Grady Memorial Hospital officials were looking at the possibility that the disease spread through the hospital's water or air. Hospital spokeswoman Denise Simpson said preliminary test results should come back Monday.
Legionnaires' disease is a bacterial infection that can cause potentially deadly pneumonia. The bacteria do not spread from person to person. Instead, people get it from inhaling contaminated mist or vapor. Tainted air conditioning systems or whirlpool spas are among the ways the bacteria can get in the air.
Officials said about 80 beds on the hospital's 11th and 12th floors have been taken out of service pending tests of hospital water samples.
The four patients all had been treated at Grady. They were released, then got sick with Legionnaire's and returned to the hospital, where they were diagnosed. None died.
Grady is working with state health officials to check into all possible ways the patients could have gotten the infection, Simpson said.
Grady - a public hospital in downtown Atlanta with about 950 beds - customarily sees only two or three cases of infection with the bacteria each year.
