P039 Septic arthritis caused by Mycoplasma hominis in a patient with systemic lupus erythematosus. (23rd April 2022)

• Record Type: Journal Article
• Authors: Hum, Ryan M; Iftikhar, Hajira; Tang, Elaine Y; Bruce, Ian; Ho, Pauline
• Is Part Of: Rheumatology. Volume 61(2022)Supplement 1
• Publication Date: 2022-04-23
• Subjects: Rheumatism -- Periodicals; Rheumatology -- Periodicals; 616.723005
• DOI: 10.1093/rheumatology/keac133.038
• Languages: English
• ISSNs: 1462-0324

Abstract

Abstract: Background/Aims: Mycoplasma hominis is a commensal bacterium of the genitourinary tract which can be associated with infection in immunocompromised patients. Colonisation with M. hominis has been associated with reactive arthritis and septic arthritis. We describe a case of M. Hominis septic arthritis in a patient with SLE on maintenance immunosuppression. Methods: A 27-year-old woman presented with a 2-week history of a swollen left elbow and fatigue which affected her ability to work. Otherwise, she was systemically well and afebrile. She had an established diagnosis of SLE since she was aged 8 years, and her SLE had included mucocutaneous, central nervous system, renal involvement, and haemolytic anaemia. Her SLE was controlled on azathioprine, hydroxychloroquine, and prednisolone 5mg daily. Clinical examination revealed a mildly warm, non-erythematous, tender and swollen left elbow with a 40° flexion deformity. Initial investigations showed raised CRP 41mg/L and ESR 32mm/hr. White blood cell and platelet count were normal. Procalcitonin was insignificant at < 0.1ng/mL. Complements and urine analysis were normal, and dsDNA was negative. X-ray of the left elbow showed joint effusion. Ultrasound revealed active synovitis, subcutaneous oedema and purulent material in the joint. The fluid aspirate was straw coloured. Microscopy showed inflammatory cell count of 4230 white blood cells/mm, with 91% neutrophils. She was treated as probable septic arthritis with intravenous (IV) flucloxacillin. After 48 hours on IV antibiotics, her CRP remained elevated, and she developed pyrexia. Blood and joint fluid cultures were negative. MRI scan confirmed active synovitis with features suggesting joint infection. On discussion with microbiology, oral doxycycline was added on day 3 to cover possible atypical organisms. After a further 4 days the swelling, range of movement, and pain in her elbow had significantly improved. She was discharged home with oral flucloxacillin and doxycycline. On day 16 M. hominis was identified from the Bacterial Identification Services Colindale, by partial sequencing of 16s rDNA from the joint aspirate. She was therefore advised to continue with oral doxycycline for a total of 6 weeks. Results: After treatment, her CRP, ESR and range of movement returned to normal. Conclusion: This case highlights the potential pathogenicity of M. hominis in immunocompromised patients. A literature review found 35 published case reports of septic arthritis by M. hominis, with two occurring in patients with SLE. Approximately 70% of the affected cases were in immunocompromised patients who had a poor response to empirical antibiotic therapy. However, identification of M. hominis on joint aspiration and subsequent treatment with appropriate antibiotics resulted in good outcomes for all published cases. Disclosure: R.M. Hum: None. H. Iftikhar: None. E.Y. Tang: None. I. Bruce: None. P. Ho: None.