IDENTIFICATION OF MYCOBACTERIUM-TUBERCULOSIS RIBOSOMAL-RNA IN MOUTHWASH SAMPLES FROM PATIENTS WITH TUBERCULOSIS

It is often not possible to obtain satisfactory sputum samples from pa tients suspected of having pulmonary tuberculosis. In this study. we a sked whether it was possible to identify M. tuberculosis ribosomal RNA (rRNA) in mouthwash samples, and in a prospective clinical study, whe ther the presence of this rRNA correlated with clinical M. tuberculosi s infection. Using a combination of reverse transcriptase and polymera se chain reaction amplification, it was possible to identify M. tuberc ulosis rRNA in mouthwash samples. M. tuberculosis rRNA was identified in mouthwash samples from patients with active tuberculosis more commo nly than in samples from control subjects (P<0.05). The test was posit ive in four of ten patients with active pulmonary tuberculosis, one of eight contacts, none of eight past cases of tuberculosis, two of eigh t patients with other diagnosis and one of five healthy volunteers. M. tuberculosis rRNA was identified in sputum from four of eight patient s and in bronchoscopy trap samples from four of five patients with act ive tuberculosis. However, one of ten sputum samples and two of five b ronchoscopy samples from subjects with a clinical diagnosis other than active tuberculosis were positive. These results indicate that althou gh it is technically possible to identify M. tuberculosis on the basis of the presence of rRNA in mouthwash samples, the poor sensitivity an d specificity of the technique suggest that it is unlikely to be usefu l clinically.