Tuberculosis transmission in an Australian healthcare setting: lessons learnt from a coordinated public health response.

OBJECTIVES AND IMPORTANCE OF STUDY: Tuberculosis (TB) remains a global public health concern. In Australia, TB incidence is low, but remains elevated among overseas-born individuals. This study investigates a TB cluster in a non-clinical hospital setting during the COVID-19 pandemic, highlighting transmission dynamics and the public health response.

METHODS: A retrospective observational study was conducted using medical records and epidemiological contact tracing data within a tertiary hospital in New South Wales, Australia. Three screening rounds targeted office contacts in different air-conditioning zones. Whole genome sequencing was used to assess Mycobacterium tuberculosis isolates.

RESULTS: Five secondary cases of TB disease were identified following exposure to the index case, a non-clinical hospital employee with cavitating pulmonary TB. Among 233 identified contacts, 117 completed screening. Initially screened high-risk contacts (n = 31) had high rates of TB disease (n = 4; 12.9%) and newly detected interferon gamma release assay-positivity (n = 14; 45.1%), with lower rates in broader screening. Transmission likely occurred via prolonged office exposure. Whole genome sequencing linked a sixth TB case in a clinical healthcare worker to the cluster, with 26 secondary contacts screened.

CONCLUSION: This study underscores the potential for highly infectious TB transmission within Australian healthcare settings. Timely contact tracing, genomic surveillance, and pre-employment screening are essential for effective prevention and control.