Clinical utility of a commercial ligase chain reaction kit for the diagnosis of smear-negative pulmonary tuberculosis.
METHODS
In paucibacillary forms of smear-negative tuberculosis it is very difficult to establish a correct and rapid diagnosis, as several weeks are usually required to obtain positive results from culture. In the last few years new rapid techniques based on molecular biology for the detection of Mycobacterium tuberculosis have been introduced.


OBJECTIVE
The aim of this study was to evaluate the utility of the ligase chain reaction method (LCx, Abbott) for the diagnosis of smear-negative pulmonary tuberculosis.


METHODS
Thirty smear-negative patients with radiographic changes and clinical signs consistent with TB participated in the study. Sputum and bronchial aspirate were assessed according to traditional methods on Löwenstein-Jensen medium, and bronchoalveolar lavage (BAL) was assessed by the LCx test and the Bactec 460 system. Another 30 patients with non-tuberculous infections were included in the study as controls.


RESULTS
Of the 30 patients suspected of tuberculosis, 19 had active disease on clinical, bacteriological and radiographic grounds, nine inactive tuberculosis and two had lung cancer. Bacteriological confirmation was obtained in 12 of the 19 (63.2%) patients with active tuberculosis. The sensitivity of sputum culture was 42.1% and bronchial aspirate culture 47.4%. BAL fluid revealed positive results in 57.9% using both LCx and Bactec. The results of the LCx assay can be obtained in 5 hours as opposed to several weeks using other methods.


CONCLUSIONS
The LCx test may be useful in the diagnosis of smear-negative pulmonary tuberculosis and may be recommended in these clinical situations.
Kwiatkowska
S
S
Department of Pneumology and Allergology, Medical University of Lódz, Poland.
Marczak
J
J
Zieba
M
M
Nowak
D
D
D000328:Adult; D001431:Bacteriological Techniques; D001992:Bronchoalveolar Lavage Fluid; D004269:DNA, Bacterial / Q000378:metabolism*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*
D004269:DNA, Bacterial; D011933:Reagent Kits, Diagnostic; D008025:Ligases