Community-acquired pneumonia pneumonia not seen on x-rays. However, congestive heart failure or other types of lung damage can mimic CAP on x-rays. Several tests can identify the cause of CAP. Blood cultures can isolate bacteria or fungi in the bloodstream. Sputum Gram staining and culture can also reveal the causative microorganism. In severe cases, bronchoscopy can collect fluid for culture. Special tests can be performed if an uncommon microorganism is suspected, such as urinalysis for Legionella antigen in Legionnaires' disease. CAP is treated with an antibiotic that kills the offending microorganism and by managing complications. If the causative microorganism is unidentified (often
1976 Philadelphia Legionnaires' disease outbreak testing specimens. While the Center for Disease Control responded rapidly, as did the Pennsylvania Health Department, it took six months for the CDC microbiologist Joseph McDade to discover the cause of the outbreak. He initially thought the cause was viral because blood and tissues from the victims failed to grow bacteria when incubated in culture medium. His subsequent attempts to isolate the viral agent in eggs included antibiotics to kill off "contaminating" bacteria. It was only when he omitted the antibiotics that the bacteria grew in eggs. Attempts to reproduce the disease in mice, the standard laboratory animal model, also