A Mycobacterium chimaera infection after 12 years since cardiac surgery: a case report

Abstract

Abstract Issues Mycobacterium chimaera bacterium, firstly identified in 2004, is mainly present in drinking water but is generally not harmful for human health. Incubation period ranges from 3 to 72 months, with a median of 17 months. Clinical signs are fever, weakness and weight loss. The infection has a lethality rate of 50%. Invasive infections are associated to the use of Heater-Cooler-Devices (HCD) in cardiovascular surgery. Description of the Problem This work reports on an unexpected Mycobacterium chimaera infection case occurred after a time period much longer than what literature reports for both incubation and surgical infection. In January 2007, a 67-year-old man underwent cardiac surgery for an aortic dissection Stanford type A, with implantation of an ascending aorta prosthesis at Udine Academic Hospital (Italy). After a chronic heart failure relapse occurred in September 2018, he developed fever of unknown origins, sepsis, and then he underwent surgery to substitute the vascular prothesis. In January 2019 the clinical condition of the patient got worse and he died in September 2019. Results The first level bacterial culture turned out to be positive for Mycobacteria, so the second level molecular biology test was carried out with GenoType NTM-DR. This analysis revealed a specific positivity for Mycobacterium chimaera. The confirmation test on the Heater-Cooler-Device (HCD) could not be carried out as this device was scrapped since years. Lessons This case report suggests that Mycobacterium chimaera incubation period can be extremely variable. Therefore, when performing differential diagnosis, it should be considered even for those patients who underwent cardiac surgery more than 5 years prior clinical manifestation. We suggest extending the current ECDC's exposure criteria, assuming that incubation period could cover the entire patient's life. Key messages Mycobacterium chimaera can have an incubation period much longer than what is usually described in literature and ECDC guidelines. This report can be considered a starting point to improve the hospital infection control surveillance system in hospitals performing cardiac surgery.