ABSTRACT
The line probe assay (LiPA), a rapid molecular method for detecting rifampicin resistance (RMPr) in Mycobacterium tuberculosis, correctly identified all 145 rifampicin-sensitive (RMPs) and 262 (98.5%) of 266 RMPr strains among 411 isolates collected from diverse countries. If used as a marker of multidrug-resistant tuberculosis (MDR-TB), detection of RMPr by LiPA would have detected 236 of the 240 MDR strains in this study but would have wrongly suggested the presence of MDR in 26 RMP-monoresistant isolates (sensitivity 98.3%, specificity 84.8%). Hence, the reliability of using LiPA (or any other rapid RMPr-detection method) as a surrogate marker of MDR-TB largely depends on the prevalence of RMP-monoresistance in the study population. This approach must therefore be validated in each local situation.
Subject(s)
Antibiotics, Antitubercular/pharmacology , Drug Resistance , Molecular Probe Techniques , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/isolation & purification , Rifampin/pharmacology , Tuberculosis, Multidrug-Resistant/diagnosis , Tuberculosis, Multidrug-Resistant/microbiology , Africa/epidemiology , Asia/epidemiology , Europe/epidemiology , Humans , Microbial Sensitivity Tests , Sensitivity and Specificity , South America/epidemiology , Species Specificity , Tuberculosis, Multidrug-Resistant/epidemiologyABSTRACT
A total of 624 respiratory specimens from 543 patients (418 Belgian, 110 Rwandan, and 15 Colombian patients) were tested for the presence of Mycobacterium tuberculosis by the Mycobacterium Tuberculosis Direct Test (MTDT, Gen-Probe). Compared to culture, the MTDT on 497 samples of sputum or broncho-alveolar lavage from Belgium had a sensitivity, specificity and positive and negative predictive value of 86.4%, 96.0%, 50.0% and 99.3% respectively. The pooled results for Rwanda (112 specimens) and Colombia (15 specimens) were 97.8%, 65.7%, 88.2%, 92% respectively. After resolution of discrepant results by taking into account the clinical data, the results for the Belgian patients were 86.9%, 96.2%, 52.6%, 99.3% respectively, and for the Rwandan-Colombian patients 98.1%, 100%, 100% and 92% respectively. Results could be improved by testing more than one specimen from each patient and the inclusion of an internal control to detect inhibitors of the reaction. Culture remains necessary for drug susceptibility tests and the isolation and identification of non-tuberculous mycobacteria.