COMPARISON OF SOLID AND LIQUID CULTURE MEDIA WITH THE POLYMERASE CHAIN-REACTION FOR DETECTION OF MYCOBACTERIUM-TUBERCULOSIS IN CLINICAL-SAMPLES

The aim of this study was to determine the sensitivity of different me thods - two commercial polymerase chain reaction (PCR) kits (a protoco l of nested PCR and a protocol of amplification of the IS6110 insertio n element), the radiometric Bactec system, the Septi-Chek AFB culture system, and culture in Lowenstein-Jensen (LJ) solid medium for the det ection of Mycobacterium tuberculosis. One hundred clinical samples fro m 51 patients with culture-positive tuberculosis (81 specimens) and 19 controls (19 specimens) were used. Eighty-nine percent of the samples were smear negative. In the 81 specimens obtained from patients with tuberculosis, the frequency of positivity was 66.6% for nested PCR, 63 % for culture in liquid media, 38.3% for the IS6110 assay, and 28.4% f or culture on LJ medium. In 18 samples obtained by invasive procedures in patients with tuberculosis, mycobacterial DNA was detected by nest ed PCR in 83.3% (including all samples positive by culture on liquid m edia), by culture in liquid media in 77.7%, by culture on LJ medium in 27.7%, and by the IS6110 assay in 11.1%. No false-positive results we re obtained from the negative control specimens with any of the techni ques tested. The sensitivity of the reamplification protocol appears t o be superior to that of the IS6110 assay and similar to that of the B actec system.