Maternal dietary intervention during lactation impacts the maternal faecal and human milk microbiota

AIMS

To determine the effect of a two-week reduced fat and sugar and increased fibre maternal dietary intervention on the maternal faecal and human milk (HM) microbiomes.

METHODS AND RESULTS

Faecal swabs and HM samples were collected from mothers (n = 11) immediately pre-intervention, immediately post-intervention, and 4 and 8 weeks post-intervention, and were analysed using full-length 16S rRNA gene sequencing. Maternal macronutrient intake was assessed at baseline and during the intervention. Maternal fat and sugar intake during the intervention were significantly lower than pre-intervention (P = <0.001, 0.005, respectively). Significant changes in the bacterial composition of maternal faeces were detected after the dietary intervention, with decreases in the relative abundance of Bacteroides caccae (P = <0.001) and increases in the relative abundance of Faecalibacillus intestinalis (P = 0.006). In HM, the diet resulted in a significant increase in Cutibacterium acnes (P = 0.001) and a decrease in Haemophilus parainfluenzae (P = <0.001). The effect of the diet continued after the intervention, with faecal swabs and HM samples taken 4 and 8 weeks after the diet showing significant differences compared to baseline.

CONCLUSION

This pilot study demonstrates that short-term changes in maternal diet during lactation can alter the bacterial composition of the maternal faeces and HM.

Skin-Microbiome Assembly in Preterm Infants during the First Three Weeks of Life and Impact of Topical Coconut Oil Application

The structure and function of infant skin is not fully developed until 34 weeks of gestation, and this immaturity is associated with risk of late-onset sepsis (LOS). Topical coconut oil improves preterm-infant skin integrity and may reduce LOS. However, data on early-life skin-microbiome succession and potential effects of emollient skin care in preterm infants are scarce. We therefore collected skin-microbiome samples from the ear, axilla, and groin on days 1, 7, 14, and 21 from preterm infants born <30 weeks of gestation as part of a randomized clinical trial of standard skin care vs. topical coconut oil. We found that within-sample microbiome diversity was highest on day 1 after birth, with a subsequent decline and emergence of Staphylococcus genus dominance from day 7. Moreover, microbiome assembly was less diverse in infants receiving coconut oil vs. standard skin care. Our study provides novel data on preterm-infant skin-microbiome composition and highlights the modifying potential of emollient skin care.

Characterisation of Mid-Gestation Amniotic Fluid Cytokine and Bacterial DNA Profiles in Relation to Pregnancy Outcome in a Small Australian Cohort

A well-established association exists between intrauterine bacteria and preterm birth. This study aimed to explore this further through documenting bacterial and cytokine profiles in Australian mid-gestation amniotic fluid samples from preterm and term births. Samples were collected during amniocenteses. DNA was extracted and the full-length 16S rRNA gene was amplified and sequenced. Levels of the cytokines IL-1β, IL-6, IL-10, TNF-α and MCP-1 were determined using the Milliplex MAGPIX system. Bacterial DNA profiles were low in diversity and richness, with no significant differences observed between term and preterm samples. No differences in the relative abundance of individual OTUs between samples were identified. IL-1β and TNF-α levels were significantly higher in samples containing reads mapping to Sphingomonas sp.; however, this result should be interpreted with caution as similar reads were also identified in extraction controls. IL-6 levels were significantly increased in samples with reads that mapped to Pelomonas sp., whilst TNF-α levels were elevated in fluid samples from pregnancies that subsequently delivered preterm. Bacterial DNA unlikely to have originated from extraction controls was identified in 20/31 (64.5%) mid-gestation amniotic fluid samples. Bacterial DNA profiles, however, were not predictive of preterm birth, and although cytokine levels were elevated in the presence of certain genera, the biological relevance of this remains unknown.

Characterisation of human milk bacterial DNA profiles in a small cohort of Australian women in relation to infant and maternal factors

Human milk is composed of complex microbial and non-microbial components that shape the infant gut microbiome. Although several maternal and infant factors have been associated with human milk microbiota, no study has investigated this in an Australian population. Therefore, we aimed to investigate associations between human milk bacterial composition of Australian women and maternal factors (body mass index (BMI), mode of delivery, breast pump use, allergy, parity) and infant factors (sex, mode of feeding, pacifier use, and introduction of solids). Full-length 16S rRNA gene sequencing was used to characterise milk bacterial DNA profiles. Milk from mothers with a normal BMI had a higher relative abundance of Streptococcus australis than that of underweight mothers, while milk from overweight mothers had a higher relative abundance of Streptococcus salivarius compared with underweight and obese mothers. Mothers who delivered vaginally had a higher relative abundance of Streptococcus mitis in their milk compared to those who delivered via emergency caesarean section. Milk of mothers who used a breast pump had a higher relative abundance of Staphylococcus epidermidis and Streptococcus parasanguinis. Milk of mothers whose infants used a pacifier had a higher relative abundance of S. australis and Streptococcus gwangjuense. Maternal BMI, mode of delivery, breast pump use, and infant pacifier use are associated with the bacterial composition of human milk in an Australian cohort. The data from this pilot study suggests that both mother and infant can contribute to the human milk microbiome.

Effect of a reduced fat and sugar maternal dietary intervention during lactation on the infant gut microbiome

Objective

A growing body of literature has shown that maternal diet during pregnancy is associated with infant gut bacterial composition. However, whether maternal diet during lactation affects the exclusively breastfed infant gut microbiome remains understudied. This study sets out to determine whether a two-week of a reduced fat and sugar maternal dietary intervention during lactation is associated with changes in the infant gut microbiome composition and function.

Design

Stool samples were collected from four female and six male (n = 10) infants immediately before and after the intervention. Maternal baseline diet from healthy mothers aged 22–37 was assessed using 24-h dietary recall. During the 2-week dietary intervention, mothers were provided with meals and their dietary intake was calculated using FoodWorks 10 Software. Shotgun metagenomic sequencing was used to characterize the infant gut microbiome composition and function.

Results

In all but one participant, maternal fat and sugar intake during the intervention were significantly lower than at baseline. The functional capacity of the infant gut microbiome was significantly altered by the intervention, with increased levels of genes associated with 28 bacterial metabolic pathways involved in biosynthesis of vitamins (p = 0.003), amino acids (p = 0.005), carbohydrates (p = 0.01), and fatty acids and lipids (p = 0.01). Although the dietary intervention did not affect the bacterial composition of the infant gut microbiome, relative difference in maternal fiber intake was positively associated with increased abundance of genes involved in biosynthesis of storage compounds (p = 0.016), such as cyanophycin. Relative difference in maternal protein intake was negatively associated with Veillonella parvula (p = 0.006), while positively associated with Klebsiella michiganensis (p = 0.047). Relative difference in maternal sugar intake was positively associated with Lactobacillus paracasei (p = 0.022). Relative difference in maternal fat intake was positively associated with genes involved in the biosynthesis of storage compounds (p = 0.015), fatty acid and lipid (p = 0.039), and metabolic regulator (p = 0.038) metabolic pathways.

Conclusion

This pilot study demonstrates that a short-term maternal dietary intervention during lactation can significantly alter the functional potential, but not bacterial taxonomy, of the breastfed infant gut microbiome. While the overall diet itself was not able to change the composition of the infant gut microbiome, changes in intakes of maternal protein and sugar during lactation were correlated with changes in the relative abundances of certain bacterial species.

Clinical trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12619000606189).

Random amplified polymorphic DNA analysis reveals no clear link between Staphylococcus epidermidis and acute mastitis

Mastitis is commonly experienced by breastfeeding women. While Staphylococcus aureus is usually implicated in infectious mastitis, coagulase‐negative staphylococci (CoNS) are a possible alternative pathogen. This case‐control study examined the role of CoNS in mastitis using isolates cultured from breast milk of 20 women with mastitis and 16 women without mastitis. Gene sequencing determined bacterial species, and random amplified polymorphic DNA (RAPD) analysis investigated strain‐level variation. The majority of CoNS isolates were Staphylococcus epidermidis (182/199; 91%). RAPD analysis identified 33 unique S. epidermidis profiles, with no specific profile associated with mastitis cases.

