Microbial contamination of dental unit water lines in H.P. Government Dental College, Shimla

Aim: To determine the microbial quality of water from DUWLs and also to determine the efficacy of flushing on reducing its microbial count in Himachal Pradesh Government Dental College, Shimla.

Method: Samples were collected from all the dental chairs in the department of public health dentistry. Ten millilitres of water was collected in a sterile container from air water syringe in the mid afternoon, once before flushing and once after flushing for two minutes. One control sample was also taken from tap in the department. The samples were then sent to department of Microbiology, Indira Gandhi Medical College, Shimla where they were investigated for gram positive and gram negative cocci; gram positive and gram negative bacilli.

Results: No organism was detected in the control sample from tap water. The only organism that was detected was staphylococcus coagulase negative. The mean of staphylococci coagulase negative colony forming units in pre flushing sample was 1460.89 and in post flushing sample was 1380. The difference between pre flushing and post flushing sample was not statistically significant.

Conclusion: Though the organism present in water was only staphylococci coagulase negative, the level was higher than as recommended by CDC, so appropriate disinfection methods should be used, and the source of staphylococci coagulase negative should be investigated. The flushing did not show any significant difference before and after flushing in the present study.