Mycobacterium chimaera
From IDWiki
Mycobacterium chimaera
Background
Microbiology
- A member of the Mycobacterium avium complex
Epidemiology
- A global outbreak of Mycobacterium chimaera infections was associated with point-source contamination of Stöckert 3T-HCD heater-cooler units (HCUs) used in cardiac bypass
- Higher rates in mainland Europe, followed by UK, followed by North America
Pathophysiology
- The HCUs aerosolized mycobacteria into the surgical field
Clinical Manifestations
- Median incubation period was 14.5 months (range 6 weeks to 5 years), with 80% of patients becoming unwell during the first two years
- Duration of symptoms median 7 weeks but up to 1 year
- Most commonly presented with unexplained fever
- Constitutional symptoms are common
- Caused prosthetic valve endocarditis, aortic graft infection, surgical site infections, and disseminated disease affecting liver, spleen, bone marrow, spine, skin, and bone
- Lymphopenia and thrombocytopenia are common, as is elevated ALP
Diagnosis
- Culture in general has sensitivity of 68% but increases to essentially 100% with two cultures
- Blood, urine, sputum, tissue, et cetera
- Two blood cultures are about 76% sensitive
Management
- No specific guidelines exist for treatment
- Typically use a MAC regimen with azithromycin, ethambutol, and rifampin
- May need additional aminoglycoside such as amikacin for severe disease
- Duration unclear, but at least several months
Prognosis
- Poor prognosis, with median survival of 30 months from initial surgery and 9 months from start of therapy
Further Reading
- Mycobacterium chimaera infection following cardiac surgery in the United Kingdom: clinical features and outcome of the first 30 cases. Clin Microbiol Infect. 2018. doi: 10.1016/j.cmi.2018.04.027
