HARRISBURG, Pa. (WPVI) -- The infection is called NTM, nontuberculous mycobacterium.
Hospitals across Pennsylvania who do heart bypass operations are being urged to take extra care after rare infections were found in patients at 2 hospitals.
Today, Penn State Hershey Medical Center warned 2300 open-heart surgery patients from the past 4 years that they may have been exposed to it.
Three patients at Hershey developed the infection.
And 8 heart surgery patients at WellSpan York Hospital, also in central Pennsylvania, developed NTM as well.
The infection is believed to be linked to heater-cooler devices used to warm or cool a patient's blood during open-heart procedures.
The machines circulate water through a closed system to raise or lower temperatures.
Although the water does not come in direct contact with patients, it may make indirect contact, with the possibility bacteria-contaminated water gets into other parts of the device, or becomes aerosolized through the device's exhaust system.
NTM bacteria are commonly found in soil and water, including tap water.
Dr. Leah Lande at Lankenau Medical Center Main Line Health says NTM are not usually harmful.
However, they can infect people with weakened immune systems, or who have invasive medical procedures.
"Only a small percentage of people who are exposed to this in the environment, actually a very small per cent, are actually getting an infection," says Dr. Lande.
NTM is not contagious and cannot spread from person-to-person.
Hershey Medical Center has replaced all its heater-cooler units.
And it has established a web page to explain the situation to patients.
Other hospitals across the state are being told to look for signs of N-T-M among past heart-surgery patients, and to meticulously clean the heater-coolers.
The University of Pennsylvania Health System was alerted to the risk in October, when the FDA sent out a safety advisory on the link between the devices and NTM.
Hospital officials tell Action News they immediately instituted extra steps for cleaning.
They also went back through records of past open-heart patients, but did not find any cases of NTM infection.