Use of Xpert® MTB/RIF assay in the first national anti-tuberculosis drug resistance survey in Pakistan

• Published in: The international journal of tuberculosis and lung disease Vol. 20; no. 4; pp. 448 - 455
• Main Authors: Tahseen, S., Qadeer, E., Khanzada, F. M., Rizvi, A. H., Dean, A., Van Deun, A., Zignol, M.
• Format: Journal Article
• Language: English
• Published: France International Union Against Tuberculosis and Lung Disease 01-04-2016
• Subjects: Adolescent; Adult; Aged; Antibiotics, Antitubercular - therapeutic use; Cluster Analysis; Cross-Sectional Studies; Drug Resistance; Drug Resistance, Multiple, Bacterial; Feasibility Studies; Female; Humans; Logistic Models; Male; Mdr-Tb; Microbial Sensitivity Tests - methods; Middle Aged; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - isolation & purification; Pakistan; Prevalence; Reproducibility of Results; rifampicin; Rifampin - therapeutic use; Sensitivity and Specificity; Sputum - microbiology; Surveillance; Surveys and Questionnaires; Tuberculosis; Tuberculosis, Multidrug-Resistant - diagnosis; Tuberculosis, Multidrug-Resistant - drug therapy; Young Adult
• ISSN: 1027-3719; 1815-7920
• DOI: 10.5588/ijtld.15.0645

SETTING: The first national anti-tuberculosis drug resistance survey in Pakistan, a high tuberculosis (TB) and low human immunodeficiency virus (HIV) burden country.OBJECTIVE: To determine the proportion of patients with multidrug-resistant TB (MDR-TB) and to compare the performance
of Xpert® MTB/RIF with conventional phenotypic drug susceptibility testing (DST).METHODS: Sputum samples were collected from 1972 consecutively enrolled pulmonary TB patients from 40 clusters. Phenotypic DST was performed in parallel with Xpert.RESULTS: The proportion
of MDR-TB patients was 3.7% (95%CI 2.5-5.0) among new and 18.1% (95%CI 13.0-23.4) among previously treated cases. A valid rifampicin (RMP) testing result was available from substantially more cases with Xpert (n = 1809) than with phenotypic DST (n = 1592). Among strains
with discordant results, rpoB sequencing revealed only one false-resistant result (new TB case) with Xpert and 7.7% (8/104) of RMP-resistant cases missed with Xpert against 3.8% (4/14) by phenotypic DST. This difference was not significant.CONCLUSIONS: This survey provides the first
representative data for Pakistan on its MDR-TB burden. The Xpert assay had nearly 100% specificity, even in a low MDR-TB prevalence setting. The use of this assay greatly simplifies survey logistics, making it a feasible option for survey implementation, especially in resource-constrained
settings.