title: Is frontloaded sputum microscopy an option in active tuberculosis case finding?
abstract: METHODS
  Active tuberculosis (TB) case finding (ACF) in Phnom Penh, Cambodia using light-emitting diode fluorescence microscopy (FM).
  
  
  OBJECTIVE
  To evaluate the smear-positive yield of frontloaded (same-day) smear microscopy in ACF.
  
  
  METHODS
  All presumptive TB cases screened through ACF were asked to provide three sputum specimens: two spot specimens on Day 1 and a morning specimen on Day 2 (spot-spot-morning, SSM). Laboratory technicians blinded to previous results read the smears using FM. We considered only SSM series with at least one positive smear to calculate the proportion of TB cases missed and to determine the difference between the spot-spot (SS) and spot-morning (SM) approach.
  
  
  RESULTS
  Of 4616 presumptive TB patients enrolled, 3306 provided three sputum samples. Of 2957 (89.4%) who followed the SSM approach, 188 (6.4%) were smear-positive: 177 on SM and 160 on SS. The incremental yield of the second sputum sample was 18.1% for SM vs. 9.4% for SS. Relative to any smear-positive case detected by SSM, 28/188 (14.9%, 95%CI 10.1-20.8) TB cases would be missed by SS vs. 11/188 (5.9%, 95%CI 3.0-10.2) by SM. The difference in the proportion of missed TB patients was 9.0% (P = 0.006).
  
  
  CONCLUSIONS
  ACF frontloaded sputum microscopy is inferior in terms of smear-positive yield: the SS approach would have missed a significant proportion of smear-positive TB.
authors.affiliation: Infectious Diseases Department, Sihanouk Hospital Center of HOPE, Phnom Penh, Cambodia; Clinical Sciences Department, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Lorent
authors.affiliation: Clinical Sciences Department, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Buyze
authors.affiliation: Mycobacteriology Laboratory, Sihanouk Hospital Center of HOPE, Phnom Penh, Cambodia.
authors.forename: T
authors.initials: T
authors.lastname: Kim
authors.affiliation: Infectious Diseases Department, Sihanouk Hospital Center of HOPE, Phnom Penh, Cambodia.
authors.forename: C
authors.initials: C
authors.lastname: Kong
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Van Deun
authors.affiliation: Clinical Sciences Department, Institute of Tropical Medicine, Antwerp, Belgium; Epidemiology and Social Medicine, University of Antwerp, Antwerp, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Colebunders
authors.affiliation: Infectious Diseases Department, Sihanouk Hospital Center of HOPE, Phnom Penh, Cambodia.
authors.forename: S
authors.initials: S
authors.lastname: Thai
authors.affiliation: Clinical Sciences Department, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Lynen
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium; Department of Biomedical Sciences, University of Antwerp, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Rigouts
mesh_terms: D000328:Adult; D002160:Cambodia / Q000453:epidemiology; D005240:Feasibility Studies; D005260:Female; D015658:HIV Infections / Q000382:microbiology; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D015995:Prevalence; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods; D013183:Sputum / Q000382:microbiology*; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology*