title: Has universal screening with Xpert® MTB/RIF increased the proportion of multidrug-resistant tuberculosis cases diagnosed in a routine operational setting?
abstract: METHODS
  Primary health services in Cape Town, South Africa where the introduction of Xpert® MTB/RIF (Xpert) enabled simultaneous screening for tuberculosis (TB) and drug susceptibility in all presumptive cases.
  
  
  OBJECTIVE
  To compare the proportion of TB cases with drug susceptibility tests undertaken and multidrug-resistant tuberculosis (MDR-TB) diagnosed pre-treatment and during the course of 1st line treatment in the previous smear/culture and the newly introduced Xpert-based algorithms.
  
  
  METHODS
  TB cases identified in a previous stepped-wedge study of TB yield in five sub-districts over seven one-month time-points prior to, during and after the introduction of the Xpert-based algorithm were analysed. We used a combination of patient identifiers to identify all drug susceptibility tests undertaken from electronic laboratory records. Differences in the proportions of DST undertaken and MDR-TB cases diagnosed between algorithms were estimated using a binomial regression model.
  
  
  RESULTS
  Pre-treatment, the probability of having a DST undertaken (RR = 1.82)(p<0.001) and being diagnosed with MDR-TB (RR = 1.42)(p<0.001) was higher in the Xpert-based algorithm than in the smear/culture-based algorithm. For cases evaluated during the course of 1st-line TB treatment, there was no significant difference in the proportion with DST undertaken (RR = 1.02)(p = 0.848) or MDR-TB diagnosed (RR = 1.12)(p = 0.678) between algorithms.
  
  
  CONCLUSIONS
  Universal screening for drug susceptibility in all presumptive TB cases in the Xpert-based algorithm resulted in a higher overall proportion of MDR-TB cases being diagnosed and is an important strategy in reducing transmission. The previous strategy of only screening new TB cases when 1st line treatment failed did not compensate for cases missed pre-treatment.
authors.affiliation: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Pren
authors.identifier: http://orcid.org/0000-0002-2681-7110
authors.initials: P
authors.lastname: Naidoo
authors.affiliation: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Rory
authors.initials: R
authors.lastname: Dunbar
authors.affiliation: City Health Directorate, Cape Town, South Africa.
authors.forename: Judy
authors.initials: J
authors.lastname: Caldwell
authors.affiliation: Biostatistics Unit, South African Medical Research Council, Cape Town, South Africa.
authors.forename: Carl
authors.initials: C
authors.lastname: Lombard
authors.affiliation: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Nulda
authors.initials: N
authors.lastname: Beyers
mesh_terms: D000328:Adult; D000465:Algorithms; D000904:Antibiotics, Antitubercular / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D011933:Reagent Kits, Diagnostic; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000904:Antibiotics, Antitubercular; D011933:Reagent Kits, Diagnostic