| Summary: | MMed, Haematology, Faculty of Health Sciences, University of the Witwatersrand === Background: Mycobacterium tuberculosis (MTB) infection remains a serious
public health challenge in sub-Saharan Africa. Rapid and early diagnosis is critical
in the successful control of this eminently treatable infection.
This study compared the diagnostic usefulness of culture, bone marrow trephine
biopsy granulomata, bone marrow trephine biopsy Ziehl-Neelsen (ZN) stain and
bone marrow mycobacterial polymerase chain reaction (PCR) in establishing the
diagnosis of mycobacterial infection in HIV infected patients.
Materials and methods: The trephine biopsies of HIV positive patients done for
the investigation of suspected tuberculosis were reviewed for granulomata and
stained with ZN stain. The corresponding bone marrow aspirates were subjected
to DNA real-time PCR analyses using LightCyler TB Kit® (Roche Diagnostic).
Culture results were used as diagnostic gold standard.
Results: Of the 60 patients studied, 24 were culture negative. Of the 34 culture
positive, 62% were Mycobacterium tuberculosis and 38% were Mycobacterium
avium intracellulare.
Using the culture method as a gold standard, the sensitivities and specificities
were 97% and 23% for bone marrow trephine biopsy granulomata, 65% and 58%
for bone marrow trephine biopsy ZN staining and 50% and 73% for bone marrow
aspirate PCR analysis respectively. Ninety-seven percent of all trephine biopsies
with positive ZN stain had granulomata.
Conclusion: The presence of granulomata in bone marrow trephine biopsies of
HIV infected patients appear to have a high diagnostic yield whilst mycobacterial
PCR has the lowest yield but highest specificity. These results should be confirmed
in a prospective case controlled study because the sample size in this study was
small, and the study was a retrospective one.
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