title: Diagnosis of lymph node tuberculosis using the GeneXpert MTB/RIF in Tunisia.
abstract: BACKGROUND
  GeneXpert MTB/RIF is a fully-automated diagnostic molecular test which simultaneously detects tuberculosis (TB) and rifampicin (RIF) drug resistance. The purpose of this study is to evaluate the performance of the GeneXpert MTB/RIF test for the detection of Mycobacterium tuberculosis complex (MTBC) in lymph node specimens and to show the place of Mycobacterium bovis as a major cause of TB lymphadenitis.
  
  
  METHODS
  This study was conducted simultaneously in the National Reference Laboratory for Mycobacteria of Ariana and the Central Laboratory of Sfax, from January to December 2013. In total, 174 lymph node specimens were processed simultaneously for Ziehl-Neelsen, auramine and immuno-histochemical staining. Conventional culture on both Lowenstein-Jensen and liquid medium (Bactec MGIT 960 BD system) and the new molecular-based GeneXpert MTB/RIF assay system were performed. Positive cultures were confirmed using molecular identification (Genotype MTBC Hain Lifescience).
  
  
  RESULTS
  Among the 174 samples tested, the GeneXpert detected the DNA of MTBC in 134 samples (77%). Standard bacteriological assays, including AFB microscopy and culture, were positive, respectively, in 41 (23.6%) and 79 (45.4%) specimens. M. bovis was isolated in 76% of positive cultures. GeneXpert sensitivity and specificity results were assessed according to smear and culture results, clinical and histological findings. The sensitivity and specificity of the Xpert assay were 87.5% (126/144) and 73.3%, respectively.
  
  
  CONCLUSIONS
  The implementation of the GeneXpert MTB/RIF assay may dramatically improve the rapid diagnosis of lymph node TB.
authors.affiliation: National Reference Laboratory of Mycobacteria, Microbiology Laboratory, A. Mami Hospital of Pneumology, Ariana, Tunisia; Faculty of Pharmacy, Monastir, Tunisia. Electronic address: ghariani_as@yahoo.fr.
authors.forename: Asma
authors.initials: A
authors.lastname: Ghariani
authors.affiliation: National Reference Laboratory of Mycobacteria, Microbiology Laboratory, A. Mami Hospital of Pneumology, Ariana, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Taha
authors.initials: T
authors.lastname: Jaouadi
authors.affiliation: Bacteriology Laboratory, Hedi Chaker Hospital, Sfax, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Selma
authors.initials: S
authors.lastname: Smaoui
authors.affiliation: National Reference Laboratory of Mycobacteria, Microbiology Laboratory, A. Mami Hospital of Pneumology, Ariana, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Emna
authors.initials: E
authors.lastname: Mehiri
authors.affiliation: Bacteriology Laboratory, Hedi Chaker Hospital, Sfax, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Chama
authors.initials: C
authors.lastname: Marouane
authors.affiliation: Bacteriology Laboratory, Hedi Chaker Hospital, Sfax, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Sana
authors.initials: S
authors.lastname: Kammoun
authors.affiliation: National Reference Laboratory of Mycobacteria, Microbiology Laboratory, A. Mami Hospital of Pneumology, Ariana, Tunisia.
authors.forename: Leila
authors.initials: L
authors.lastname: Essalah
authors.affiliation: Anatomopathology Laboratory, Institut Salah Azaiez, Tunisia.
authors.forename: Maha
authors.initials: M
authors.lastname: Driss
authors.affiliation: Bacteriology Laboratory, Hedi Chaker Hospital, Sfax, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Feriele
authors.initials: F
authors.lastname: Messadi
authors.affiliation: National Reference Laboratory of Mycobacteria, Microbiology Laboratory, A. Mami Hospital of Pneumology, Ariana, Tunisia; Faculty of Pharmacy, Monastir, Tunisia.
authors.forename: Leila
authors.initials: L
authors.lastname: Slim-Saidi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing / Q000295:instrumentation / Q000379:methods*; D009163:Mycobacterium bovis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis / Q000382:microbiology*; D014416:Tunisia; D055815:Young Adult
keywords: Extrapulmonary; Lymph node; Lymphadenitis; Tuberculosis; Xpert