Implementation of Guidelines To Monitor Dental Unit Water Quality

ISSUE: In December of 2003 the Centers for Disease Control and Prevention published guidelines recommending testing of water lines in dental units. The guideline recommends a limit of <500 CFU/ml for heterotrophic bacteria in water used in nonsurgical dental procedures. PROJECT: The infection control team worked closely with dental staff to implement a testing protocol. To establish testing sites, a copy of the floor plan for dental services was obtained. Infection control collected 100ml of water in sterile glass bottles. A 250 microliter sample was then spread on a petri dish containing tryptic soy agar and colony counts were determined at forty-eight hours. RESULTS: Initially there was one sample out of ten outside of the expected range (≥1,000 CFU/ml). Additional samples were collected in the rooms surrounding the positive sample. Four out of four samples were positive (≥1,000 CFU/ml). Additional troubleshooting with the cleaning protocol and evaluations of the source water was done. Sporadic positive samples continued in one area. All internal tubing was changed and machines with this design are disinfected daily instead of weekly. Changes were made in disinfection practices after staff identified units with horizontal internal components were the units with high bacteria counts. All samples collected were negative following the changes. LESSONS LEARNED: A team approach is necessary to implement new guidelines. Disinfection protocols alone did not address the biofilm issues within the units. The understanding of the design of the machines by the dental hygienists and involvement of the vendor was essential in evaluating the microbiology results.