Clinical efficacy of anti-glycopeptidolipid-core IgA test for diagnosing M ycobacterium avium complex infection in lung.

Background and objective It is difficult to verify the bacteriological diagnosis of M ycobacterium avium complex ( MAC) infection. The anti-glycopeptidolipid ( GPL)-core IgA antibody test was recently developed as a diagnostic method for MAC pulmonary disease. Only a few studies evaluate its clinical efficacy. We conducted retrospective evaluations of clinical characteristics of patients suspected of MAC infection to explore the usefulness of the anti- GPL-core IgA antibody test. Methods We retrospectively evaluated 296 patients who were suspected to have MAC infection and underwent anti- GPL-core IgA antibody test between March 2013 and July 2014 in Jikei University hospital. Results A total of 29 patients were diagnosed with 'definite MAC' based on the American Thoracic Society ( ATS) criteria with multiple identifications of MAC. On the other hand, 106 patients were diagnosed with other pulmonary diseases than MAC. The sensitivity and specificity of anti- GPL-core IgA antibody test for MAC diagnosis were 58.6% and 98.1%, respectively. The definite MAC group showed no significant differences in strains, treatment history or number of segments involved. The duration of MAC disease in the positive-antibody group was significantly longer than in the negative-antibody group ( P = 0.046). A significant increase in the false-negative rate was observed in patients with malignant disease ( P = 0.029). Conclusions The anti- GPL-core IgA antibody test demonstrated high sensitivity and specificity for the diagnosis of MAC infection especially in patients without malignant diseases. [ABSTRACT FROM AUTHOR]