Urine-lipoarabinomannan-might fill the gap in delayed diagnosis of life-threatening tuberculosis

Abstract

Mycobacterium tuberculosis bacilli is a causative organism for tuberculosis disease. The lungs are the most commonly affected organ with this infection but it can infect any vital organ of the body. The person with signs and symptoms of tuberculosis disease was identified with detection of acid-fast bacilli in the biological specimen and with rapid molecular testing. However, the limiting factor for the early tuberculosis (Tb) diagnosis is the running cost of the diagnostic test. It is the common reason preventing the advancement of diagnostic laboratories in low and middle-income countries. The person and community both suffered from this diagnostic delay. This delay causes significant morbidity and mortality in the patient. An alternate test and an alternate sample that can be easily obtained would be beneficial to prevent these diagnostic delay issues. Lipoarabinomannan (LAM) antigen detection in the urine sample is one such promising diagnostic test. Mycobacterium tuberculosis’s inner layer is made up of glycolipids. LAM is derived from phosphatidylinositol. LAM is a heat-stable amphiphilic cell wall component. It is the precursor of phosphatidyl-inositol-mannosidase and lipomannan. An extra mannose cap is a characteristic feature of a virulent strain of Mycobacterium. LAM has immunogenic and immunomodulatory properties. It is a promising diagnostic test because it is simple to do, the assay can be performed at the patient’s bedside and takes a while to perform. This assay sensitivity varies from 56% to 85% and it has greater than 88% specificity. In HIV seropositive patients, use of LAM assay can reduce 8-week mortality. LAM detection is also a very good assay for the detection of tuberculosis in renal failure and disseminated tuberculosis patients.Lipoarabinomannan detection in the urine is a possible test that can prevent delay in diagnosis. This is a promising test because it's easy to perform, the test can be done with a card test besides the patient's bed. It can be used in HIV seropositive patients and various other forms of extra pulmonary tuberculosis. It can be a very useful test for diagnosing a critically ill patient who is not able to produce a target sample.