title: LED fluorescence microscopy for the diagnosis of pulmonary tuberculosis: a multi-country cross-sectional evaluation.
abstract: BACKGROUND
  The diagnosis of tuberculosis (TB) in resource-limited settings relies on Ziehl-Neelsen (ZN) smear microscopy. LED fluorescence microscopy (LED-FM) has many potential advantages over ZN smear microscopy, but requires evaluation in the field. The aim of this study was to assess the sensitivity/specificity of LED-FM for the diagnosis of pulmonary TB and whether its performance varies with the timing of specimen collection.
  
  
  RESULTS
  Adults with cough ≥2 wk were enrolled consecutively in Ethiopia, Nepal, Nigeria, and Yemen. Sputum specimens were examined by ZN smear microscopy and LED-FM and compared with culture as the reference standard. Specimens were collected using a spot-morning-spot (SMS) or spot-spot-morning (SSM) scheme to explore whether the collection of the first two smears at the health care facility (i.e., "on the spot") the first day of consultation followed by a morning sample the next day (SSM) would identify similar numbers of smear-positive patients as smears collected via the SMS scheme (i.e., one on-the-spot-smear the first day, followed by a morning specimen collected at home and a second on-the-spot sample the second day). In total, 529 (21.6%) culture-positive and 1,826 (74.6%) culture-negative patients were enrolled, of which 1,156 (49%) submitted SSM specimens and 1,199 (51%) submitted SMS specimens. Single LED-FM smears had higher sensitivity but lower specificity than single ZN smears. Using two LED-FM or two ZN smears per patient was 72.8% (385/529, 95% CI 68.8%-76.5%) and 65.8% (348/529, 95% CI 61.6%-69.8%) sensitive (p<0.001) and 90.9% (1,660/1,826, 95% CI 89.5%-92.2%) and 98% (1,790/1,826, 95% CI 97.3%-98.6%) specific (p<0.001). Using three LED-FM or three ZN smears per patient was 77% (408/529, 95% CI 73.3%-80.6%) and 70.5% (373/529, 95% CI 66.4%-74.4%, p<0.001) sensitive and 88.1% (95% CI 86.5%-89.6%) and 96.5% (95% CI 96.8%-98.2%, p<0.001) specific. The sensitivity/specificity of ZN smear microscopy and LED-FM did not vary between SMS and SSM.
  
  
  CONCLUSIONS
  LED-FM had higher sensitivity but, in this study, lower specificity than ZN smear microscopy for diagnosis of pulmonary TB. Performance was independent of the scheme used for collecting specimens. The introduction of LED-FM needs to be accompanied by appropriate training, quality management, and monitoring of performance in the field.
  
  
  BACKGROUND
  Current Controlled Trials ISRCTN53339491. Please see later in the article for the Editors' Summary.
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom. cuevasl@who.int
authors.forename: Luis Eduardo
authors.initials: LE
authors.lastname: Cuevas
authors.forename: Najla
authors.initials: N
authors.lastname: Al-Sonboli
authors.forename: Lovett
authors.initials: L
authors.lastname: Lawson
authors.forename: Mohammed Ahmed
authors.initials: MA
authors.lastname: Yassin
authors.forename: Isabel
authors.initials: I
authors.lastname: Arbide
authors.forename: Nasher
authors.initials: N
authors.lastname: Al-Aghbari
authors.forename: Jeevan Bahadur
authors.initials: JB
authors.lastname: Sherchand
authors.forename: Amin
authors.initials: A
authors.lastname: Al-Absi
authors.forename: Emmanuel Nnamdi
authors.initials: EN
authors.lastname: Emenyonu
authors.forename: Yared
authors.initials: Y
authors.lastname: Merid
authors.forename: Mosis Ifenyi
authors.initials: MI
authors.lastname: Okobi
authors.forename: Juliana Olubunmi
authors.initials: JO
authors.lastname: Onuoha
authors.forename: Melkamsew
authors.initials: M
authors.lastname: Aschalew
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.forename: Greg
authors.initials: G
authors.lastname: Harper
authors.forename: Rachel Mary Anderson
authors.initials: RM
authors.lastname: de Cuevas
authors.forename: Sally Jane
authors.initials: SJ
authors.lastname: Theobald
authors.forename: Carl-Michael
authors.initials: CM
authors.lastname: Nathanson
authors.forename: Jean
authors.initials: J
authors.lastname: Joly
authors.forename: Brian
authors.initials: B
authors.lastname: Faragher
authors.forename: Stephen Bertel
authors.initials: SB
authors.lastname: Squire
authors.forename: Andrew
authors.initials: A
authors.lastname: Ramsay
mesh_terms: D000328:Adult; D019411:Clinical Laboratory Techniques; D003371:Cough / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D012016:Reference Values; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult