Mixed Bacterial Growth in Prenatal Urine Cultures; An Investigation into Prevalence, Contributory Factors and the Impact of education-based Interventions.

PURPOSE: Undiagnosed urinary tract infections (UTIs) in pregnancy are associated with adverse perinatal outcome. Urine microbiology cultures reported as 'mixed bacterial growth' (MBG) frequently present a diagnostic dilemma for healthcare providers. We investigated external factors contributing to elevated rates of (MBG) within a large tertiary maternity centre in London, UK, and assessed the efficacy of health service interventions to mitigate these. DESCRIPTION: This prospective, observational study of asymptomatic pregnant women attending their first prenatal clinic appointment aimed to establish (i) the prevalence of MBG in routine prenatal urine microbiology cultures, (ii) the association between urine cultures and the duration to laboratory processing and (iii) ways in which MBG may be reduced in pregnancy. Specifically we assessed the impact of patient-clinician interaction and that of an education package on optimal urine sampling technique. ASSESSMENT: Among 212 women observed over 6 weeks, the negative, positive and MBG urine culture rates were 66%, 10% and 2% respectively. Shorter duration from urine sample collection to laboratory arrival correlated with higher rates of negative cultures. Urine samples arriving in the laboratory within 3 hours of collection were most likely to be reported as culture negative (74%), and were least likely to be reported as MBG (21%) or culture positive (6%), compared to samples arriving > 6 hours (71%, 14% and 14% respectively; P < 0.001). A midwifery education package effectively reduced rates of MBG (37% pre-intervention vs 19% post-intervention, RR 0.70, 95% CI 0.55 to 0.89). Women who did not receive verbal instructions prior to providing their sample had 5-fold higher rates of MBG (P < 0.001). CONCLUSION: As many as 24% of prenatal urine screening cultures are reported as MBG. Patient-midwife interaction before urine sample collection and rapid transfer of urine samples to the laboratory within 3 hours reduces the rate of MBG in prenatal urine cultures. Reinforcing this message through education may improve accuracy of test results.

The role of the obstetrician in the prevention of retinopathy of prematurity.

This review underlines the important role that obstetricians play in the prevention of retinopathy of prematurity. Efforts predominately focus on predicting which pregnant women are at highest risk of preterm birth, instigating treatments to prevent pre-eclampsia, fetal growth restriction and maternal infection which could lead to iatrogenic or spontaneous preterm birth, and optimizing care when preterm birth is inevitable. More broadly, optimizing maternal health pre-conception through stopping smoking, improving diet, reducing obesity with its associated gestational diabetes, and treating hypertension may reduce preterm birth and other pregnancy complications. This is a message that all healthcare professionals including obstetricians, neonatologists and GPs, nursing and midwifery staff need to communicate all women and men who are contemplating having a baby.

First Trimester Circulating MicroRNA Biomarkers Predictive of Subsequent Preterm Delivery and Cervical Shortening.

Preterm birth (PTB) is the leading cause of infant death and disability worldwide. The onset of preterm uterine contractions is preceded by asymptomatic cervical remodelling and ripening, which can be seen on trans-vaginal ultrasound as cervical shortening. This study aimed to identify plasma miRNA biomarkers that predict preterm birth and/or cervical shortening. We collected serial plasma samples from pregnant women prospectively from 12 to 22 weeks gestation. The nCounter miRNA assay was used to identify differentially expressed miRNAs associated with spontaneous PTB and/or cervical shortening (n = 16 term no short, n = 13 preterm, n = 24 short). Predictive values of the miRNA biomarkers were confirmed in an independent validation cohort consisting of 96 women who delivered at term, 14 preterm and 21 early cervical shortening at <20 weeks gestation. Nine miRNAs (hsa-let-7a-5p, hsa-miR-374a-5p, hsa-miR-15b-5p, hsa-miR-19b-3p, hsa-miR-23a-3p, hsa-miR-93-5p, hsa-miR-150-5p, hsa-miR-185-5p and hsa-miR-191-5p) were differentially expressed (P < 0.001) in women subsequently experiencing PTB or cervical shortening. Hsa-miR-150-5p had the strongest ability to predict PTB (AUC = 0.8725) and cervical shortening (AUC = 0.8514). Plasma miRNAs in the first trimester can predict PTB and cervical shortening in women at risk of preterm delivery. This is a key period in pregnancy when early identification of PTB risk allows time to deliver outcome-modifying interventions.

Vaginal dysbiosis increases risk of preterm fetal membrane rupture, neonatal sepsis and is exacerbated by erythromycin.

BACKGROUND: Preterm prelabour rupture of the fetal membranes (PPROM) precedes 30% of preterm births and is a risk factor for early onset neonatal sepsis. As PPROM is strongly associated with ascending vaginal infection, prophylactic antibiotics are widely used. The evolution of vaginal microbiota compositions associated with PPROM and the impact of antibiotics on bacterial compositions are unknown. METHODS: We prospectively assessed vaginal microbiota prior to and following PPROM using MiSeq-based sequencing of 16S rRNA gene amplicons and examined the impact of erythromycin prophylaxis on bacterial load and community structures. RESULTS: In contrast to pregnancies delivering at term, vaginal dysbiosis characterised by Lactobacillus spp. depletion was present prior to the rupture of fetal membranes in approximately a third of cases (0% vs. 27%, P = 0.026) and persisted following membrane rupture (31%, P = 0.005). Vaginal dysbiosis was exacerbated by erythromycin treatment (47%, P = 0.00009) particularly in women initially colonised by Lactobacillus spp. Lactobacillus depletion and increased relative abundance of Sneathia spp. were associated with subsequent funisitis and early onset neonatal sepsis. CONCLUSIONS: Our data show that vaginal microbiota composition is a risk factor for subsequent PPROM and is associated with adverse short-term maternal and neonatal outcomes. This highlights vaginal microbiota as a potentially modifiable antenatal risk factor for PPROM and suggests that routine use of erythromycin for PPROM be re-examined.

