Objective: The aim of the study was an evaluation of results of Chlamydia trachomatis antigen detection by means of direct immunofluorescence in samples from patients suspected from this infection. Design: Retrospective study. Setting: Institute of clinical microbiology, University Hospital and Medical Faculty of Charles University, Hradec Králové. Methods: Samples from females were swabs from uterine cervix, vagina and urethra, from male urethral swabs; moreover conjunctival swabs, bronchoalveolar irrigation, lower respiratory tract aspirates and sputum. Samples were fixed and „dyed” with monoclonal specific antibody labeled by fluorescent dye in the lab with a commercial diagnostic kit and they were evaluated microscopically after adding a drop of glycerol and covering with a top slide. Results: Within a group of 6126 samples from patients suspected from Chlamydia infection we have found positivity in 14.4 %. Of this subgroup 14.1 % in samples from genitourinary tract of females and 15.2 % in males, 14.1 % from conjunctival swabs and 3.7 % from lower respiratory tract. According to an age differentiation, positive samples in individual life-decades from genitourinary tract were 0–13–14.4–13.9–13.9 and in females over 60 13.9 %. In males the corresponding walues were 0–21.4–15.1–16–13.4 and those over 60 years 16 %. So, the highest positivity in our region has been detected in samples from young men aged 20–30, where it is nearly two-fold higher comparison to age-matched females. Conclusion: Direct detection of Chlamydia trachomatis antigen with immunofluorescence method still remains a reliable diagnostic tool. But for a control or confirmation of disputable results it is inconditionally necessary to have at least one more method available, e.g. PCR.

        Key words: Chlamydia trachomatis, antigen detection, immunofluorescence, genitourinary tract, eye, conjunctiva, sputum, irrigation