Main Findings
Pregnancy are known to be the main risk factors for Candida albicans infection (15). In vitro experiments confirmed that estrogen-pretreated mice with the same concentration of progesterone(10-6M) in late pregnancy could strongly inhibit the anti-Candida activity of neutrophils, which led to an increase in the susceptibility of pregnant women to VVC(16). A study on the vagina of castrated rats showed that compared with rats not treated with estrogen, the vaginal microflora was more diverse in rats treated with estrogen and colonized with vaginal yeast(17), indicating that hormone status was involved in the characteristics of vaginal flora under Candida infection, which may also be the cause of mixed fungal and bacterial infection.
Diabetes is known to be the main risk factor for C.albicansinfection(15, 18). In 2018, Xinhong et al. (19) compared 186 gestational diabetes (GDM) patients with 200 healthy pregnant women and found that GDM not only increase the incidence of VVC, but also increase the incidence of BV+VVC mixed infection. Our study found that a positive glucose tolerance test during pregnancy is a risk factor leading to mixed VVC+BV infection, which is consistent with the above studies. However, another study did not find a difference in the incidence of BV and VVC between the diabetes group and the control group(20). Perhaps this study analyzed the difference in vaginitis during the first trimester.
In 2007, Britton et al.(20) studied the risk factors of BV in pregnancy and found that sexual intercourse during early pregnancy was associated with an increased risk of BV in the second trimester. Our research showed that sexual intercourse during pregnancy is a risk factor leading to VVC+BV in late pregnancy, which may be related to the fact that sexual intercourse itself has a greater interference effect on normal vaginal flora(21). Immunity during pregnancy is lower than during non-pregnancy, and the ability to recover the normal flora after sexual intercourse is reduced, which leads to the occurrence of mixed vaginitis.
Patients with mixed vaginitis have complex genital symptoms and signs(22). Our team previously analyzed the clinical symptoms, signs and laboratory characteristics of patients with AV mixed vaginitis(22). Similar to this research, our research found that patients with VVC+AV often had genital itching. Furthermore, our research also found that compared with patients with AV, the genital burning, redness and edema vulva and vaginal erythema were more obvious in patients with VVC+AV; compared with patients with VVC, the genital burning, vaginal erythema, and yellow discharge in patients with VVC+AV were more obvious; and compared with patients with VVC, pH > 4.5 and WBC > 10/hpf were significantly higher in patients with VVC+AV. Similar to this research, our research also found that compared with patients with BV, yellow vaginal discharge in patients with AV+BV was more significant. However, our literature also found that compared with patients with BV, pH > 4.5 and WBC > 10/hpf were significantly higher in patients with AV+BV. Therefore, our research believes that mixed vaginitis has complex symptoms and signs, which is difficult to distinguish from the corresponding single vaginitis, and laboratory examination is the most effective method to distinguish mixed vaginitis from single vaginitis.
Mixed vaginitis is associated with adverse pregnancy outcomes . In 2018, Cha Han et al.(5) studied the pregnancy outcomes of pregnant women with AV and found that AV was associated with a high incidence of PROM. Our research found that the incidence of PROM increases in patients with VVC+AV compared with patients with VVC, which may be caused by AV. In 2016, Dingens et al.(23) studied the relationship between BV and adverse pregnancy outcomes in 12340 matched pregnant women and their newborns in Washington State. This research found that the incidence of neonatal ICU admission of BV-positive pregnant women increased. Our research finds that compared with patients with BV, the incidence of NICU admission is higher in patients with VVC+BV, which may be related to the increased incidence of NICU admission caused by VVC mixed vaginitis in the case of BV. Abnormal vaginal flora during pregnancy is associated with puerperal infection(19). In 2019, Wei Dai et al. (24)conducted a research on 380 women in late pregnancy and found that the puerperium infection was related to the colonization of Group B streptococcus (GBS) (AV pathogen) during pregnancy. Similar to our study, the VVC+AV mixed infection has an increased incidence of puerperal infection compared with the VVC group and the normal group, which may be related to AV. Analysis of the reason may be related to intrauterine infection caused by ascending infection of lower genital tract, activating intrauterine inflammation pathways, further causing puerperal infections(25-27).