Ureaplasma parvum genotype, combined vaginal colonisation with Candida albicans, and spontaneous preterm birth in an Australian cohort of pregnant women

Abstract

BackgroundDetection of Ureaplasma, Mycoplasma and Candida spp. in the vagina during pregnancy has previously been associated with preterm birth (PTB). However, the prevalence of these microorganisms and the associated obstetric risks (likely to be population-specific) have not been determined in Australian women; furthermore, in the case of Ureaplasma spp., very few studies have attempted characterisation at the species level and none have examined genotype/serovar status to further refine risk assessment.MethodsIn order to address these issues we sampled the vaginal fluid of 191 pregnant Australian women at three time points in pregnancy. Culture methods were used for detection of Ureaplasma spp. and Candida spp., and real-time PCR was used for speciation of U. parvum and U. urealyticum, non-albicans Candida spp., Mycoplasma hominis and Mycoplasma genitalium. High-resolution melt PCR was used to genotype U. parvum. Data on various lifestyle factors (including sex during pregnancy and smoking), antimicrobial use and pregnancy outcome were collected on all participants. Chi-square tests were used to assess the association of vaginal microorganisms with PTB.ResultsDetection of Ureaplasma spp. was higher among spontaneous PTB cases, specifically in the presence of U. parvum [77 % preterm (95 % confidence interval (CI) 50–100 %) vs. 36 % term (CI: 29–43 %), p = 0.004], but not U. urealyticum. The association with PTB strengthened when U. parvum genotype SV6 was detected (54 % preterm (CI: 22–85 %) vs. 15 % term (CI: 10–20 %), p = 0.002); this genotype was also present in 80 % (4/5) of cases of PTB <34 weeks gestation. When present with Candida albicans in the same sample, the association with PTB remained strong for both U. parvum [46 % preterm (CI: 15–78 %) vs. 13 % term (CI: 8–18 %), p = 0.005] and U. parvum genotype SV6 [39 % preterm (CI: 8–69 %) vs. 7 % term (CI: 3–11 %), p = 0.003]. With the exception of Candida glabrata, vaginal colonisation status for all organisms was stable throughout pregnancy. Smoking significantly increased the likelihood of detection of all target organisms.ConclusionsThese data suggest that the presence of different species and serovars of Ureaplasma spp. in the vagina confers an increased risk of spontaneous PTB, findings which may be useful in risk assessment for identifying women who would benefit from antimicrobial treatment.

First Trimester Vaginal <b><i>Ureaplasma</i></b> Biovar Colonization and Preterm Birth: Results of a Prospective Multicenter Study

“…In our study, the statistically significant association between U. parvum colonization and SPB was independent of concomitant BV or fungal infection, although the risk for SPB increased significantly in cases with 2 or more of these risk factors present, which is in accordance with previous reports [17,22]. The statistically significant association between lower GA at birth and higher incidence of not only U. parvum colonization, but also diagnosis of BV and fungal infection, suggests that SPB might be a result of polymicrobial infection with U. parvum and other microorganisms in some cases.…”

“…A recent report investigated the effect of ureaplasmas in the context of the vaginal microbiome and raised the hypothesis that alterations of the microbiome with an abundance of ureaplasmas as well as other pathogens might increase the risk for adverse pregnancy outcome [22]. In addition, Payne et al [17] hypothesized that the combination of U. parvum and VC might particularly elevate the risk for SPB. Other risk factors for ascending infection might include a short cervix, genetic factors of the host, as well as virulence factors of the pathogen [23].…”

“…Although previous PCR studies have given conflicting results regarding the pathogenicity of different biovars and sample sizes of clinical studies were small, there is some evidence that U. parvum rather than U. urealyticum might be associated with an adverse pregnancy outcome [11,12,17]. Furthermore, there is evidence from the available literature that interaction between vaginal U. parvum and other microorganisms, such as Candida spp.…”

“…Furthermore, there is evidence from the available literature that interaction between vaginal U. parvum and other microorganisms, such as Candida spp. or bacterial vaginosis (BV), might alter the risk for preterm delivery [17,18]. …”

Maternal Group B Streptococcus colonisation

“…Initial retrospective studies of vaginal specimens from the UPCAN study 18 found interesting results compared to those previously reported in Australasia (Figure 1). The main differences in serotypes compared to other studies are seen for cps Ib, II, VI and IX in our WA cohort.…”