Serodiagnostic value of the 19 kilodalton antigen ofMycobacterium tuberculosis in indian patients

Abstract

Previous studies in UK subjects suggested that the 19 kDa protein antigen of Mycobacterium tuberculosis might be valuable in the serodiagnosis of paucibacillary tuberculosis. In this study, antibody titres for the 19 kDa antigen were higher in healthy controls in India than in the UK. Consequently, the diagnostic sensitivity of this antigen and its TB23 epitope was negligible in Indian patients with tuberculosis. However, a diagnostic sensitivity of 50% was achieved in patients with skin tuberculosis on the basis of a high ratio between antibody titres for the whole antigen and its TB23 epitope.

Humoral response to low molecular weight antigens of Mycobacterium tuberculosis by tuberculosis patients and contacts

“…These data provide important evidence even though they cannot be considered definitive, since significant geographical variation in antibody titer to some antigens exists (37). Heterogeneous recognition of antigens by serum antibodies in tuberculosis can result from multiple factors (5), and characteristics such as the use of BCG vaccination (38) should also be assessed.…”

Clinical evaluation of a serological assay using a monoclonal antibody (TB72) to the 38 kDa antigen of Mycobacterium tuberculosis

“…An increase in sensitivity with treatment was noted. Although, at first sight, the 19 kDa antigen would appear to be the most valuable reagent in the diagnosis of smear-negative tuberculosis [3,15], significant geographical variation in antibody titres to this antigen in control samples makes it less attractive [16]. Healthy control sera from India, Indonesia and Europe do not show geographical variation in antibody levels to the TB72 epitope of the 38 kDa antigen of M. tuberculosis (unpublished data).…”

“…Few serological tests have been shown to be valuable in the diagnosis of smear-negative disease [3-5, 14, 15]. The initial promise afforded by the purified 19 kDa antigen [3,15] has faded, in the light of significant geographical variation in the antibody response to this antigen [16].…”

Tuberculosis en patrón esporotricoide: una presentación inusual de tuberculosis cutánea en un paciente inmunocompetente

“…En el caso presentado se obtuvo un cultivo y un resultado de RPC positivos para M. tuberculosis, respaldando el concepto de que las técnicas de tinción, cultivo y la biología molecular debiesen ser realizadas simultánea-mente. En casos de mayor dificultad diagnóstica, incluso se han implementado ensayos terapéuticos con fármacos antituberculosos para lograr la confirmación etiológica 20,21 . La RPC, así como otras técnicas de biología molecular, ha sido una herramienta útil para detectar y diferenciar M. tuberculosis de otras especies de micobacterias 22 .…”

“…Un factor limitante es que su sensibilidad se ve reducida significativamente al examinar muestras paucibacilares. En general, la sensibilidad reportada es de 50-72% en este tipo de ejemplares, con una especificidad que va desde 80-100% 18,20,21,[23][24][25][26][27] . Según Tan y cols, la RPC alcanzaría una sensibilidad de 100% en tuberculosis cutánea multibacilar; sin embargo, en muestras paucibacilares, como en las formas verrucosa cutis y lupus vulgar, sólo logra detectar 55% y 60% de los casos, respectivamente 27 .…”