Immunochromatographic IgG/IgM Test for Rapid Diagnosis of Active Tuberculosis

Abstract

For rapid diagnosis and discrimination between active tuberculosis (TB) and other pulmonary diseases, we evaluated the clinical usefulness of detection of serum immunoglobulin IgG and IgM antibodies raised against mycobacterial 38-kDa, 16-kDa, and 6-kDa antigens by a commercial rapid immunochromatographic IgG/IgM test (Standard Diagnostics, South Korea) in 246 serum samples from three groups of patients: (i) 171 patients with active TB (128 with pulmonary TB [pTB] and 43 with extrapulmonary TB [epTB]), (ii) 73 patients with pulmonary non-TB diseases, and (iii) two leprosy patients. The sensitivities of IgG and IgM in patients with active TB (pTB and epTB) were 68.4% and 2.3%, respectively. IgG had the best performance characteristics, with sensitivities of 78.1% and 39.5% in sera from patients with active pTB and epTB, respectively, and a specificity of 100%. The sensitivities of IgM were poor and were similar for pTB and epTB (2.3%). In contrast, specificity was very elevated (100%). The combination of IgG with IgM did not improve its sensitivity. IgG-mediated responses against the mycobacterial 38-kDa, 16-kDa, and 6-kDa antigens might constitute a clinically useful tool for presumptive diagnosis and discrimination of active pTB from other pulmonary diseases. Moreover, based on its simplicity and rapidity of application, it could be a screening tool for active pTB in poorly equipped laboratories.Tuberculosis (TB) is still a serious public health problem in the world, with about 8.9 to 9.9 million new cases and 1.3 million deaths occurring worldwide annually (45); it has been estimated that one-third of the world's population is infected with Mycobacterium tuberculosis (MT) (41). One of the principles of TB control is rapid and accurate diagnosis of infected patients in order to allow prompt initiation of antibiotic therapy and to prevent transmission (2). Microscopic examination of sputum is a rapid, technically simple, and inexpensive test available for the routine diagnosis of TB in most developing countries. However, sputum smear microscopy with ZiehlNeelsen staining is only 60 to 70% sensitive for the diagnosis of pulmonary TB (pTB) compared with the sensitivity of sputum culture (27,29). Mycobacterial cultures are more sensitive but take at least 2 weeks, or longer if solid media are used, and culture facilities are not available in many countries. On the other hand, the lack of radiological appearances specific to TB makes chest radiography a relatively subjective and errorprone practice for the diagnosis of pTB (28). In addition, coinfection with HIV may change the clinical presentation of TB and reduce the sensitivity of classical microbiology methods (12,20,31). Therefore, in developing countries, it is especially important to have an inexpensive and rapid test for TB identification so that infected individuals can be isolated and treated immediately (21).There is an urgent need for rapid, cost-effective, and accurate methods for the diagnosis of active TB. A serological test may be attractive because ...

The Reliability of Immunochromatographic Test in Tuberculous Children Diagnosed by Scoring System at Mohamed Elamin Hamid Hospital – Sudan

“…identified 30 children as negative (true negative) and one child as positive (false positive). This result compatible with the study done in (Algeria) which revealed poor sensitivity and high specificity of ICT test; the sensitivities of ICT was (2.3%), while its specificity was 100% [12] . There was study done in Sudan by Ali compatible with our result which was very low about 2% the sensitivity.…”

Evaluation of Antigen-Specific Immunoglobulin G Responses in Pulmonary Tuberculosis Patients and Contacts

“…Based on the reports showing significantly higher sensitivities of the IgG test compared with the IgM, IgA, or IgG/IgM tests in response to mycobacterial antigens (21,22), we aimed to evaluate the IgG responses to five different M. tuberculosis antigens, 38-kDa and 16-kDa antigens, ESAT-6, CFP-10, and lipoarabinomannan (LAM), in the sera of active TB patients, TB contacts with LTBI, and controls. We correlated antigen-specific IgG responses with infection state, TB recurrence, drug resistance, bacterial burden, M. tuberculosis genotype, and patient body mass index (BMI) and gender, in order to identify candidate antigens with clinical value for TB diagnosis and elucidate factors that may influence M. tuberculosis-specific IgG responses in TB patients.…”

Expression and diagnostic value of proteins in Mycobacterium tuberculosis

“…The use of antigens has shifted from purified proteins of mycobacterial culture to genetically engineered antigens. The currently used TB antigens include the 38-kDa protein (Silva et al, 2003;Ben-Selma et al, 2011), the 16-kDa protein (Senol et al, 2007;Ben-Selma et al, 2011), lipoarabinomannan, HspX, MTB48 (Lodes et al, 2001), and Mtb81 (Silva et al, 2003;Perkins et al, 2003;Ben-Selma et al, 2011). Despite significant research efforts, the sensitivity, specificity, sputum acid-fast bacilli-positive concordance rate, and relevance of a serious condition reveal little useful information.…”

“…However, the limitations of this method include its low sensitivity, multiple testing, and loss of manpower, among others (Steingart et al, 2006). Recently, serological methods for TB diagnosis have been applied, and early laboratory diagnosis of TB has achieved good results; however, several limitations remain (Zhu et al, 2004;Steingart et al, 2009;Ben-Selma et al, 2011). Identification of stable and efficient specific antigens or antigen combinations has been challenging.…”