Dental Unit Waterlines: Biofilms, Disinfection and Recurrence

Meiller, Timothy F.; DePaola, Louis G.; Kelley, Jacqueline I.; Baqui, A. A. M. A.; Turng, Been-Foo; Falkler, William A.

doi:10.14219/jada.archive.1999.0030

Cited by 60 publications

(56 citation statements)

References 7 publications

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“…Strategies developed for the control of DUWS contamination must eliminate both the biofilms and the waterborne bacteria in these systems (23,31,36). In addition, although significantly lower levels of biofilm contamination were found in the five units reported to have been recently decontaminated, more bacteria were recovered from the water phase in these systems.…”

Section: Discussionmentioning

confidence: 98%

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

Walker

Bradshaw

Bennett

et al. 2000

Appl Environ Microbiol

199

166

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Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 10 5 CFU ⅐ ml ؊1; in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this "viable by BacLight" fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered "cleaner" than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.

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Section: Discussionmentioning

confidence: 98%

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

Walker

Bradshaw

Bennett

et al. 2000

Appl Environ Microbiol

199

166

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“…It was also pointed out that the use of selected biocides (sodium hypochlorite, glutaraldehyde, isopropanol) may lead to the accumulation of these substances in biofi lm matrix and their uncontrolled release. The authors consider this fact an additional risk for patients (6). Risk factors responsible for the contamination of DUWL water include the microbiological, biological, physical, and chemical indicators of the incoming water.…”

Section: Introductionmentioning

confidence: 99%

Legionella spp. in dental unit waterlines

Jurásková¹,

Sedlackova²,

Janska³

et al. 2017

BLL

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OBJECTIVE: To determine the current presence of Legionella spp. in the output water of dental unit waterlines (DUWLs) and examine its mitigation by disinfection at the Institute of Dentistry and Oral Sciences, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc. MATERIAL AND METHODS: The fi rst stage of our survey involved collecting samples of DUWL output water from 50 dental chair units (DCUs), and 2 samples of the incoming potable water. In October 2015, a one-time disinfection (1 % Stabimed) of DUWLs was conducted. This was followed by collecting 10 control samples (survey stage 2). RESULTS: From the total of 50 samples (survey stage 1), 18 samples (36.0 %) tested positive for Legionella spp. Following the disinfection, nine of the ten samples no longer showed any presence of Legionella. CONCLUSION: Based on culture results, the one-time disinfection (1 % Stabimed) was effective. We are unable to comment on the duration of positive effect of disinfection on the occurrence of Legionella spp. in the outlet water. It was a one-time survey (Tab. 2, Ref. 32). Text in PDF www.elis.sk. KEY WORDS: Legionella spp., water of dental unit waterlines, disinfection.

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“…However, for the study of adherent communities, viability tests alone are insufficient (24). The biofilm matrix can be recolonized, and assays should therefore target viable mass and matrix in a discriminatory way (9,12,25). For example, a recently developed S. aureus model uses dimethyl methylene blue (DMMB) for detecting the matrix, while resazurin is used as a viability indicator (24).…”

mentioning

confidence: 99%

Inhibitory Effect of Biocides on the Viable Masses and Matrices of Staphylococcus aureus and Pseudomonas aeruginosa Biofilms

Toté

Horemans

Berghe

et al. 2010

Appl Environ Microbiol

142

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Bacteria and matrix are essential for the development of biofilms, and assays should therefore target both components. The current European guidelines for biocidal efficacy testing are not adequate for sessile microorganisms; hence, alternative discriminatory test protocols should be used. The activities of a broad range of biocides on Staphylococcus aureus and Pseudomonas aeruginosa biofilms were evaluated using such in vitro assays. Nearly all selected biocides showed a significant decrease in S. aureus biofilm viability, with sodium hypochlorite and peracetic acid as the most active biocides. Only hydrogen peroxide and sodium hypochlorite showed some inhibitory effect on the matrix. Treatment of P. aeruginosa biofilms was roughly comparable to that of S. aureus biofilms. Peracetic acid was the most active on viable mass within 1 min of contact. Isopropanol ensured a greater than 99.999% reduction of P. aeruginosa viability after at least 30 min of contact. Comparable to results with S. aureus, sodium hypochlorite and hydrogen peroxide markedly reduced the P. aeruginosa matrix. This study clearly demonstrated that despite their aspecific mechanisms of action, most biocides were active only against biofilm bacteria, leaving the matrix undisturbed. Only hydrogen peroxide and sodium hypochlorite were active on both the biofilm matrix and the viable mass, making them the better antibiofilm agents. In addition, this study emphasizes the need for updated and standardized guidelines for biofilm susceptibility testing of biocides.Microbial communities irreversibly attached to a surface and encapsulated in a self-produced polymeric matrix are known as biofilms. A particular characteristic is their extreme resistance to antimicrobial treatment (6). This resistance is mediated by several mechanisms that can act together: (i) poor penetration or inactivation of antimicrobials in the matrix, (ii) an altered bacterial metabolic state, (iii) the formation of persister cells, and (iv) resistance induced by the antimicrobial itself following the use of sublethal concentrations and the upregulation of efflux pumps (2, 7). Hence, biofilms are hard to eradicate and are claimed to be responsible for up to 60% of all infections in humans (1, 5). Staphylococcus aureus and Pseudomonas aeruginosa are notorious biofilm producers, the first being nosocomial and responsible mainly for medical device-associated infections (13, 28) and the latter being an opportunistic pathogen causing life-threatening infections mainly in cystic fibrosis patients (13,19).Looking at the high biofilm-related morbidity and mortality, the antibiofilm properties of antimicrobials have been studied extensively, with a main focus on the activity of antibiotics (1,17,20,26). However, a recent study indicated that the prospect of using solely antibiotics to achieve complete biofilm destruction is limited, since the biofilm matrix persists (25). As their mechanisms of action are not limited to the bacterial metabolism, biocides should also be considered as valuable...

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Dental Unit Waterlines: Biofilms, Disinfection and Recurrence

Cited by 60 publications

References 7 publications

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

Legionella spp. in dental unit waterlines

Inhibitory Effect of Biocides on the Viable Masses and Matrices of Staphylococcus aureus and Pseudomonas aeruginosa Biofilms

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