1.                   Report

Mycoplasma hominis (Mh) and Ureaplasma urealyticum (Uu) were isolated in 1937 and 1954, respectively [1]. Researches proved the both organisms colonize the human genital tract and may been associated with adverse pregnancy outcomes, which may play a role in chorioamnionitis, salpingitis, bacterial vaginosis, and post-partum endometritis [2]. Sole presence of these microorganisms in the vaginal flora might be insufficient to cause pathological issues, but their combination with other factors such as bacterial vaginosis or cervical incompetence may be additionally needed to induce preterm birth [3]. Mh and Uu been confirmed relatively easy to culture [1]. However, to our knowledge, no studies have been proceeded to ascertain the optimum culture time for Mh and Uu in pregnant women, the present study was carried out to confirm the optimum culture time (from specimen collection to inoculation) for both organisms.

This is a retrospective study, 733 pregnant women in early stage were enrolled in present research from 2015-6-10 to 2016-12-30. All of them underwent vaginal secretion culture of MH and UU, which were incubated at 37℃ for 48 hours (Zhongaisheng, China). The mean age was 29±6 years, culture time ranges from 6 to 2650 minutes, all 733 pregnant women were dividing into group Ⅰ (from 0 to 120 minutes, n=302) and group Ⅱ (no less than 121 minutes, n=431) according to the culture time, respectively. The corresponding culture results (shown in Table 1).

Mh culture positive rate between group Ⅰ and group Ⅱ were 3.97% and 2.09% (c²=2.268, P=0.132), respectively. Uu culture positive rate between group Ⅰ and group Ⅱ were 14.57% and 6.73% (c²=12.175, P=0.001), respectively. Group Ⅰ were further divided into three subgroups according to culture time, they were group A (from 0 to 30 minutes, n=67) and group B (from 31 to 60 minutes, n=85) and group C (from 61 to 120 minutes, n=150), respectively. Uu culture positive rate among the three subgroups were 13.43%, 15.29% and 14.67% (c²=0.107, P=0.948), respectively.

There was no significant difference of Mh culture positive rate between group Ⅰ and Ⅱ, so we could not confirm the optimum culture time for Mh in pregnant women, more cases should be tested to make a conclusion. Conversely, Uu culture positive rate was significantly higher in group Ⅰ than that of group Ⅱ, however, when we further grouped for group Ⅰ, no significant difference was observed among the three subgroups (A, B and C), so we conclude that the optimum culture time for Uu in pregnant women is no more than 120 minutes. Several studies [4-6] support the idea that both Mh and Uu may infect the products of conception, but predominantly, Uu seems more virulent of the two opportunistic organisms. In conclusion, the optimum culture time for Uu in pregnant women is no more than 120 minutes, however, as for Mh, there is no definite conclusion. 

Table 1: Mh and Uu culture result of pregnant women.

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2.       Larsen B, Hwang J (2010) Mycoplasma, Ureaplasma, and adverse pregnancy outcomes: a fresh look. Infect Dis Obstet Gynecol.

3.       Capoccia R, Greub G and Baud D (2013) Ureaplasma urealyticum, Mycoplasma hominis and adverse pregnancy outcomes. Curr Opin Infect Dis 26: 231-240.

4.       Pickler R, Brown L, McGrath J, Lyon D, Rattican D, et al. (2010) Integrated review of cytokines in maternal, cord, and newborn blood: part II-- associations with early infection and increased risk of neurologic damage in preterm infants. Biol Res Nurs 11: 377-386.

5.       Lee SE, Romero R, Kim EC, Yoon BH (2009) A high Nugent score but not a positive culture for genital mycoplasmas is a risk factor for spontaneous preterm birth. J Matern Fetal Neonatal Med 22: 212-227.

6.       McGowin CL, Spagnuolo RA, Pyles RB (2010) Mycoplasma genitalium rapidly disseminates to the upper reproductive tracts and knees of female mice following vaginal inoculation. Infect Immun. 78: 726-736.