Tsukamurella conjunctivitidis peritonitis diagnosed by 16S rRNA gene sequencing in a patient undergoing peritoneal dialysis.

Peritoneal dialysis (PD)-associated peritonitis remains a serious and life-threatening complication in patients undergoing PD. Majority of peritonitis cases are caused by bacteria, with coagulase-negative Staphylococcus being the most common cause. Tsukamurella species are obligate aerobic gram-positive bacilli found in various environments; however, peritonitis caused by Tsukamurella species in association with PD is rare, with few reports of infections caused by T. conjunctivitidis, including PD-associated peritonitis. We describe a rare case of peritonitis caused by T. conjunctivitidis in a patient undergoing PD. A 62-year-old man undergoing PD was referred to our hospital for fever and abdominal pain lasting for 4 days and was diagnosed with PD-associated peritonitis based on abdominal pain, cloudy effluent, elevated white blood cell count in the peritoneal fluid, and presence of gram-positive rods in the effluent culture. Yellow-grayish, dry, membrane-like colonies were observed on a blood agar plate. The isolated strain was identified as T. conjunctivitidis through 16S rRNA gene sequencing. Because the PD-associated peritonitis was refractory to antibiotics, the PD catheter was removed, and the patient was switched to hemodialysis on day 21 of admission. Clinicians should consider peritonitis caused by T. conjunctivitidis as a differential diagnosis in cases where diagnosis using routine examination is challenging. Notably, 16S rRNA gene sequencing is a useful diagnostic tool for identifying T. conjunctivitidis. Further analyses of similar cases are required to understand the characteristics of such infections and establish adequate diagnostic methods and treatment regimens.