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 bronchoalveolar lavages) from 88 children were prospectively tested in a blinded manner for the presence of Mycobacterium tuberculosis complex, by use of the Amplicor M. tuberculosis test and by means of in-house polymerase chain reaction (PCR). The results were compared with those obtained by conventional culture and by direct microscopy. All of the children underwent extended follow-up to verify or exclude the clinical diagnosis of tuberculosis. The results of the different tests, when compared to the final clinical diagnosis, were a sensitivity of 60% and a specificity of 96.8% for in-house PCR, 44% and 93.7% respectively for the Amplicor test, 44% and 100% for mycobacterial culture and 12% and 100% for microscopy. Amplicor tests presented false-positive findings in children without tuberculous infection. We conclude that both in-house PCR and the Amplicor test are rapid methods that can be helpful for difficult or urgent diagnosis of tuberculosis in children. However, efforts should be aimed toward improvement of the sensitivity and specificity of an easy-to-use PCR kit.

Diagnosis of tuberculosis in children using a polymerase chain reaction.

We investigated the value of the polymerase chain reaction (PCR) in the diagnosis of active tuberculosis in children and evaluated the relationship between PCR results in children with tuberculous infections and mediastinal adenopathies detected by computerized tomography (CT-Scan). This was a controlled, blinded, prospective study comparing nested PCR, mycobacterial cultures and the clinical diagnosis based on 350 clinical specimens from 117 children referred for evaluation of suspected pulmonary tuberculosis. All children with tuberculous infection but without active disease underwent a chest CT-scan to detect the presence of mediastinal adenopathies not evident on chest x-ray. The sensitivity of PCR was 56.8% in children with clinically active disease (culture: 37.8%; smears: 13.5%). A major advantage of PCR over cultures was noted when there was no parenchymal involvement on chest radiograph and when the patient was undergoing anti-tuberculous treatment. There were nine specimens with false-negative PCR results due to the presence of amplification reaction inhibitors. PCR was positive in five children with tuberculous infection without active disease and these children presented mediastinal adenopathies on the CT-scan that were not evident on chest radiography. There were no false-positive PCR results in the control groups of children. We conclude that nested PCR is a rapid and sensitive method for the early diagnosis of tuberculosis in children. It is especially useful when the diagnosis of active tuberculosis is difficult. In our study children with tuberculous infection without apparent disease who have positive PCR results have mediastinal adenopathies on CT-scan.

Preservation of anaplastic features in Wilms' tumors after preoperative chemotherapy.

In 4 of 35 childhood Wilms' tumors on record in the Hospital Infantil Virgen de Rocio de Sevilla, it was possible to identify diffuse anaplasia despite the fact these children had received cytoreductive chemotherapy preoperatively.