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1.  Reprocessing of dental instruments in washer-disinfectors: does a representative test soil exist in dentistry? 
Background: Reprocessing of medical devices, being classified as semi-critical B is recommended to be performed in a washer-disinfector. In order to estimate, whether the expected contaminants of the various medical disciplines can be effectively removed by this washer-disinfector, different so called “test soils” have been proposed to be tested as a marker of cleaning efficacy of the disinfector. Todays described test soils are optimised for the testing of contaminations occurring in surgical procedures, but not for dental procedures.
Methods: In this study the test soils being proposed in the EN 15883-5 (e.g. KMNE soil, recipe by Koller and coagulated sheep’s blood) were compared with 8 reference substances used in the conservative-prosthetic dental practice. The success of the cleaning efficacy in the washer-disinfector was checked visually and by determining the residual protein concentration on the contaminated instruments after the cleaning procedure.
Results: It could be shown that in contrast to the proposed test soils of the EN 15883-5, the used reference substances of the dental practice could not be removed by the washer-disinfector. Removal of these reference substances was only possible after manual or ultrasonic cleaning.
Conclusions: Since blood plays a subordinate role as a contaminant of instruments during conservative-prosthetic dental treatments, testing of the cleaning efficacy of the washer-disinfector with test soils according to the proposals of the EN 15883-5 is not representative in this discipline of dentistry. Most of the materials used in dental practice can only be removed manually or with the help of the ultrasound bath.
PMCID: PMC3334948  PMID: 22558047
reprocessing; cleaning; disinfection; washer-disinfector; dentistry; test soil; protein assay; dental materials
2.  Testing for aerobic heterotrophic bacteria allows no prediction of contamination with potentially pathogenic bacteria in the output water of dental chair units 
Background: Currently, to our knowledge, quality of output water of dental chair units is not covered by specific regulations in the European Union, and national recommendations are heterogeneous. In Germany, water used in dental chair units must follow drinking water quality. In the United States of America, testing for aerobic heterotrophic bacteria is recommended. The present study was performed to evaluate whether the counts of aerobic heterotrophic bacteria correlate with the presence of potentially pathogenic bacteria such as Legionella spp. or Pseudomonas aeruginosa.
Methods: 71 samples were collected from 26 dental chair units with integrated disinfection device and 31 samples from 15 outlets of the water distribution pipework within the department were examined. Samples were tested for aerobic heterotrophic bacteria at 35°C and 22°C using different culture media and for Legionella spp. and for Pseudomonas aeruginosa. Additionally, strains of Legionella pneumophila serogroup 1 were typed with monoclonal antibodies and representative samples of Legionella pneumophila serogroup 1 were typed by sequence based typing.
Results: Our results showed a correlation between different agars for aerobic heterotrophic bacteria but no correlation for the count of aerobic heterotrophic bacteria and the presence of Legionella spp. or Pseudomonas aeruginosa.
Conclusion: Testing for aerobic heterotrophic bacteria in output water or water distribution pipework within the departments alone is without any value for predicting whether the water is contaminated with potentially pathogenic bacteria like Legionella spp. or Pseudomonas aeruginosa.
PMCID: PMC3334951  PMID: 22558046
dental chair unit; water; disinfection; Legionella spp.; Pseudomonas aeruginosa; aerobic heterotrophic bacteria
3.  Snapshot of Moving and Expanding Clones of Mycobacterium tuberculosis and Their Global Distribution Assessed by Spoligotyping in an International Study†  
Journal of Clinical Microbiology  2003;41(5):1963-1970.
The present update on the global distribution of Mycobacterium tuberculosis complex spoligotypes provides both the octal and binary descriptions of the spoligotypes for M. tuberculosis complex, including Mycobacterium bovis, from >90 countries (13,008 patterns grouped into 813 shared types containing 11,708 isolates and 1,300 orphan patterns). A number of potential indices were developed to summarize the information on the biogeographical specificity of a given shared type, as well as its geographical spreading (matching code and spreading index, respectively). To facilitate the analysis of hundreds of spoligotypes each made up of a binary succession of 43 bits of information, a number of major and minor visual rules were also defined. A total of six major rules (A to F) with the precise description of the extra missing spacers (minor rules) were used to define 36 major clades (or families) of M. tuberculosis. Some major clades identified were the East African-Indian (EAI) clade, the Beijing clade, the Haarlem clade, the Latin American and Mediterranean (LAM) clade, the Central Asian (CAS) clade, a European clade of IS6110 low banders (X; highly prevalent in the United States and United Kingdom), and a widespread yet poorly defined clade (T). When the visual rules defined above were used for an automated labeling of the 813 shared types to define nine superfamilies of strains (Mycobacterium africanum, Beijing, M. bovis, EAI, CAS, T, Haarlem, X, and LAM), 96.9% of the shared types received a label, showing the potential for automated labeling of M. tuberculosis families in well-defined phylogeographical families. Intercontinental matches of shared types among eight continents and subcontinents (Africa, North America, Central America, South America, Europe, the Middle East and Central Asia, and the Far East) are analyzed and discussed.
PMCID: PMC154710  PMID: 12734235
4.  Global Distribution of Mycobacterium tuberculosis Spoligotypes 
Emerging Infectious Diseases  2002;8(11):1347-1349.
We present a short summary of recent observations on the global distribution of the major clades of the Mycobacterium tuberculosis complex, the causative agent of tuberculosis. This global distribution was defined by data-mining of an international spoligotyping database, SpolDB3. This database contains 11,708 patterns from as many clinical isolates originating from more than 90 countries. The 11,708 spoligotypes were clustered into 813 shared types. A total of 1,300 orphan patterns (clinical isolates showing a unique spoligotype) were also detected.
PMCID: PMC2738532  PMID: 12453368
Mycobacterium tuberculosis; spoligotyping
5.  Genus Level Identification of Mycobacteria from Clinical Specimens by Using an Easy-To-Handle Mycobacterium-Specific PCR Assay 
Journal of Clinical Microbiology  1998;36(3):614-617.
An easy-to-handle Mycobacterium-specific PCR assay for detection of the presence of a wide range of mycobacterial species in clinical samples was evaluated. The performance of the genus probe was compared with the performance of probes specific for Mycobacterium tuberculosis and Mycobacterium avium and with that of standard culture. In addition, the utility of an internal control in monitoring amplification inhibitors was studied. Of 545 respiratory and 325 nonrespiratory specimens (a total of 870 specimens), 58 (6.7%) showed the presence of amplification inhibitors, as determined by a negative result for the internal control. Of these 58 specimens, 31 (53%) were stool specimens; other material, even citrate blood after lysis of erythrocytes, did not pose a problem with regard to inhibition of PCR amplification. Eighty-one of the remaining 812 specimens had a positive Mycobacterium culture result. Of these culture-positive specimens, 58 (71.6%) showed a positive result with the Mycobacterium genus-specific probe. Seventy-two samples had a positive result with the Mycobacterium-specific probe but a negative culture result. Of these 72 samples, 26 samples were regarded as true positive, either because the M. tuberculosis- or M. avium-specific probe was also positive at the same time or because other specimens from the same patient taken at the same time were culture positive. The sensitivity of the Mycobacterium-specific probe was 78.5% and the specificity was 93.5%. This study showed that pretesting of clinical specimens for mycobacteria to the genus level with a Mycobacterium-specific probe offers the routine clinical laboratory the possibility of detecting tuberculous and nontuberculous mycobacteria with one test. Furthermore, specimens testing positive with the genus-specific probe can be immediately identified with species-specific probes.
PMCID: PMC104595  PMID: 9508282

Results 1-5 (5)