A latex agglutination test for the detection of Mycoplasma pneumoniae in respiratory exudates: a comparative study with a commercially available DNA-probe test.

We prepared polyclonal antibody specific to Mycoplasma pneumoniae. Using this antibody, we developed a latex agglutination test (LAT) for detecting the organism in respiratory exudates as rapid diagnosis of M. pneumoniae infection. Further, LAT was compared with DNA-probe test (DP) which was the only commercially available test for the rapid detection of the organism. In LAT, both M. pneumoniae and M. genitalium give positive agglutination, but the titer of M. genitalium was significantly lower than that of M. pneumoniae. The detection limit of LAT was 2 x 10(5) CFU/ml and that of DP was 5 x 10(4) CFU/ml in vitro. It was considered that target molecules in LAT were accumulated in the pharyngeal portion of the patients, because of their long half-life at 37 C. However, ribosomal RNA which was target molecule in DP was destroyed at 37 C much sooner, and the accumulation could not be expected. Actually, positive rate in LAT was higher than that in DP among clinical specimens in which M. pneumoniae was detected by culture method. The procedure of LAT is much easier and more rapid than that of DP in which radioactive isotope is required. LAT could be the choice of test for rapid diagnosis of M. pneumoniae infection.