Direct detection in clinical samples of multiple gene mutations causing resistance of Mycobacterium tuberculosis to isoniazid and rifampicin using fluorogenic probes.

Background: This study evaluates a method based on real-time PCR for direct detection in clinical samples of the common mutations responsible for isoniazid and rifampicin resistance of Mycobacterium tuberculosis.

Methods: Six pairs of fluorogenic 5' exonuclease probes (Taqman), mutated and wild-type, were designed for six targets: codon 315 of katG, substitution C209T in the regulatory region of inhA, and codons 513, 516, 526 and 531 of rpoB.

Results: A total of 98 clinical samples harbouring resistant bacilli from 55 patients and 126 samples harbouring susceptible bacilli from 126 patients were processed.

Catalase-peroxidase activity has no influence on virulence in a murine model of tuberculosis.

The capacity to generate a chronic and persistent infection in the experimental murine model of tuberculosis induced aerogenically by a low-dose inoculum was determined in eight isoniazid-resistant clinical strains of Mycobacterium tuberculosis showing different catalase-peroxidase (C-P) activities. Determination of bacillary concentration in lung and spleen and the percentage of pulmonary parenchyma occupied by granulomas were monitored. Data showed no relation between the lack of C-P activity and the ability to develop a persistent infection, highlighting the potential of C-P negative strains to spread through the community.

Evaluation of two different cell lysis methods for releasing mycobacterial nucleic acids in the INNO-LiPA mycobacteria test.

The INNO-LiPA Mycobacteria Test (Innogenetics, N.V., Belgium) is a PCR-based reverse hybridization assay for the simultaneous identification of several mycobacterial species.

Comparison of the sodium dodecyl sulfate-sodium hydroxide specimen processing method with the C18-carboxypropylbetaine specimen processing method using the MB/BacT liquid culture system.

The ability of physicians to diagnose tuberculosis is impacted by the use of smear and culture techniques combined with specimen processing methods. The objective of this study was to evaluate the effects of specimen processing on smear and culture sensitivity by comparing the specimen processing method that uses C(18)-carboxypropylbetaine with the method that combines sodium dodecyl sulfate and sodium hydroxide. A total of 1,201 specimens were entered into this study.