Helicobacter cinaedi knee infection after arthroscopy in an immunocompetent patient.

An otherwise healthy 36-year-old man was hospitalised due to a traumatic tear of the meniscus in the left knee. An arthroscopy was performed and his meniscus was partially resected. Thirty days later, he was rehospitalised with arthritis in the left knee and cellulitis on the left tibia. Helicobacter cinaedi was isolated from the synovial fluid, which was incubated in a BACTEC Paediatric bottle. The patient was treated with oral rifampicin and moxifloxacin for 6 weeks with good clinical response without relapse. The source of the infection was not found. The case emphasises the importance of incubating the synovial fluid in a rich medium such as a BACTEC Peds Plus/F bottle. Physicians and microbiologists should be aware of H. cinaedi as a human pathogen causing a range of disease manifestations, including infective arthritis and cellulitis, particularly if symptoms evolve in the weeks following a surgical procedure.