Purpose. To measure the aerosolization of Mycobacterium avium subspecies hominissuis and Mycobacterium abscessussubspecies abscessus from ultrasonic humidifiers.
Methodology. An ultrasonic humidifier was filled with sterile tap water and inoculated with water-acclimated cells of either the M. avium or M. abscessus strains to achieve a range of densities similar to those of mycobacteria found in drinking waters. During operation of the humidifier, aerosols were collected using an Andersen 6-Stage Cascade Sampler.
Results. Cells of the M. avium and M. abscessus strains were readily aerosolized and recovered in particles (1–5 µm diameter); small enough to enter the furthest reaches of the human lung. Aerosolization of M. abscessus was significantly reduced in the presence of a normal drinking water bacterial flora. Significantly greater numbers of M. avium cells were aerosolized from high-density suspensions (1200 c.f.u. ml−1), than from low-density (120 c.f.u. ml−1) and very low-density (12 c.f.u. ml−1) suspensions.
Conclusions. This report documents the potential for M. avium subspecies hominissuis and M. abscessus subspecies abscessus cells in drinking water to be aerosolized from one type of portable humidifier; an ultrasonic humidifier. Care should be taken in using an ultrasonic humidifier where an individual at risk for mycobacterial pulmonary disease could be exposed.