Polymerase chain reaction detection of potentially pathogenic free-living amoebae in dental units.

Several genera of amoebae can be found in water from dental units and on the inner surface of waterlines. The presence of bacterial biofilms on these surfaces is thought to favor the proliferation of amoebae. Potentially pathogenic Acanthamoeba and Naegleria spp. may be an infection risk for patients through contact with open surgical sites or aerosolization. A polymerase chain reaction of DNA extracted from pelleted samples showed that Acanthamoeba spp. and Naegleria spp. were present in water from dental units, suction lines, and suction filters at the dental clinic of the Université de Montréal. Acanthamoeba spp. were detected in 24.2% of 66 samples and Naegleria spp. in 3.0%. We discuss the infection risk associated with these results.