Human Milk Lactose, Insulin, and Glucose Relative to Infant Body Composition during Exclusive Breastfeeding

Human milk (HM) components may influence infant growth and development. This study aimed to investigate relationships between infant body composition (BC) and HM lactose, insulin, and glucose (concentrations and calculated daily intakes (CDI)) as well as 24-h milk intake and maternal BC at 3 months postpartum. HM samples were collected at 2 months postpartum. Infant and maternal BC was assessed with bioimpedance spectroscopy. Statistical analysis used linear regression accounting for infant birth weight. 24-h milk intake and CDI of lactose were positively associated with infant anthropometry, lean body mass and adiposity. Higher maternal BC measures were associated with lower infant anthropometry, z-scores, lean body mass, and adiposity. Maternal characteristics including BC and age were associated with concentrations and CDI of HM components, and 24-h milk intake. In conclusion, 24-h intake of HM and lactose as well as maternal adiposity are related to development of infant BC.

The human milk microbiome: who, what, when, where, why, and how?

Human milk (HM) contains an incredible array of microorganisms. These likely contribute to the seeding of the infant gastrointestinal microbiome, thereby influencing infant immune and metabolic development and later-life health. Given the importance of the HM microbiota in this context, there has been an increase in research efforts to characterize this in different populations and in relation to different maternal and infant characteristics. However, despite a decade of intensive research, there remain several unanswered questions in this field. In this review, the "5 W+H" approach (who, what, when, where, why, and how) is used to comprehensively describe the composition, function, and origin of the HM microbiome. Here, existing evidence will be drawn together and critically appraised to highlight avenues for further research, both basic and applied. Perhaps the most interesting of these is the potential to modulate the HM microbiome using pre/probiotics or dietary interventions. Another exciting possibility is the personalization of donor milk for women with insufficient supply. By gaining a deeper understanding of the HM microbiome, opportunities to intervene to optimize infant and lifelong health may be identified.

Sequential Exposure to Antenatal Microbial Triggers Attenuates Alveolar Growth and Pulmonary Vascular Development and Impacts Pulmonary Epithelial Stem/Progenitor Cells

Perinatal inflammatory stress is strongly associated with adverse pulmonary outcomes after preterm birth. Antenatal infections are an essential perinatal stress factor and contribute to preterm delivery, induction of lung inflammation and injury, pre-disposing preterm infants to bronchopulmonary dysplasia. Considering the polymicrobial nature of antenatal infection, which was reported to result in diverse effects and outcomes in preterm lungs, the aim was to examine the consequences of sequential inflammatory stimuli on endogenous epithelial stem/progenitor cells and vascular maturation, which are crucial drivers of lung development. Therefore, a translational ovine model of antenatal infection/inflammation with consecutive exposures to chronic and acute stimuli was used. Ovine fetuses were exposed intra-amniotically to Ureaplasma parvum 42 days (chronic stimulus) and/or to lipopolysaccharide 2 or 7 days (acute stimulus) prior to preterm delivery at 125 days of gestation. Pulmonary inflammation, endogenous epithelial stem cell populations, vascular modulators and morphology were investigated in preterm lungs. Pre-exposure to UP attenuated neutrophil infiltration in 7d LPS-exposed lungs and prevented reduction of SOX-9 expression and increased SP-B expression, which could indicate protective responses induced by re-exposure. Sequential exposures did not markedly impact stem/progenitors of the proximal airways (P63+ basal cells) compared to single exposure to LPS. In contrast, the alveolar size was increased solely in the UP+7d LPS group. In line, the most pronounced reduction of AEC2 and proliferating cells (Ki67+) was detected in these sequentially UP + 7d LPS-exposed lambs. A similar sensitization effect of UP pre-exposure was reflected by the vessel density and expression of vascular markers VEGFR-2 and Ang-1 that were significantly reduced after UP exposure prior to 2d LPS, when compared to UP and LPS exposure alone. Strikingly, while morphological changes of alveoli and vessels were seen after sequential microbial exposure, improved lung function was observed in UP, 7d LPS, and UP+7d LPS-exposed lambs. In conclusion, although sequential exposures did not markedly further impact epithelial stem/progenitor cell populations, re-exposure to an inflammatory stimulus resulted in disturbed alveolarization and abnormal pulmonary vascular development. Whether these negative effects on lung development can be rescued by the potentially protective responses observed, should be examined at later time points.

Can we modulate the breastfed infant gut microbiota through maternal diet?

Initial colonisation of the infant gut is robustly influenced by regular ingestion of human milk, a substance that contains microbes, microbial metabolites, immune proteins, and oligosaccharides. Numerous factors have been identified as potential determinants of the human milk and infant gut microbiota, including maternal diet; however, there is limited data on the influence of maternal diet during lactation on either of these. Here, we review the processes thought to contribute to human milk and infant gut bacterial colonisation and provide a basis for considering the role of maternal dietary patterns during lactation in shaping infant gut microbial composition and function. Although only one observational study has directly investigated the influence of maternal diet during lactation on the infant gut microbiome, data from animal studies suggests that modulation of the maternal gut microbiota, via diet or probiotics, may influence the mammary or milk microbiota. Additionally, evidence from human studies suggests that the maternal diet during pregnancy may affect the gut microbiota of the breastfed infant. Together, there is a plausible hypothesis that maternal diet during lactation may influence the infant gut microbiota. If substantiated in further studies, this may present a potential window of opportunity for modulating the infant gut microbiome in early life.

A specific bacterial DNA signature in the vagina of Australian women in midpregnancy predicts high risk of spontaneous preterm birth (the Predict1000 study)

BACKGROUND

Intrauterine infection accounts for a quarter of the cases of spontaneous preterm birth; however, at present, it is not possible to efficiently identify pregnant women at risk to deliver preventative treatments.

OBJECTIVE

This study aimed to establish a vaginal microbial DNA test for Australian women in midpregnancy that will identify those at increased risk of spontaneous preterm birth.

STUDY DESIGN

A total of 1000 women with singleton pregnancies were recruited in Perth, Australia. Midvaginal swabs were collected between 12 and 23 weeks' gestation. DNA was extracted for the detection of 23 risk-related microbial DNA targets by quantitative polymerase chain reaction. Obstetrical history, pregnancy outcome, and demographics were recorded.

RESULTS

After excluding 64 women owing to losses to follow-up and insufficient sample for microbial analyses, the final cohort consisted of 936 women of predominantly white race (74.3%). The overall preterm birth rate was 12.6% (118 births); the spontaneous preterm birth rate at <37 weeks' gestation was 6.2% (2.9% at ≤34 weeks' gestation), whereas the preterm premature rupture of the membranes rate was 4.2%. No single individual microbial target predicted increased spontaneous preterm birth risk. Conversely, women who subsequently delivered at term had higher amounts of Lactobacillus crispatus, Lactobacillus gasseri, or Lactobacillus jensenii DNA in their vaginal swabs (13.8% spontaneous preterm birth vs 31.2% term; P=.005). In the remaining women, a specific microbial DNA signature was identified that was strongly predictive of spontaneous preterm birth risk, consisting of DNA from Gardnerella vaginalis (clade 4), Lactobacillus iners, and Ureaplasma parvum (serovars 3 and 6). Risk prediction was improved if Fusobacterium nucleatum detection was included in the test algorithm. The final algorithm, which we called the Gardnerella Lactobacillus Ureaplasma (GLU) test, was able to detect women at risk of spontaneous preterm birth at <37 and ≤34 weeks' gestation, with sensitivities of 37.9% and 44.4%, respectively, and likelihood ratios (plus or minus) of 2.22 per 0.75 and 2.52 per 0.67, respectively. Preterm premature rupture of the membranes was more than twice as common in GLU-positive women. Adjusting for maternal demographics, ethnicity, and clinical history did not improve prediction. Only a history of spontaneous preterm birth was more effective at predicting spontaneous preterm birth than a GLU-positive result (odds ratio, 3.6).

CONCLUSION

We have identified a vaginal bacterial DNA signature that identifies women with a singleton pregnancy who are at increased risk of spontaneous preterm birth and may benefit from targeted antimicrobial therapy.

