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Mycoplasma hominis septic arthritis in a patient with hypogammaglobinaemia and rheumatoid arthritis
  1. Naila Bozo1,
  2. Christen Ravn2,
  3. Ulrik Stenz Justesen3 and
  4. Line Dahlerup Rasmussen1
  1. 1Department of Infectious Diseases, Odense University Hospital, Odense, Fyn, Denmark
  2. 2Department of Orthopedic Surgery, Odense University Hospital, Odense, Fyn, Denmark
  3. 3Department of Clinical Microbiology, Odense University Hospital, Odense, Fyn, Denmark
  1. Correspondence to Dr Naila Bozo; naila.jajan.bozo{at}


We describe the case of Mycoplasma hominis septic arthritis in a 58-year-old woman with a history of rheumatoid arthritis and ulcerative colitis on immunosuppressive therapy with rituximab. Treatment with anti-CD20 antibodies (eg, rituximab) leads to an immediate depletion of B cells and hence risk of reductions in immunoglobulins and increased risk of infections. This effect may last long after drug cessation. M. hominis is commensal to the genitourinary tract in sexually active adults. Extragenital M. hominis infections including septic arthritis are rare, but hypogammaglobulinaemia is a predisposing factor. As M. hominis requires extended culture, special media or PCR analysis, it is not tested routinely, which in many cases delays diagnosis and correct treatment. In our case, a diagnosis of M. hominis septic arthritis was made after 9 weeks by PCR analysis and culture of joint fluid. The patient responded well to an 8-week treatment course of moxifloxacin and doxycycline.

  • bone and joint infections
  • drugs: infectious diseases
  • immunology

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  • Contributors NB and LDR described the course of the patient’s admission, the various examinations and diagnosis. They reviewed articles relevant to the themes of the case report, Mycoplasma hominis and immunosuppression after treatment with rituximab and composed the discussion paragraph. CR and USJ contributed with vital intellectual feedback on each their expert field, orthopedic infections and microbiology, respectively.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.