Performance of nested PCR in the specific detection of Mycobacterium tuberculosis complex in blood samples of pediatric patients* Desempenho da técnica nested PCR na detecção específica do complexo Mycobacterium tuberculosis em amostras sanguíneas de pacientes pediátricos

摘要: Objective: To evaluate the performance of nested PCR (nPCR) in detecting Mycobacterium tuberculosis complex blood samples patients suspected having TB, order to determine its potential for use as an auxiliary tool laboratory diagnosis TB children. Methods: Detection M. using a target insertion sequence IS6110 genomic DNA bacillus. Blood 120 were evaluated. All under 15 years age at time their treatment public hospitals city Recife, Brazil (between January 2003 and August 2005). Attending physicians diagnosed based on criteria recommended by American Thoracic Society. The nPCR amplified 123-bp fragment with outer oligonucleotides (IS1/IS2) and, subsequent reaction, inner (IS3/IS4), generating 81-bp amplicon. Results: Active or latent was found 65 patients, ruled out 28 cases, 27 TB-free (controls). sensitivity 26.15% significantly higher extrapulmonary form disease (55.56%) than pulmonary (18.18%). specificity 92.73%. Conclusions: Despite difficulties diagnosing children low number cases evaluated present study, proved be rapid specific technique, albeit one sensitivity. In establish true usefulness paucibacillary forms, especially further studies need carried larger sample analyzing biological specimens other blood.