Two more heart-surgery patients in the Philadelphia area have tested positive for a worrisome, slow-growing bacteria that has been linked to a device called a heater-cooler.

One of the two patients, at Christiana Hospital in Newark, Del., has died, though hospital officials said it was not yet clear what role the bacteria may have played in the death.

In Pennsylvania, 21 cases have been reported at three facilities, according to the state department of health.

That includes 12 at WellSpan York Hospital, five at Penn State Hershey Medical Center, and three at Penn Presbyterian Medical Center, officials at those hospitals have said. A fourth patient at Penn Presbyterian tested positive for the bacteria but did not develop symptoms.

Another case at a New Jersey hospital, previously identified as possible, has now been confirmed, said Donna Leusner, a spokeswoman for that state's department of health. Officials declined to identify the facility, citing the possibility that the patient's identity would be compromised.

While federal officials say the risk of infection is low, infectious-disease experts have warned that the true scope of the problem remains unclear. That is because the bacteria grow so slowly that symptoms may develop months or even years after the patient is exposed.

Heater-coolers are used to regulate the temperature of blood in patients who are hooked up to a heart-lung bypass machine during surgery. The devices contain circulating water that does not come into direct contact with the patient. But studies have found that bacteria in the water can become aerosolized through a vent in the device.

Most reported cases to date have involved a model of heater cooler called the Stöckert 3T, which federal health officials say may have been contaminated during the manufacturing process.

That model was used at Christiana as well, officials said. The hospital has ordered replacements made by a different manufacturer, and expects to have them in a few weeks, spokesman Hiran Ratnayake said.

In the meantime, the hospital has taken precautions such as directing the device exhaust vents outside the operating room, following guidelines from the federal Centers for Disease Control and Prevention, Ratnayake said.


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