Microbial contamination in an in vitro fertilization-embryo transfer system

To determine sources and transmission of microorganisms in IVF-ET and efficacy of in-place controlling systems. Prospective study. In Vitro Fertilization-Embryo Transfer Unit at a university teaching hospital. Twenty-eight couples undergoing 30 completed IVF-ET cycles. Gamete and embryo processing in a penicillin- and streptomycin-rich medium. Presence of microorganisms at various stages of IVF-ET. Fertilization, cleavage, and pregnancy rates. In 50% of cycles no microorganisms were isolated and in the other 50% microbes were cultured from various loci. Cultures of four preprocessed semen samples were positive and corresponding postprocessed samples negative. Microbes were detected in 27% of needle washes after oocyte collection; in 40% and 32% of follicular fluids from left and right ovaries, respectively; and in two culture media from egg-sperm incubations at 20 hours after insemination. No microorganisms were grown from media from zygote incubations. Fertilization, cleavage, and pregnancy rates were independent of microbial presence. Seminal fluid and transvaginally collected oocytes are potential sources of microbial contamination of the IVF-ET culture system. A penicillin- and streptomycin-rich culture medium is effective in removing contaminating microbes. End point measures are not affected by commensal contamination.