title: Testing for aerobic heterotrophic bacteria allows no prediction of contamination with potentially pathogenic bacteria in the output water of dental chair units.
abstract: BACKGROUND
  Currently, to our knowledge, quality of output water of dental chair units is not covered by specific regulations in the European Union, and national recommendations are heterogeneous. In Germany, water used in dental chair units must follow drinking water quality. In the United States of America, testing for aerobic heterotrophic bacteria is recommended. The present study was performed to evaluate whether the counts of aerobic heterotrophic bacteria correlate with the presence of potentially pathogenic bacteria such as Legionella spp. or Pseudomonas aeruginosa.
  
  
  METHODS
  71 samples were collected from 26 dental chair units with integrated disinfection device and 31 samples from 15 outlets of the water distribution pipework within the department were examined. Samples were tested for aerobic heterotrophic bacteria at 35°C and 22°C using different culture media and for Legionella spp. and for Pseudomonas aeruginosa. Additionally, strains of Legionella pneumophila serogroup 1 were typed with monoclonal antibodies and representative samples of Legionella pneumophila serogroup 1 were typed by sequence based typing.
  
  
  RESULTS
  Our results showed a correlation between different agars for aerobic heterotrophic bacteria but no correlation for the count of aerobic heterotrophic bacteria and the presence of Legionella spp. or Pseudomonas aeruginosa.
  
  
  CONCLUSIONS
  Testing for aerobic heterotrophic bacteria in output water or water distribution pipework within the departments alone is without any value for predicting whether the water is contaminated with potentially pathogenic bacteria like Legionella spp. or Pseudomonas aeruginosa.
authors.affiliation: Bernhard Gottlieb University Clinic of Dentistry, Department of Fixed and Removable Prosthodontics, Medical University Vienna, Austria.
authors.forename: Margit
authors.initials: M
authors.lastname: Bristela
authors.forename: Astrid
authors.initials: A
authors.lastname: Skolka
authors.forename: Martina
authors.initials: M
authors.lastname: Schmid-Schwap
authors.forename: Eva
authors.initials: E
authors.lastname: Piehslinger
authors.forename: Alexander
authors.initials: A
authors.lastname: Indra
authors.forename: Günther
authors.initials: G
authors.lastname: Wewalka
authors.forename: Fritz
authors.initials: F
authors.lastname: Stauffer