Ecology of nontuberculous mycobacteria--where do human infections come from?

Nontuberculous mycobacteria (NTM) are environmental, opportunistic human pathogens whose reservoirs include peat-rich potting soil and drinking water in buildings and households. In fact, humans are likely surrounded by NTM. NTM are ideally adapted for residence in drinking water distribution systems and household and building plumbing as they are disinfectant-resistant, surface adherent, and able to grow on low concentrations of organic matter. For individuals at risk for NTM infection, measures can be taken to reduce NTM exposure. These include avoiding inhalation of dusts from peat-rich potting soil and aerosols from showers, hot tubs, and humidifiers. A riskanalysis of the presence of NTM in drinking water has not been initiated because the virulence of independent isolates of even single NTM species (e.g., Mycobacterium avium) is quite broad, and virulence determinants have not been identified.