Setting: In many cases of extra-pulmonary tuberculosis (EPTB), with the exception of paucibacillary analysed specimens, the suspected site of mycobacterial infection is relatively inaccessible or unknown, making laboratory confirmation of TB laborious and problematic.
Objective: Two different polymerase chain reaction (PCR) based methods were compared to investigate the validity of bone marrow aspiration material as an easily accessible alternative sample for molecular analysis in EPTB.
Design: We amplified the same sequence of IS6110 of Mycobacterium tuberculosis complex in 19 confirmed cases of EPTB using two different nested PCR techniques: one in-house 'classic' PCR and another based on LightCycler technology.
Results: Both methods demonstrated the same reliability when performed in samples of infected tissue. However, the LightCycler protocol was superior to the in-house system when applied in bone marrow aspiration material, revealing positivity in 18/19 compared to 13/19 samples of 'classic' PCR.
Conclusion: The application of an optimised LightCycler nested amplification protocol in bone marrow aspirates may promote diagnostic accuracy in difficult and/or urgent cases of EPTB.