Aero-environmental bacteriological survey of respiratory non-tuberculosis mycobacterial disease patients

Background: The treatment of diseases by non-tuberculosis mycobacterium (NTM) is not established, then the recurrence of NTM disease often occurs. Several reports suggest NTM infections from environment like bathroom and soil, but there are few investigations detecting infectious aerosol. We investigated patients9 home environments with air-sampling system for the direct detection of NTM from aerosol. Methods: We collected samples from the bathrooms of five respiratory NTM disease patients; two MAC, two M. massiliense , and one M. abscessus diseases. Aerosols were collected using air sampler, and the swabs were collected from the surfaces of the bathroom. We used Middlebrook 7H11 agar, supplemented with OADC, malachite green, cycloheximide and PANTA. The isolates were identified by direct sequencing of rpoB . Results: In one case, M. massiliense was detected from the aerosol only during hot water running into bathtub. The VNTR analysis (10 loci) identified same genotype between the isolates from aerosol and patient9 sputum. Increasing number of floating NTMs was identified in all cases, during or after hot water supply. Several NTMs were isolated from the swabs, but not identical to the species from patients. Discussion and Conclusion: To our knowledge, this is the first case of identifying the same clone of M. masiliense from patient and aerosol environment. It was also evidenced that the number of NTM increased in aerosol during hot water supply. It may indicate the aerosol is direct route of NTM infection from environment. The whole genome analyses onto two M. massiliense derived from the patient and the aerosol, may reveal the question; the dilemma of causality.