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Diagnosis of cutaneous tuberculosis by polymerase chain reaction using a species-specific gene
M Faizal1, G Jimenez, C Burgos
1Dermatology Department, Hospital San Juan de Dios, Universidad Nacional de Colombia, Santafé de Bogotá, D.C. Columbia.
Background:
Diagnosis of tuberculosis (TB), especially cutaneous TBC, by conventional microbiologic methods is still a very laborious process and the results are usually inconclusive. Our purpose was to identify M. tuberculosis bacilli in uncultured clinical samples from skin lesions by means of the rapid, specific, and sensitive polymerase chain reaction (PCR).
Methods:
The PCR, using a set of species-specific primers, was performed on biopsies and fluid secretions from lesions.
Results:
A positive amplification reaction was observed in three of the four samples studied. For one of the samples, the result was confirmed by a positive culture in Löwenstein-Jensen medium and for the other two, by molecular hybridization and the clinical course of the patients after treatment. Samples obtained from a patient with panniculitis of Christian-Weber and a normal skin biopsy were included as negative controls.
Conclusions:
We propose the PCR method as a tool for the diagnosis of cutaneous TBC. The presence of the M. tuberculosis in an erythema induratum of Bazin suggests a revision of the concept of this disease as a tuberculide reaction.