Use of a Molecular Diagnostic Test in AFB Smear Positive Tuberculosis Suspects Greatly Reduces Time to Detection of Multidrug Resistant Tuberculosis

Abstract

BackgroundThe WHO has recommended the implementation of rapid diagnostic tests to detect and help combat M/XDR tuberculosis (TB). There are limited data on the performance and impact of these tests in field settings.MethodsThe performance of the commercially available Genotype MTBDRplus molecular assay was compared to conventional methods including AFB smear, culture and drug susceptibility testing (DST) using both an absolute concentration method on Löwenstein-Jensen media and broth-based method using the MGIT 960 system. Sputum specimens were obtained from TB suspects in the country of Georgia who received care through the National TB Program.ResultsAmong 500 AFB smear-positive sputum specimens, 458 (91.6%) had both a positive sputum culture for Mycobacterium tuberculosis and a valid MTBDRplus assay result. The MTBDRplus assay detected isoniazid (INH) resistance directly from the sputum specimen in 159 (89.8%) of 177 specimens and MDR-TB in 109 (95.6%) of 114 specimens compared to conventional methods. There was high agreement between the MTBDRplus assay and conventional DST results in detecting MDR-TB (kappa = 0.95, p<0.01). The most prevalent INH resistance mutation was S315T (78%) in the katG codon and the most common rifampicin resistance mutation was S531L (68%) in the rpoB codon. Among 13 specimens from TB suspects with negative sputum cultures, 7 had a positive MTBDRplus assay (3 with MDR-TB). The time to detection of MDR-TB was significantly less using the MTBDRplus assay (4.2 days) compared to the use of standard phenotypic tests (67.3 days with solid media and 21.6 days with broth-based media).ConclusionsCompared to conventional methods, the MTBDRplus assay had high accuracy and significantly reduced time to detection of MDR-TB in an area with high MDR-TB prevalence. The use of rapid molecular diagnostic tests for TB and drug resistance should increase the proportion of patients promptly placed on appropriate therapy.

Evaluation of Drug Induced Liver Injury in Tuberculosis and Hepatitis Coinfection by Liver Fibrosis Index Score

“…Our results are comparable with results of other investigator who found that the onset of DILI ranged from 13 days to 58 days (median, 26 days) after initiation of treatment [36]. And in another study, the median latent period for developing DILI was found to be 19 [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] days [37].…”

“…Culture was performed using solid (Lowenstein-Jensen) and liquid (MGIT BACTEC 960) media using standard methodologies [14,15].…”

Rendimiento de la prueba Xpert MTB/RIF en muestras respiratorias en un escenario real de trabajo de un país en desarrollo

“…The national surveillance study on resistance to anti-TB drugs conducted in Colombia during 2004 and 2005 showed a prevalence of MDR-TB among untreated patients of 2.38% (95% CI 1.58 -3.57) and of 50.6% among patients classified in Category I treatment failure (basic scheme for new tuberculosis patients) (21). In a recent study, a molecular test reduced MDR-TB detection time from 67.3 days (solid medium) and 21.6 days (liquid medium) to less than 5 days (4.2 days) compared to phenotypic methods (22).…”

Lung Tissue Concentrations of Pyrazinamide among Patients with Drug-Resistant Pulmonary Tuberculosis

“…Prior to culture, all tissue samples were first homogenized with a tissue grinder before inoculation on Lowenstein-Jensen (LJ)-based solid medium. For cultures with growth of M. tuberculosis, first-and second-line DST was performed as previously described (26,27). DST for pyrazinamide was not performed.…”