Mycobacterium chimaera infections following cardiac surgery in Italy: results from a National Survey Endorsed by the Italian Society of Cardiac Surgery

Abstract

Aims: A global outbreak of Mycobacterium chimaera infections following cardiac surgery and linked to contaminated heater-cooler units (HCUs) is currently ongoing. Neither the status of this outbreak in Italy nor the mitigation strategies adopted by adult cardiac surgery units (ACSUs) are currently known. In 2017, the Italian Society of Cardiac Surgery launched a national survey among the Italian ACSU to shed some light on this issue.

Methods: In Italy, there are 90 ACSUs across 20 regions. From May to November 2017, these ACSUs were surveyed collecting data on patients diagnosed with MC infections, ACSU workload, HCU models in use and control measures adopted in the operatory room.

Results: The response rate was 87.8%. The median number of cardiac procedures at each ACSU was 450/year [interquartile range (IQR) 350-650 procedures/year], and nationally, the number of procedures/year exceeded 40k. In Italy, seven patients with M. chimaera infections following cardiac procedures have been reported since 2015: all had aortic or valvular surgery as the first procedure; the median latency between the first operation and the infection was 2 years (IQR 2-3.25). Mortality for patients requiring redo cardiac surgery was 50%. M. chimaera infections risk was 0.4-1 patient every 1000 cardiac procedures. The most common HCU model in Italy is the 3T HCU (70.9%). The most common control measures adopted included implementing new HCU disinfection protocols, using sterile or filtrated water in the HCU and displacing HCU fans away from the patient: HCU replacement and microbiology testing were instead infrequent.

Conclusion: In Italy, the risk of contracting M. chimaera infections and the mortality reported are in line with other European countries, but significant heterogeneity exists on the mitigation strategies adopted to prevent further M. chimaera inoculations, suggesting the development of national guidelines.