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[Confirmation by molecular typing of cross-contamination in a mycobacteria laboratory]
B Perfecto1, I Dorronsoro, I López-Goñi
1Servicio de Microbiología, Hospital de Navarra, Pamplona.
Background:
Detection of cross-contamination in the laboratory by restriction fragments length polymorphism (RFLP) analysis of Mycobacterium tuberculosis strains.
Material And 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.