Impact of expression mode and timing of sample collection, relative to milk ejection, on human milk bacterial DNA profiles

AIM

To investigate the impact of expression mode: electric breast pump or hand expression, and timing of sample collection: pre- and post-milk ejection on human milk (HM) bacterial DNA profiles.

METHODS AND RESULTS

Three HM samples from the same breast were collected from 30 breastfeeding mothers: a pre-milk ejection pump-expressed sample (pre-pump), a post-milk ejection pump-expressed sample (post-pump) and a post-milk ejection hand-expressed sample (post-hand). Full-length 16S rRNA gene sequencing was used to assess milk bacterial DNA profiles. Bacterial profiles did not differ significantly based on mode of expression nor timing of sample collection. No significant differences were detected in the relative abundance of any OTUs based on expression condition (pre-pump/ post-pump and post-pump/post-hand) with univariate linear mixed-effects regression analyses (all P-values > 0·01; α = 0·01). Similarly, no difference in richness was observed between sample types (number of observed OTUs: post-pump/post-hand P = 0·13; pre-pump/post-pump P = 0. 45).

CONCLUSION

Bacterial DNA profiles of HM did not differ according to either expression method or timing of sample collection.

SIGNIFICANCE AND IMPACT OF THE STUDY

Hand or pump expression can be utilized to collect samples for microbiome studies. This has implications for the design of future HM microbiome studies.

DNA extraction method influences human milk bacterial profiles

AIMS

To evaluate four DNA extraction methods to elucidate the most effective method for bacterial DNA recovery from human milk (HM).

METHODS AND RESULTS

Human milk DNA was extracted using the following methods: (i) Qiagen MagAttract Microbial DNA Isolation Kit (kit QM), (ii) Norgen Milk Bacterial DNA Isolation Kit (kit NM), (iii) Qiagen MagAttract Microbiome DNA/RNA Isolation Kit (kit MM) and (iv) TRIzol LS Reagent (method LS). The full-length 16S rRNA gene was sequenced. Kits MM and method LS were unable to extract detectable levels of DNA in 9/11 samples. Detectable levels of DNA were recovered from all samples using kits NM (mean = 0·68 ng μl^-1 ) and QM (mean = 0·55 ng μl^-1 ). For kits NM and QM, the greatest number of reads were associated with Staphylococcus epidermidis, Streptococcus vestibularis, Propionibacterium acnes, Veillonella dispar and Rothia mucilaginosa. Contamination profiles varied substantially between kits, with one bacterial species detected in negative extraction controls generated with kit QM and six with kit NM.

CONCLUSIONS

Kit QM is the most suitable of the kits tested for the extraction of bacterial DNA from human milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

Choice of extraction method impacts the efficiency of bacterial DNA extraction from human milk and the resultant bacterial community profiles generated from these samples.

Host range, morphological and genomic characterisation of bacteriophages with activity against clinical Streptococcus agalactiae isolates

Streptococcus agalactiae or Group B Streptococcus (GBS) is a leading cause of sepsis in neonates. As a preventative measure prophylactic antibiotic administration is common in pregnant women colonised with GBS, but antibiotic-resistance and adverse effects on neonatal microbiomes may result. Use of bacteriophages (phages) is one option for targeted therapy. To this end, four phages (LF1 –LF4) were isolated from wastewater. They displayed lytic activity in vitro against S. agalactiae isolates collected from pregnant women and neonates, with 190/246 isolates (77.2%) and 10/10 (100%) isolates susceptible to at least one phage, respectively. Phage genomes ranged from 32,205–44,768 bp and all phages were members of the Siphoviridae family. High nucleotide identity (99.9%) was observed between LF1 and LF4, which were closely related to a putative prophage of S. agalactiae. The genome organisation of LF2 differed, and it showed similarity to a different S. agalactiae prophage, while LF3 was more closely related to a Streptococcus pyogenes phage. Lysogenic gene presence (integrase, repressor and regulatory modules), was suggestive of temperate phages. In a therapeutic context, temperate phages are not ideal candidates, however, the broad host range activity of these phages observed on clinical isolates in vitro is promising for future therapeutic approaches including bioengineered phage or lysin applications.

Chronic Intra-Uterine Ureaplasma parvum Infection Induces Injury of the Enteric Nervous System in Ovine Fetuses

Background: Chorioamnionitis, inflammation of the fetal membranes during pregnancy, is often caused by intra-amniotic (IA) infection with single or multiple microbes. Chorioamnionitis can be either acute or chronic and is associated with adverse postnatal outcomes of the intestine, including necrotizing enterocolitis (NEC). Neonates with NEC have structural and functional damage to the intestinal mucosa and the enteric nervous system (ENS), with loss of enteric neurons and glial cells. Yet, the impact of acute, chronic, or repetitive antenatal inflammatory stimuli on the development of the intestinal mucosa and ENS has not been studied. The aim of this study was therefore to investigate the effect of acute, chronic, and repetitive microbial exposure on the intestinal mucosa, submucosa and ENS in premature lambs. Materials and Methods: A sheep model of pregnancy was used in which the ileal mucosa, submucosa, and ENS were assessed following IA exposure to lipopolysaccharide (LPS) for 2 or 7 days (acute), Ureaplasma parvum (UP) for 42 days (chronic), or repetitive microbial exposure (42 days UP with 2 or 7 days LPS). Results: IA LPS exposure for 7 days or IA UP exposure for 42 days caused intestinal injury and inflammation in the mucosal and submucosal layers of the gut. Repetitive microbial exposure did not further aggravate injury of the terminal ileum. Chronic IA UP exposure caused significant structural ENS alterations characterized by loss of PGP9.5 and S100β immunoreactivity, whereas these changes were not found after re-exposure of chronic UP-exposed fetuses to LPS for 2 or 7 days. Conclusion: The in utero loss of PGP9.5 and S100β immunoreactivity following chronic UP exposure corresponds with intestinal changes in neonates with NEC and may therefore form a novel mechanistic explanation for the association of chorioamnionitis and NEC.

The duration of fetal antenatal steroid exposure determines the durability of preterm ovine lung maturation

BACKGROUND

Antenatal corticosteroids (ACS) are the standard of care for maturing the fetal lung and improving outcomes for preterm infants. Antenatal corticosteroid dosing remains nonoptimized, and there is little understanding of how different treatment-to-delivery intervals may affect treatment efficacy. The durability of a lung maturational response is important because the majority of women treated with antenatal corticosteroids do not deliver within the widely accepted 1- to 7-day window of treatment efficacy.

OBJECTIVE

We used a sheep model to test the duration of fetal exposures for efficacy at delivery intervals from 1 to 10 days.

MATERIALS AND METHODS

For infusion studies, ewes with single fetuses were randomized to receive an intravenous bolus and maintenance infusion of betamethasone phosphate to target 1-4 ng/mL fetal plasma betamethasone for 36 hours, with delivery at 2, 4 ,or 7 days posttreatment or sterile saline solution as control. Animals receiving the clinical treatment were randomised to receive either a single injection of 0.25 mg/kg with a 1:1 mixture of betamethasone phosphate + betamethasone acetate with delivery at either 1 or 7 days posttreatment, or 2 treatments of 0.25 mg/kg betamethasone phosphate + betamethasone acetate spaced at 24 hours (giving ∼48 hours of fetal steroid exposure) with delivery at 2, 5, 7, or 10 days posttreatment. Negative control animals were treated with saline solution. All lambs were delivered at 121 ± 3 days gestational age and ventilated for 30 minutes to assess lung function.

RESULTS

Preterm lambs delivered at 1 or 2 days post-antenatal corticosteroid treatment had significant improvements in lung maturation for both intravenous and single-dose intramuscular treatments. After 2 days, the efficacy of 36-hour betamethasone phosphate infusions was lost. The single dose of 1:1 betamethasone phosphate + betamethasone acetate also was ineffective at 7 days. In contrast, animals treated with 2 doses had significant improvements in lung maturation at 2, 5, and 7 days, with treatment efficacy reduced by 10 days.

