Streptococcus gordonii Peritonitis in a Patient on CAPD

Abstract

We report the first case of Streptococcus gordonii-related continuous ambulatory peritoneal dialysis (CAPD) peritonitis. He is a 69-year-old man with end-stage renal failure due to chron ic glomerulonephritis who had been put on CAPD for 1 year. He was successfully treated with a 2-week course of cefazolin. This case highlights the emerging threat that S. gordonii can be the source of infection in patients on CAPD.

• Streptococcus gordonii
• peritoneal dialysis
• peritonitis

INTRODUCTION

Streptococcus gordonii is a member of the viridans streptococci (VS) and is a general inhabitant of the buccal cavity, where it is commonly involved in the development of dental caries. It is also one of the strains most often associated with bacterial endocarditis.¹ However, S. gordonii infection has not previously been reported in patients receiving continuous ambulatory peritoneal dialysis (CAPD). Here, we report the first case of S. gordonii-related CAPD peritonitis.

CASE REPORT

A 69-year-old man with end-stage renal failure due to chronic glomerulonephritis had been put on CAPD for 1 year. This time he came back to the dialysis center because of abdominal pain and turbid peritoneal dialysate fluid for 3 days. There was no fever. He had no recent history of invasive dental procedures. The catheter exit site was clean and there was no tunnel infection. The peritoneal fluid was turbid, with a total leukocyte count of 2020 per mm³ (neutrophil count 99%). He was diagnosed to have CAPD peritonitis and empirical therapy of intraperitoneal cefazolin, and cefepime was initiated according to our protocol. Gram-positive cocci were identified on Gram stain examination. After 48 h of incubation, the sheep blood agar isolated a pure growth isolate of scanty growth of Gram-positive cocci in chains, which did not grow on bile esculin or 6.5% salt agars. Identification testing with a Vitek 2 system (BioMerieux, France) showed excellent identification, with a probability of 97.97% for S. gordonii. Antimicrobial testing for this isolate with the disc diffusion method, according to the Clinical and Laboratory Standards Institute criteria for Streptococcus, showed it to be resistant to cotrimoxazole, whereas sensitive to penicillin, ampicillin, erythromycin, clindamycin, and vancomycin. By day 4 of empirical antibiotics, the peritoneal fluid became clear again with leukocyte count in dialysate fluid normalized. Cefepime was stopped when culture and sensitivity results were available. A full course of cefazolin (total 14 days) was completed and he made an uneventful recovery.

S. gordonii was formerly known by the name of Streptococcus sanguis I, a subspecies of the Streptococcus sanguinis subgroup, which in turn is a member of the larger Streptococcus mitis species group. S. gordonii has now been reclassified as a direct subspecies in the S. mitis species group. Other members of the S. mitis species group include S. mitis and Streptococcus oralis, as well as S. sanguinis and now S. gordonii.² Collectively, the subspecies of the S. mitis group, including S. gordonii belong to the heterogeneous VS that are common etiologic agents of subacute infective endocarditis and are capable of causing a variety of pyogenic infections. However, streptococci are generally rare causes of CAPD peritonitis.³ Due to their heterogeneity and their variable abilities to demonstrate hemolysis and react with different Lancefield group antisera, the many species and subspecies of VS are difficult to differentiate by phenotypic traits alone. An oligonucleotide array based on 16S–23S rRNA gene intergenic spacer sequences has hence been developed and described by Chen et al. to identify different species of clinically relevant VS that include Streptococcus anginosus, Streptococcus constellatus, S. gordonii, Streptococcus intermedius, S. mitis, Streptococcus mutans, S. oralis, Streptococcus parasanguinis, Streptococcus salivarius, S. sanguinis, and Streptococcus uberis.⁴

S. gordonii is a commensal bacterium that usually colonizes the human tooth surfaces and is an important member of community that forms dental plaque. This bacterium is known to be involved in the development of dental caries and also considered as a potential causative agent of bacterial endocarditis. To the best of our knowledge, this is the first reported case of S. gordonii-related CAPD peritonitis. In our patient, the exact source of S. gordonii could not be ascertained. However, he had no signs or symptoms suggestive of dental caries or systemic infection, making hematogenous spread unlikely. The route of transmission in this case was probably related to the direct contamination of the connection devices during peritoneal exchange. Two weeks of treatment with cefazolin was effective in eradicating the microorganism, without catheter removal or recurrence.

In conclusion, we highlight the emerging threat that S. gordonii can be the source of infection in patients on CAPD, especially those with poor dental health.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.