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The Global Outbreak of M. chimaera Infection Following Cardiac Surgery: Another Piece of the Puzzle
Savina Ditommaso1, Gabriele Memoli1, Francesca Anselmi2
1Department of Public Health and Paediatrics, University of Turin, 10124 Torino, TO, Italy.
Abstract:
Invasive cases of Mycobacterium chimaera have been found in Europe, and beyond, and have been associated with the use of heater-cooler units necessary to regulate the temperature of blood in extracorporeal circulation during cardiac surgery, mostly due to contamination of patients by aerosol coming from the water in the tanks of the devices. An outbreak of five cases of M. chimaera infection associated with heater-cooler units Stockert 3T (LivaNova) was also identified in the Piedmont region (Italy). M. chimaera strains isolated from 10 Stockert 3T heater-cooler units used in 3 regional cardiac surgery operating rooms were subjected to whole-genome sequencing. The results were analysed according to van Ingen's criteria. M. chimaera was isolated from 59% of heater-cooler units Stockert 3T (LivaNova) monitored. By whole-genome sequencing analysis performed on M. chimaera strains obtained from 10 heater-cooler units, four strains were classified as subgroup 1.1 or 1.8, which are the two subgroups associated with the HCU-related outbreak worldwide. Our data and their comparisons with global heater-cooler unit isolates provide further evidence of the hypothesis that contamination occurs at the production site of LivaNova following exposure to M. chimaera-contaminated factory plumbing systems.
Insights
Mycobacterium chimaera infections linked to heater-cooler units (HCUs) were investigated. Whole-genome sequencing confirmed strains from Italian HCUs match those in global outbreaks, suggesting production site contamination.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Genomics
Background:
- Invasive Mycobacterium chimaera infections have been reported globally, primarily associated with heater-cooler units (HCUs) used in cardiac surgery.
- These infections are often linked to aerosolized water from HCU tanks, posing a risk to patients undergoing extracorporeal circulation.
- An outbreak of five M. chimaera cases linked to Stockert 3T (LivaNova) HCUs occurred in Italy's Piedmont region.
Purpose of the Study:
- To investigate the genetic relatedness of M. chimaera strains isolated from HCUs in the Piedmont region to those implicated in global outbreaks.
- To determine the prevalence of M. chimaera contamination in Stockert 3T HCUs within regional cardiac surgery operating rooms.
Main Methods:
- Whole-genome sequencing (WGS) was performed on M. chimaera strains isolated from 10 Stockert 3T HCUs.
- M. chimaera isolates were analyzed according to van Ingen's criteria for classification.
- Prevalence of M. chimaera in monitored HCUs was assessed.
Main Results:
- Mycobacterium chimaera was detected in 59% of the monitored Stockert 3T HCUs.
- WGS analysis revealed that four of the ten sequenced M. chimaera strains belonged to subgroups 1.1 or 1.8.
- These subgroups are known to be associated with the worldwide HCU-related M. chimaera outbreaks.
Conclusions:
- The findings provide further evidence supporting the hypothesis that M. chimaera contamination originates at the LivaNova production site.
- Exposure to contaminated factory plumbing systems is implicated as the source of M. chimaera in the HCUs.
- This highlights the need for stringent quality control measures during HCU manufacturing to prevent patient infections.
