Elimination of bacteria from human semen during sperm preparation using density gradient centrifugation with a novel tube insert.

The occurrence of bacteria in sperm samples intended for in vitro fertilisation can compromise the outcome of assisted reproductive techniques. Effective semen processing procedures should therefore be implemented to remove bacteria from semen. Unfortunately, technique failure does occur whereby bacteria can be found in processed sperm preparations. To improve the effectiveness of semen processing, a novel centrifuge tube insert was developed to facilitate the layering of density gradients and semen, and to prohibit the re-infection of purified sperm pellets. The purpose of this study was to: (i) determine the prevalence and type of bacteria present in semen of patients participating in the Unit's assisted reproduction program and (ii) evaluate the effectiveness of density gradient centrifugation with the novel tube insert, for the elimination of bacteria and yeast from spiked human semen samples. A survey in 2007-2010 indicated that 50% of semen samples were found to have positive bacterial cultures. Semen processing by means of density gradient centrifugation with the novel tube insert eliminated significantly more in vitro derived (spiked) bacteria and yeast from semen compared to processing without the insert (P < 0.004). Therefore, it is highly recommended that the centrifuge tube insert, ProInsert™, be incorporated into assisted reproductive programs.