Use of whole genome sequencing in a bronchoscopy-related pseudo-outbreak of Mycobacterium mucogenicum linked to ice machines.

BACKGROUND

To investigate and determine the cause of an increase of isolation of Mycobacterium mucogenicum in broncho-alveolar lavage samples in a tertiary hospital.

METHODS

Outbreak investigation including 30 patients who underwent bronchoscopy procedures in a minor procedural area of a university-affiliated, tertiary-care medical center between January and October 2022. The investigation included epidemiological analysis and response, environmental sampling, and whole genome sequencing (WGS) of clinical and environmental isolates.

RESULTS

Environmental sampling identified M mucogenicum group from procedure room sinks, sterile processing sinks, bronchoscopes, and ice machine water. WGS of 9 patient isolates and 5 environmental isolates revealed clonal relatedness (0-5 single nucleotide polymorphisms) between patient isolates and potable water isolates. No patients developed active infections requiring treatment.

CONCLUSIONS

A pseudo-outbreak of M mucogenicum group was linked to ice used to cool saline used to vasoconstrict biopsy collection sites in bronchoscopy procedures. WGS provided high-resolution evidence of the transmission source, distinguishing between multiple strains present in the environment. Implementation of modified processes for saline handling, equipment reprocessing, and prevention of supply contamination from potable water sources successfully addressed the source of contamination.