Investigating contamination of dental-unit waterline systems and microbial biofilm ecology
type: CreativeWork
description: Introduction: Biofilms within dental-unit waterlines (DUWLs) are acknowledged sources of contamination in the dental clinical environment and affect the quality of clinical treatment water. As a standard for reducing exposure to potentially harmful microorganisms, the Department of Health (DoH), UK suggests that water discharged from DUWL should contain 100 to 200 CFU/mL. However, local audits suggest that the quality of clinical treatment water often fails to meet the standards required. The aim: The aim was to be able to readily identify waterlines with higher levels of contamination via validation of a rapid existing “in-office” test and subsequently understand biofilm ecology. Materials and Methods: Water samples from 31 DUWLs in general dental practices were taken during the working day and cultured using the PetrifilmTM AC plate test as per manufacturer’s instructions and for extended incubation periods under laboratory conditions. The samples were also cultured using the laboratory based benchmark R2A agar. Further culture methods were employed for investigating spread of human pathogens with aerosolization and splatter of DUWL water; retraction valve failure; waterborne biofilm ecology and environment within a simulated laboratory DUWL (sDUWL) and whether amoebae were harboring nosocomial bacteria. Results: The bacterial concentration of the water samples cultured on R2A agar varied significantly (1 × 101 to 4.3 × 106); in surgeries (48%) which met DoH standards and those that failed (52%). A retest of water from surgeries which delivered safe and contaminated water revealed that approximately 55% of practices met the recommended threshold values whilst around 45% failed. The PetrifilmTM AC Plate method gave variable sensitivity values on different occasions with 100% specificity. Only the nosocomial clinical isolate of Serratia marcescens was recovered from one clinical water sample. The opportunistic yeast, Candida parapsilosis from 1 sample indicated poss…
abstract: Introduction: Biofilms within dental-unit waterlines (DUWLs) are acknowledged sources of contamination in the dental clinical environment and affect the quality of clinical treatment water. As a standard for reducing exposure to potentially harmful microorganisms, the Department of Health (DoH), UK suggests that water discharged from DUWL should contain 100 to 200 CFU/mL. However, local audits suggest that the quality of clinical treatment water often fails to meet the standards required. The aim: The aim was to be able to readily identify waterlines with higher levels of contamination via validation of a rapid existing “in-office” test and subsequently understand biofilm ecology. Materials and Methods: Water samples from 31 DUWLs in general dental practices were taken during the working day and cultured using the PetrifilmTM AC plate test as per manufacturer’s instructions and for extended incubation periods under laboratory conditions. The samples were also cultured using the laboratory based benchmark R2A agar. Further culture methods were employed for investigating spread of human pathogens with aerosolization and splatter of DUWL water; retraction valve failure; waterborne biofilm ecology and environment within a simulated laboratory DUWL (sDUWL) and whether amoebae were harboring nosocomial bacteria. Results: The bacterial concentration of the water samples cultured on R2A agar varied significantly (1 × 101 to 4.3 × 106); in surgeries (48%) which met DoH standards and those that failed (52%). A retest of water from surgeries which delivered safe and contaminated water revealed that approximately 55% of practices met the recommended threshold values whilst around 45% failed. The PetrifilmTM AC Plate method gave variable sensitivity values on different occasions with 100% specificity. Only the nosocomial clinical isolate of Serratia marcescens was recovered from one clinical water sample. The opportunistic yeast, Candida parapsilosis from 1 sample indicated poss…
author: Lal, Sham
language: en
keywords: C500 - Microbiology
date published: 2016-06
date modified: 2026-07-24T01:35:56Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Central Lancashire