Comparison of PCR with standard culture of fine needle aspiration samples in the diagnosis of tuberculosis lymphadenitis

  • Yohannes Derese Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Elena Hailu Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Tekalign Assefa Addis Ababa University, School of laboratory Science, Addis Ababa, Ethiopia
  • Yonas Bekele Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Adane Mihret Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Abraham Aseffa Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Jemal Hussien Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Ibrahim Ali Armauer Hansen Research Institute, Addis Ababa, Ethiopia
  • Markos Abebe Armauer Hansen Research Institute, Addis Ababa, Ethiopia
Keywords: tuberculosis, lymphadenitis, FNA, PCR

Abstract

Introduction: 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.
Methodology: 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.

Author Biographies

Yohannes Derese, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

TB Unit

Research Laboratory technologist

Elena Hailu, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

Molecular Biology

Researcher

Tekalign Assefa, Addis Ababa University, School of laboratory Science, Addis Ababa, Ethiopia
Laboratory technologist
Yonas Bekele, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
Immunologist Research Asistant
Adane Mihret, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

Immunology

Researcher

Abraham Aseffa, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
Scientific Director of AHRI
Jemal Hussien, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

Pathology Unit

Pathologist

Ibrahim Ali, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

TB Unit

PhD student

Markos Abebe, Armauer Hansen Research Institute, Addis Ababa, Ethiopia

Immunology and molecular biology

Postdoctoral Scientist

Published
2011-11-30
How to Cite
1.
Derese Y, Hailu E, Assefa T, Bekele Y, Mihret A, Aseffa A, Hussien J, Ali I, Abebe M (2011) Comparison of PCR with standard culture of fine needle aspiration samples in the diagnosis of tuberculosis lymphadenitis. J Infect Dev Ctries 6:53-57. doi: 10.3855/jidc.2050
Section
Original Articles