Antibiotic use during pregnancy and asthma in preschool children: the influence of confounding

Antibiotic exposure during pregnancy increases risk for childhood atopic diseases: a nationwide cohort study

PURPOSE

The prevalence of atopic diseases has increased in recent decades. A possible link between antibiotic use during pregnancy and childhood atopic disease has been proposed. The aim of this study is to explore the association of antibiotic exposure during pregnancy with childhood atopic diseases from a nationwide, population-based perspective.

METHODS

This was a nationwide population-based cohort study. Taiwan's National Health Insurance Research Database was the main source of data. The pairing of mothers and children was achieved by linking the NHIRD with the Taiwan Maternal and Child Health Database. This study enrolled the first-time pregnancies from 2004 to 2010. Infants of multiple delivery, preterm delivery, and death before 5 years old were excluded. All participants were followed up at least for 5 years. Antenatal antibiotics prescribed to mothers during the pregnancy period were reviewed. Children with more than two outpatient visits, or one admission, with a main diagnosis of asthma, allergic rhinitis, or atopic dermatitis were regarded as having an atopic disease.

RESULTS

A total of 900,584 children were enrolled in this study. The adjusted hazard ratios of antibiotic exposure during pregnancy to childhood atopic diseases were 1.12 for atopic dermatitis, 1.06 for asthma, and 1.08 for allergic rhinitis, all of which reached statistical significance. The trimester effect was not significant. There was a trend showing the higher the number of times a child was prenatally exposed to antibiotics, the higher the hazard ratio was for childhood atopic diseases.

CONCLUSIONS

Prenatal antibiotic exposure might increase the risk of childhood atopic diseases in a dose-dependent manner.

Maternal gut microbiota in the health of mothers and offspring: from the perspective of immunology

Due to the physiological alteration during pregnancy, maternal gut microbiota changes following the metabolic processes. Recent studies have revealed that maternal gut microbiota is closely associated with the immune microenvironment in utero during pregnancy and plays a vital role in specific pregnancy complications, including preeclampsia, gestational diabetes, preterm birth and recurrent miscarriages. Some other evidence has also shown that aberrant maternal gut microbiota increases the risk of various diseases in the offspring, such as allergic and neurodevelopmental disorders, through the immune alignment between mother and fetus and the possible intrauterine microbiota. Probiotics and the high-fiber diet are effective inventions to prevent mothers and fetuses from diseases. In this review, we summarize the role of maternal gut microbiota in the development of pregnancy complications and the health condition of future generations from the perspective of immunology, which may provide new therapeutic strategies for the health management of mothers and offspring.

Prenatal and postnatal exposure to antibiotics and risk of food allergy in the offspring: A nationwide birth cohort study in South Korea

BACKGROUND

There are only preliminary studies examining the associations of postnatal antibiotic exposure with food allergy in childhood, and the effect of antibiotic exposure in utero has not been resolved. Thus, we aimed to investigate the effect of prenatal and postnatal antibiotic exposure on the risk of food allergy in childhood.

METHODS

Using the nationwide birth cohort in South Korea, all 3,163,206 infants (pairing mother; n = 2,322,735) born in South Korea between 2010 and 2017 were included in the analysis. The primary outcome was the diagnosis of food allergy, and the observation period was between January 1, 2009, and December 31, 2020. We implemented four different designs for the study, which consisted of a full unmatched cohort, 1:1 propensity-matched cohort, sibling comparison cohort, and health screening cohort along with multiple subgroup analyses.

RESULTS

During the follow-up period (median 6.92 years [IQR, 4.72-9.00]) of the 3,161,858 infants (52.6% male) in the birth cohort, 29,973 (1.9%) were diagnosed with food allergies. After a 1:1 propensity score matching, the use of antibiotics increased the risk of overall food allergy (prenatal [HR, 1.05; 95% CI, 1.04-1.09] and postnatal [HR, 1.05; 95% CI, 1.01-1.10] periods). The association was more significantly accentuated when antibiotic exposure was used in the short term, and the children were born preterm or with low birthweight; however, a trimester-specific effect was not observed. We observed more pronounced risks of food allergy in the health screening cohort (prenatal, 17%; postnatal, 15%), thus addressing the adverse effects of critical factors including maternal BMI, smoking status, and type of infant feeding. Similar trends were observed across all four differnt cohorts.

CONCLUSION

This study reported a moderate association between early-life antibiotic use and subsequent food allergy during childhood throughout four different designs of analyses. This study suggests that clinicians need to consider the risks and benefits of antibiotics when administering antibiotics to individuals in the prenatal and postnatal periods.

