A new study presented this week at a global conference in Portland, Oregon revealed that a significant number of heater-cooler units tested positive for bacteria associated with fatal infections in open-heart surgery patients.

The research was presented by John Rihs, vice president of laboratory services at Special Pathogens Laboratory, at the 44th annual conference hosted by the Association for Professionals in Infection Control and Epidemiology (APIC).

In the study, 37 percent of heater-cooler units assessed between July 2015 and December 2016 had traces of a deadly bacteria called mycobacterium chimaera. Meanwhile, many other units were contaminated with other strains of the bacteria. A total of 653 water samples from 89 units were tested from 23 hospitals in 14 states, the Distric of Columbia and Canada.

"Our results showed M. chimera in 37 percent of units tested and is consistent with previous findings,” Rihs said in a statement. “The extent of contamination from such a rare organism in multiple units from all over the country was surprising. Some devices remained positive for M. chimera for months, indicating that disinfection can be difficult and routine testing is advisable. Beyond M. chimera, we found other NTM species, Legionella, and fungi, indicating these units are capable of supporting a diverse microbial population."

The bacteria is usually not associated with infections when people are normally exposed to it, but during an open-heart surgery, it becomes much more dangerous. And often times, diagnosis of these infections can be missed or delayed since symptoms can take months to emerge.

"These results highlight the importance of monitoring the decontamination and maintenance schedules of these devices to minimize the risk of patient harm," said Linda Greene, president of the APIC, in a statement. "Hospitals must follow the cleaning and disinfection instructions provided in the manufacturer's device labeling, as well as updated communications from the FDA and CDC."