Evaluation of the polymerase chain reaction in the diagnosis of miliary tuberculosis in bone marrow smear.

OBJECTIVE

Miliary tuberculosis (MTB) is difficult to diagnose. When prompt diagnosis is necessary, the polymerase chain reaction (PCR) to detect mycobacterial DNA may be valuable.

SETTING

Tuberculosis clinic in an academic tertiary-level hospital in Mexico.

DESIGN

Bone marrow (BM) aspiration samples from 30 consecutive clinically suspected MTB patients and 58 non-tuberculosis hematologic patients were evaluated by in-house PCR using a fragment of the insertion sequence IS6110; results were compared with those obtained by acid-fast-stained smears, culture in Löwenstein-Jensen medium, histology, and serology.

RESULTS

Tuberculosis diagnosis was confirmed in all MTB suspects, 28 by microscopy and culture in pulmonary or extra-pulmonary samples other than BM, and two by clinical and radiologic improvement after antituberculosis treatment. In fresh BM specimens, in-house PCR was positive in 21/30 (70%) suspects, contrasting with only one positive (3.3%) in staining and culture, and four with compatible histologic findings (13.3%). BM samples from the control group showed negative results in bacteriologic and histologic studies, except in nine who had positive PCR results. These nine control cases had malignant processes.

CONCLUSION

PCR in aspirates of BM is a useful diagnostic assay in cases of MTB, mainly when bacteriological results are negative.