The Impact of Maternal Antibiotics on Neonatal Disease

Neonatal outcomes in term and preterm infants following adjunctive azithromycin antibiotic prophylaxis for non-elective cesarean delivery

OBJECTIVE

It is currently unknown whether adjunctive azithromycin prophylaxis at the time of non-elective cesarean has differential effects on neonatal outcomes in the context of prematurity. The objective of this study was to compare whether neonatal outcomes differ in term and preterm infants exposed to adjunctive azithromycin prophylaxis before non-elective cesarean delivery.

STUDY DESIGN

A planned secondary analysis of a multi-center randomized controlled trial that enrolled women with singleton pregnancies ≥24 weeks gestation undergoing non-elective cesarean delivery (during labor or ≥4 h after membrane rupture). Women received standard antibiotic prophylaxis and were randomized to either adjunctive azithromycin (500 mg) or placebo. The primary composite outcome was neonatal death, suspected or confirmed neonatal sepsis, and serious neonatal morbidities (NEC, PVL, IVH, BPD). Secondary outcomes included NICU admission, neonatal readmission, culture positive infections and prevalence of resistant organisms. Odds ratios (OR) for the effect of azithromycin versus placebo were compared between gestational age strata (preterm [less than 37 weeks] versus term [37 weeks or greater]). Tests of interaction examined homogeneity of treatment effect with gestational age.

RESULTS

The analysis includes 2,013 infants, 226 preterm (11.2%) and 1,787 term. Mean gestational ages were 34 and 39.5 weeks, respectively. Within term and preterm strata, maternal and delivery characteristics were similar between the azithromycin and placebo groups. There was no difference in the odds of composite neonatal outcome between those exposed to azithromycin versus placebo in preterm neonates (OR 0.82, 95% CI 0.48-1.41) and in term neonates (OR 1.06, 95% CI 0.77-1.46), with no difference between gestational age strata (p = 0.42). Analysis of secondary outcomes also revealed no differences in treatment effects within or between gestational age strata.

CONCLUSION

Exposure to adjunctive azithromycin antibiotic prophylaxis for non-elective cesarean delivery does not increase neonatal morbidity or mortality in term or preterm infants.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov, NCT01235546.

Early antibiotics and risk for necrotizing enterocolitis in premature infants: A narrative review

While prompt initiation of antibiotics at birth due to concerns for early onset sepsis is common, it often leads to many preterm infants being exposed to treatment despite negative blood cultures. Such exposure to early antibiotics can impact the developing gut microbiome putting infants at increased risk of several diseases. Necrotizing enterocolitis (NEC), a devastating inflammatory bowel disease that affects preterm infants, is among the most widely studied neonatal disease that has been linked to early antibiotics. While some studies have demonstrated an increased risk of NEC, other studies have demonstrated seemingly contrary findings of decreased NEC with early antibiotics. Studies using animal models have also yielded differing findings of benefit vs. harm of early antibiotic exposure on subsequent NEC susceptibility. We thus sought to conduct this narrative review to help clarify the relationship between early antibiotics exposure and future risk of NEC in preterm infants. Our objectives are to: (1) summarize findings from human and animal studies that investigated the relationship between early antibiotics and NEC, (2) highlight important limitations of these studies, (3) explore potential mechanisms that can explain why early antibiotics may increase or decrease NEC risk, and (4) identify future directions for research.

Gut microbiota promotes stem cell differentiation through macrophage and mesenchymal niches in early postnatal development

Intestinal stem cell maturation and development coincide with gut microbiota exposure after birth. Here, we investigated how early life microbial exposure, and disruption of this process, impacts the intestinal stem cell niche and development. Single-cell transcriptional analysis revealed impaired stem cell differentiation into Paneth cells and macrophage specification upon antibiotic treatment in early life. Mouse genetic and organoid co-culture experiments demonstrated that a CD206+ subset of intestinal macrophages secreted Wnt ligands, which maintained the mesenchymal niche cells important for Paneth cell differentiation. Antibiotics and reduced numbers of Paneth cells are associated with the deadly infant disease, necrotizing enterocolitis (NEC). We showed that colonization with Lactobacillus or transfer of CD206+ macrophages promoted Paneth cell differentiation and reduced NEC severity. Together, our work defines the gut microbiota-mediated regulation of stem cell niches during early postnatal development.

