Serodiagnosis of tuberculous lymphadenitis using a combination of antigens.
BACKGROUND
The diagnosis of extra-pulmonary tuberculosis (EPTB) by conventional methods such as culture and microscopy has low sensitivity and requires an invasive procedure. A simple rapid serological test would be of great value.


METHODS
Six antigens (ESAT-6, Ag85A, TB10.4, Rv3881c, lipoarabinomannan (LAM) and Ara6-BSA) were tested in an ELISA to detect antigen specific IgG and IgM antibodies in sera from 54 culture and histology-confirmed tuberculous lymphadenitis (TBLN) patients, among whom four were HIV seropositive, sera from 25 smear positive pulmonary tuberculosis (PTB) patients, 15 culture and histology-negative lymphadenitis (non-TBLN) patients (n=15) and 22 healthy controls (HCs).


RESULTS
The sensitivities of the antigens for the detection of IgG in sera of TBLN patients ranged from 4 to 30 %. Specificities ranged from 91 to 100 % with sera from HCs. Sensitivities of the antigens for detection of IgM ranged from 0 to 15 % and specificities ranged from 91 to 100 %. LAM was the most potent antigen followed by ESAT-6 and Rv3881c for detection of IgG. However, the sensitivity for antigen specific IgG antibody detection was improved when LAM was combined with ESAT-6 and Rv3881c.The sensitivity was 54 % and the specificity 91 %.


CONCLUSIONS
The study suggests that the combined use of LAM, ESAT-6 and Rv3881c for the detection of IgG in sera of TBLN patients could be a supplement to microscopy of fine- needle aspirate (FNA) to diagnose EPTB.
Beyene
Demissew
D
Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia. beyene@gmail.com
Lumc Franken
Kees
K
Yamuah
Lawrence
L
Aseffa
Abraham
A
Wiker
Harald G
HG
Kolk
Arend
A
Engers
Howard
H
Klatser
Paul
P
Sviland
Lisbet
L
D000328:Adult; D000942:Antigens, Bacterial / Q000097:blood*; D001426:Bacterial Proteins / Q000097:blood; D015415:Biomarkers / Q000097:blood; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008070:Lipopolysaccharides / Q000097:blood; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods; D014388:Tuberculosis, Lymph Node / Q000150:complications / Q000175:diagnosis*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D015415:Biomarkers; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D008070:Lipopolysaccharides; C050016:lipoarabinomannan