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PITTSBURGH — The strain of bacteria that caused a fatal outbreak of Legionnaires' disease in a Veterans Affairs hospital in western Pennsylvania is "almost identical" to the strain found there more than three decades ago, a newspaper reported.
The Pittsburgh Tribune-Review http://triblive.com/news/allegheny/3520955-74/outbreak-1982-legionella">said Sunday it had obtained documents indicating that the Legionella bacteria found in October at the Oakland hospital match five of seven genes of the 1982 bacteria.
"This indicates the Legionella found in the hospital in 1982 is almost identical to the Legionella found in this outbreak, suggesting that the pathogenic strain may have persisted in the hospital's water system for many years," the Centers for Disease Control and Prevention said in a report last month.
The report said the bacteria linked to at least five deaths might have survived in the water system decades of hot water flushes, chemical disinfectant cycles and installation of a copper-silver ionization system designed to kill it.
Janet Stout, a microbiologist who worked on the research team that responded to the 1982 outbreak, told the paper that layers of slime and calcium in pipes could shelter the bacteria.
"It's never completely killed because, as you can imagine, a water distribution system has many pipes, many sections" that disinfecting treatments might not reach, said Stout, who later worked in the VA Oakland pathogens lab before it closed.
VA spokesman David Cowgill declined comment, citing "pending investigations and legal claims." The VA Inspector General's Office and a U.S. House subcommittee are separately reviewing the outbreak. U.S. Attorney David Hickton in Pittsburgh has also vowed to look into the matter when the inspector general's report is completed next month.
Legionnaires' disease, which most often strikes the elderly and can cause deadly pneumonia, is caused by bacteria that can be spread through mist or vapor from contaminated water or air conditioning systems. Groundbreaking research at the Pittsburgh-area hospital in 1982 following a three-year outbreak tied the spread of the disease for the first time to water systems rather than to mist from building cooling towers.
The VA announced the most recent outbreak Nov. 16 and switched its water treatment systems at two hospitals in Pittsburgh. A CDC report earlier this month says the VA hospital lab in Pittsburgh didn't report positive test results for Legionnaires for more than two days in violation of hospital protocols. Five patients who were infected at Pittsburgh's Veterans Affairs hospitals died, and tests on another veteran who died last month are awaited to see whether the patient contracted the bacteria.