title: External quality assurance for the laboratory diagnosis of Buruli ulcer disease in Ghana.
abstract: OBJECTIVE
  To assure the quality of the laboratory diagnosis of Buruli ulcer disease; microscopy and PCR were subjected to external quality assurance (EQA).
  
  
  METHODS
  Slides were read by test laboratory staff, followed by blinded re-reading by the controller. Parallel testing of PCR specimens was carried out at the local and external reference laboratory. Slides and PCR specimens with discordant results were subjected to a second reading/testing by the controller to determine the final result. For training purposes, slides and PCR specimens with discrepant results were subsequently re-read/re-tested under supervision at the test laboratory.
  
  
  RESULTS
  Microscopy. First reading: concordance rate 82.9%, discordance rate 17.1%, percentage false negatives 27.1% (sensitivity 72.9%), percentage false positives 10.1% (specificity 89.9%). Second reading: concordance rate 97.9%, discordance rate 2.1%, percentage false negatives 4.2% (sensitivity 95.8%), percentage false positives 0.6% (specificity 99.4%). PCR. First testing: concordance rate 87.9%, discordance rate 12.1%, percentage false negatives 8.2% (sensitivity 91.8%), percentage false positives 19.1% (specificity 80.9%). Second testing: concordance rate 96.2%, discordance rate 3.8%, percentage false negatives 4.7% (sensitivity 95.3%), percentage false-positives 2.1% (specificity 97.9%).
  
  
  CONCLUSIONS
  EQA identified deficiencies in the laboratory performance. Corrective action consisted in on-site training and reduced the number of false-negative and false-positive microscopy and PCR results.
authors.affiliation: Department of Infectious Diseases and Tropical Medicine, University of Munich, Munich, Germany. bretzel@lrz.uni-muenchen.de
authors.forename: G
authors.initials: G
authors.lastname: Bretzel
authors.forename: V
authors.initials: V
authors.lastname: Siegmund
authors.forename: J
authors.initials: J
authors.lastname: Nitschke
authors.forename: K H
authors.initials: KH
authors.lastname: Herbinger
authors.forename: R
authors.initials: R
authors.lastname: Thompson
authors.forename: E
authors.initials: E
authors.lastname: Fleischmann
authors.forename: B
authors.initials: B
authors.lastname: Fleischer
authors.forename: O
authors.initials: O
authors.lastname: Adjei
mesh_terms: D019411:Clinical Laboratory Techniques / Q000592:standards*; D005188:False Negative Reactions; D005189:False Positive Reactions; D005869:Ghana / Q000453:epidemiology; D006801:Humans; D016013:Likelihood Functions; D008853:Microscopy / Q000379:methods / Q000592:standards; D009165:Mycobacterium Infections, Nontuberculous / Q000175:diagnosis* / Q000453:epidemiology; D019911:Mycobacterium ulcerans / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods / Q000592:standards; D011237:Predictive Value of Tests; D011786:Quality Control; D012680:Sensitivity and Specificity