title: Comparison of two laboratory-developed PCR methods for the diagnosis of pulmonary tuberculosis in Brazilian patients with and without HIV infection.
abstract: BACKGROUND
  Direct smear examination with Ziehl-Neelsen (ZN) staining for the diagnosis of pulmonary tuberculosis (PTB) is cheap and easy to use, but its low sensitivity is a major drawback, particularly in HIV seropositive patients. As such, new tools for laboratory diagnosis are urgently needed to improve the case detection rate, especially in regions with a high prevalence of TB and HIV.
  
  
  OBJECTIVE
  To evaluate the performance of two in house PCR (Polymerase Chain Reaction): PCR dot-blot methodology (PCR dot-blot) and PCR agarose gel electrophoresis (PCR-AG) for the diagnosis of Pulmonary Tuberculosis (PTB) in HIV seropositive and HIV seronegative patients.
  
  
  METHODS
  A prospective study was conducted (from May 2003 to May 2004) in a TB/HIV reference hospital. Sputum specimens from 277 PTB suspects were tested by Acid Fast Bacilli (AFB) smear, Culture and in house PCR assays (PCR dot-blot and PCR-AG) and their performances evaluated. Positive cultures combined with the definition of clinical pulmonary TB were employed as the gold standard.
  
  
  RESULTS
  The overall prevalence of PTB was 46% (128/277); in HIV+, prevalence was 54.0% (40/74). The sensitivity and specificity of PCR dot-blot were 74% (CI 95%; 66.1%-81.2%) and 85% (CI 95%; 78.8%-90.3%); and of PCR-AG were 43% (CI 95%; 34.5%-51.6%) and 76% (CI 95%; 69.2%-82.8%), respectively. For HIV seropositive and HIV seronegative samples, sensitivities of PCR dot-blot (72% vs 75%; p=0.46) and PCR-AG (42% vs 43%; p=0.54) were similar. Among HIV seronegative patients and PTB suspects, ROC analysis presented the following values for the AFB smear (0.837), Culture (0.926), PCR dot-blot (0.801) and PCR-AG (0.599). In HIV seropositive patients, these area values were (0.713), (0.900), (0.789) and (0.595), respectively.
  
  
  CONCLUSIONS
  Results of this study demonstrate that the in house PCR dot blot may be an improvement for ruling out PTB diagnosis in PTB suspects assisted at hospitals with a high prevalence of TB/HIV.
authors: Post Graduation Program in Biological Science-Biochemistry Department, Federal University of Rio Grande do Sul-UFRGS, Porto Alegre/RS/Brazil. luciene.scherer@hotmail.com
authors: Luciene C
authors: LC
authors: Scherer
authors: Rosa D
authors: RD
authors: Sperhacke
authors: Carla
authors: C
authors: Jarczewski
authors: Patrícia I
authors: PI
authors: Cafrune
authors: Candice T
authors: CT
authors: Michelon
authors: Rubia
authors: R
authors: Rupenthal
authors: Marta Osorio
authors: MO
authors: Ribeiro
authors: Antonio Ruffino
authors: AR
authors: Netto
authors: Maria L R
authors: ML
authors: Rossetti
authors: Afrânio L
authors: AL
authors: Kritski
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D015897:Comorbidity; D004269:DNA, Bacterial / Q000235:genetics; D015658:HIV Infections / Q000175:diagnosis / Q000453:epidemiology*; D015497:HIV-1 / Q000276:immunology; D015498:HIV-2 / Q000276:immunology; D006801:Humans; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D015995:Prevalence; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology*
chemical_list: D000914:Antibodies, Viral; D004269:DNA, Bacterial