Legionella at Home

摘要

A case of Legionella pneumonia caused by an unusual serogroup and originally believed to be nosocomial was eventually traced to home water sources. During the worldwide coronavirus outbreak, we should remember that many other etiologies of severe pneumonia exist. A single case report describes a patient aged 70 to 79 years with a diagnosis of combined immunodeficiency who was admitted to a hospital in Wisconsin and died of complications from septic shock 10 days later. The patient had been treated with antibiotics for leg cellulitis and abscesses and had exhibited a recent change in mental status. On admission, the patient complained of dry cough and shortness of breath and had fever and a rash considered a reaction to antibiotics. The patient’s cough became productive of dark brown sputum, and radiography showed a right upper lobe opacity not present on admission. The etiologic diagnosis was not established, but the patient was treated for presumed nosocomial pneumonia with several classes of antibiotics. On day 6, urinary antigen testing for Legionella pneumophila and culture of bronchoalveolar lavage fluid were initiated. Urinary antigen for L. pneumophila serogroup 1 was negative, but on day 16 (6 days after the patient died) the Wisconsin State Laboratory isolated L. pneumophila serogroup 3. L. pneumophila isolation triggered extensive examination of multiple hospital water sources for the organism, which were negative. However, cultures from samples of two showers in the patient’s home on day 26 were positive for L. pneumophila essentially genetically identical to the organism isolated from the patient. Despite remediation, further culture from plumbing fixtures throughout the house on day 62 yielded the same organism.