The aim of this study was to detect Mycobacterium tuberculosis complex, M. avium subsp. avium and M. intracellulare, Mycobacterium contamination and to explore the aerosol transmission of mycobacteria in public buildings in China.
A total of 552 environmental samples, namely 165 aerosol, 199 water, 70 air duct dust, and 118 soil samples, were collected from 39 public buildings and analysed using nested polymerase chain reaction.
The positivity rate of Mycobacterium tuberculosis complex, M. avium subsp. avium and M. intracellulare in air samples were 0.6% and 1.8%, respectively. There was significant difference in the positivity rate of Mycobacterium aerosol among the three types of public building (χ = 6.108, p = 0.047). No positive results of Mycobacterium tuberculosis complex and M. avium and M. intracellulare were obtained from cooling, tap, shower, or fountain water. The positivity rate of Mycobacterium for water samples was 31.7% (63/199). The positivity rate of Mycobacterium tuberculosis complex, M. avium subsp. avium and M. intracellulare, Mycobacterium in soil samples were 1.1%, 34.6% and 43.6%, respectively. There was significant difference in the positivity rate of M. avium and M. intracellulare (χ = 47.219, p < 0.001) and Mycobacterium (χ = 33.535, p < 0.001) in the different origins of soil samples.
Mycobacteria are widespread in public buildings. Mycobacterium tuberculosis complex, M. avium and M. intracellulare were simultaneously present in the air ducts of central air conditioning systems and indoor air in public buildings, which indicates that aerosol transmission is a potential route.