An Italian investigation on non-tuberculous mycobacteria in an urban water supply.

Background: Atypical or non-tuberculous mycobacteria (NTM) are considered opportunistic pathogenic bacteria. They are natural inhabitants of a broad variety of environmental reservoirs, including natural and treated waters. Due to the lack of Italian studies on these microorganisms in drinking water, an investigation was carried out on their occurrence and on species present in a municipal water distribution system in Rome. The presence of the traditional indicators of faecal contaminations and free living amoebae were also verified.
Methods: Two different methodological approaches based on cultural and molecular techniques have been applied in parallel.
Results: Mean concentrations of NTM obtained with the two analytical methodologies were roughly 102 CFU/L. Among the numerous NTM species identified, M. chelonae was the most frequently isolated. No correlation of NTM with indicators of faecal contamination and amoebae was found.
Conclusions: Mycobacteria can be present even if routine tests show water to have an excellent hygienic quality.