Prevalence of gram positive cocci contamination in the water lines of Shahid Beheshti Dental School units and drinking water supply of local area

Contamination of dental unit water lines had been discussed to be the source of bacterial infection specially in immuncompromized and sensile patients in recent years. This study carried out in order to evaluate gram positive cocci contamination in the water lines of Shahid Beheshti Dental School units and drinking water supply of local area during 1381. Methods & Materials: The study was descriptive and it’s technique was observation and data questionnaire usage. 15 units from dental school and 15 ones from local area were selected randomly before the beginning of daily work. The samples were carried into transport media and sent to microbiology lab then. Smears of the samples were stained with gram staining and all specimens were cultured on blood and nutrient agar. The cases were incubated for 48 hours at 37 0C and microbial colonies were counted for the purpose. No case of gram positive cocci contamination was observed in drinking water samples. In the examination of dental units’ water, contamination of gram positive cocci and gram negative bacillus were seen, i.e. Entrococcus in periodontic Dept., Staphylococcus epidermidis in Orthodontic Dept. Staphylococcus aureus in Crown and Bridge Dept. The peak of contamination level was found in the third floor. Existence of gram negative bacillus in third floor and Enterococcus in first floor was probably for the contamination of water be fece, while staphylococcus epidermidis existence can be discussed by back flow of saliva via suction or water supply line of the unit through handpiece hoses.