CONCLUSION

In preterm lambs, the durability of antenatal corticosteroids treatment depends on the duration of fetal exposure and is independent of the intravenous or intramuscular maternal route of administration. For acute 24- to 48-hour posttreatment deliveries, a 24-hour fetal antenatal corticosteroids exposure was sufficient for lung maturation. A fetal exposure duration of at least 48 hours was necessary to maintain long-term treatment durability. A single-dose ACS treatment should be sufficient for women delivering within <48 hours of antenatal corticosteroids treatment.

Infection-mediated preterm birth: Bacterial origins and avenues for intervention

Preterm birth (PTB) is globally the leading cause of death and disability in children under five years of age. Intra-amniotic infection is well recognised as a major cause of PTB. Importantly, it is the most common cause of extreme PTB (birth prior to 28 weeks gestation), which is frequently associated with a wide range of serious neonatal morbidities. Recent developments in next generation sequencing technologies, combined with many years of culture-based microbiological data have allowed us to gain a deeper understanding of the pathogenesis of infection-mediated PTB. In particular, studies have revealed numerous potential routes to intra-amniotic infection beyond the classically described ascending vaginal route. Currently, antibiotic therapy is standard treatment for suspected or confirmed intra-amniotic infection, although its use in this context has had mixed success due to problems ranging from inappropriate antibiotic selection in relation to the target organism/s, to poor transplacental drug passage. In this review, we will draw together evidence from animal models and human studies to characterise pathways to intra-amniotic infection. We will then thoroughly outline current therapeutic protocols for cases of intra-amniotic infection and suggest potential new avenues for treatment.

Genomic characterisation of perinatal Western Australian Streptococcus agalactiae isolates

As a leading cause of neonatal sepsis, Streptococcus agalactiae, commonly known as Group B Streptococcus, is a major neonatal pathogen. Current global screening practices employ risk- or culture-based protocols for detection of these organisms. In Western Australia (WA), universal culture-based screening is provided, with subsequent intrapartum antibiotic prophylaxis for all S. agalactiae-positive women during labour. Widespread antibiotic exposure is not ideal and this is one of the factors driving development of vaccines against S. agalactiae. Vaccine candidates have focused on the capsule, surface proteins and pilus types, however, capsule serotypes are known to vary geographically. The aim of this study was to use genome sequencing to gain an understanding of the circulating genotypes in WA, and to assess variations in the associated gene pools. We sequenced 141 antenatal carriage (vaginal/rectal) isolates and 10 neonatal invasive disease isolates from WA. Based on the global PubMLST database, the 151 strains were characterised into 30 sequence types, with clustering of these mainly into clonal complexes 1, 12, 17, 19 and 23. Of the genes encoding eleven surface proteins that were analysed, the most prevalent were fbp, lmb and scpB which were present in ≥ 98% of isolates. A cluster of non-haemolytic isolates, one of which was a neonatal invasive disease isolate, appeared to lack the entire cyl locus. Admixture analysis of population structure revealed evidence of genetic transfer among the WA isolates across structural groups. When compared against the PubMLST S. agalactiae data, WA isolates showed high levels of strain diversity with minimal apparent clustering. This is the first whole genome sequence study of WA S. agalactiae isolates and also represents the first addition of Australian isolate data to PubMLST. This report provides insight into the distribution and diversity of vaccine targets of S. agalactiae within Western Australia, indicating that the most appropriate capsular vaccine for this population would be the proposed pentavalent (Cps Ia, Ib, II, III and V) preparation, whilst vaccines targeting surface proteins should ideally utilise Fbp, Lmb and/or ScpB.

Placental and intra-amniotic inflammation are associated with altered fetal immune responses at birth

INTRODUCTION

High-grade placental inflammation is associated with preterm birth and poor neonatal outcomes. Recent reports suggest that low-grade placental inflammation is common in uncomplicated pregnancies. The relationship between placental inflammation and innate immune anti-microbial responses is unknown. In this study we sought to identify any association between placental inflammation and fetal immune responses.

METHODS

Cord blood samples collected from late preterm and full-term Caesarean section deliveries (n = 44) were exposed to various immune challenges (resiquimod, LPS, PGN, poly (I:C), cGAMP, and 5'ppp-dsRNA) and production of inflammatory mediators (G-CSF, IFN-γ, IL-1β, IL-6, IL-8, IL-10, and TNF-α) was measured by multiplex assay. Hospital histology reports were used to assess the extent of inflammation in the placenta.

RESULTS

Almost half (47.7%) of placentae examined here showed histological evidence of inflammation. Resiquimod, LPS, and PGN elicited strong inflammatory responses in neonatal cord blood, while poly (I:C), cGAMP, and 5'ppp-dsRNA elicited weaker responses. Fetuses with evidence of chorioamnionitis and fetal inflammatory reaction in their placentae had significantly increased immune responses to cGAMP and 5'ppp-dsRNA (ligands for STING and RIG-I, respectively) and significantly decreased immune responses to poly (I:C) (a TLR3 agonist). Interestingly, STING, RIG-I, and TLR3 are all involved in viral response pathways, suggesting that fetuses exposed to chorioamnionitis or fetal inflammatory reaction might respond differently to viruses postnatally.

CONCLUSION

Our data suggest that low-level placental inflammation is associated with altered innate cytokine responses at birth.

Detection of group B Streptococcus during antenatal screening in Western Australia: a comparison of culture and molecular methods

AIM

Global screening strategies for Group B Streptococcus (GBS) include risk- or culture-based methods to guide intrapartum prophylaxis. In Western Australia (WA), antenatal culture-based screening is routine; however, numerous culture methods exist, in addition to molecular methods. We aimed to assess the comparability of research and diagnostic screening approaches.

METHODS AND RESULTS

Vaginal and rectal swabs were self-collected by pregnant women (n = 531) from King Edward Memorial Hospital, WA, in parallel to routine screening (35-37 weeks of gestation). Research methods involved culture (Strep B Carrot Broth™ and StrepB CHROMagar™) and molecular methods (real-time PCR) and were compared to routine diagnostic screening (Lim Broth and Granada agar). Overall, GBS detection was comparable between research and diagnostic approaches (3-5% discrepancy, kappa = 0·76). Specificity/sensitivity of Carrot Broth^™ was 100%/89%, while that of CHROMagar^™ was 73%/100%, respectively. Direct PCR was unable to detect GBS in ~18% of specimens which were culture positive; however, it exhibited 100% specificity.

CONCLUSIONS

This clinical evaluation of GBS screening methods provides support for current practice.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although CHROM was highly sensitive, further testing is recommended due to a high false-positive rate. Molecular assays are useful for rapid detection; however, low-titre samples may require additional enrichment prior to molecular analysis to improve sensitivity.

The Not-so-Sterile Womb: Evidence That the Human Fetus Is Exposed to Bacteria Prior to Birth

The human microbiome includes trillions of bacteria, many of which play a vital role in host physiology. Numerous studies have now detected bacterial DNA in first-pass meconium and amniotic fluid samples, suggesting that the human microbiome may commence in utero. However, these data have remained contentious due to underlying contamination issues. Here, we have used a previously described method for reducing contamination in microbiome workflows to determine if there is a fetal bacterial microbiome beyond the level of background contamination. We recruited 50 women undergoing non-emergency cesarean section deliveries with no evidence of intra-uterine infection and collected first-pass meconium and amniotic fluid samples. Full-length 16S rRNA gene sequencing was performed using PacBio SMRT cell technology, to allow high resolution profiling of the fetal gut and amniotic fluid bacterial microbiomes. Levels of inflammatory cytokines were measured in amniotic fluid, and levels of immunomodulatory short chain fatty acids (SCFAs) were quantified in meconium. All meconium samples and most amniotic fluid samples (36/43) contained bacterial DNA. The meconium microbiome was dominated by reads that mapped to Pelomonas puraquae. Aside from this species, the meconium microbiome was remarkably heterogeneous between patients. The amniotic fluid microbiome was more diverse and contained mainly reads that mapped to typical skin commensals, including Propionibacterium acnes and Staphylococcus spp. All meconium samples contained acetate and propionate, at ratios similar to those previously reported in infants. P. puraquae reads were inversely correlated with meconium propionate levels. Amniotic fluid cytokine levels were associated with the amniotic fluid microbiome. Our results demonstrate that bacterial DNA and SCFAs are present in utero, and have the potential to influence the developing fetal immune system.

