A not so innocuous playground fall: lymphocutaneous nocardiosis in an immunocompetent boy

Abstract

An otherwise well, fully immunised 9yearold boy presented due to systemic malaise with an infected knee laceration 10 days after falling onto concrete in his school playground. On examination his growth parameters were ageappropriate; he was febrile to 39.1°C, with purulent exudate oozing from his knee (figure 1). There was evidence of nodular lymphangitis with lymphocutaneous spread (figure 2). Investigations revealed white cell count of 12.2×10/L with mild neutrophilia (9.37×10/L), C reactive protein of 58 mg/L, and his blood culture was negative. Imaging excluded an underlying bone infection. He was commenced on flucloxacillin (50 mg/kg/dose 6hourly) and vancomycin was added (15 mg/kg/dose 6hourly) due to insufficient clinical response. Subsequently, his knee exudate grew Nocardia brasiliensis (resistant to cephalosporins, ciprofloxacin and imipenem). Immunological investigations were normal. The patient was commenced on linezolid and cotrimoxazole until imaging of the central nervous system ruled out disseminated infection (a common presentation of Nocardia infection), at which point he was changed to amoxicillinclavulanic acid (following a delayed hypersensitivity reaction to cotrimoxazole). Due to the relapsing nature of Nocardia infections, 6 months of therapy was prescribed, resulting in resolution of his lymphocutaneous infection. Nocardia spp are Grampositive, variably acidfast bacteria present in soil that may inoculate the skin following trauma. 2 Nocardiosis is typically regarded as an opportunistic infection in the immunocompromised, but approximately onethird of infected patients are immunocompetent. 3 Nocardia are a rare cause of skin and soft tissue infection with ubiquitous worldwide distribution yet with geographical variation in their prevalence, tending to be more common in tropical climates. Nocardiosis should be considered when empirical therapy against usual skin pathogens fails, alongside consideration of other pathogens that may be implicated in nodular lymphangitis (such as Sporothrix schenckii and nontuberculous mycobacteria).