Serodiagnosis of Mycobacterium avium-complex pulmonary disease using an enzyme immunoassay kit.
BACKGROUND
The diagnosis of Mycobacterium avium-complex pulmonary disease (MAC-PD) and/or its discrimination from pulmonary tuberculosis (TB) is sometimes complicated and time consuming.


OBJECTIVE
We investigated in a six-institution multicenter study whether a serologic test based on an enzyme immunoassay (EIA) kit was useful for diagnosing MAC-PD and for distinguishing it from other lung diseases.


METHODS
An EIA kit detecting serum IgA antibody to glycopeptidolipid core antigen specific for MAC was developed. Antibody levels were measured in sera from 70 patients with MAC-PD, 18 with MAC contamination, 37 with pulmonary TB, 45 with other lung diseases, and 76 healthy subjects.


RESULTS
Significantly higher serum IgA antibody levels were detected in patients with MAC-PD than in the other groups (P < 0.0001). Setting the cutoff point at 0.7 U/ml resulted in a sensitivity and specificity of the kit for diagnosing MAC-PD of 84.3 and 100%, respectively. Significantly higher antibody levels were also found in patients with nodular-bronchiectatic disease compared with fibrocavitary disease in MAC-PD (P < 0.05). There was a positive correlation between the extent of disease on chest computed tomography scans and the levels of antibody (r = 0.43, P < 0.05) in patients with MAC-PD.


CONCLUSIONS
The EIA kit is useful for the rapid diagnosis of MAC-PD and for differentiating MAC-PD from pulmonary TB and, if validated by studies in other populations, could find wide application in clinical practice.
Kitada
Seigo
S
Department of Internal Medicine, National Hospital Organization National Toneyama Hospital, 5-1-1 Toneyama, Toyonaka-shi, Osaka 560-8552, Japan. kitadas@toneyama.hosp.go.jp
Kobayashi
Kazuo
K
Ichiyama
Satoshi
S
Takakura
Shunji
S
Sakatani
Mitsunori
M
Suzuki
Katsuhiro
K
Takashima
Tetsuya
T
Nagai
Takayuki
T
Sakurabayashi
Ikunosuke
I
Ito
Masami
M
Maekura
Ryoji
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008171:Lung Diseases / Q000175:diagnosis* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis*; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis
D011933:Reagent Kits, Diagnostic