Protection of the Ovine Fetal Gut against Ureaplasma-Induced Chorioamnionitis: A Potential Role for Plant Sterols

Chorioamnionitis, clinically most frequently associated with Ureaplasma, is linked to intestinal inflammation and subsequent gut injury. No treatment is available to prevent chorioamnionitis-driven adverse intestinal outcomes. Evidence is increasing that plant sterols possess immune-modulatory properties. Therefore, we investigated the potential therapeutic effects of plant sterols in lambs intra-amniotically (IA) exposed to Ureaplasma. Fetal lambs were IA exposed to Ureaplasma parvum (U. parvum, UP) for six days from 127 d-133 d of gestational age (GA). The plant sterols β-sitosterol and campesterol, dissolved with β-cyclodextrin (carrier), were given IA every two days from 122 d-131 d GA. Fetal circulatory cytokine levels, gut inflammation, intestinal injury, enterocyte maturation, and mucosal phospholipid and bile acid profiles were measured at 133 d GA (term 150 d). IA plant sterol administration blocked a fetal inflammatory response syndrome. Plant sterols reduced intestinal accumulation of proinflammatory phospholipids and tended to prevent mucosal myeloperoxidase-positive (MPO) cell influx, indicating an inhibition of gut inflammation. IA administration of plant sterols and carrier diminished intestinal mucosal damage, stimulated maturation of the immature epithelium, and partially prevented U. parvum-driven reduction of mucosal bile acids. In conclusion, we show that β-sitosterol and campesterol administration protected the fetus against adverse gut outcomes following UP-driven chorioamnionitis by preventing intestinal and systemic inflammation.

Group B streptococcus prevalence, serotype distribution and colonization dynamics in Western Australian pregnant women

PURPOSE

Streptococcus agalactiae, or group B streptococcus (GBS), is a leading neonatal pathogen that causes sepsis, meningitis and pneumonia. Globally, strategies have been implemented to address vertical transmission, and in Western Australia (WA), culture-based screening at 35-37 weeks' gestation is part of routine care and guides antibiotic administration. Previous Australian studies have focused on other regions or included low sample-size representatives; we aimed to describe antenatal GBS colonization in WA.

METHODOLOGY

A cohort of 814 pregnant women attending antenatal clinics (2015-2017) self-collected vaginal and rectal swabs at ≤22 weeks (n=814) and ≥33 weeks' (n=567) gestation. These were assessed for GBS presence using culture and PCR, and serotyping was conducted using molecular methods. Lifestyle questionnaires and medical data were collected.

RESULTS

We observed an overall GBS colonization rate of 24%, with 10.6  % of positive participants transiently colonized. Ethnicity (Aboriginal, Torres Strait Islander and African), maternal age ≥25 years, vitamin use, frequent sexual intercourse (≥5 times/week) and use of sex toys were associated with GBS colonization. The dominant serotypes identified were Ia (27.9%), III (20.9%), II (16.3%), V (15.8%), Ib (8.4%), VI (5.1%), IV (2.8%), NT (1.9), VIII (0.5%) and IX (0.5%) at visit one, with V (18.9%) preceding serotype II (18.2%) at visit two. Serotype VII was not detected.

CONCLUSION

This is the first cohort study to assess GBS colonization in Western Australian pregnant women and will be highly beneficial for guiding clinical practice and future therapeutic options, in particular, the selection of suitable vaccine candidates.

Characterization of the bacterial microbiome in first-pass meconium using propidium monoazide (PMA) to exclude nonviable bacterial DNA

Numerous studies have reported bacterial DNA in first-pass meconium samples, suggesting that the human gut microbiome is seeded prior to birth. However, these studies have not been able to discriminate between DNA from living bacterial cells, DNA from dead bacterial cells or cell-free DNA. Here we have used propidium monoazide (PMA) together with 16S rRNA gene sequencing to determine whether there are intact bacterial cells in the fetal gut. DNA was extracted from first-pass meconium (n = 5) and subjected to 16S rRNA gene sequencing with/without PMA treatment. All meconium samples, regardless of PMA treatment, contained detectable levels of bacterial DNA; however, treatment with PMA prior to DNA extraction decreased the DNA yield by approximately 20%. PMA-treated meconium samples did not differ significantly from untreated samples in terms of observed number of OTUs (P = 0·945); although they did differ taxonomically, with around one quarter of OTUs identified in untreated samples only, suggesting that they have originated from cell-free/nonviable DNA. The mean Sørensen coefficient for treated vs untreated samples was 0·527. Our findings suggest that the fetal gut is seeded with intact bacterial cells prior to birth. This is an important finding, as exposure to live bacteria during gestation might have a significant impact on the developing fetus. SIGNIFICANCE AND IMPACT OF THE STUDY: DNA-based microbiome studies performed using 16S rRNA gene sequencing are limited by their inability to discriminate between live bacterial cells, dead bacterial cells and cell-free DNA. Here we use propidium monoazide (PMA) to exclude nonviable bacteria from microbiome analysis of first-pass meconium samples and thereby reveal that the majority of the purported fetal gut microbiome is from intact bacterial cells. This work demonstrates the importance of excluding nonviable bacteria when analysing the microbial community in low-biomass samples such as meconium.

Re: "Amniotic fluid from healthy term pregnancies does not harbor a detectable microbial community" (2018) 6:87, https://doi.org/10.1186/s40168-018-0475-7

A recent publication by Lim et al. 2018 (Amniotic fluid from healthy term pregnancies does not harbor a detectable microbial community) strongly concluded that the microbiome of amniotic fluid primarily originates from reagent contamination. However, upon closer inspection of the methods used and data presented in this study, in particular the supplementary data, such conclusions do not appear to be supported by the results. We outline such methodological/data interpretation concerns and invite the authors to discuss these.

Identification and removal of contaminating microbial DNA from PCR reagents: impact on low-biomass microbiome analyses

Reagent-derived contamination can compromise the integrity of microbiome data, particularly in low microbial biomass samples. This contamination has recently been attributed to the 'kitome' (contamination introduced by the DNA extraction kit), prior to which attention was mostly paid to potential contamination introduced by PCR reagents. In this study, we assessed the proportion to which our DNA extraction kit and PCR master mix introduce contaminating microbial DNA to bacterial microbial profiles generated by 16S rRNA gene sequencing. Utilizing a commercial dsDNase treatment protocol to decontaminate the PCR master mix, we demonstrated that the vast majority of contaminating DNA was derived from the PCR master mix. Importantly, this contamination was almost completely eliminated using the simple dsDNase treatment, resulting in a 99% reduction in contaminating bacterial reads. We suggest that dsDNase treatment of PCR reagents should be explored as a simple and effective way of reducing contamination in low-biomass microbiome studies and producing more robust and reliable data. SIGNIFICANCE AND IMPACT OF THE STUDY: Reagent contamination with microbial DNA is a major problem in microbiome studies of low microbial biomass samples. Levels of such contaminating DNA often outweigh what is present in the sample and heavily confound subsequent data analysis. Previous studies have suggested this contamination is primarily derived from DNA extraction kits. Here, we identified the PCR master mix as the primary source of contamination, and showed that enzymatic removal of the contamination drastically reduced the blank signal and improved precision. Decontamination of PCR master mixes may have the potential to improve the sensitivity and accuracy of low-biomass microbiome studies.

Bacteriophage Therapy: Clinical Trials and Regulatory Hurdles

Increasing reports of antimicrobial resistance and limited new antibiotic discoveries and development have fuelled innovation in other research fields and led to a revitalization of bacteriophage (phage) studies in the Western world. Phage therapy mainly utilizes obligately lytic phages to kill their respective bacterial hosts, while leaving human cells intact and reducing the broader impact on commensal bacteria that often results from antibiotic use. Phage therapy is rapidly evolving and has resulted in cases of life-saving therapeutic use and multiple clinical trials. However, one of the biggest challenges this antibiotic alternative faces relates to regulations and policy surrounding clinical use and implementation beyond compassionate cases. This review discusses the multi-drug resistant Gram-negative pathogens of highest critical priority and summarizes the current state-of-the-art in phage therapy targeting these organisms. It also examines phage therapy in humans in general and the approaches different countries have taken to introduce it into clinical practice and policy. We aim to highlight the rapidly advancing field of phage therapy and the challenges that lie ahead as the world shifts away from complete reliance on antibiotics.

