Correlation between the Diagnostic Validity of Enzymeimmunoassay and the Hyperreactivity of the Respiratory Tract for the Diagnosis of Mycoplasma pneumoniae / 소아알레르기및호흡기학회지

ABSTRACT

PURPOSE:Mycoplasma pneumoniae (M. pneumoniae) is one of the common causes of lower respiratory tract diseases. Several studies have suggested that respiratory infection by M. pneumoniae may be associated with a reactive airway disease and asthma. In order to find such relationships, we compared the particle agglutination test with enzyme immunoassay (EIA) which were checked on the 1st, and at 1 and 5 or 7 days of follow-up. We also evaluated EIA in association with bronchial hypersensitivity. METHODS:One hundred eleven children who were out patients or hospitalized with pneumonia at Inje University and Hallym University Hospitals were included in the study. Patients were grouped according to the M. pneumoniae antibody titer. Patients who showed initial M. pneumoniae antibody titer and EIA Immunoglobulin (Ig) G/IgM greater than 1320 were designated as group 1 (n=46). In group 2 (n=33), patients showed initial M. pneumoniae antibody titer lower than 1320 but it increased more than fourfold between acute and convalescent stages. Group 3 (n=32) was a control group. We measured eosinophil counts, the total IgE, and the eosinophil cationic protein (ECP). Thirty-five children were checked with the methacholine test 3 or 4 months, after the first visit. Bronchial hypersensitiveness was defined positive if the concentration of methacholine was less than the lower limit (8 mg/mL methacholine). RESULTS:All 111 patients participated in the particle agglutination test at the initial and convalescent stages. The sensitivity and specificity for EIA were obtained from the results of the particle agglutination test. The sensitivity and specificity of acute and convalescent EIA IgG were 44.3% and 90.6%, and 67.1% and 96.9%, respectively. The sensitivity and specificity of acute and convalescent EIA IgM were 60.8% and 100%, and 92.4% and 100%, respectively. The M. pneumoniae antibody titer was associated with hospitalized days and improvement of chest X-rays. Only in group 3, the M. pneumoniae antibody titer correlated with the ECP level, but there was no significant difference between the methacholine test and eosinophil counts. CONCLUSION:The results of this study suggest that EIA may be a useful diagnostic method for detecting early phase of M. pneumoniae infection.