[Mycoplasma pneumoniae isolation and IHA antibody detection in patients with M. pneumoniae infection].
Throat swab culture was compared with indirect hemagglutination (IHA) antibody detection for diagnosis of Mycoplasma pneumoniae infection. These two methods were tried on the patients several times for a long term after onset of the disease. For five years from 1982 to 1986 in Kanagawa prefecture, a total of 566 patients were tested and 141 (25%) were diagnosed as M. pneumoniae infection by either of the two test methods. Both culture and antibody detection were performed on 110 patients out of 141, revealing that 96 patients (87%) were positive by culture and 89 (81%) were positive by antibody detection. Most of the patients with M. pneumoniae infection showed positive culture within a week after onset of the disease, and half of the patients treated with antibiotics such as macrolides or tetracyclines showed positive for two or three months after the onset. Positive rate of IHA antibody detection in the patients with M. pneumoniae infection was 43% within a week after onset of the disease and reached the maximum (92%) in 15 to 21 days after the onset. The rate did not decrease to less than 70% three months after the onset. Geometric mean titer of the antibody reached the maximum at the same time as the antibody positive rate. Both antibody positive rate and geometric mean titer declined significantly four months after the onset. In general, IHA antibody of infants with M. pneumoniae infection increased satisfactorily day by day after onset of the disease. Nine percent of the patient with M. pneumoniae infection developed otitis media with effusion, and M. pneumoniae was isolated from two of six patient effusions.