A Critical Review of the Bacterial Baptism Hypothesis and the Impact of Cesarean Delivery on the Infant Microbiome

Numerous studies suggest that infants delivered by cesarean section are at a greater risk of non-communicable diseases than their vaginal counterparts. In particular, epidemiological studies have linked Cesarean delivery with increased rates of asthma, allergies, autoimmune disorders, and obesity. Mode of delivery has also been associated with differences in the infant microbiome. It has been suggested that these differences are attributable to the "bacterial baptism" of vaginal birth, which is bypassed in cesarean deliveries, and that the abnormal establishment of the early-life microbiome is the mediator of later-life adverse outcomes observed in cesarean delivered infants. This has led to the increasingly popular practice of "vaginal seeding": the iatrogenic transfer of vaginal microbiota to the neonate to promote establishment of a "normal" infant microbiome. In this review, we summarize and critically appraise the current evidence for a causal association between Cesarean delivery and neonatal dysbiosis. We suggest that, while Cesarean delivery is certainly associated with alterations in the infant microbiome, the lack of exposure to vaginal microbiota is unlikely to be a major contributing factor. Instead, it is likely that indication for Cesarean delivery, intrapartum antibiotic administration, absence of labor, differences in breastfeeding behaviors, maternal obesity, and gestational age are major drivers of the Cesarean delivery microbial phenotype. We, therefore, call into question the rationale for "vaginal seeding" and support calls for the halting of this practice until robust evidence of need, efficacy, and safety is available.

Antenatal Corticosteroid Exposure Disrupts Myelination in the Auditory Nerve of Preterm Sheep

BACKGROUND

Antenatal corticosteroids (ACS) improve preterm neonatal outcomes. However, uncertainty remains regarding the safety of ACS exposure for the developing fetus, particularly its neurosensory development.

OBJECTIVES

We investigated the effect of single and multiple ACS exposures on auditory nerve development in an ovine model of pregnancy.

METHODS

Ewes with a single fetus (gestational age [GA] 100 days) received an intramuscular injection of 150 mg medroxyprogesterone-acetate, followed by intramuscular (i) betamethasone (0.5 mg/kg) on days 104, 111, and 118 GA; (ii) betamethasone on day 104 and saline on days 111 and 118 GA; or (iii) saline on days 104, 111, and 118 GA, with delivery on day 125 GA. Transmission electron microscope images of lamb auditory nerve preparations were digitally analyzed to determine auditory nerve morphology and myelination.

RESULTS

Relative to the control, mean auditory nerve myelin area was significantly increased in the multiple-treatment group (p < 0.001), but not in the single-treatment group. Increased myelin thickness was significantly changed only in a subgroup analysis for those axons with myelin thickness greater than the median value (p < 0.001). Morphological assessments showed that the increased myelin area was due to an increased likelihood of decompacted areas (p = 0.005; OR = 2.14, 95% CI 1.26-3.63; 31.6 vs. 18.2% in controls) and irregular myelin deposition (p = 0.001; OR = 5.91, 95% CI 2.16-16.19; 49.0 vs. 16.8% in controls) in the myelin sheath.

CONCLUSIONS

In preterm sheep, ACS exposure increased auditory nerve myelin area, potentially due to disruption of normal myelin deposition.

Comparison of Meconium DNA Extraction Methods for Use in Microbiome Studies

The establishment of human gut microbiota commences initially in utero. Meconium—the first fecal material passed after birth—can be used to study fetal gut contents; however, processing meconium samples for microbiome studies presents significant technical challenges. Meconium hosts a low biomass microbiome, is tar-like in texture and contains high concentrations of PCR inhibitors. This study aimed to evaluate four different DNA extraction methods to elucidate the most effective method for bacterial DNA recovery and sequencing analysis from first-pass meconium. Samples from five infants were collected and processed using the following extraction kits: (1) Qiagen QIAamp DNA Stool Mini (QS); (2) Qiagen QIAamp DNA Microbiome (QM); (3) MoBio PowerSoil (PS); (4) MoBio MagAttract PowerMicrobiome (PM). Additionally, Kit PM was employed with a double inhibitor removal treatment (IRT) step (PM2). Bacterial DNA recovery was assessed by qPCR. Any PCR inhibition in samples was measured by spiking DNA eluates with 0.1 ng of pure Streptococcus agalactiae (GBS) DNA followed by qPCR quantitation. Kit PM yielded the highest average total DNA yield (79.3 ng per gram of meconium). Samples extracted with kit PS had the highest detectable levels of 16S rRNA gene by qPCR. The ability of each kit to overcome PCR inhibition varied, with qPCR on GBS-spiked DNA from kits QS, QM, PS, and PM recovering 87.1, 91.0, 88.8, and 37.9% GBS DNA, respectively. Double IRT improved the performance of kit PM, increasing GBS recovery to 56.5%. However, once DNA yield was normalized to the level recovered with the other kits 100% of GBS DNA was detected, suggesting that levels of PCR inhibitors are related to DNA yield from kit PM. Ion Torrent 16S rRNA gene sequencing revealed a high level of inter-kit variation in meconium microbiome structure. In particular, kit QM showed a bias toward extracting Firmicute DNA, while the other kits extracted primarily Proteobacterial DNA. Choice of extraction kit greatly impacts on the ability to extract and detect bacterial DNA in meconium and on the microbiome community structure generated from these samples.

Applications for Bacteriophage Therapy during Pregnancy and the Perinatal Period

Pregnant women and their unborn children are a population that is particularly vulnerable to bacterial infection. Physiological changes that occur during pregnancy affect the way women respond to such infections and the options that clinicians have for treatment. Antibiotics are still considered the best option for active infections and a suitable prophylaxis for prevention of potential infections, such as vaginal/rectal Streptococcus agalactiae colonization prior to birth. The effect of such antibiotic use on the developing fetus, however, is still largely unknown. Recent research has suggested that the fetal gut microbiota plays a critical role in fetal immunologic programming. Hence, even minor alterations in this microbiota may have potentially significant downstream effects. An ideal antibacterial therapeutic for administration during pregnancy would be one that is highly specific for its target, leaving the surrounding microbiota intact. This review first provides a basic overview of the challenges a clinician faces when administering therapeutics to a pregnant patient and then goes on to explore common bacterial infections in pregnancy, use of antibiotics for treatment/prevention of such infections and the consequences of such treatment for the mother and infant. With this background established, the review then explores the potential for use of bacteriophage (phage) therapy as an alternative to antibiotics during the antenatal period. Many previous reviews have highlighted the revitalization of and potential for phage therapy for treatment of a range of bacterial infections, particularly in the context of the increasing threat of widespread antibiotic resistance. However, information on the potential for the use of phage therapeutics in pregnancy is lacking. This review aims to provide a thorough overview of studies of this nature and discuss the feasibility of bacteriophage use during pregnancy to treat and/or prevent bacterial infections.

