Abstract
Background: Mycobacterium tuberculosis is supposed to stay in a quiescent state when it establishes a latent infection, being unable to grow in culture.
Objectives: The aim of this study was to evaluate the detection of noncultivable bacilli in human clinical samples using a procedure that is independent of the immunological status of the patient.
Materials/Patients and methods: The study was performed on 61 samples obtained from samples received for routine diagnosis to rule out a mycobacterial infection. Specimens from pulmonary and extra-pulmonary origins were studied by real-time quantitative PCR and the amplification of Mycobacterium tuberculosis was observed at the DNA and RNA levels. Clinical records of 52 patients were also reviewed.
Results: Mycobacterium tuberculosis genomic sequences were detected in all culturepositive samples whereas they were detected in 26% of the culture-negative samples, including 24% with a basal metabolic activity detected.
Conclusions: We were able to detect viable but non-cultivable bacilli with a metabolic activity in both pulmonary and extra-pulmonary samples. The amplifications of the ftsZ gene and of the main promoter of the ribosomal operon, namely PCL1, seem to be good targets to detect active bacilli putatively involved in latent Tuberculosis.
- © 2011 ERS