Stappia aquimarina sp. nov., isolated from seawater

A case of Stappia indica-induced relapsing peritonitis confirmed by 16S ribosomal RNA gene sequencing analysis in a patient undergoing continuous ambulatory peritoneal dialysis

A 69-year-old woman with 26-year history of systemic lupus erythematosus and 4-year history of peritoneal dialysis was hospitalized for treatment of bacterial peritonitis. On admission, peritoneal dialysate was collected and subjected to bacterial culture. Cell count in the cloudy peritoneal dialysate was 4194/μL, and Gram-negative bacilli were detected. Vancomycin (1 g/day) and ceftazidime (1 g/day) were administered intraperitoneally, which resulted in rapid decrease in cell count in the peritoneal dialysate. However, on the 7th hospital day, peritonitis relapsed with abdominal pain and cloudy dialysate. 16S ribosomal RNA gene sequencing analysis identified Stappia indica sp. as the causative bacteria. Although treatment with 1 g/day meropenem for an additional 3 weeks was effective, bacterial peritonitis relapsed 7 days after its discontinuation. Because biofilm formation was suspected, the peritoneal catheter was removed, and she was transferred to maintenance hemodialysis. After removal of the peritoneal catheter, bacterial peritonitis never relapsed. Stappia indica was initially discovered in the deep seawater of the Indian Ocean. The bacterium is rod-shaped, Gram-negative, and oxidase- and catalase-positive. There have been no reports on the clinical effects of genus Stappia. Given the frequent relapse in the present case, Stappia indica sp. may easily form biofilms and are likely resistant to antibiotics. Timely peritoneal catheter removal may be required in some cases of bacterial peritonitis as in the present case. Further case reports are required to further elucidate the clinical effects of Stappia indica on humans.