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: Prospecti ve study. Setting: In Vitro Fertilization-Embryo Transfer Unit at a un iversity teaching hospital. Patients: Twenty-eight couples undergoing 30 completed IVF-ET cycles. Interventions: Gamete and embryo processin g in a penicillin- and streptomycin-rich medium. Main Outcome Measures : Presence of microorganisms at various stages of IVF-ET, Fertilizatio n, cleavage, and pregnancy rates. Results: In 50% of cycles no microor ganisms were isolated and in the other 50% microbes were cultured from various loci. Cultures of four preprocessed semen samples were positi ve and corresponding postprocessed samples negative. Microbes were det ected 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 insemi nation, No microorganisms were grown from media from zygote incubation s. Fertilization, cleavage, and pregnancy rates were independent of mi crobial presence. Conclusion: Seminal fluid and transvaginally collect ed 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 a re not affected by commensal contamination.