Improving Cohort-Hospital Matching Accuracy through Standardization and Validation of Participant Identifiable Information

Linking very large, consented birth cohorts to birthing hospitals clinical data could elucidate the lifecourse outcomes of health care and exposures during the pregnancy, birth and newborn periods. Unfortunately, cohort personally identifiable information (PII) often does not include unique identifier numbers, presenting matching challenges. To develop optimized cohort matching to birthing hospital clinical records, this pilot drew on a one-year (December 2020-December 2021) cohort for a single Australian birthing hospital participating in the whole-of-state Generation Victoria (GenV) study. For 1819 consented mother-baby pairs and 58 additional babies (whose mothers were not themselves participating), we tested the accuracy and effort of various approaches to matching. We selected demographic variables drawn from names, DOB, sex, telephone, address (and birth order for multiple births). After variable standardization and validation, accuracy rose from 10% to 99% using a deterministic-rule-based approach in 10 steps. Using cohort-specific modifications of the Australian Statistical Linkage Key (SLK-581), it took only 3 steps to reach 97% (SLK-5881) and 98% (SLK-5881.1) accuracy. We conclude that our SLK-5881 process could safely and efficiently achieve high accuracy at the population level for future birth cohort-birth hospital matching in the absence of unique identifier numbers.

Umbilical cord blood interleukin-6 level as a predictor of early-onset neonatal sepsis

    Background Neonatal sepsis is a global health problem contributing significantly to neonatal morbidity and mortality. It is difficult to clinically distinguish neonates with and without sepsis. Interleukin-6 (IL-6) concentration in neonates has high sensitivity and specificity to predict neonatal sepsis in infants at risk. Objective  To determine the utility of umbilical cord blood IL-6 as a predictor of early-onset neonatal sepsis. Methods This prospective cohort study was conducted in neonates born to mothers with sepsis risk factors from December 2020 to January 2021. We measured IL-6 from umbilical cord blood taken after placental expulsion. IL-6 ³16.4 pg/ml was considered to be elevated. Subjects were monitored for signs of clinical sepsis until 72 hours after birth. We also recorded the presence of other maternal and infant risk factors of sepsis and assessed association between IL-6 and other risk factors with the occurrence of sepsis, expressed as relative risk (RR) with 95% confidence interval (95%CI). Results During the study period, 40 neonates were born to mothers with sepsis risk factors; 13 (32.5%) developed clinical sepsis. Significantly more infants with elevated IL-6 developed neonatal sepsis (55.5%) than those with normal IL-6 (13.6%). After multivariate analysis incorporating other significant variables, the risk factors predictive of clinical early-onset neonatal sepsis were IL-6 [RR 5.54 (95%CI 1.68-18.25); P=0.016], prematurity [RR 4.92 (95%CI 1.66-14.59); P=0.014], and initial Apgar score [RR 3.38 (95%CI 1.34-3.38); P=0.046]. Conclusion In neonates with maternal risk factors, an IL-6 level of ³16.4 pg/ml is associated with an increased risk of early-onset neonatal sepsis.

Fetal-neonatal exposure to antibiotics and NEC development: A systematic review and meta-analysis

BACKGROUND

Fetal and neonatal exposure to antibiotics may contribute to the development of necrotizing enterocolitis (NEC) in preterm infants. This systematic review and meta-analysis investigate whether exposure to third trimester maternal antibiotics (MAB) and/or prolongation of empirical antibiotics (PEAB) are associated with NEC development in preterms.

METHOD

We included observational and randomized controlled studies, including those on preterm or very low birth weight (VLBW) infants, from MEDLINE and EMBASE, published between 1990 and June 2021. Exposure was defined as third trimester MAB and/or PEAB. The two reviewers independently performed study selection, data extraction, and quality assessment.

RESULTS

Three cohort studies compared third trimester MAB with no antibiotics. MAB was associated with lower NEC incidence, unadjusted pooled odds ratio (OR) is 0.57 (95% CI: 0.35-0.93). Twelve cohort studies showed that PEAB was associated with an increased risk of NEC. Ten observational cohort studies show an unadjusted OR of 2.72 (1.65-4.47), and two case-control studies show an unadjusted mean difference of 2.31 (0.94-3.68). Moderate to substantial heterogeneity was observed but decreased in studies with low risk of bias and large sample size.

CONCLUSION

Evidence suggests an association between MAB and decreased risk of NEC and an association between PEAB and increased risk of NEC. Further studies should confirm these associations and explore causality.

SYSTEMATIC REVIEW REGISTRATION

identifier [CRD42022304937].

