Objective: To investigate whether the presence of pathogenic microorganisms in genital tract of woman and/or man affects fertilization rate, development of embryo and nidation and whether it alters the outcome of in vitro fertilization (IVF). Design: Retrospective comparative clinical study. Setting: Repromeda, Centre of reproductive medicine, Ltd., Viniční 235, 615 00 Brno. Methods: 382 cycles of IVF were evaluated during the period 8/1999 - 11/2000. Age, body mass index, number of collected oocytes, fertilization rate, quality and number of transferred embryos, un/known microbial flora, pregnancy rate and pregnancy outcome were evaluated in all women. Parameters of spermiogram and un/known microbial flora in semen were evaluated in all men. Couples were divided into four groups: A. known microbial flora in both (woman and man); B. known microbial flora in woman; C. known microbial flora in man; D. unknown microbial flora in both. Results: The presence of pathogenic microorganisms in genital tract has no influence on fertilization, nor on development of embryo. Number of pregnancies per embryotransfer was higher in the groups A, B, C vs. group D; the difference is statistically significant (29%, 24%, 29% vs. 18%, P < 0.05). Conclusion: The presence of pathogenic microorganisms has no influence on fertilization, nor on development of embryo but has an influence on embryo implantation. The presence of pathogenic microbial flora is associated with poor IVF outcome.

        Key words: pathogenic microbial flora, sexually transmitted diseases, in vitro fertilization, implantation, embryo