Comparison of direct immunofluorescence and cell culture for detecting Chlamydia trachomatis

Conventional cell culture methods were compared with a direct immunofluorescence test (MicroTrak, Syva UK, Maidenhead, Berkshire) to detect Chlamydia trachomatis in 137 patients (126 women, 11 men) attending a sexually transmitted diseases (STD) clinic. Results obtained by the two tests agreed in 87.6% of cases. Of 34 positive specimens, 17 were detected by culture and fluorescence, 15 by fluorescence only, and two by culture only. The excess of specimens that were negative on culture but positive on fluorescence might be accounted for by delays in culture (up to 18 hours). The MicroTrak test appears to be of value in peripheral hospitals that have to rely on transporting specimens to larger centres for culture.