title: Use of Xpert(®) MTB/RIF assay in the first national anti-tuberculosis drug resistance survey in Pakistan.
abstract: METHODS
  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.
authors.affiliation: National Tuberculosis Control Programme and National Tuberculosis Reference Laboratory, Islamabad, Pakistan.
authors.forename: S
authors.initials: S
authors.lastname: Tahseen
authors.affiliation: National Tuberculosis Control Program Pakistan, Islamabad, Pakistan.
authors.forename: E
authors.initials: E
authors.lastname: Qadeer
authors.affiliation: National Tuberculosis Control Programme and National Tuberculosis Reference Laboratory, Islamabad, Pakistan.
authors.forename: F M
authors.initials: FM
authors.lastname: Khanzada
authors.affiliation: National Tuberculosis Control Programme and National Tuberculosis Reference Laboratory, Islamabad, Pakistan.
authors.forename: A H
authors.initials: AH
authors.lastname: Rizvi
authors.affiliation: Global TB Programme, World Health Organization, Geneva, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Dean
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Van Deun
authors.affiliation: Global TB Programme, World Health Organization, Geneva, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Zignol
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D024901:Drug Resistance, Multiple, Bacterial; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods*; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D010154:Pakistan; D015995:Prevalence; D015203:Reproducibility of Results; D012293:Rifampin / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D011795:Surveys and Questionnaires; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy*; D055815:Young Adult
chemical_list: D000904:Antibiotics, Antitubercular; D012293:Rifampin