Emphysematous cystitis due to Streptococcus salivarius infection in a patient with a neurogenic bladder

Streptococcus salivarius (S. salivarius) is an oral commensal bacterium that rarely causes disease. Here, we report a case of emphysematous cystitis due to S. salivarius infection in a patient with a neurogenic bladder. A 56-year-old woman was hospitalized and managed for left putamen hemorrhage. Afterward, she developed poor oral intake. Although the patient was afebrile, laboratory test results suggested an inflammatory response. Urinalysis revealed pyuria and hematuria. Abdominal computed tomography revealed a thickened urinary bladder wall and intraluminal gas. Additionally, she was diagnosed with a neurogenic bladder as she had approximately 200 mL of residual urine. The patient was diagnosed with emphysematous cystitis, and S. salivarius was isolated from urine culture specimens. The patient's condition improved immediately after treatment, which included bladder drainage and administration of appropriate antibiotics. We could not find any report on S. salivarius causing urinary tract infections, such as emphysematous cystitis. Accordingly, we report this case along with a review of the literature.