Clinical and operational impact of a four-year-long bronchoscopy-associated pseudo-outbreak of Mycobacterium...

To report on the investigation of a pseudo-outbreak of Mycobacterium mucogenicum and examine its clinical and operational impact.

Outbreak investigation, retrospective cohort study.

Academic medical center in Los Angeles, California.

Patients whose bronchoalveolar lavage (BAL) cultures grew M. mucogenicum from 2020-2024.

We performed an institutional outbreak investigation of M. mucogenicum, reviewed electronic medical records of a subset of affected patients (2023-2024), and assessed the operational impact.

The incidence of M. mucogenicum in BAL cultures at Hospital A increased from 6.1% (29/473) in 2020 to 18.6% (29/156) in the first quarter of 2024. Epidemiologic investigation revealed non-sterile ice baths used to cool uncapped sterile syringes during bronchoscopy procedures as the contamination source. Next generation sequencing linked clinical isolates to M. mucogenicum recovered from a perioperative ice machine. Nearly all (157/160) clinical isolates grew from nocardia media rather than acid-fast bacilli media. Among 154 patients, including 51 (33.1%) who were highly immunocompromised, no true infections were identified. Thirty-nine (25.3%) patients were referred to infectious diseases for consultation, seven (4.5%) underwent additional workup, and only one received targeted treatment. The pseudo-outbreak incurred 458 hours of microbiology technologist and infection preventionist time and cost the laboratory $88,426.

A four-year pseudo-outbreak of M. mucogenicum traced to contaminated ice baths used during bronchoscopy resulted in unnecessary infectious disease referrals and substantial operational and financial burden to the institution. Avoidance of non-sterile ice use in procedures prevents costly and burdensome pseudo-outbreaks of environmental mycobacteria in healthcare settings.