Investigation of the bacterial load and antibiotic susceptibility of dental units

Abstract

The aim of this study was to evaluate the bacterial contamination level and to determine the antibiotic susceptibility of the isolated bacteria from dental unit waterlines (DUWLs) in Istanbul. Bacterial quality of DUWLs is very important, as patients and dental staff are regularly exposed to water and aerosols generated by the unit. If opportunistic pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, and Legionella pneumophila are present in DUWLs, patient and dental staff can be infected. One hundred water samples were collected from high-speed drills and input waters from 50 dental units. Aerobic heterotrophic bacteria counts and the presence of Legionella, Pseudomonas, oral streptococci, and Staphylococcus were investigated in dental unit waters and aerosol samples. In addition, the antibiotic susceptibility of the isolated and identified bacteria from DUWLs was examined. This research found that 37 out of 50 dental unit water samples exceeded the American Dental Association's limit of 200 colony-forming units (CFU)/mL(-1). Legionella, oral streptococci, and S. aureus were not detected in any water or aerosol samples, but P. aeruginosa was isolated in three DUWLs. Also, Pseudomonas and Staphylococcus were found in water and aerosol samples. Cefoperazone, ofloxacin, gentamicin, ciprofloxacin, and piperacillin were the most effective antibiotics against the isolated bacteria from DUWLs.

Occurrence and biofilm forming ability of Pseudomonas aeruginosa in the water output of dental unit waterlines in a dental center in Alexandria, Egypt

“…Dentists, like other healthcare professionals, are ethically obliged to provide patients with a safe and clean clinical environment including the water supplied by DUs. This piece of work has confirmed the results of earlier research, 7,12 which reported that the microbiological quality of water emerging from DUs did not conform to the accepted guidelines for potable water. In the present study, 88.3% of the examined DUWL output water samples failed to meet the Egyptian standards for HPC bacteria.…”

“…This seems to be consistent with the results obtained by other authors, 1,14 who attributed the higher contamination of high-speed handpiece to their In accordance with the results reported by Turetgen et al, 15 the current study found that DUWLs output water was more contaminated than the source water. Some researchers 7,12 have attributed the higher level of contamination in the output water compared to the inlet water to the release of bacteria from biofilms lining the DUWLs; an explanation that can apply to the results of the current study too. The decrease in the mean HPC values after clinical activity observed in this study has also been previously reported; 16,17 it can be attributed to the continued flushing of the waterlines during and between treatment sessions which can decrease the count in the midday samples.…”

“…1,12 Reservoirs are manually filled with water and may become contaminated with skin flora such as staphylococci. 7 In addition, the growth of biofilm on their internal surfaces can cause rapid deterioration in the microbiological quality of the water. 3 Previous research has demonstrated that bacterial counts differed among the DUWLs supplying different dental instruments.…”

“…The minimal sample size was calculated based on a previously reported frequency of isolation of P. aeruginosa from DUWLs of 6%. 7 By using a power of 80% (β=20%) to detect the prevalence of P. aeruginosa in DUWLs, precision 5% and α=0.05 (significance level 95%), the minimal required sample size was found to be 87 samples. When the anticipated prevalence was increased to 10%, the minimal required sample size became 140.…”

Comparing Efficiency Between Conventional and Molecular Methods for Detecting Legionella pneumophilia in Dental Unit Waterline Systems

“…in any DUWLs, they were able to detect L. pneumophilia in one of the tap water samples using the SCT. In another study regarding bacterial load of dental units conducted by Güngör et al in İstanbul, Turkey [21], Legionella was not detected in any water and aerosol samples, but Pseudomonas aeruginosa was isolated in three DUWLs. Furthermore, Pseudomonas and Staphylococcus also were found in water and aerosol samples.…”