Molecular diagnosis of pulmonary tuberculosis by automated extraction and real-time PCR on non-decontaminated pulmonary specimens

Excerpt

With the incidence of tuberculosis still increasing, the infection is considered a worldwide public health priority by the World Health Organization. The picture looks similar in countries with both high- and low-level endemicity. In countries with low endemicity, the highest incidence is presently observed in migrant populations originating from highly endemic areas. This is exemplified by the current situation in France, particularly in cities like Paris and its suburbs [1, 2]. Because of the slow growth of mycobacteria, conventional laboratory procedures may require turnaround times of 3–4 weeks or longer. Molecular assays thus represent a good alternative, facilitating rapid and precise identification to the species level. When assessing molecular assays and culture in association with treatment success, similar sensitivities have been observed [3, 4]. Previous studies have also found molecular assays to always be more sensitive than acid-fast bacilli (AFB) smears [3, 4]. Over the years, PCR technologies have steadily improved, and real-time-based platforms currently seem to offer numerous advantages over conventional nucleic acid amplification assays. Real-time PCR (RT-PCR) using two primers and a specific detection probe is a recent molecular method that offers many advantages, and is now used for the detection and identification of viruses, bacteria and mycobacteria [5]. The aim of the present study was to evaluate a fully automated DNA extraction method followed by RT-PCR for rapidly detecting Mycobacterium tuberculosis DNA and diagnosing pulmonary tuberculosis; the method was applied directly to non-decontaminated respiratory specimens from patients suspected of having pulmonary tuberculosis. …