The interaction between vaginal microbiota, cervical length, and vaginal progesterone treatment for preterm birth risk.

BACKGROUND: Preterm birth is the primary cause of infant death worldwide. A short cervix in the second trimester of pregnancy is a risk factor for preterm birth. In specific patient cohorts, vaginal progesterone reduces this risk. Using 16S rRNA gene sequencing, we undertook a prospective study in women at risk of preterm birth (n = 161) to assess (1) the relationship between vaginal microbiota and cervical length in the second trimester and preterm birth risk and (2) the impact of vaginal progesterone on vaginal bacterial communities in women with a short cervix. RESULTS: Lactobacillus iners dominance at 16 weeks of gestation was significantly associated with both a short cervix <25 mm (n = 15, P < 0.05) and preterm birth <34+0 weeks (n = 18; P < 0.01; 69% PPV). In contrast, Lactobacillus crispatus dominance was highly predictive of term birth (n = 127, 98% PPV). Cervical shortening and preterm birth were not associated with vaginal dysbiosis. A longitudinal characterization of vaginal microbiota (<18, 22, 28, and 34 weeks) was then undertaken in women receiving vaginal progesterone (400 mg/OD, n = 25) versus controls (n = 42). Progesterone did not alter vaginal bacterial community structure nor reduce L. iners-associated preterm birth (<34 weeks). CONCLUSIONS: L. iners dominance of the vaginal microbiota at 16 weeks of gestation is a risk factor for preterm birth, whereas L. crispatus dominance is protective against preterm birth. Vaginal progesterone does not appear to impact the pregnancy vaginal microbiota. Patients and clinicians who may be concerned about "infection risk" associated with the use of a vaginal pessary during high-risk pregnancy can be reassured.

Preterm Birth Prevention Post-Conization: A Model of Cervical Length Screening with Targeted Cerclage.

Women with a history of excisional treatment (conization) for cervical intra-epithelial neoplasia (CIN) are at increased risk of preterm birth, perinatal morbidity and mortality in subsequent pregnancy. We aimed to develop a screening model to effectively differentiate pregnancies post-conization into low- and high-risk for preterm birth, and to evaluate the impact of suture material on the efficacy of ultrasound indicated cervical cerclage. We analysed longitudinal cervical length (CL) data from 725 pregnant women post-conization attending preterm surveillance clinics at three London university Hospitals over a ten year period (2004-2014). Rates of preterm birth <37 weeks after targeted cerclage for CL<25mm were compared with local and national background rates and expected rates for this cohort. Rates for cerclage using monofilament or braided suture material were also compared. Of 725 women post-conization 13.5% (98/725) received an ultrasound indicated cerclage and 9.7% (70/725) delivered prematurely, <37weeks; 24.5% (24/98) of these despite insertion of cerclage. The preterm birth rate was lower for those that had monofilament (9/60, 15%) versus braided (15/38, 40%) cerclage (RR 0.7, 95% CI 0.54 to 0.94, P = 0.008). Accuracy parameters of interval reduction in CL between longitudinal second trimester screenings were calculated to identify women at low risk of preterm birth, who could safely discontinue surveillance. A reduction of CL <10% between screening timepoints predicts term birth, >37weeks. Our triage model enables timely discharge of low risk women, eliminating 36% of unnecessary follow-up CL scans. We demonstrate that preterm birth in women post-conization may be reduced by targeted cervical cerclage. Cerclage efficacy is however suture material-dependant: monofilament is preferable to braided suture. The introduction of triage prediction models has the potential to reduce the number of unnecessary CL scan for women at low risk of preterm birth.

Relationship between vaginal microbial dysbiosis, inflammation, and pregnancy outcomes in cervical cerclage.

Preterm birth, the leading cause of death in children under 5 years, may be caused by inflammation triggered by ascending vaginal infection. About 2 million cervical cerclages are performed annually to prevent preterm birth. The procedure is thought to provide structural support and maintain the endocervical mucus plug as a barrier to ascending infection. Two types of suture material are used for cerclage: monofilament or multifilament braided. Braided sutures are most frequently used, although no evidence exists to favor them over monofilament sutures. We assessed birth outcomes in a retrospective cohort of 678 women receiving cervical cerclage in five UK university hospitals and showed that braided cerclage was associated with increased intrauterine death (15% versus 5%; P = 0.0001) and preterm birth (28% versus 17%; P = 0.0006) compared to monofilament suture. To understand the potential underlying mechanism, we performed a prospective, longitudinal study of the vaginal microbiome in women at risk of preterm birth because of short cervical length (≤25 mm) who received braided (n = 25) or monofilament (n = 24) cerclage under comparable circumstances. Braided suture induced a persistent shift toward vaginal microbiome dysbiosis characterized by reduced Lactobacillus spp. and enrichment of pathobionts. Vaginal dysbiosis was associated with inflammatory cytokine and interstitial collagenase excretion into cervicovaginal fluid and premature cervical remodeling. Monofilament suture had comparatively minimal impact upon the vaginal microbiome and its interactions with the host. These data provide in vivo evidence that a dynamic shift of the human vaginal microbiome toward dysbiosis correlates with preterm birth.