Bone marrow aspirate microscopy v. bone marrow trephine biopsy microscopy for detection of Mycobacterium tuberculosis infection.

Background: Tuberculosis (TB) remains a global health problem. According to the 2013 Global Report on Tuberculosis, 8.6 million people developed TB in 2012 and 1.3 million died from the disease. An estimated 13% of people who developed TB in 2012 were HIV-positive, and 75% of these lived in Africa. While pulmonary TB is the commonest form of Mycobacterium tuberculosis infection, extrapulmonary TB is increasingly being detected in HIV-positive patients. Definitive diagnosis of disseminated TB is a challenge owing to atypical presentations and diagnostic difficulties (negative chest radiograph and sputum microscopy and culture). A rapid diagnosis of disseminated TB is desirable, as early initiation of treatment can reduce mortality. Although TB culture is the gold standard for diagnosis of TB, it has a long turnaround time (up to 6 weeks).

Objectives: To identify a potentially faster and more effective diagnostic strategy for disseminated TB.

Methods: A retrospective 18-month review, conducted at a tertiary hospital, comparing histological findings of an auramine O-stained bone marrow aspiration (BMA) smear and a bone marrow trephine (BMT) biopsy specimen with the gold standard of TB culture.

Results: Microscopic examination of BMA smears and BMT biopsy specimens offers a rapid diagnostic strategy, with results available on the same day for the former and within 4 days for the latter. BMT histological examination had a significantly higher detection rate than BMA auramine O staining compared with TB culture.

Conclusion: We recommend that BMT biopsies remain an essential part of the diagnostic work-up for disseminated TB.