Rapid diagnosis of tuberculosis by detection of mycobacterial lipoarabinomannan in urine

There is an urgent need for improved tools fbr laboratory diagnosis of acti ve tuberculosis (TB), Here, we describe two methods, a catch-up ELISA and a dipstick test based on die detection in urine of lipoarabinomannan (LAM). LAM is a major and specific glycolipid component of the outer mycobacterial cell wall. Preliminary experiments showed that LAM is excreted in the urin e of mice injected intraperitoneally with a crude cell wall preparation of Mycobacterium tuberculosis. Both methods were highly sensitive, detecting L AM at concentrations of 1 ng/ml and 5 pg/ml, respectively. Of 15 patients w ith active IB, all showed intermediate to high levels of LAM in their urine (absorbance values from 0.3 to 1.2, mean 0.74). Only one sample showed an absorbance value below the chosen cut off value of 0.4. All but one of the urine samples from 26 healthy nursing workers exhibited OD value below 0.4 cut off. These methods may prove valuable for rapid and simple diagnosis of TB in particular in developing countries lacking biosafety level 3 (BSL3) facilities. (C) 2001 Elsevier Science B.V. All rights reserved.