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Rapid and efficient detection of extra-pulmonary Mycobacterium tuberculosis by PCR analysis
L Portillo-Gómez1, S L Morris, A Panduro
1Molecular Biology in Medicine, Hospital Civil de Belén, CUCS, University of Guadalajara, Mexico. hcivil@udgserv.cencar.udg.mx
Setting:
The diagnosis of extra-pulmonary tuberculosis (EPTB) remains an important clinical problem, primarily because of the inadequate sensitivity of conventional bacteriologic methods for detecting Mycobacterium tuberculosis in extra-pulmonary specimens.
Objective:
To evaluate whether a IS6110-based polymerase chain reaction (PCR) method can be utilized to detect M. tuberculosis in non-pulmonary specimens.
Design:
Specimens from 286 Mexican patients with a presumptive clinical diagnosis of EPTB were prospectively examined by Ziehl-Neelsen staining, mycobacterial culture on Löwenstein-Jensen slants, and by PCR. The DNA for PCR was extracted by the buffer lysis method and phenol-guanidine thiocyanate-chloroform. Primers that amplify a 200 bp fragment from the insertion-like M. tuberculosis sequence element IS6110 were utilized.
Results:
Our results demonstrate that this PCR method is highly specific (100%) for identifying M. tuberculosis from a variety of specimens including cerebrospinal fluid (CSF), pleural fluid, ascitic fluid, pericardial fluid, urine, and lymph node exudate. Moreover, the sensitivity of PCR for detecting M. tuberculosis in CSF (94%), pleural fluid (94%), ascitic fluid and other extrapulmonary specimens (93%) greatly exceeds the sensitivity of conventional smear and culture methods.
Conclusion:
These results demonstrate that PCR can be a highly specific and sensitive aid in the detection of M. tuberculosis from extra-pulmonary specimens.