Coccidioidal septic arthritis: lessons learned from a clinical and laboratory perspective

The Medical Journal of Australia ISSN: 0025729X 18 June 2012 196 11 705-706 ©The Medical Journal of Australia 2012 www.mja.com.au Case reports — lessons from Practice MJA 2012; 196: 705–706 doi: 10.5694/mja11.10533 Coccidioidomycosis (“pseudotu sive fungal infection caused by immitis and C. posadasii). It is acquired in Australia, being end sph re deserts, primarily in the so States, and Mexico. After respirat Imported pathogens are increasingly recognised as potential biosecurity concerns, but may be overlooked when the clinical syndrome and causative organism are unexpected. This case highlights the need to consider an infectious aetiology in an older migrant with a chronic inflammatory monoarthritis. It emphasises the need for good communication between laboratory disciplines, and demonstrates preliminary success with a combined surgical–medical– pathology–pharmacological approach. berculosis”) is an invaCoccidioides species (C. not autochthonously emic to western-hemiuth-west of the United ory inoculation, arthroconidia (hyphal forms) transform into multinucleated spherules, which rupture, propagating new spherules.5 Crucial diagnostic information obtained through the histopathological detection of spherules in this patient (Box 2) was rapidly relayed to the microbiology laboratory. Coccidioides spp are classified as Risk Group 3 pathogens in Australia (as is Bacillus anthracis).6 Analytical work performed on these pathogens must be carried out in a biological safety cabinet in a physical containment level 3 sealed laboratory with negative air pressure.6 As one of the ten most common laboratory-acquired infections,7 with laboratory attack rates exceeding those of natural exposure,8 travel history to an endemic area is crucial information for laboratory staff.3,9 Suspected C. immitis colonies take up to 5 days to manifest with “typical” morphological Clinical record An 81-year-old non-English-speaking Filipino woman with type 2 diabetes mellitus presented with left knee pain and swelling of 18 months’ duration. Her mobility was restricted to less than 2m because of pain. Synovial fluid obtained by needle aspiration during a recent visit to the Philippines had yielded a white cell count of 12200 cells/L (55% polymorphonucleocytes; reference interval [RI] not available) and no bacterial organisms. On her return to Australia, she was referred to an orthopaedic surgeon. Physical examination revealed chronically discharging wounds at previous aspiration sites of the medial and lateral aspects of the knee, which was swollen and tender but with good range of movement. The patient did not have a fever, and her C-reactive protein level was 18 mg/L (RI, < 10 mg/L)]. Magnetic resonance imaging demonstrated florid erosive synovitis, considered most consistent with rheumatoid or seronegative arthritis, although bone oedema was noted, suggesting osteomyelitis (Box 1). Culture of material from the sinuses for bacteria was negative.