[SERODIAGNOSIS OF THE MYCOBACTERIUM AVIUM COMPLEX BY USING IgA ANTIBODIES FOR THE GLYCOPEPTIDOLIPID CORE ANTIGEN].
OBJECTIVE
The diagnosis of Mycobacterium avium complex pulmonary disease (MAC-PD) can be challenging. A serodiagnosis enzyme immunoassay (EIA) kit, which detects the serum anti-glycopeptidolipid (GPL) core IgA antibody, has been commercialized recently; however, its clinical usefulness in the diagnosis of MAC-PD is still unclear. This study aimed to evaluate the availability of this kit and identify factors affecting testing accuracy.


METHODS
We performed a retrospective study of 195 patients who were evaluated with an EIA kit at Nagasaki University Hospital between November 2012 and March 2014.


RESULTS
12 of 16 (75.0%) MAC patients have underlying diseases ; 8 of 16 (50%) had complications associated with respiratory diseases. There were no significant differences between the seropositive and seronegative background of patients with confirmed MAC-PD. Regarding the accuracy of serodiagnosis EIA kit, its sensitivity and specificity were 81.3% and 88.3% (with a cut-off value of 0.7 U/ml), respectively. Of false-positive patients with bronchiectasis, 28.6 % demonstrated a good response to anti-MAC treatment, indicating that the sensitivity of the EIA kit might be higher than that of culture-based diagnosis because patients with clinically diagnosed MAC-PD were included in the false-positive population.


CONCLUSIONS
In the current study, the serodiagnosis EIA kit demonstrated good sensitivity and specificity for the diagnosis of MAC-PD. Further clinical investigations are necessary to clarify the role of this kit in definitively diagnosing MAC infections.
Yoshitsugu
Y
Higashi
Shigeki
S
Nakamura
Hiromi
H
Tomono
Shotaro
S
Ide
Takahiro
T
Takazono
Taiga
T
Miyazaki
Koichi
K
Izumikawa
Katsunori
K
Yanagihara
Yoshihiro
Y
Yamamoto
Shigeru
S
Kohno
D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D000941:Antigens / Q000276:immunology*; D001987:Bronchiectasis; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005189:False Positive Reactions; D005260:Female; D006017:Glycolipids / Q000276:immunology*; D006020:Glycopeptides / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000276:immunology*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis*; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*
D000907:Antibodies, Bacterial; D000941:Antigens; D006017:Glycolipids; D006020:Glycopeptides; D007070:Immunoglobulin A; D011933:Reagent Kits, Diagnostic