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      Microbial contamination of dental unit waterlines in dental practices in Hesse, Germany: A cross-sectional study

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          The quality of water from dental units is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This study analyzed the microbial quality of water obtained for periodical monitoring from 56 dental units in different dental practices in Hesse. Contamination by Legionella spp., Pseudomonas aeruginosa, and increased total colony counts were detected in 27.8%, 3.5%, and 17% of samples. Legionella pneumophila serogroup 1 accounted for 28% of Legionella isolates. The Legionella concentration was >100 cfu/100 ml in 84% of contaminated samples. Samples collected from an instrument channel were more frequently contaminated by Legionella than those from cup filler (41.7% vs. 18.6%, p = 0.02). After release of these results, decontamination measures were performed in units that had revealed unsatisfactory results. The outcome of the intervention was followed-up by microbiological analysis. At follow-up, 65.2% and 72.7% of waterlines that had previously been contaminated by Legionella or had shown increased total colony counts were free of contamination. Our results show a high rate of contamination of water from dental units in dental practices in Hesse. They highlight the risk of exposure for patients and personnel and the need for effective strategies to reduce microbial contamination.

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          Most cited references 14

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          Community-acquired Legionella pneumonia: new insights from the German competence network for community acquired pneumonia.

          The Competence Network for Community Acquired Pneumonia (CAPNETZ) offers a unique opportunity to study the epidemiology of legionellosis throughout Germany, applying sophisticated diagnostic tools. The incidence, clinical characteristics, and outcome of Legionella pneumonia in 2503 adult patients with community-acquired pneumonia, participating in the German Multicenter Study of the CAPNETZ, were studied. Legionella pneumonia was diagnosed in 94 patients (3.8%), thus identifying Legionella species as one of the most common pathogens to cause community-acquired pneumonia. It was equally common among ambulatory and hospitalized patients (3.7% and 3.8%, respectively). The predominant species causing community-acquired pneumonia was Legionella pneumophila; however, 10% of cases were caused by other species not detectable by the urinary antigen test. Patients whose disease was diagnosed by urinary antigen testing experienced a more severe clinical course. Compared with hospitalized patients, ambulatory patients with Legionella pneumonia showed an equal sex distribution, were younger, had fewer comorbidities, fewer cases of discordant initial antimicrobial treatment, and a milder clinical course without fatalities. Thirty percent of patients with Legionella pneumonia received discordant initial antimicrobial treatment without increased mortality. Legionella is a leading cause of community-acquired pneumonia in Germany. It needs to be considered equally in hospitalized and ambulatory patients. A positive result of a urine antigen test is associated with a more severe clinical course and leads to a potentially relevant underrecognition of species other than L. pneumophila. Legionella pneumonia in outpatients differs significantly from that in hospitalized patients in terms of clinical presentation and outcome. There was an unacceptably high rate of discordant initial antimicrobial treatment.
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            Pneumonia associated with a dental unit waterline.

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              Legionella contamination of dental-unit waters.

              Water samples collected from 28 dental facilities in six U.S. states were examined for the presence of Legionella pneumophila and other Legionella spp. by the PCR-gene probe, fluorescent-antibody microscopic, and viable-plate-count detection methods. The PCR and fluorescent-antibody detection methods, which detect both viable and viable nonculturable Legionella spp., gave higher counts and rates of detection than the plate count method. By the PCR-gene probe detection method, Legionella spp. were detected in 68% of the dental-unit water samples and L. pneumophila was detected in 8%. Concentrations of Legionella spp. in dental-unit water reached 1,000 organisms per ml or more in 36% of the samples, and 19% of the samples were in the category of 10,000/ml or above. L. pneumophila, when present in dental-unit water, never reached concentrations of 1,000/ml or more. Microscopic examination with fluorescent-antibody staining indicated that the contamination was in the dental-unit water lines rather than in the handpieces. Legionella spp. were present in 61% of potable water samples collected for comparative analysis from domestic and institutional faucets and drinking fountains; this percentage was not significantly different from the rate of detection of Legionella spp. in dental-unit water. However, in only 4% of the potable water samples did Legionella spp. reach concentrations of 1,000 organisms per ml, and none was in the 10,000 organisms-per-ml category, and so health-threatening levels of Legionella spp. in potable water were significantly lower than in dental-unit water. L. pneumophila was found in 2% of the potable water samples, but only at the lowest detectable level.(ABSTRACT TRUNCATED AT 250 WORDS)

                Author and article information

                European Journal of Microbiology and Immunology
                Akadémiai Kiadó, co-published with Springer Science+Business Media B.V., Formerly Kluwer Academic Publishers B.V.
                1 March 2013
                : 3
                : 1
                : 49-52
                [ 1 ] Hesse State Health Office, Centre for Health Protection, Dillenburg, Germany
                [ 2 ] Hessisches Landesprüfungs- und Untersuchungsamt im Gesundheitswesen, Zentrum für Gesundheitsschutz, Wolframstrasse 33, D-35683, Dillenburg, Germany
                Author notes
                [* ] +98 2771 320631, +98 2771 36667, mardjan.arvand@


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