[Contamination of dental scaler water lines with legionella pneumophila, pseudomonas aeruginosa and gram positive cocci]

Dental staff are exposed to aerosols. Water supply of dental units has insignificant bacterial count but the existing water in the waterlines has over 100,000 microorganisms per milliliter. Various types of microorganisms exist in the waterline of dental units. Legionella pneumophila, Pseudomonas aeruginosa and Gram-positive cocci are among the most important ones. Scaling and root planning is a dental procedure carrying a high risk of bacterial contamination. This study aimed to assess water contamination in private dental offices in Isfahan. In this descriptive study, sampling was done in 50 private offices; 10 ml samples of dental unit water were collected from each scaler and a sample from the city tap water as control. We used 3-step PCR for Legionella detection. The extracted DNA was evaluated for the presence of mip gene sequence using spectrophotometry. For detection of Pseudomonas aeruginosa, samples were cultured in Brilliant Green Bile broth. To confirm P. aeruginosa, the grown colonies were cultured in Cetrimide agar medium and presence of P. aeruginosa was re-confirmed with oxidase test. For evaluation of Gram-positive cocci, multiple smeares were prepared and after Gram staining, Gram-positive specimens were cultured in blood agar medium. Data were analyzed using SPSS version 20 and reported in tables and diagrams as number and percentage. None of the control samples were positive for any bacterium. Thirty-two test samples were also negative for the understudy bacteria; but 18 offices tested positive for these bacteria. Our results shows that hazardous bacteria may be present in dental unit biofilm. Special attention must be paid to the cleanliness of water used in dental procedures