Case report Septic arthritis of the ankle due to Moraxella osloensis L.N. Banks * , N.M. Kurdy, I. Hassan, A.S. Aster Wythenshawe University Teaching Hospital, Manchester M23 9LT, United Kingdom Received 13 December 2006; received in revised form 20 February 2007; accepted 9 March 2007 Abstract We present an unusual case of septic arthritis of the ankle due to Moraxella osloensis. The implications of a diplococcus culture are discussed, including notification of the disease, the suggestion of sexual impropriety and drug-induced side effects for the treating doctors and other contacts. The case is of a 56-year-old man presenting with a past medical history of gout (great hallux) and increasing pain in his ankle. Systemic examination revealed a low-grade pyrexia and lateral malleolar swelling with evidence of an effusion. Initial gram stain revealed a raised WBC. Laboratory evaluation showed a raised CRP, ESR and urate. The patient was commenced on intravenous antibiotics. Initial blood cultures suggested a possibility of Neisseria meningitidis and primary contacts were commenced on rifampicin. The cultures were later confirmed as the rather unusual penicillin sensitive, gram-negative, aerobic Moraxella oseloensis. Antibiotics were discontinued at 6 weeks and the patient discharged at 3 months. The recognition of septic arthritis, obtaining systemic blood cultures, joint aspirates followed by prompt treatment with a suitable antibiotic regime will reduce morbidity and mortality. Recognition of any potential pathogens that may be harmful to health professionals or other close contacts is also of vital importance. # 2007 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. Keywords: Septic arthritis; Ankle; Moraxella osloensis We present an unusual case of septic arthritis of the ankle due to Moraxella osloensis. The implications of a diplococcus culture are discussed, including notification of the disease, the suggestion of sexual impropriety and drug-induced side effects for the treating doctors and other contacts. 1. Case report The case is of a 56-year-old man presenting to the emergency department with increasing pain in his right ankle. He had no preceding history of trauma and was systemically well. He had a past medical history of gout affecting his right hallux, which was quiescent at the time of presentation. Apart from local tenderness over the lateral malleolus, there were no other positive findings and routine radiographs were negative. Repeat examination the follow- ing day showed the patient to be systemically well, normocardic, with a low-grade pyrexia of 37.5 8C. There was no cellulitis or erythema associated with the ankle joint. There was swelling over the lateral malleolus, with minimal tenderness and evidence of an effusion. Dorsiflexion and plantarflexion were limited to 108 each, with pain at the extreme. Three millilitres of yellow, blood-stained fluid was aspirated from the joint. Initial gram stain revealed >10,000 Â 10 6 /l WBC and 4000 Â 10 6 /l RBC, with no crystals or organisms. Laboratory evaluation was as follows: CRP, 30 mg/l (normal range <10 mg/l); ESR, 13 mm/h (1– 12 mm/h); WCC, 8.4 (4–11 Â 10 9 /l); urate, 0.47 mmol/l (<0.42 mmol/l). The provisional working diagnosis was early septic arthritis and the patient was commenced on intra-venous flucloxacillin (1 g, QDS) and benzylpenicillin (1.2 g, QDS). Blood cultures were initially reported as having grown a gram-negative diplococcus, with a strong possibility of Neisseria meningitidis sensitive to penicillin. N. meningitidis is a notifiable disease and medical staff and other close contacts to the patient were advised by the occupational health department to take prophylactic www.elsevier.com/locate/fas Foot and Ankle Surgery 13 (2007) 189–191 * Corresponding author. E-mail address: louisabanks@hotmail.com (L.N. Banks). 1268-7731/$ – see front matter # 2007 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.fas.2007.03.002