title: Comparison of PCR with standard culture of fine needle aspiration samples in the diagnosis of tuberculosis lymphadenitis.
abstract: BACKGROUND
  Lymphadenopathy is the commonest form of extrapulmonary tuberculosis (TB) Clinical diagnosis of TB in lymph nodes requires aspiration of the material and isolation of mycobacteria.  Bacterial culture is the gold standard for detection of tubercle bacilli, but it is time-consuming and requires specialized safety procedures and a BSL3 laboratory. However, PCR is a rapid method which requires small volumes of samples and can also be performed on killed bacilli to ensure safety. This project was designed to compare direct fine needle aspirate (FNA) PCR with culture in the diagnosis of tuberculosis lymphadenitis.
  
  
  METHODS
  Direct examination of samples with EZN staining, culture, cytology and PCR was performed on previously collected FNA from the patients with suspected tuberculosis lymphadenitis.
  
  
  RESULTS
  In total, 38% of the samples were positive for TB by culture, 11.8% by EZN staining, 23.4% by PCR, and 59.8% by cytology. Cytology had the highest sensitivity (81%) and EZN stain the least (22.9%). The specificity of EZN stain was the highest (92.4%) while cytology was the lowest (50%). In this study, out of 50 culture-positive samples, 21 (42%) were positive by PCR while 8 (10.8%) out of 74 culture-negative samples were positive by PCR.
  
  
  CONCLUSIONS
  Although PCR is a sensitive diagnostic method, its sensitivity was shown to be low in this study. Therefore, we recommend that further studies should be conducted on fresh aspirate samples to investigate for possible PCR inhibitors which may limit the sensitivity of PCR diagnosis.
authors.affiliation: Armauer Hansen Research Institute, Addis Ababa, Ethiopia. yohannesderese@gmail.com
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Derese
authors.forename: Elena
authors.initials: E
authors.lastname: Hailu
authors.forename: Tekalign
authors.initials: T
authors.lastname: Assefa
authors.forename: Yonas
authors.initials: Y
authors.lastname: Bekele
authors.forename: Adane
authors.initials: A
authors.lastname: Mihret
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.forename: Jemal
authors.initials: J
authors.lastname: Hussien
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Ali
authors.forename: Markos
authors.initials: M
authors.lastname: Abebe
mesh_terms: D000293:Adolescent; D000328:Adult; D001431:Bacteriological Techniques; D044963:Biopsy, Fine-Needle / Q000379:methods; D002648:Child; D002675:Child, Preschool; D003470:Culture Media; D003584:Cytological Techniques; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D005002:Ethiopia; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000382:microbiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis* / Q000382:microbiology; D055815:Young Adult
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial