This report presents a case of fulminant community-acquired Pseudomonas aeruginosa necrotizing pneumonia in a previously healthy young man, including an analysis of the virulence of the P.aeruginosa isolated from the patient. The patient was successfully treated with intensive care and antibiotic treatment. This study analyzed the pathogenicity of the isolated strain both in vivo (using a mouse pneumonia model) and in vitro (using biofilm production), but could not explain how an otherwise healthy young man developed such severe community-acquired P.aeruginosa pneumonia. Although rare in community-acquired pneumonia, P.aeruginosa infection should be considered in patients with severe rapidly progressive pneumonia.