Community-acquired lobar pneumonia caused by Pseudomonas aeruginosa infection in Japan: a case report with histological and immunohistochemical examination

Pseudomonas aeruginosa is a common pathogen in nosocomial and/or healthcare-associated pneumonia, but is rare in community-acquired pneumonia. A 50-year-old previously healthy woman was taken to the emergency department because of rapidly progressing dyspnea. Chest radiograph showed consolidation of the entire right upper lobe, a finding suggestive of lobar pneumonia. The patient died of respiratory failure with bronchial bleeding, on the same day of admission. Autopsy revealed that the alveoli throughout the upper right lobe were filled with dense inflammatory cells mainly consisting of macrophages and neutrophils. Immunoreactive bacilli by using an anti-P. aeruginosa antibody were localized within macrophages accumulated in the alveoli as well in the vessel walls. Lobar pneumonia composed of dense neutrophils and bacteria-laden macrophages with total lung congestion and edema may be characteristic for community-acquired P. aeruginosa pneumonia in a healthy adult.