[Studies on 5 kinds of methods combination for detection of smear and culture negative pulmonary tuberculosis]

To evaluate the diagnostic value of 5 kinds of methods used jointly for smear and culture negative pulmonary tuberculosis.

The high specificity methods were PCR examination for sputum TB-DNA, immunological examination (ELISA method) for serum LAM IgG, PPD IgG, SCIC and PPD 0.1 U skin test. Smear and culture positive cases were 31, smear and culture negative 54, healthy control 53, other lung disease 30. Methods were used for every case synchronously, then the sensitivity and specificity of single method and the diagnostic value of single and joint examination for smear and culture negative patients were evaluated.

In single examination sensitivity of PCR, LAM IgG, PPD IgG, SCIC, PPD 0.1 U was 96.8%, 69.2%, 62.1%, 32.0%, 53.8% respectively; specificity was 96.2%, 98.1%, 98.1%, 98.1% correspondingly. The positive detection rate of single examination for sputum TB negative patients was just 21.4%-44.4%. In combination examination the positive rates increased remarkblely by the number combined from 2 to 5, they were 66.9%, 70.5%, 80.4%, 85.7% respectively and they were more notable than that of TB positive group. The specificity of combination examination was slightly decreased by the number combined. It decreased just by 9% and the specificity of most examination methods kept on no less than 90%.

For diagnosis of smear and culture negative pulmonary tuberculosis combination examination using the high specificity methods can increase the sensitivity obviously and the specificity just decrease slightly. It is valuable for widely use of combination method in detection of smear and culture negative patients.