title: Comparative performance of PCR-based assay versus microscopy and culture for the direct detection of Mycobacterium tuberculosis in clinical respiratory specimens in Lebanon.
abstract: METHODS
  American University of Beirut Medical Center, Lebanon.
  
  
  OBJECTIVE
  To assess the performance of a polymerase chain reaction (PCR) using primers that flank 542 bp within IS6110 in Mycobacterium tuberculosis (TB) vs. microscopy and BACTEC culture, in the diagnosis of tuberculosis.
  
  
  METHODS
  A total of 82 clinical respiratory pulmonary specimens and 73 samples from BACTEC vials were tested by the three methods.
  
  
  RESULTS
  Of 24 smear-positive culture-positive (SP-CP) and 11 smear-negative culture-positive (SN-CP) TB specimens, PCR detected 83% and 64%, respectively. Among 17 specimens yielding mycobacteria other than tuberculosis (MOTT), the PCR was positive in 33% SP-CP and 14% SN-CP specimens. Among the 73 BACTEC vials, PCR was positive in 36 of 38 (95%) yielding culture-positive TB, and in one of 20 (5%) yielding culture positive MOTT. None of the 30 smear-negative culture-negative (SN-CN) clinical specimens and 15 of the CN vials were positive by PCR. The overall sensitivity of PCR was 77% and 95% for TB detection in respiratory specimens and BACTEC vials, respectively, and the specificity was 94% in both.
  
  
  CONCLUSIONS
  Because a substantial number of TB cases are missed, especially in SN-CP specimens, a PCR-based assay utilizing these primers cannot be used reliably, alone, in clinical laboratory diagnosis of mycobacterial respiratory infections.
authors.affiliation: Department of Pathology and Laboratory Medicine, American University of Beirut, Lebanon. garaj@aub.edu.lb
authors.forename: G F
authors.initials: GF
authors.lastname: Araj
authors.forename: R S
authors.initials: RS
authors.lastname: Talhouk
authors.forename: L Y
authors.initials: LY
authors.lastname: Itani
authors.forename: W
authors.initials: W
authors.lastname: Jaber
authors.forename: G W
authors.initials: GW
authors.lastname: Jamaleddine
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000032:analysis*; D006801:Humans; D007861:Lebanon; D008853:Microscopy / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000254:growth & development*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial