Low sensitivity of a urine LAM-ELISA in the diagnosis of pulmonary tuberculosis.
BACKGROUND
The development and evaluation of rapid and accurate new diagnostic tools is essential to improve tuberculosis (TB) control in developing countries. In a previous study, the first release of a urine LAM-ELISA by Chemogen (Portland, USA) has been evaluated with a promising sensitivity and specificity for the diagnosis of pulmonary TB. In the present study, the now commercially available assay has been clinically assessed regarding its diagnostic value alone and in combination with clinical co-factors.


METHODS
The test was applied to two urine samples from 291 consecutively enrolled Tanzanian patients with suspected pulmonary tuberculosis. The participants were subsequently assigned to classification groups according to microbiological, clinical and radiological findings at recruitment and during a maximum follow up period of 56 days.


RESULTS
Only 35 out of 69 pulmonary TB cases -confirmed by smear microscopy and/or solid culture and/or liquid culture- showed at least one positive LAM-ELISA result (sensitivity 50.7%). The sensitivity was noticeably higher in females (66.7%) and in HIV positive participants (62.0%). The specificity amounted to 87.8% and was determined in participants with negative results in all microbiological tests and with sustained recovery under antibiotic treatment at day 56. Correlation with urinalysis revealed that proteinuria was significantly and positively associated with LAM-positivity (P = 0.026).


CONCLUSIONS
This commercially available generation of LAM-ELISA does not appear to be useful as an independent diagnostic test for pulmonary tuberculosis. The question whether the assay is suitable as a supplemental device in the diagnosis of HIV-associated TB, requires further investigations.
Reither
Klaus
K
Department of Infectious Diseases and Tropical Medicine, Klinikum of the Ludwig-Maximilians-University of Munich, Munich, Germany. kreither@mmrp.org
Saathoff
Elmar
E
Jung
Jutta
J
Minja
Lilian T
LT
Kroidl
Inge
I
Saad
Eiman
E
Huggett
Jim F
JF
Ntinginya
Elias N
EN
Maganga
Lucas
L
Maboko
Leonard
L
Hoelscher
Michael
M
D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D008070:Lipopolysaccharides / Q000652:urine*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D011507:Proteinuria / Q000652:urine; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000652:urine
D008070:Lipopolysaccharides; D011933:Reagent Kits, Diagnostic; C050016:lipoarabinomannan