Leukocytospermia or pyospermia is still a confusing and controversial topic for clinicians. Although it has been proposed by the World Health Organization as an indicator of reproductive tract infection and inflammation, the evidence is not convincing. The frequency of leukocytospermia among infertile males is quite wide, and the reliable incidence is about 30%(17) [18, 19]. Some pathophysiological views recognize that bacteria and infiltrating leukocytes, two major inflammatory mediators, directly or indirectly affect human sperm function , However, most leukocytospermia is not caused by bacterial infection or bacteriospermia, or there is no evidence of microbial infection, this may be because the invasion of male reproductive tract by microorganisms may be divided into three different stages. In the first stage, bacterial infection can be induced by microorganisms, and pathological bacterial strains can be observed in semen, without attracting a large number of white blood cells; in the second stage, activated white blood cells appear in ejaculation; in the third stage, bacteria are removed, usually with isolated leukocytospermia as the representative . Bacteria are mainly involved in the intrinsic and mitochondrial dependent apoptosis cell death, while oxidative stress may play a role in reducing the conventional sperm parameters in leukocytospermia, and the combined effect of bacteria and leukocytes accelerated the apoptosis and necrosis of sperm . The increased seminal leukocytes may mediate reactive oxygen species (ROS) production by direct cell-cell contact or soluble products released by leukocytes . A Systematic Review and Meta-Analysis of Case-Control Studies indicated that patients with leukocytospermia showed lower sperm concentration and lower progressive motility compared to men without leukocytospermia, however, the significant differences disappeared, along with the large inter-study heterogeneity, when analyses were restricted to studies clearly reporting the inclusion of men without clinical evidence of seminal tract infection . It seems that the clinical evidence of seminal tract infection is the key to sperm quality decline, and clinical studies have also found that compared with some pathogenic bacterial strains, the direct contact between conditioned pathogenic bacteria and sperm may play a greater role in promoting apoptosis .
Ureaplasma urealyticum (UU), usually considered as a conditional pathogen, belongs to the genus Ureaplasma and the family Mycoplasmataceae in the order Mycoplasmatales. A meta-analysis found that UU, but not undifferentiated Ureaplasma infections or U. parvum, has been shown to be the pathogen of nongonococcal urethritis (NGU) . Moreover, UU is easy to be implanted in urethra, but not necessarily cause urethritis , quite a few patients with these infections are not aware of their infections because they may be asymptomatic, even whether it is pathogenic and the impact on fertility is still uncertain. The incidence of UU was reported inconsistently, a study of 19,098 infertile men and 3,368 fertile men found that 10.22% and 3.65% of UU infertile and fertile men's urethra specimens, and 3.16% and 0.89% of MH specimens, UU infection will significantly affect sperm quality, and there is a significant relationship between UU infection and male infertility . A systematic review and meta-analysis found that there was a significant relationship between UU and Mycoplasma hominis with male infertility, and compared with the global average, the UU-positive rate was significantly higher in both the infertility group and the control group in China, while the positive rate was significantly lower in Mycoplasma hominis . Similarly, UU infection can directly affect sperm, cause leukocyte-mediated inflammatory response, and affect sperm by producing ROS .
Oxidative stress (OS) is considered to be the pathological molecular mechanism of most clinical, environmental and lifestyle factors that lead to male infertility. OS occurs when the physiological balance of oxidants and reducers in the system is reduced by excessive ROS or antioxidant levels , including some internal and external factors, such as inflammation and infection, varicocele, smoking, drinking, obesity, exposure to radiation and chemotherapy  , and even male reproductive hormone disorders . In the process of spermatogenesis, reactive oxygen species are very harmful, and the content of unsaturated fatty acids in sperm membrane is easily affected by oxidative stress, and these lipids can be oxidized through a series of chain reactions to release potential toxicity and mutagenic aldehydes and alkenals [34-36], finally, excessive ROS has a pathological impact on spermatogenesis, resulting in the decrease of sperm concentration, motility and fertilization rate . A large number of clinical studies have shown that leukocytospermia-induced sperm damage may be due to high levels of leukocyte-derived ROS and inflammatory mediators, Such as toll-like receptors 2 and 4 (TLR-2/4), cyclooxygenase-2 (COX-2), nuclear factor erythryoid-2 related factor (Nrf-2), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), etc [38, 39], even low levels of leukocytospermia have seminal oxidative stress . It is not certain that the effect of leukocytospermia or UU infection on sperm exists, but it seems to be explainable from the current mechanism research. However, on this issue, clinicians need more clinical evidence and feasible clinical solutions.
In our observation, there was no significant change in the semen volume and pH in all groups. Patients with leukocytospermia have lower sperm concentration, PR and normal morphology than patients with non-leukocytospermia. However, when we exclude UU-positive leukocytospermia patients and only consider UU-negative leukocytospermia patients, although there was a difference in the total motility, the difference between the PR and normal morphology disappeared, but only consider the UU-positive leukocytospermia patients, the sperm concentration, PR, total motility and normal morphology were significantly lower than the patients with non-leukocytospermia. At the same time, compared with UU-negative leukocytospermia patients, the PR, total motor ability and normal morphology of UU-positive leukocytospermia patients were significantly lower. These results seem to confirm that leukocytospermia has a definite effect on semen parameters, at least in terms of sperm concentration. Perhaps the leukocytes in semen itself is a factor that affects semen parameters, of course, these need more extensive research to confirm. However, the effect on PR and normal morphology, like many controversial studies on leukocytospermia, is not convincing. Our research showed that UU-negative leukocytospermia was not like leukocytospermia in terms of PR and normal morphology, which was no significantly different from non-leukocytospermia. Such results indicate that the effect of UU-negative leucospermia on sperm quality is rather limited. However, when patients with leukocytospermia are infected with UU at the same time, the effect on sperm quality is more obvious and serious, which can involve multiple aspects of semen parameters such as PR, total motor ability and normal morphological. This seems to suggest that infectious factors may be an important factor in the decline of sperm quality in asymptomatic leukocytospermia, and UU infection is a common infectious factor in asymptomatic leukocytospermia. Therefore, screening for UU infection in asymptomatic leukocytospermia is meaningful.
According to the antibiotic sensitivity test of UU, the top three susceptible antibiotics were Cyclolipoerythromycin, Minocycline and Doxycycline, and because doxycycline is inexpensive and easy to obtain, we prefer to choose doxycycline in clinic. According to the results of the 7-day and the 14-day treatment plan, there is no significant difference in cure rates, and there is no significant difference in the effect of the two plans on the sperm quality of UU cured leukocytospermia patients. If patients are susceptible to doxycycline and have no history of allergies and contraindications, we think that the doxycycline 7-day treatment plan is a good choice and this antibiotic treatment is meaningful. From our results, the semen parameters such as sperm concentration, PR, total motility, and normal morphology of UU-positive leukocytospermia patients were significantly improved 1 month after UU was cured. Unfortunately, some patients also received antioxidant and other treatments after our observation period, and no correct pregnancy rate was observed. However, our research shows that screening and treating UU in asymptomatic leukocytospermia is meaningful, not only can improve sperm quality but also save a lot of resources and costs, reduce the use of antibiotics, which seems to be an efficient diagnosis and treatment program.
This study has some limitations. Since more pathogens such as chlamydia or mycoplasma have been tested only in symptomatic leukocytespermia rather than asymptomatic leukocytospermia, this may miss some pathogens. In addition, some patients received additional treatments later, and we were unable to follow up with the UU-cured patients for longer periods to obtain more data.