Legionella bacteria in the water supply of the Allegheny General Hospital in Pittsburgh likely caused a cancer patient to contract Legionnaires’ disease. Officials previously believed that the patient, now recovered, had contracted the illness elsewhere, but new tests show that the bacteria originated in the hospital.
After a cancer patient who had previously been treated at the hospital was readmitted with respiratory problems at the end of May, doctors tested the patient for Legionnaires’ disease. (Click here for our original blog post on this story.) The test was positive, and the patient was treated and made a full recovery. At the time, hospital officials believed that the patient had contracted the disease outside of the hospital, but they nevertheless followed health recommendations and commissioned intensive testing of water samples. Over 70 water samples were tested, of which one was positive for Legionella. Since Legionella bacteria exists in a number of subtypes, advanced testing was necessary to determine whether the patients were infected by bacteria of the same serogroup that was in the water.
Officials commissioned this advanced testing at the end of June, and results have now come back confirming that the water was the source of the bacteria. Bacteria from the patient’s sputum samples and hospital water samples both belonged to Legionella pneumophilia serogroup 5, which is a relatively uncommon form. Since this is suggestive but not conclusive, further testing was done to determine whether the two types of bacteria shared DNA. These DNA tests revealed that the bacteria were in fact related, proving that the patient had contracted Legionnaires’ disease from the hospital.
Allegheny General Hospital reported the results of this test to county health officials and are taking steps to prevent an outbreak of Legionnaires’ disease. Affected tanks have been shut off and patients, especially those with compromised immune systems, have been instructed to avoid the showers and to drink bottled water. Such measures are especially crucial at large hospitals, where many patients have weakened immune systems or are taking immunosuppressants, and in any building with a complex water system.
For more on this story, including information on different types of Legionella testing, click here.