title: Identification of the causative organism of tuberculous lymphadenitis in ethiopia by PCR.
abstract: Tuberculous lymphadenitis (TBLN) is a common form of extrapulmonary tuberculosis with multiple differential diagnoses. Demonstration of the etiologic agent by smear microscopy or culture of fine needle aspirate (FNA) specimens is often unsuccessful. FNA specimens from 40 patients presenting at a rural health center in South Ethiopia and diagnosed as positive for TBLN on the basis of clinical and cytological criteria were analyzed for mycobacterial DNA by PCR. Thirty (75%) had cervical lymphadenitis and 11 (27.5%) were seropositive for human immunodeficiency virus (HIV). Three primer sets were initially used to identify the causative agent at the genus (antigen 85 complex), complex (IS6110 insertion sequence), and species (pncA gene and allelic variation) levels. Among the forty TBLN cases, 35 (87.5%) were positive by PCR at the genus and complex levels. Based on PCR for detection of allelic variation at position 169, 24 (68.6%) of the 35 were positive for Mycobacterium tuberculosis and 6 (17.1%) were positive for M. bovis. These six were positive in additional PCR assays using the JB21-JB22 primer set, which is highly specific for M. bovis. Five (14.1%) showed amplification for both M. tuberculosis and M. bovis with the allele-specific primer set. Cooccurrence of pyrazinamide (PZA)-sensitive and -resistant M. tuberculosis in those five cases was indicated, since all were negative in assays with the JB21-JB22 primer set. This feature was seen in 3 of 11 HIV-positive and 2 of 29 HIV-negative individuals (P < 0.001).
  
  
  CONCLUSIONS
  among 35 PCR-positive cases of TBLN from southern Ethiopia, 29 (82.9%) were caused by M. tuberculosis and six (17.1%) were caused by M. bovis.
authors.affiliation: Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia.
authors.forename: Dawit
authors.initials: D
authors.lastname: Kidane
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Olobo
authors.forename: Abebe
authors.initials: A
authors.lastname: Habte
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Negesse
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.forename: Getahun
authors.initials: G
authors.lastname: Abate
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Yassin
authors.forename: Kiflu
authors.initials: K
authors.lastname: Bereda
authors.forename: Morten
authors.initials: M
authors.lastname: Harboe
mesh_terms: D001707:Biopsy, Needle; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D005002:Ethiopia; D006801:Humans; D009163:Mycobacterium bovis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014388:Tuberculosis, Lymph Node / Q000382:microbiology
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial