Detecting Mycobacterium tuberculosis complex DNA, based on post-mortem examination of hilar lymph nodes with real-time PCR: initial study.

INTRODUCTION: According to the WHO, almost a third of the world population are thought to be infected with Mycobacterium tuberculosis. Some studies of the prevalence of latent tuberculosis infection (LTBI) have already been performed in Poland, showing that almost a quarter of the Mazovia population could be infected. It also indicated a higher prevalence of LTBI among seniors. Those studies were based on indirect diagnostic methods. MATERIAL AND METHODS: We randomly collected hilar lymph nodes from decedents aged 40 years and older during post-mortem examination. We excluded patients with previous confirmed tuberculosis. In addition, an autopsy was performed in all patients. Finally, we used real-time PCR Xpert MTB/RIF (Cepheid, USA) for the specific capture of mycobacterial DNA. RESULTS: Twenty-two of 23 patients had a negative result of the real-time PCR examination and no signs of caseous necrosis in hilar lymph nodes. We found the only positive sample in a patient with histopathological signs of tuberculosis (the presence of caseous necrosis in the specimens obtained from lymph nodes and lung). Due to the change of cartridges from version G3 to G4, further reactions were inhibited and no more post-mortem samples were tested. CONCLUSIONS: Real-time PCR Xpert MTB/RIF was capable of detecting M. tuberculosis complex DNA in a patient with tuberculosis recognised on autopsy. In the remaining patients, no M. tuberculosis complex DNA was found, in accordance with negative results of histological examination. Since the technology of cartridges has changed, it is no longer possible to use real-time PCR Xpert MTB/RIF (Cepheid USA) on post-mortem material.