title: [Confirmation by molecular typing of cross-contamination in a mycobacteria laboratory].
abstract: BACKGROUND
  Detection of cross-contamination in the laboratory by restriction fragments length polymorphism (RFLP) analysis of Mycobacterium tuberculosis strains.
  
  
  METHODS
  224 strains isolated during a five years period were characterized by IS6110 fingerprinting performed (RFLP) by standardized protocols.
  
  
  RESULTS
  Four groups of isolates with smear-negative specimens and low number of colony form its units were detected. They were processed in the same batch and day than other smear-positive specimens with identical RFLP patterns. Fifteen patients were involved and the review of four patients' charts showed that they did not have the typical manifestations of tuberculosis.
  
  
  CONCLUSIONS
  When M. tuberculosis isolates were obtained from smear-negative specimens, the results of specimens processed in the same batch and the patients' charts should be reviewed. If with these data the possibility of cross-contamination is suspected, the isolates must be analyzed by molecular typing methods.
authors.affiliation: Servicio de Microbiología, Hospital de Navarra, Pamplona.
authors.forename: B
authors.initials: B
authors.lastname: Perfecto
authors.forename: I
authors.initials: I
authors.lastname: Dorronsoro
authors.forename: I
authors.initials: I
authors.lastname: López-Goñi
mesh_terms: D019411:Clinical Laboratory Techniques; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis; D005189:False Positive Reactions; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D014376:Tuberculosis / Q000175:diagnosis
chemical_list: D004269:DNA, Bacterial