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Clin Infect Dis. 2015 Jul 1;61(1):67-75. doi: 10.1093/cid/civ198. Epub 2015 Mar 11.

Prolonged Outbreak of Mycobacterium chimaera Infection After Open-Chest Heart Surgery.

Author information

1
Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich.
2
Institute of Medical Microbiology, National Centre for Mycobacteria, University of Zurich.
3
Institute of Surgical Pathology.
4
Division of Cardiac Surgery, University Hospital Zurich, Switzerland.

Abstract

BACKGROUND:

Invasive Mycobacterium chimaera infections were diagnosed in 2012 in 2 heart surgery patients on extracorporeal circulation. We launched an outbreak investigation to identify the source and extent of the potential outbreak and to implement preventive measures.

METHODS:

We collected water samples from operating theaters, intensive care units, and wards, including air samples from operating theaters. Mycobacterium chimaera strains were characterized by randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Case detection was performed based on archived histopathology samples and M. chimaera isolates since 2006, and the patient population at risk was prospectively surveyed.

RESULTS:

We identified 6 male patients aged between 49 and 64 years with prosthetic valve endocarditis or vascular graft infection due to M. chimaera, which became clinically manifest with a latency of between 1.5 and 3.6 years after surgery. Mycobacterium chimaera was isolated from cardiac tissue specimens, blood cultures, or other biopsy specimens. We were able also to culture M. chimaera from water circuits of heater-cooler units connected to the cardiopulmonary bypass, and air samples collected when the units were in use. RAPD-PCR demonstrated identical patterns among M. chimaera strains from heater-cooler unit water circuits and air samples, and strains in 2 patient clusters.

CONCLUSIONS:

The epidemiological and microbiological features of this prolonged outbreak provided evidence for the airborne transmission of M. chimaera from contaminated heater-cooler unit water tanks to patients during open-heart surgery.

KEYWORDS:

Mycobacterium chimaera; infection control; nontuberculous mycobacteria; open-chest heart surgery; outbreak

PMID:
25761866
DOI:
10.1093/cid/civ198
[Indexed for MEDLINE]
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