Investigation Of Infection And Role Of Mycoplasma In Infertility

Objective:We used the PCR for the detection of Ureaplasma urealyticum, Mycoplasma genitalium and Mycoplasma hominis. To compare the difference of mycoplasma infection rates between infertile women and health women, in order to determine the effect of mycoplasma on infertility. At the same time, we evaluate the existing general detection methods in order to provide the evidence for choosing the clinical screening methods. On the other hand, in our study in vitro cell test was used to investigate the effect of Ureaplasma urealyticum on the THP-1 cells, to provide the foundation for the understanding of the pathogenic mechanism of Ureaplasma urealyticum. Then we could cut off the pathogenic pathway and remove the pathogenic factors on purpose, and then provide the clinical guidline for treatment.Methods:(1) 148 cases of female infertility and 67 cases of normal female who went to a hospital of Tianjin in 2010 were enrolled in the study. Their secretions of cervix specimens were inoculated in the liquid culture and solid culture. The DNA of the secretions of cervix specimens was extracted.(2) The DNA of the secretions of cervix specimens was used to detect mycoplasma by PCR. The mycoplasma infection rate was compared. The diagnostic value of liquid culture and PCR was evaluated.(3) Ureaplasma urealyticum cultures were used to infect the THP-1 cells, and THP-1 cells with medium of Ureaplasma urealyticum infected were used as the control group. The final concentrations of Ureaplasma urealyticum which infected THP-1 cells were 104,105 and 106CCU/ml. After 6h,12h,18h, and 24h of infection, the infected cells were observed.(4) The RNA of the infected cells was extracted. The gene expression of macrophage migration inhibitory factor was detected by RT-PCR. Concentration of macrophage migration inhibitory factor in the supernatants was detected by ELISA.Results: (1) In the inferile group, the prevalence rate of mycoplasma was 99/148(66.89%) while the health group was 22/67(32.83%), there was significant difference in the mycoplasma infection rate between the two groups (χ2=22.892, P<0.05); Of the three mycoplasmas, the Ureaplasma urealyticum infection rate was 52.7%and 28.36% respectively in infertile group and health group, there is significance between the two groups (χ2=11.039, P<0.05); No difference was detected between the two groups in the infection rate of Mycoplasma genitalum, Mycoplasma hominis, mycoplasma combined infection (P>0.05).(2) 92 of the 215 cases of infertile women and normal women after the liquid culture of the specimens were positive, the positive cases of the solid culture were 81, and the positive cases of the PCR were 97. There is no significant difference among the results of the three methods (χ2=2.561, P=0.278).(3) After Ureaplasma urealyticum cultures infected the THP-1 cells with different concentration (104,105,106CCU/ml), after 6h,12h, and 18h of infection, the expression of macrophage migration inhibitory factor increased little. After 24h, in the group of infection concentration of 10'CCU/ml and 106CCU/ml,the expression of macrophage migration inhibitory factor increased obviously. There was significant difference between the control group and 105CCU/ml,106CCU/ml group through analysis of variance (P<0.05).24h after infection, There was significant difference between the control group and 105CCU/ml,106CCU/ml group by pair wise comparison (P<0.05).Conclusions:(1) The Ureaplasma urealyticum infection rate of infertile female is higher than the health female. It is proved that Ureaplasma urealyticum infection is closely related to infertility. We have not found Mycoplasma genitalum in the fertile female. Although Mycoplasma genitalum and Mycoplasma hominis infection rate was low, may because the number of cases investigated was limited, we can not ignore their pathogenicity in the urinary genital tract. There is no significant difference in the combined infection rate between the infertility group and normal female, we could not say that the combined infection is not pathogenic, because the pathogenicity of Mycoplasma hominis, Mycoplasma genitalum and Ureaplasma urealyticum was not cooperative, or because the number of cases investigated was limited.(2) Liquid culture and PCR are capable of rapid diagnosis, although there are some false positives with both methods; no significant difference was detected between the two methods and solid culture. The application value of the two methods for clinical Ureaplasma urealyticum detection of infection is excellent.In practice, laboratory shall select a method based its own situations.(3) In vitro cell test, it has shown that Ureaplasma urealyticum increased the expression of macrophage migration inhibitory factor in THP-1 cells. Ureaplasma urealyticum promotes the immune cells to secrete the macrophage migration inhibitory factor. acclerates the inflammation, and thus resultes in local damage. But, the mechanism of Ureaplasma urealyticum promoting the secretion of macrophage inhibitory factor is unkown. It needs further study to understand the pathogenicity of Ureaplasma urealyticum.