COMPARISON OF 3 SEROLOGICAL METHODS FOR DIAGNOSING MYCOPLASMA-PNEUMONIAE INFECTION

Aims-To compare the novel Serofast latex agglutination test (Internati onal Mycoplasma, Toulon-Cedex, France) with the complement fixation te st and enzyme immunoassay (EIA) for diagnosing acute Mycoplasma pneumo niae infection. Methods-Paired sera from 60 patients with respiratory infection who had tested positive for M pneumoniae by complement fixat ion test were analysed with Serofast and indirect EIA for specific IgG and IgM antibodies. Results-Serofast was less sensitive than the two other tests. Only 30 (50%) out of 60 paired sera which showed a diagno stic seroconversion or had high positive, unchanged antibody titres by complement fixation test or EIA, or both, tested positive with Serofa st. Positive test results with Serofast were associated with the prese nce of a complement fixation test titre of greater-than-or-equal-to 51 2 and high positive IgM antibody titres measurable by EIA; virtually a ll patients with a complement fixation test titre of <256 or those res ponding primarily in the IgG class tested negative with Serofast. Base d on analysis of sera taken at the acute phase of infection, 10 (17%) of the 60 patients tested positive by complement fixation test, 10 (17 %) by EIA, and only four (7%) by Serofast. Conclusions-Serofast was le ss sensitive than complement fixation test and EIA and it cannot be re commended as a replacement for either test in routine diagnostic use. It might prove useful in laboratories where non-specific tests, such a s the determination of cold agglutinins, are still used for the diagno sis of M pneumoniae infection. Testing paired sera is, however, a prer equisite for obtaining acceptable sensitivity by Serofast as well as o ther serological methods currently available.