Case
A previously healthy 37-year-old man presented with a five-day history of high fever, dry cough, nasal discharge, headache, and back pain. There were no chest auscultation findings and respiratory failure; however, chest X-ray showed bilateral extensive shadow and computed tomography (CT) revealed multilobar bronchopneumonia (Figures 1, 2). Blood examination showed an elevated white blood cell count of 10,100/μL and a C-reactive protein level of 7.04 mg/dL. Azithromycin was empirically initiated on the assumption of Mycoplasma pneumoniae(MP) pneumonia, and all findings resolved in only three days (Figure 1). Multiplex polymerase chain reaction (mPCR) of the sputum was negative for MP but positive for human metapneumovirus (hMPV). Sputum culture, Pneumococcal and Legionella urinary antigen, and MP antibody pairs were negative.
CT imaging findings of hMPV pneumonia are multilobar bronchiolitis consisting of bronchial wall thickening and centrilobular nodules, often with hilar-predominant consolidation, which then resembles bronchopneumonia of MP. The presence of reticular opacities on CT may suggest MP pneumonia1,2. Additionally, since the clinical presentation of the two are similar, a certain number of cases of hMPV pneumonia may be misdiagnosed. The use of mPCR could make the diagnosis of community-acquired pneumonia more accurate1, and reduce the inappropriate use of antimicrobials.