Acremonium strictum pulmonary infection in a horse

A 10-year-old Thoroughbred gelding was admitted to the Veterinary Medical Teaching Hospital of the University of California-Davis with a 2-week history of intermittent fever and acute onset of lethargy, anorexia, and ataxia. Although the clinical signs were nonspecific, the results of initial hematologic and biochemical analysis were consistent with a chronic inflammatory process. Thoracic radiographs revealed an increased fine reticulonodular interstitial opacity throughout the dorsal caudal lung fields. Cytologic examination of bronchoalveolar lavage (BAL) fluid showed mixed inflammation with many mononuclear phagocytes containing single, spherical, intracytoplasmic fungal organisms. Four mold species were cultured in low numbers from the BAL fluid. One of the fungal elements observed on the culture plates was identified as Acremonium strictum by real-time polymerase chain reaction (PCR). A diagnosis of fungal pneumonia due to A strictum was made based on the results of thoracic imaging, cytologic evaluation, culture, and PCR testing. The horse made an uneventful recovery with supportive treatment and was disease-free based on normal physical, radiographic, and cytologic findings at 21 days after presentation. To our knowledge, this is the first report of isolation of A strictum from the BAL fluid of a horse with interstitial pneumonia.