Maternal Antibiotic Treatment Disrupts the Intestinal Microbiota and Intestinal Development in Neonatal Mice

Maternal antibiotic treatment (MAT) during prenatal and intrapartum periods alters the bacterial composition and diversity of the intestinal microbiota of the offspring. The effect of MAT during pregnancy on the intestinal microbiota and its relationship with intestinal development remain unknown. This study investigated the effects of MAT during pregnancy on intestinal microbiota, injury and inflammation, vascularization, cellular proliferation, and the intestinal barrier in neonatal mice. At timed intervals, we fed pregnant C57BL/6N mice sterile drinking water containing antibiotics (ampicillin, gentamicin, and vancomycin; all 1 mg/ml) from gestational day 15 to delivery. The control dams were fed sterile drinking water. Antibiotic administration was halted immediately after birth. On postnatal day 7, the intestinal microbiota was sampled from the lower gastrointestinal tract and the ileum was harvested for histology, Western blot, and cytokines analyses. MAT significantly reduced the relative abundance of Bacteroidetes and Firmicutes and significantly increased the relative abundance of Proteobacteria in the intestine compared with their abundances in the control group. MAT also significantly increased intestinal injury score and cytokine levels, reduced the number of intestinal goblet cells and proliferating cell nuclear antigen-positive cells, and reduced the expressions of vascular endothelial growth factor and tight junction proteins. Therefore, we proposed that maternal antibiotic exposure during pregnancy disrupts the intestinal microbiota and intestinal development in neonatal mice.

Potential Prenatal Origins of Necrotizing Enterocolitis

Necrotizing enterocolitis is a serious and yet incompletely understood gastrointestinal disease of infancy that predominately impacts premature neonates. Prevention is a key strategy for the management of necrotizing enterocolitis. Although postnatal risk factors have been the focus of prevention efforts, obstetric complications, including intrauterine inflammation and infection, growth restriction, preeclampsia, and prenatal medications, have been associated with an increased risk of necrotizing enterocolitis. This article reviews the evidence behind the prenatal risk factors for necrotizing enterocolitis, and discusses how these risk factors may elucidate the pathogenesis of necrotizing enterocolitis and provide insight into prevention and treatment.

Use of antibiotics during pregnancy is associated with infection in children at four years of age in Portugal

AIM

To assess the association between taking antibiotics in pregnancy and the occurrence of infections in children at four years of age.

METHODS

We studied children who participated in the follow-up of the birth cohort Generation XXI, Porto-Portugal, at the age of four years. We evaluated the associations between the use of antibiotics by the mother at any time in pregnancy with the occurrence of infections. Data were analysed using logistic regression, controlling for potential confounding variables.

RESULTS

We studied 7459 children (50.7% boys). The use of antibiotics at any stage of pregnancy, and not only in the third trimester, was associated with the occurrence of tonsillitis at four years, even after controlling for potential confounders (OR 1.19, 95% CI 1.03-1.38). Other infections did not show association.

CONCLUSION

Maternal use of antibiotics during pregnancy was associated with an increased risk of tonsillitis reported at four years of age. Antibiotics could favour the potential transmission of an unfavourable microbiome from mother to child.

Pathogenesis of necrotising enterocolitis: The impact of the altered gut microbiota and antibiotic exposure in preterm infants

Necrotising enterocolitis (NEC) is a devastating condition with high morbidity and mortality seen predominately in preterm infants. Multiple factors are associated with the pathogenesis of NEC. The widespread use of antibiotics in the neonatal intensive care unit might play a role in the pathogenesis of NEC in preterm infants. This review provides a summary on the intestinal microbiota in preterm infants with a focus on how antibiotic exposure may reduce the biodiversity of the intestinal microbiota and may predispose preterm infants to NEC. CONCLUSION: Prolonged antibiotic therapy has been suggested as a risk factor for the development of NEC in preterm infants.

Antenatal Antibiotic Exposure Affects Enteral Feeding, Body Growth, and Neonatal Infection in Preterm Infants: A Retrospective Study

Background: Antibiotics are widely prescribed by obstetricians, which exposes a large number of infants to antenatal antibiotics (AAB). The effect of AAB on various aspects of neonatal development of preterm infants remains unclear. Methods: In this retrospective study, infants born with gestational age (GA) between 22 ⁺⁰ and 36 ⁺⁶ weeks at our unit from 2017 to 2019 were included. Multivariable analysis was adopted to examine the associations between AAB exposure and various outcomes related to enteral feeding process, body growth, and neonatal infection after adjusting for potential confounders. Further subanalysis on the exposure level of AAB and stratified analysis by GA (<34 vs. ≥34 weeks) were also conducted. Results: In this cohort comprising 2,543 preterm infants, AAB was associated with decreased risks of feeding intolerance (odds ratio [OR]: 0.63, 95% confidence interval [CI]: 0.48-0.82) and neonatal infection (OR: 0.63, 95% CI: 0.41-0.94). Higher AAB exposure level was associated with higher Z scores of birth weight (β = 0.37, 95% CI: 0.27-0.47), but lower Δbodyweight Z-scores (β = -0.20, 95% CI: -0.27 to -0.13). AAB was positively associated with the parameters related to body growth in infants with GA <34 weeks but negatively associated in those with GA ≥34 weeks. Conclusions: AAB exposure affects the enteral feeding process and neonatal infection. The effects on body growth vary by the exposure level of AAB and GA of infants. A well-designed prospective and preferably multi-centre study with predefined parameters is required to confirm our findings.

