Swine flu: false-positive rapid flu swab with resulting misdiagnosis of a case of Legionella pneumonia.

A 59-year-old man presented with a severe flu-like illness and widespread pulmonary infiltrates on chest x-ray. A rapid influenza direct test was positive and the patient was nursed in isolation. On subsequent review, a diagnosis of probable atypical pneumonia was made, which was confirmed with positive urinary serology for Legionella pneumophila and treatment with appropriate antibiotics was started. A real-time PCR test for influenza A and B was negative at 72 h. The patient made a slow but full recovery and was discharged after 14 days.