Los Angeles County health officials say they've identified several cases of an infection that's been linked to contaminated heart-surgery equipment.
The Department of Public Health on Wednesday says three people who had open-chest surgeries were confirmed as having infections caused by Mycobacterium chimaera. Officials also identified one suspected case.
All four patients survived.
The patients had surgeries in 2014 and 2015. The bacterium is slow-growing and symptoms may not appear for months or even years.
Outbreaks have been tracked to a type of LivaNova-brand heater-cooler device used during surgeries.
Authorities say more than 70 cases have been identified worldwide and there have been several deaths.
However, more than 250,000 cardiopulmonary bypass operations are performed in the U.S. each year and authorities say the overall infection risk is low.