Comparison of Amplicor, in-house polymerase chain reaction, and conventional culture for the diagnosis of tuberculosis in children

A total of 251 clinical specimens (235 gastric aspirates and 16 bronchoalve olar lavages) from 88 children were prospectively tested in a blinded manne r for the presence of Mycobacterium tuberculosis complex, by use of the Amp licor M. tuberculosis test and by means of in-house polymerase chain reacti on (PCR). The results were compared with those obtained by conventional cul ture and by direct microscopy. All of the children underwent extended follo w-up to verify or exclude the clinical diagnosis of tuberculosis. The resul ts of the different tests, when compared to the final clinical diagnosis, w ere a sensitivity of 60% and a specificity of 96.8% for in-house PCR, 44% a nd 93.7% respectively for the Amplicor test, 44% and 100% for mycobacterial culture and 12% and 100% for microscopy. Amplicor tests presented false-po sitive findings in children without tuberculous infection. We conclude that both in-house PCR and the Amplicor test are rapid methods that can be help ful for difficult or urgent diagnosis of tuberculosis in children. However, efforts should be aimed toward improvement of the sensitivity and specific ity of an easy-to-use PCR kit.