Value of mycobacterium tuberculosis direct assay in early diagnosis of extrapulmonary tuberculosis.

The objective of the present study is to evaluate in situ detection of living mycobacterium tuberculosis rRNA using Mycobacterium Tuberculosis Direct Assay (MTD) and its clinical significance in early diagnosis of extrapulmonary tuberculosis. 86 patients having been diagnosed to have extrapulmonary tuberculosis including tuberculous peritonitis (n=22), lymphatic tuberculosis (n=21), tuberculous meningitis (n=15), HIV-associated tuberculosis (n=13), nephrotuberculosis (n=9), spinal tuberculosis (n=2), cutaneous tuberculosis (n=13), parotid tuberculosis (n=1), chest wall tuberculosis (n=1), intestinal tuberculosis (n=1) were recruited from Shanghai Public Health Clinical Center from June to November in 2010, 105 extrapulmonary specimens including CSF, puncture fluid, drainage, pleural fluid, urine, secrete, ascites, lymphatic tissue and marrow were collected from those patients. The samples were examined using acid fast stain, solid culture, liquid culture and MTD in parallel. In MTD, the target segments of MTB rRNA in either cultures or clinical specimens were amplified prior to be qualitatively detected with hybridization protection assay (HPA). The sensitivity of MTD, acid fast stain, liquid culture and solid culture was 48.6%, 41.9%, 20.0% and 14.3% respectively. MTD's sensitivity was higher than the others and its specificity was 100%. MTD rRNA detection is an effective, rapid, convenient, sensitive and reliable method in early diagnosis of extrapulmonary TB.