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 25 had died. Both the first week and later, there were 149 Legionnaires who became sick and 33 other persons associated with the hotel or in the area who also became sick. Of these total of 182 cases, 29 persons died. The U.S. Centers for Disease Control and Prevention mounted an unprecedented investigation and, by September, the focus had shifted from outside causes, such as a disease carrier, to the hotel environment itself. In January 1977, the "Legionella" bacterium was finally identified and isolated and was found to be breeding in the cooling tower of the hotel’s air conditioning system,