Williamsia muralis is an environmental bacterium first detected in 1999. We present a case of facial cellulitis and bacteremia caused by W. muralis following hematopoietic cell transplantation (HCT). Case presentation: A 10-year-old Japanese boy presented with fever and the left cheek swelling 8 days after HCT for the treatment of Fanconi anemia. Gram-positive, rod-shaped bacteria were isolated from the blood cultures after five day’s incubation. The 16S ribosomal RNA sequencing but not mass spectrometry identified the strain of W. muralis (1,414 bp, %ID: 100%). The phlegmon did not respond to antimicrobial therapy but remitted with defervescence after a successful engraftment with teicoplanin and meropenem therapy on day 16 after HCT. The same strain was isolated from the cultured tip of central venous catheter that was later removed to control recurrent bacteremia. The isolated infection with W. muralis has been reported in two elderly patients with surgical intervention. The first case of W. muralis bacteremia was determined to arise from the catheter-related bloodstream infection after HCT. Conclusion: W. muralis bacteremia developed in an immunocompromised child. Introduction of artificial objects into the body raises a risk of rare infection with the slowly growing environmental bacteria.

No abstract