The Paradoxical Effects of Chronic Intra-Amniotic Ureaplasma parvum Exposure on Ovine Fetal Brain Development

Chorioamnionitis is associated with adverse neurodevelopmental outcomes in preterm infants. Ureaplasma spp. are the microorganisms most frequently isolated from the amniotic fluid of women diagnosed with chorioamnionitis. However, controversy remains concerning the role of Ureaplasma spp. in the pathogenesis of neonatal brain injury. We hypothesize that reexposure to an inflammatory trigger during the perinatal period might be responsible for the variation in brain outcomes of preterms following Ureaplasma-driven chorioamnionitis. To investigate these clinical scenarios, we performed a detailed multimodal study in which ovine neurodevelopmental outcomes were assessed following chronic intra-amniotic Ureaplasma parvum (UP) infection either alone or combined with subsequent lipopolysaccharide (LPS) exposure. We show that chronic intra-amniotic UP exposure during the second trimester provoked a decrease in astrocytes, increased oligodendrocyte numbers, and elevated 5-methylcytosine levels. In contrast, short-term LPS exposure before preterm birth induced increased microglial activation, myelin loss, elevation of 5-hydroxymethylcytosine levels, and lipid profile changes. These LPS-induced changes were prevented by chronic preexposure to UP (preconditioning). These data indicate that chronic UP exposure has dual effects on preterm brain development in utero. On the one hand, prolonged UP exposure causes detrimental cerebral changes that may predispose to adverse postnatal clinical outcomes. On the other, chronic intra-amniotic UP exposure preconditions the brain against a second inflammatory hit. This study demonstrates that microbial interactions and the timing and duration of the inflammatory insults determine the effects on the fetal brain. Therefore, this study helps to understand the complex and diverse postnatal neurological outcomes following UP driven chorioamnionitis.

A novel one-step real-time multiplex PCR assay to detect Streptococcus agalactiae presence and serotypes Ia, Ib, and III

Streptococcus agalactiae is the leading cause of early-onset neonatal sepsis. Culture-based screening methods lack the sensitivity of molecular assays and do not indicate serotype; a potentially important virulence marker. We aimed to develop a multiplex PCR to detect S. agalactiae while simultaneously identifying serotypes Ia, Ib, and III; commonly associated with infant disease. Primers were designed to target S. agalactiae serotype-specific cps genes and the dltS gene. The assay was validated with 512 vaginal specimens from pregnant women. 112 (21.9%) were dltS positive, with 14.3%, 0.9%, and 6.3% of these identified as cps Ia, Ib, and III, respectively. Our assay is a specific and sensitive method to simultaneously detect S. agalactiae and serotypes Ia, Ib, and III in a single step. It is of high significance for clinical diagnostic applications and also provides epidemiological data on serotype, information that may be important for vaccine development and other targeted non-antibiotic therapies.

Planting the seed: Origins, composition, and postnatal health significance of the fetal gastrointestinal microbiota

It has long been assumed that establishment of the fetal microbiome commences with the birthing process. However, recent studies have found bacterial DNA in umbilical cord blood, placenta, amniotic fluid, meconium, and fetal membranes in healthy normal pregnancies, leading to suggestions that the seeding of the fetal microbiome may commence in utero long before delivery. The origins of the microbiota of the fetal gastrointestinal (GI) tract have not yet been conclusively determined, although bacterial translocation from the maternal circulation, or ascension from the vagina, are both likely to be contributing pathways. Mother-to-child efflux of bacteria during pregnancy has the potential to markedly influence postnatal health, as the composition of gut microbiota determines production of important metabolites which are absorbed systemically and which modify immune function and development. Hence, the importance of understanding the colonization of the fetal GI microbiome is becoming clear, although few studies have investigated the origins, dynamics, and timing of the fetal microbiome. This is the topic of this review. By gaining a deeper understanding of the mechanisms underpinning fetal microbiome seeding, strategies may be developed to optimize fetal immune development and reduce the risk of adverse health and developmental outcomes.

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

BACKGROUND

Detection 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.

METHODS

In 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.

RESULTS

Detection 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.

CONCLUSIONS

These 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.

Intra-amniotic Candida albicans infection induces mucosal injury and inflammation in the ovine fetal intestine

Chorioamnionitis is caused by intrauterine infection with microorganisms including Candida albicans (C.albicans). Chorioamnionitis is associated with postnatal intestinal pathologies including necrotizing enterocolitis. The underlying mechanisms by which intra-amniotic C.albicans infection adversely affects the fetal gut remain unknown. Therefore, we assessed whether intra-amniotic C.albicans infection would cause intestinal inflammation and mucosal injury in an ovine model. Additionally, we tested whether treatment with the fungistatic fluconazole ameliorated the adverse intestinal outcome of intra-amniotic C.albicans infection. Pregnant sheep received intra-amniotic injections with 10⁷ colony-forming units C.albicans or saline at 3 or 5 days before preterm delivery at 122 days of gestation. Fetuses were given intra-amniotic and intra-peritoneal fluconazole treatments 2 days after intra-amniotic administration of C.albicans. Intra-amniotic C.albicans caused intestinal colonization and invasive growth within the fetal gut with mucosal injury and intestinal inflammation, characterized by increased CD3⁺ lymphocytes, MPO⁺ cells and elevated TNF-α and IL-17 mRNA levels. Fluconazole treatment in utero decreased intestinal C.albicans colonization, mucosal injury but failed to attenuate intestinal inflammation. Intra-amniotic C.albicans caused intestinal infection, injury and inflammation. Fluconazole treatment decreased mucosal injury but failed to ameliorate C.albicans-mediated mucosal inflammation emphasizing the need to optimize the applied antifungal therapeutic strategy.

A New, Potent, and Placenta-Permeable Macrolide Antibiotic, Solithromycin, for the Prevention and Treatment of Bacterial Infections in Pregnancy

Intrauterine infection–inflammation is a major cause of early preterm birth and subsequent neonatal mortality and acute or long-term morbidity. Antibiotics can be administered in pregnancy to prevent preterm birth either prophylactically to women at high risk for preterm delivery, or to women with diagnosed intrauterine infection, prelabor rupture of membranes, or in suspected preterm labor. The therapeutic goals of each of these scenarios are different, with different pharmacological considerations, although effective antimicrobial therapy is an essential requirement. An ideal antibiotic for these clinical indications would be (a) one that is easily administered and orally bioactive, (b) has a favorable adverse effect profile (devoid of reproductive toxicity or teratogenicity), (c) is effective against the wide range of microorganisms known to be commonly associated with intra-amniotic infection, (d) provides effective antimicrobial protection within both the fetal and amniotic compartments after maternal delivery, (e) has anti-inflammatory properties, and (f) is effective against antibiotic-resistant microorganisms. Here, we review the evidence from clinical, animal, and ex vivo/in vitro studies that demonstrate that a new macrolide-derived antibiotic – solithromycin – has all of these properties and, hence, may be an ideal antibiotic for the treatment and prevention of intrauterine infection-­related pregnancy complications. While this evidence is extremely encouraging, it is still preliminary. A number of key studies need to be completed before solithromycin’s true potential for use in pregnancy can be ascertained.

Neuroinflammation and structural injury of the fetal ovine brain following intra-amniotic Candida albicans exposure

BACKGROUND

Intra-amniotic Candida albicans (C. Albicans) infection is associated with preterm birth and high morbidity and mortality rates. Survivors are prone to adverse neurodevelopmental outcomes. The mechanisms leading to these adverse neonatal brain outcomes remain largely unknown. To better understand the mechanisms underlying C. albicans-induced fetal brain injury, we studied immunological responses and structural changes of the fetal brain in a well-established translational ovine model of intra-amniotic C. albicans infection. In addition, we tested whether these potential adverse outcomes of the fetal brain were improved in utero by antifungal treatment with fluconazole.

METHODS

Pregnant ewes received an intra-amniotic injection of 10(7) colony-forming units C. albicans or saline (controls) at 3 or 5 days before preterm delivery at 0.8 of gestation (term ~ 150 days). Fetal intra-amniotic/intra-peritoneal injections of fluconazole or saline (controls) were administered 2 days after C. albicans exposure. Post mortem analyses for fungal burden, peripheral immune activation, neuroinflammation, and white matter/neuronal injury were performed to determine the effects of intra-amniotic C. albicans and fluconazole treatment.

RESULTS

Intra-amniotic exposure to C. albicans caused a severe systemic inflammatory response, illustrated by a robust increase of plasma interleukin-6 concentrations. Cerebrospinal fluid cultures were positive for C. albicans in the majority of the 3-day C. albicans-exposed animals whereas no positive cultures were present in the 5-day C. albicans-exposed and fluconazole-treated animals. Although C. albicans was not detected in the brain parenchyma, a neuroinflammatory response in the hippocampus and white matter was seen which was characterized by increased microglial and astrocyte activation. These neuroinflammatory changes were accompanied by structural white matter injury. Intra-amniotic fluconazole reduced fetal mortality but did not attenuate neuroinflammation and white matter injury.

