EVALUATION OF THE SEMIAUTOMATED ABBOTT LCX MYCOBACTERIUM-TUBERCULOSISASSAY FOR DIRECT-DETECTION OF MYCOBACTERIUM-TUBERCULOSIS IN RESPIRATORY SPECIMENS

Five hundred twenty processed respiratory specimens from 326 patients received for the diagnosis of tuberculosis or other mycobacterial infe ctions were tested by means of the LCx Mycobacterium tuberculosis Assa y from Abbott Laboratories, which uses ligase chain reaction technolog y for the direct detection of M; tuberculosis comp:eu in respiratory s pecimens, The results of the LCx: ill, tuberculosis Assay were compare d with the results of culture and staining techniques, After a combina tion of culture results and the patient's clinical data, a total of 19 5 specimens were collected from 110 patients who were positively diagn osed as having pulmonary; tuberculosis. Twenty-three of these 195 spec imens which corresponded to 10 patients with a history of pulmonary tu berculosis (TB) and anti-TB treatment ranging from 1 to 6 months were culture negative, The other 172 specimens were culture positive for M. tuberculosis. With an overall positivity rate of 37.5% (195 of 520 sp ecimens), the sensitivity, specificity, and positive and negative pred ictive values were 90.8, 100, 100, and 94.7%, respectively, for the LC x M. tuberculosis Assay; 88.2, 100, 100, and 93.4%, respectively, for culture; and 82.6, 92, 72.9, and 97.6%, respectively; for acid-fast st aining, For 161 specimens (82.6%) from patients smear positive for the disease and 34 specimens (17.4%) from patients smear negative for the disease, the sensitivity values for the LCx nrl. tuberculosis assay w ere 98.8 and 53%, respectively. There were no statistically significan t differences in the sensitivities and specificities between the LCx i ll. tuberculosis Assay and culture (P > 0,05), Conclusively, the LCx n l, tuberculosis Assay has proved to have an acceptable sensitivity and a high specificity in detecting ill, tuberculosis and has the potenti al of reducing the diagnosis time to an 8-h working day.