[Studies on the mycotic and bacterial risk of contamination and the use of nipagin in the artificial insemination of cryosperm].
Primary bacterial and mycological contamination was studied in random human ejaculates. After various phases of cryopreservation secondary microbiological contamination was investigated. Furthermore, semen samples of several donors were inoculated with suspension of different concentrations of yeasts and with the test bacteria Escherichia coli K12 and Staphylococcus aureus SG 511. Microbiological results were then compared before an after cryopreservation. The cryopreserving process was carried out with and without antibiotics to test the antibacterial effectiveness of antibiotics under these conditions. Moreover, we investigated the usability of a chemical preservative (Nipagin) at cryopreservation. The following results were obtained: 9.8 per cent of samples showed primary mycological contamination (1.9 per cent with Candida albicans). Cryopreservation reduced the concentration of fungi by more than 90 per cent on average. The bacteriological investigations have shown, that with one exception the semen was without pathogenetic bacteria. This situation was altered scarcely during the cryopreserving process (also by use of cryoprotective medium without antibiotics). Out of 25 ejaculates 11 had primary non-pathogenetic bacteria. Test bacteria inoculated into semen were not influenced by the addition of antibiotics to the cryoprotective medium (CPM). Nipagin prevented respectively reduced a bacterial or a mycological contamination of the CPM during a storage of 14 days dependent of nipagin concentration but reduced the motility of human spermatozoa after cryopreservation. The results suggest the conclusion to prefer a portionate storage without nipagin at a temperature of nearly + 1 degree C, thereby the microbiological contamination may be neglected.