CONCLUSIONS

Intra-amniotic C. albicans exposure provoked acute systemic and neuroinflammatory responses with concomitant white matter injury. Fluconazole treatment prevented systemic inflammation without attenuating cerebral inflammation and injury.

Outside-in? Acute fetal systemic inflammation in very preterm chronically catheterized sheep fetuses is not driven by cells in the fetal blood

BACKGROUND

The preterm birth syndrome (delivery before 37 weeks gestation) is a major contributor to the global burden of perinatal morbidity and death. The cause of preterm birth is complex, multifactorial, and likely dependent, at least in part, on the gestational age of the fetus. Intrauterine infection is frequent in preterm deliveries that occur at <32 weeks gestation; understanding how the fetus responds to proinflammatory insult will be an important step towards early preterm birth prevention. However, animal studies of infection and inflammation in prematurity commonly use older fetuses that possess comparatively mature immune systems.

OBJECTIVE

Aiming to characterize acute fetal responses to microbial agonist at a clinically relevant gestation, we used 92-day-old fetuses (62% of term) to develop a chronically catheterized sheep model of very preterm pregnancy. We hypothesized that any acute fetal systemic inflammatory responses would be driven by signaling from the tissues exposed to Escherichia coli lipopolysaccharide that is introduced into the amniotic fluid.

STUDY DESIGN

Eighteen ewes that were carrying a single fetus at 92 days of gestation had recovery surgery to place fetal tracheal, jugular, and intraamniotic catheters. Animals were recovered for 24 hours before being administered either intraamniotic E coli lipopolysaccharide (n = 9) or sterile saline solution (n = 9). Samples were collected for 48 hours before euthanasia and necroscopy. Fetal inflammatory responses were characterized by microarray analysis, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay.

RESULTS

Intraamniotic lipopolysaccharide reached the distal trachea within 2 hours. Lipopolysaccharide increased tracheal fluid interleukin-8 within 2 hours and generated a robust inflammatory response that was characterized by interleukin-6 signaling pathway activation and up-regulation of cell proliferation but no increases in inflammatory mediator expression in cord blood RNA.

CONCLUSIONS

In very preterm sheep fetuses, lipopolysaccharide stimulates inflammation in the fetal lung and fetal skin and stimulates a systemic inflammatory response that is not generated by fetal blood cells. These data argue for amniotic fluid-exposed tissues that play a key role in driving acute fetal and intrauterine inflammatory responses.

Determinants of mastitis in women in the CASTLE study: a cohort study

BACKGROUND

Mastitis is an acute, debilitating condition that occurs in approximately 20 % of breastfeeding women who experience a red, painful breast with fever. This paper describes the factors correlated with mastitis and investigates the presence of Staphylococcus aureus in women who participated in the CASTLE (Candida and Staphylococcus Transmission: Longitudinal Evaluation) study. The CASTLE study was a prospective cohort study which recruited nulliparous women in late pregnancy in two maternity hospitals in Melbourne, Australia in 2009-2011.

METHODS

Women completed questionnaires at recruitment and six time-points in the first eight weeks postpartum. Postpartum questionnaires asked about incidences of mastitis, nipple damage, milk supply, expressing practices and breastfeeding problems. Nasal and nipple swabs were collected from mothers and babies, as well as breast milk samples. All samples were cultured for S. aureus. "Time at risk" of mastitis was defined as days between birth and first occurrence of mastitis (for women who developed mastitis) and days between birth and the last study time-point (for women who did not develop mastitis). Risk factors for incidence of mastitis occurring during the time at risk (Incident Rate Ratios [IRR]) were investigated using a discrete version of the multivariable proportional hazards regression model.

RESULTS

Twenty percent (70/346) of participants developed mastitis. Women had an increased risk of developing mastitis if they reported nipple damage (IRR 2.17, 95 % CI 1.21, 3.91), over-supply of breast milk (IRR 2.60, 95 % CI 1.58, 4.29), nipple shield use (IRR 2.93, 95 % CI 1.72, 5.01) or expressing several times a day (IRR 1.64, 95 % CI 1.01, 2.68). The presence of S. aureus on the nipple (IRR 1.72, 95 % CI 1.04, 2.85) or in milk (IRR 1.78, 95 % CI 1.08, 2.92) also increased the risk of developing mastitis.

CONCLUSIONS

Nipple damage, over-supply of breast milk, use of nipple shields and the presence of S. aureus on the nipple or in breast milk increased the mastitis risk in our prospective cohort study sample. Reducing nipple damage may help reduce maternal breast infections.

Detection of Candida spp. in the vagina of a cohort of nulliparous pregnant women by culture and molecular methods: Is there an association between maternal vaginal and infant oral colonisation?

BACKGROUND

Most studies describing vaginal Candida spp. in pregnancy focus on symptomatic vaginitis, rather than asymptomatic colonisation, and solely utilise microbiological culture. The extent to which asymptomatic vaginal carriage may represent a reservoir for infant oral colonisation has been highly debated.

MATERIALS AND METHODS

This study formed part of the Candida and Staphylococcus Transmission Longitudinal Evaluation (CASTLE) study, in Melbourne, Australia, from 2009 to 2011 and used culture and molecular methods to examine vaginal swabs collected late in the third trimester of pregnancy for Candida spp. Oral swabs from infants were also examined using culture methods.

RESULTS

Overall, 80 of 356 (22%) women were positive for Candida spp; the majority being Candida albicans (83%). Candida glabrata and other Candida spp. were also identified, but in much lower numbers. Molecular analysis identified numerous positive samples not detected by culture, including 13 cases of C. albicans. In addition, some positive samples only recorded to genus level by culture were accurately identified as either C. albicans or C. glabrata following molecular analyses. Eighteen infants recorded positive Candida spp. cultures, predominantly C. albicans. However, there were only four (25%) mother/infant dyads where C. albicans was detected.

CONCLUSIONS

This study provides valuable data on asymptomatic colonisation rates of Candida spp. within an asymptomatic population of women late in pregnancy. The utilisation of molecular methods improved the rate of detection and provided a more accurate means for identification of non-albicans Candida spp. The low mother/infant colonisation rate suggests that non-maternal sources are likely involved in determining infant oral colonisation status.

In vitro activity of solithromycin and its metabolites, CEM-214 and N-acetyl-CEM-101, against 100 clinical Ureaplasma spp. isolates compared with azithromycin

There is a strong association between vaginal and/or amniotic fluid Ureaplasma spp. colonisation and risk of preterm birth. The novel fluoroketolide antibiotic solithromycin (CEM-101) is active against Ureaplasma spp. in vitro. Evidence from ex vivo and in vivo models suggests that, unlike most macrolide antibiotics, solithromycin readily crosses the placenta. Solithromycin metabolism varies according to species; in pregnant sheep, the bioactive metabolites CEM-214 and N-acetyl-CEM-101 (NAc-CEM-101) have been shown to accumulate in the amniotic cavity following maternal solithromycin administration, potentially contributing to its antimicrobial effects. To determine the antimicrobial activity of these metabolites against Ureaplasma spp., the effects of solithromycin, CEM-214, NAc-CEM-101 and the comparator azithromycin were tested on a collection of 100 clinical Ureaplasma spp. isolates from the UK and Australia using a modified 96-well broth microdilution method. MIC90 values observed for the combined cohort were: solithromycin, 0.125 mg/L; CEM-214, 0.5mg/L; NAc-CEM-101, 0.5mg/L; and azithromycin, 2mg/L. Solithromycin showed 34-fold greater activity against Ureaplasma spp. isolates than azithromycin, whilst CEM-214 and NAc-CEM-101 possessed ca. 22% and 17% of the activity of solithromycin, respectively, significantly greater than that of azithromycin. One bacterial isolate showed resistance to azithromycin (MIC=16 mg/L) but had a much lower MIC for solithromycin (MIC=0.25mg/L). In conclusion, the metabolites of solithromycin had reduced, but still potent, activity against 100 clinical Ureaplasma spp. isolates in vitro. This may be important in some instances such as pregnancy, however studies to determine levels of the metabolites in these settings are required.