1976 Philadelphia Legionnaires' disease outbreak 1976 Philadelphia Legionnaires' disease outbreak The 1976 Legionnaires disease outbreak, occurring in the late summer in Philadelphia, Pennsylvania, was the first occasion in which a cluster of a particular type of pneumonia cases were determined to be caused by the "Legionella pneumophila" bacteria. Previous outbreaks were retroactively diagnosed as being most probably caused by Legionella bacteria. On July 21, 1976, the American Legion opened its annual three-day convention at the Bellevue-Stratford Hotel in Philadelphia, Pennsylvania. More than 2,000 Legionnaires, mostly men, attended the convention. The date and city were chosen to coincide with America’s celebration of the 200th anniversary of
Classification of pneumonia now the most commonly used classification scheme, attempts to identify a person's risk factors when he or she first comes to medical attention. The advantage of this classification scheme over previous systems is that it can help guide the selection of appropriate initial treatments even before the microbiologic cause of the pneumonia is known. There are two broad categories of pneumonia in this scheme: community-acquired pneumonia and hospital-acquired pneumonia. A recently introduced type of healthcare-associated pneumonia (in patients living outside the hospital who have recently been in close contact with the health care system) lies between these two categories. Classification