One-third of heart surgery devices contaminated with bacteria: Study

Over a third of heater-cooler devices that are used in open heart surgery may be contaminated with life-threatening bacteria, putting patients at risk for deadly infections, a study has revealed.

The study showed that 33 of 89 or 37 per cent heater-cooler units assessed between July 2015 and December 2016 in the US tested positive for Mycobacterium chimaera (M. chimaera) — a bacterium associated with fatal infections in open-heart surgery patients.

“The extent of contamination from such a rare organism in multiple units from all over the country was surprising,” said John Rihs, Vice President of Laboratory Services at Special Pathogens Laboratory in Pennsylvania, in the US.

“Some devices remained positive for M. chimera for months, indicating that disinfection can be difficult and routine testing is advisable,” Rihs added.

Beyond M. chimera, the researchers also found other non-tuberculous mycro-bacteria (NTM) species, Legionella, and fungi, indicating these units are capable of supporting a diverse microbial population.

Heater-cooler units (HCUs) control the temperature of a patient’s blood and organs during heart bypass surgery.

These HCUs have water tanks that provide temperature-controlled water during surgery through closed circuits.

Although the water in the instrument does not come into direct contact with the patient, it can aerosolise. If this water gets contaminated they can transmit bacteria through the air into the environment, and ultimately to the patient.

These results highlight the importance of monitoring the decontamination and maintenance schedules of these devices to minimise the risk of patient harm, the researchers said.

The findings were presented at the 44th Annual Conference of the Association for Professionals in Infection Control and Epidemiology (APIC).

For the study, the team tested a total of 653 water samples from 89 units. Samples were received from 23 hospitals in 14 states, the District of Columbia, and Canada.

Thirty-three of the units (37 percent) tested positive for M. chimaera, while four units were colonised with Legionella. (IANS)