A considerable proportion of male factor infertility cases are associated with inflammatory processes. The most common sexually transmissible agents causing sexually transmitted diseases in industrial countries are Chlamydia trachomatis, genital Ureaplasma and Mycoplasma spp. This study was undertaken to investigate whether these bacterial contaminants in semen affect sperm quality parameters and particularly DNA integrity (detected by sperm chromatin structure assay) in males from infertile couples (n = 293). The results showed that semen contaminations with the investigated bacterial species were not associated with sperm DNA fragmentation. However, contaminations with Mycoplasma spp. and C. trachomatis were associated with decreased sperm concentrations. Total sperm numbers in contaminated semen samples tended to be decreased, but not significantly. Mycoplasma had the highest adverse effect on sperm quality (concentration, motility, morphology and DNA condensation). Antibiotic therapy of the selected 47 men was successful in 55%, but semen quality parameters did not improve at least up to 3 months after the therapy. The presence of pathogenic bacteria in semen is primarily associated with low sperm production. Our data showed that Mycoplasma spp. contamination of semen had the highest adverse effect on sperm quality. Sperm chromatin integrity assessed by the presence of DNA breaks was not disturbed.

Sperm chromatin status in fresh dog semen and the effect of long-term storage of chilled and frozen dog semen on sperm chromatin integrity was assessed by the sperm chromatin structure assay (SCSA). In the first experiment, the chromatin integrity of fresh semen from 60 dogs with different historiy of fertility was compared with other sperm parameters (total sperm count, sperm motility, viability, acrosomal integrity and sperm morphology). Except for 15 dogs that had never mated before, all were used in breeding as semen donors. Thirty-three of them were successful breeding males while in 12 repeated fertility problems were noted. Ejaculates were assigned to groups with good and poor quality, based on determined sperm motility and percentage of morphologically normal sperm. In the second experiment, chromatin status was measured in fresh and chilled spermatozoa (on day 0, 2, 4, 6, 8 and 10 of storage). Finally, in the third experiment, the chromatin status was measured in fresh and cryopreserved spermatozoa. Evaluating fresh dog semen, we observed that DNA fragmentation index (DFI) and percentage of cells with high DNA stainability (HDS) negatively correlated with total sperm count, percentage of total and progressively motile spermatozoa, sperm viability and percentage of morphologically normal spermatozoa, even with rather low correlation indices. Lower chromatin integrity was found in the group of dog ejaculates showing poor quality in comparison with the group of good quality ejaculates. All dogs with repeated fertility problems were classed in the group showing poor quality, and even though their DFI was significantly higher than the DFI of successful breeding males, the highest DFI we obtained was only just below 9%. We can assume that the chromatin damage level in any of the evaluated dogs was not high enough to have a significant effect on their fertility. Concerning the potential cause of reduced male fertility, the assessment of chromatin integrity in fresh dog ejaculates failed to add any additional information to the results obtained by other techniques of semen analysis. Thus, the current study indicates that neither 10-day preservation of canine sperm chilled in commercial extenders nor long-term cryopreservation in extenders recommended for canine sperm preservation produce adverse effects on sperm chromatin integrity.

Damage to the genetic component of spermatozoa seems to play the main role in a majority of cases where current approaches fail to reveal the specific cause of male infertility. In this study, we compared semen quality in men assigned to two defined groups: men from couples with unexplained infertility - idiopathic infertility (A) and young men with no experiences of infertility (B). All samples were examined by standard ejaculate analysis and sperm chromatin structure assay (SCSA). Sperm chromatin damage was significantly higher in men from group A than in those from group B. Similar results were obtained by comparison of men from group A (all men were normozoospermic) with normozoospermic men from group B. According to these results, we can suppose that chromatin disorders may be the causal factor of subfertility or infertility in some of these men. No evidence for a strong association between chromatin disorders and standard parameters of ejaculates was found. We failed to confirm a relationship between smoking and sperm quality in men from any of the investigated groups. SCSA is a method that facilitates the identification of infertile men who otherwise show normal semen variables.

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Chlamydia trachomatis was found to be a possible factor in sperm pathology. These results could help to elucidate the role of Chlamydia trachomatis in male infertility.