LAUSR

Dear Editor, Approximately 10–25% of all peritoneal dialysis (PD)-related peritonitis cases are by Streptococcus species, of which the most common is Streptococcus (S.) viridans (1,2). S. vestibularis is a member of the salivarius group of streptococci (Lancefield group F). A 58-year-old female with end stage renal disease secondary to nephrolithiasis who was on automated PD for 41 months, was admitted to our hospital with abdominal pain, vomiting and a cloudy peritoneal effluent in July 2014. During her physical examination, her body temperature was 37.2°C, blood pressure was 135/80 mm Hg and heart rate was 76 bpm. She had poor oropharyngeal/dental health and abdominal tenderness. No signs of infection around the exit site and catheter tunnel were observed. Laboratory tests results are listed in Table 1. She was diagnosed with PD-related peritonitis. Peritoneal effluent and blood cultures for aerobic bacteria, anaerobic bacteria, fungi and mycobacteriae were taken, and 1 g/day/intraperitoneal (IP) and 4 g day/IP ampicillin-sulbactam were empirically initiated. On the second day of treatment, the abdominal pain and cloudy PD effluent resolved. On the third day of treatment, S. vestibularis was identified in the peritoneal effluent culture, which was sensitive for amoxicillin, vancomycin, penicillin G, clindamycin and chloramphenicol. Treatment with combined IP ampicillin-sulbactam and ceftazidime was continued for 14 days and resulted in total cure. Streptococcus vestibularis was described as a new microorganism by Whiley et al. in 1988, and it was first isolated from the vestibular mucosa of the human oral cavity (3). It is a Gram-positive, alpha hemolytic, catalase-negative, non motile, 1 μm diameter facultative anaerobe organism and that grows in chains. It produces urease and hydrogen peroxide. It has been uncommonly associated with human diseases including meningitis, prosthetic and native valve endocarditis, dental infections, bacteremia and septicemia in immunosuppressed organisms (4). S. vestibularis is susceptible to vancomycin and resistant to optochin. In the study by Doyuk et al., treatment was initiated with 2 g day intravenous ceftriaxone and 1 mg/kg tid gentamicin, and was switched to 500 mg bid vancomycin with a good clinical response (4). Infections are likely attributable to hematogenous spread from dental procedures or transluminal contaminationwithoral flora.Considering thepoordental hygiene in our patient, we suggest that our casewas related to contaminationoriginating from theoral cavity. Despite evidence that streptococcal peritonitis cases in general may have a lower mortality rate and less catheter loss than peritonitis cases caused by other Grampositive bacteria, some studies have reported that S. viridans peritonitis may have a higher rate of recurrence and slower response to treatment than peritonitis cases caused by other Streptococcus spp. (1,2). Our patient’s response to treatment was excellent, with no eventual catheter loss and no relapse. Although S. vestibularis is a very rare cause of PDrelated peritonitis, until now, undefined types of Streptococcus spp. might have been the cause of some PD-related peritonitis cases. Some of them may be have been caused by S. vestibularis, however, ours is the first published case on PD-related peritonitis. TABLE 1. Laboratory Tests