fluid was 6000/μL (85% neutrophils). Gram stain of the peritoneal fluid revealed no bacteria. Peritoneal fluid samples that had been inoculated into BACTEC bottles for culture grew S. anginosus. After dialysate aspirate specimens were taken for culture, both patients received ampicillin–sulbactam 1.5 g twice daily and ciprofloxacin 200 mg twice daily intravenously. This therapy was continued for 14 days. In both cases, peritoneal fluid WBC count decreased to normal limits during the following week. Both patients are well and still receiving CAPD at time of writing. The SAG group is a member of the Streptococcus viridans group, which was previously termed the “Streptococcus milleri group.” These gram-positive cocci are distinguished by their microaerophilic growth requirements, their formation of colonies <0.5 mm in diameter, and the presence of a distinct caramel-like odor that they release when cultured (1). These organisms are commensals of the oral cavity, gastrointestinal tract, and urogenital tract. SAG organisms cause pyogenic invasive infections and have been found in dental, neck, liver, brain, pelvic, and subcutaneous tissue abscesses, in cases of bacteremia with endocarditis, and in patients with thoracic empyema (1,3,5). People with underlying medical conditions such as cirrhosis, diabetes mellitus, or a malignancy, are predisposed to invasive infections with SAG (3). Pathogens in the S. anginosus group are often associated with abscesses (3); however, ultrasonographic examination of the abdomen in Patients 1 and 2 and of the neck in Patient 1 revealed no abscess. These patients had no history of invasive dental procedures or pharyngotonsillitis, but they had poor dental health. On the basis of our findings, we concluded that the infection in both patients was caused by the direct inoculation of bacteria through the peritoneal catheter and into the peritoneal fluid. Because we could not isolate the organism in blood samples, we assumed that transmission had resulted from direct inoculation rather than from hematogenous spread. That hypothesis was supported by findings such as the patients’ poor dental health and lower socioeconomic status. They may have infected themselves during peritoneal exchange. We suggest that Streptococcus anginosus be kept in mind as a cause of CAPD peritonitis, particularly in patients with cervical lymphadenitis or poor dental health. Microbiologic procedures should be performed with care to isolate this fragile micro-organism. Also, we think that CAPD patients should be informed of and under regular control of a dentist for dental hygiene.