An alarming new study published earlier this month in the American Journal of Infection Control indicates that the bacterial contamination of heater-cooler units such as the Stockert 3T is more widespread than previously thought. Furthermore, there are other strains of bacteria beyond the one that has been at the center of concern.
The study was presented last week at the annual conference of the Association for Professionals in Infection Control and Epidemiology (APIC) by one of the authors, Dr. John Rihs, vice president of laboratory services at the Special Pathogens Lab in Pittsburgh. In press release, Dr. Rihs said that “the extent of contamination from such a rare organism in multiple units from all over the country was surprising.”
Dr. Rihs and his colleagues examined and analyzed a total of 89 heater-cooler units in 23 hospitals throughout Canada and the U.S. over a two-year period. Of those units, 33 (37%) were found to contain mycobacterium chimaera contamination. That particular strain – relatively harmless to healthy people, but potentially deadly to those with compromised immune systems or those who undergo invasive surgery – has been the main source of concern. Health authorities in the U.S. and Canada began issuing warnings to open heart surgery patients last year. This past February, Health Canada published an alert about the Liva-Nova Stockert 3T specifically, advising hospitals to remove contaminated units from service.
This latest study has shown that m. chimaera isn't the only danger. “Beyond m. chimaera, we found other NTM [non-tuberculous mycobacteria] species, Legionella, and fungi, indicating these units are capable of supporting a diverse microbial population,” Dr. Rihs reports. Legionella is the bacterium that causes “Legionnaire's Disease,” a form of pneumonia that is also spread by contact with water or humidity.
Out of five manufacturers producing heater-cooler units, four, including Liva-Nova, have reported bacterial contamination. APIC president Linda Green says this news points out the necessity of close monitoring and the importance of rigorous cleaning and maintenance of the units, stating that “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.”
The chief surgeon of the Montreal Hearth Institute goes further. Dr. Louis Perrault believes that contaminated units should be taken out of service altogether. Speaking to the Canadian media, he said that “contaminated units should most likely be set aside, replaced if possible.”
The greatest danger from bacterial infections caused by heater-cooler units is the dormancy period; symptoms from these infections may not present symptoms until months or even years after initial exposure. These infections are fatal in approximately 50% of cases. Stockert units represent 60% of the heater-cooler units currently in use, with approximately 2,000 of them being used in the U.S. Worldwide, as many as half a million people are at risk for potentially fatal bacterial infections.