Rajvi H. Mehta
23 September 2007
Embryo culture media are routinely supplemented with antibiotics to prevent bacterial growth during embryo culture. The most commonly used antibiotics being Penicillin and Streptomycin. The anti-bacterial effect of penicillin is attributed to its ability to inhibit the synthesis of peptidoglycan, unique glycoproteins of bacterial cell wall. Since peptidoglycan is not synthesized by human cells, there is no apprehension about using penicillin as one would not expect it to have any detrimental effects on human embryos. Streptomycin and gentamycin belong to the aminoglycoside group of antibiotics which exert their antibacterial effect by inhibiting bacterial protein synthesis, which incidentally are similar to mitochondrial proteins. Therefore, it is of concern on whether the antibiotics used in embryo culture media would have any detrimental effects on embryonic development. This issue has not been addressed despite the routine use of these antibiotics in culture media. Recently, Lemeire et al (2007) tested the toxicity of streptomycin in four bio-assays: 1) follicle bio-assay (FBA), a multi-parametric long-term follicle culture system mimicking ovarian function, 2) in vitro fertilisation (IVF) of exposed oocytes enabling gamete quality determination through fecundability 3) the mouse embryo assay (MEA) which analyses pre-implantation embryo development, and 4) the embryonic stem cell test (EST) for post-implantation embryo-toxicity. The FBA revealed a concentration-dependent decrease in mice oocyte nuclear maturation during continuous exposure starting with 50mug/ml streptomycin characterised by a significantly reduced first polar body-rate (40% vs. 92% in the control group). Oocytes that remained arrested in metaphase I had aberrant spindle formation. IVF of long-term exposed oocytes in the FBA to 50mug/ml streptomycin resulted in a significantly lower fertilization rate of 23% vs. 74% in the control group and were unable to develop to the blastocyst stage. The MEA revealed no effect on pre-implantation embryo development. The EST also did not demonstrate any post-implantation detrimental effect. This study although done in mice indicates that one needs to be cautious before using streptomycin in human IVF and embryo culture media. Lemeire K, Van Merris V, Cortvrindt R. (2007) The antibiotic streptomycin assessed in a battery of in vitro tests for reproductive toxicology. Toxicol In Vitro E-pub ahead of print.
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4.00 (out of 5)