Microbial contamination in an in vitro fertilization-embryo transfer system

Objective: To determine sources and transmission of microorganisms in IVF-ET and efficacy of in-place controlling systems. Design: Prospective study. Setting: In Vitro Fertilization-Embryo Transfer Unit at a university teaching hospital. Patients: Twenty-eight couples undergoing 30 completed IVF-ET cycles. Interventions: Gamete and embryo processing in a penicillin- and streptomycin-rich medium. Main Outcome Measures: Presence of microorganisms at various stages of IVF-ET, Fertilization, cleavage, and pregnancy rates. Results: 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. Conclusion: 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.