Molecular techniques reveal high prevalence of Legionella in dental units.

Legionella bacteria are ubiquitous in freshwater aquatic systems, and humans are infected by them primarily through inhalation of contaminated aerosols. This study analyzed a total of 47 water samples from dental lines in private dental offices and university and hospital dental clinics for Legionella using the polymerase chain reaction, direct fluorescent antibody staining and culture techniques. The typical temperature of dental waterlines (23 C) combined with Legionella's ability to form biofilms, stagnation of the water in the lines and a low chlorine residual all potentially create a unique niche for this microorganism.