Epidemiology of readmissions in early infancy following nonelective cesarean delivery

OBJECTIVE

Determine incidence and risk factors for readmissions in early infancy.

STUDY DESIGN

Secondary analysis of data from the Cesarean Section Optimal Antibiotic Prophylaxis trial. All unplanned revisits (unplanned clinic, ER visits, and hospital readmissions) and hospital readmissions (initial discharge to 3-month follow-up) were analyzed.

RESULTS

295 (15.9%) of 1850 infants had revisits with risk factors being ethnicity (adjusted odds ratio (aOR): 0.6 for Hispanic), maternal postpartum antibiotics (1.89), azithromycin treatment (1.22), small for gestational age (1.68), apnea (3.82), and hospital stay after birth >90th percentile (0.49). 71 (3.8%) of 1850 infants were readmitted with risk factors being antenatal steroids (aOR 2.49), elective repeat C/section (0.72), postpartum maternal antibiotics (2.22), O₂ requirement after delivery room (2.82), and suspected/proven neonatal sepsis (0.55).

CONCLUSION(S)

Multiple risk factors were identified, suggesting potential impact on the neonatal microbiome (maternal postpartum antibiotics) or issues related to access/cost of care (Hispanic ethnicity associated with fewer revisits).

Mothers of Preterm Infants Have Individualized Breast Milk Microbiota that Changes Temporally Based on Maternal Characteristics

Mother's milk contains complex microbial communities thought to be important for colonizing a preterm infant's gastrointestinal tract. However, little is known about the microbiota in the preterm mother's milk and factors influencing its composition. We characterized the temporal dynamics of microbial communities in 490 breast milk samples from 86 mothers of preterm infants (born <1,250g) over the first 8 weeks postpartum. Highly individualized microbial communities were identified in each mother's milk that changed temporally with notable alterations in predicted microbial functions. However, pre-pregnancy BMI, delivery mode, and antibiotics were associated with changes in these microbial dynamics. Individual classes of antibiotics and their duration of exposure during prenatal and postpartum periods showed unique relationships with microbial taxa abundance and diversity in mother's milk. These results highlight the temporal complexity of the preterm mother's milk microbiota and its relationship with maternal characteristics as well as the importance of discussing antibiotic stewardship for mothers.

Uncertainties in Screening and Prevention of Group B Streptococcus Disease

In autumn 2016, the UK Department of Health (now Department of Health and Social Care) convened 2 meetings to discuss how to address research evidence gaps in order to minimize the impact of infant group B streptococcus (GBS) disease in the United Kingdom. At that meeting, a number of research priorities were highlighted, including improving the screening for GBS colonization in pregnant women, offering intrapartum antibiotic prophylaxis and point-of-care testing, and understanding the effect of widespread intrapartum antibiotic use on long-term infant health. Further discussions involved investigating the feasibility of a large prospective study of pregnant women and their infants in order to understand the role of antibodies in the protection against GBS disease in infancy following maternal exposure to GBS colonization. Here, we summarize the research uncertainties identified at that meeting.

Preventing dysbiosis of the neonatal mouse intestinal microbiome protects against late-onset sepsis

Late-onset sepsis (LOS) is thought to result from systemic spread of commensal microbes from the intestines of premature infants. Clinical use of probiotics for LOS prophylaxis has varied owing to limited efficacy, reflecting an incomplete understanding of relationships between development of the intestinal microbiome, neonatal dysbiosis and LOS. Using a model of LOS, we found that components of the developing microbiome were both necessary and sufficient to prevent LOS. Maternal antibiotic exposure that eradicated or enriched transmission of Lactobacillus murinus exacerbated and prevented disease, respectively. Prophylactic administration of some, but not all Lactobacillus spp. was protective, as was administration of Escherichia coli. Intestinal oxygen level was a major driver of colonization dynamics, albeit via mechanisms distinct from those in adults. These results establish a link between neonatal dysbiosis and LOS, and provide a basis for rational selection of probiotics that modulate primary succession of the microbiome to prevent disease.

A critical analysis of risk factors for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common serious gastrointestinal morbidity in preterm infants. A number of risk factors for NEC have been reported in the literature. With the exception of decreasing gestational age, decreasing birth weight and formula feeding, there is disagreement on the importance of reported risk factors with uncertain causality. Causal risk factors may be observed at any time before the onset of NEC, including prior to an infant's birth. The purpose of this review is to examine the existing literature and summarize risk factors for NEC. This review may be helpful in understanding the epidemiology of NEC and inform the measurement and assessment of risks factors for NEC in research studies and quality improvement projects.