Prenatal and Perinatal Antibiotic Exposure and Long-Term Outcome

Antibiotics are frequently administered during pregnancy. Although necessary to address acute infections, their use facilitates antibiotic resistance. Other associations have also been found with the use of antibiotics, such as perturbations of gut bacteria, delays in microbial maturation, and increased risks of allergic and inflammatory diseases. Little is known about how the prenatal and perinatal administration of antibiotics to mothers affects the clinical outcomes of their offspring. A literature search was conducted of the Cochrane, Embase, and PubMed engines. The retrieved articles were reviewed by two authors and verified for relevance. The primary outcome was the effect of pre- and perinatal maternal antibiotic use on clinical outcomes. Thirty-one relevant studies were included in the meta-analysis. Various aspects are discussed, including infections, allergies, obesity, and psychosocial factors. In animal studies, antibiotic intake during pregnancy has been suggested to cause long-term alterations in immune regulation. In humans, associations have been found between antibiotic intake during pregnancy and different types of infections and an increased risk of pediatric infection-related hospitalization. A dose-dependent positive association between pre- and perinatal antibiotic use and asthma severity has been reported in animal and human studies, while positive associations with atopic dermatitis and eczema were reported by human studies. Multiple associations were identified between antibiotic intake and psychological problems in animal studies; however, relevant data from human studies are limited. However, one study reported a positive association with autism spectrum disorders. Multiple animal and human studies reported a positive association between pre- and perinatal antibiotic use by mothers and diseases in their offspring. Our findings have potentially significant clinical relevance, particularly considering the implications for health during infancy and later in life as well as the related economic burden.

Intestinal Microflora Altered by Vancomycin Exposure in Early Life Up-regulates Type 2 Innate Lymphocyte and Aggravates Airway Inflammation in Asthmatic Mice

Allergic asthma is a chronic inflammatory disease primarily mediated by Th2 immune mechanisms. Exposure to antibiotics during early life is associated with an increased risk of allergic asthma, although the exact mechanism is not fully understood. In this study, mice were randomly divided into a normal saline control group (NS group), an OVA-induced asthma group (OVA group), a vancomycin treatment control group (VAN.NS group), and a vancomycin treatment the OVA-induced asthma group (VAN.OVA group). The results showed that vancomycin altered dominant species in experimental mice. The phylum level histogram showed that Bacteroides abundance was increased, and Firmicutes abundance was decreased in the OVA group. Airway inflammation and airway hyperresponsiveness (AHR) were aggravated in the vancomycin-exposed group. Enzyme-linked immunosorbent assay (ELISA) showed that the serum levels of IL-5, IL-13, and IL-33 in the OVA group were higher than those in the NS group, especially in the VAN.OVA group. The expression of GATA binding protein-3(GATA3) and retinoid acid receptor-related orphan receptor alpha (RORa) increased in the OVA group, even more so in the VAN.OVA group. Group 2 innate lymphoid cells (ILC2s) in the lung detected by flow cytometry was increased in OVA mice more than those in control mice, with a more remarkable increase in the VAN.OVA. Our results demonstrated that vancomycin used in early life could alter the intestinal microecology of mice, which, in turn, aggravates airway inflammation and upregulate type 2 innate lymphocytes.

Prenatal antibiotic exposure, asthma, and the atopic march: A systematic review and meta-analysis

Antibiotic use during pregnancy may increase the risk for asthma in children. We performed a meta-analysis assessing prenatal antibiotic exposure and the risk for childhood wheeze or asthma, as well as for diseases associated with the atopic march. A systematic literature search protocol (PROSPERO-ID: CRD42020191940) was registered and searches were completed using Medline, Proquest, Embase, and the Cochrane central register of controlled trials. Screening for inclusion criteria: published in English, German, French, Dutch, or Arabic, intervention (use of any antibiotic at any time point during pregnancy), and disease (reporting atopic disease incidence in children with a primary outcome of asthma or wheeze), and exclusion criteria: reviews, preclinical data, and descriptive studies, yielded 27 studies. Study quality was assessed using the Newcastle-Ottawa Assessment Scale. Quality of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Our meta-analysis demonstrates that antibiotic use during pregnancy is associated with an increased relative risk (RR) of developing wheeze RR 1.51 (95% CI: 1.17-1.94) or asthma RR 1.28 (95% CI 1.22-1.34) during childhood. Assessment of the atopic march in association with asthma or wheeze revealed that antibiotic use during pregnancy also increases the risk for eczema/dermatitis RR 1.28 (95% CI: 1.06-1.53) and allergic rhinitis RR 1.13 (95% CI: 1.02-1.25). One study found an increase in food allergy RR 1.81 (95% CI: 1.11-2.95). Maternal antibiotic use during pregnancy is associated with an increased risk for wheeze or asthma development in children, as well as for diseases involved in the atopic march. There was high heterogeneity in the data, and the certainty of the evidence was determined to be low quality, highlighting the need for more high-quality studies on this topic. These results have importance for antibiotic stewardship throughout the prenatal period. This work was supported by the Deutsche Forschungsgemeinschaft and the Konrad Adenauer Foundation.

Maternal antibiotic use and infections during pregnancy and offspring asthma: the Norwegian Mother, Father and Child Cohort Study and a nationwide register cohort

Maternal antibiotic use during pregnancy has been linked to asthma risk in children, but the role of underlying infections remains unclear. We investigated the association of maternal antibiotic use and infections during pregnancy with offspring risk of asthma. We used two population-based cohorts: the Norwegian Mother, Father and Child Cohort Study (MoBa) (n = 53 417) and a register-based cohort (n = 417 548). Asthma was defined based on dispensed asthma medications at 7 and 13 years from the Norwegian Prescription Database. Self-reported information on antibiotic use and infections during pregnancy was available in MoBa, while registrations of dispensed prescriptions were used to classify use of antibiotics in the register-based cohort. Maternal antibiotic use during pregnancy was associated with asthma at 7 in both cohorts (adjusted risk ratio (aRR) 1.23, 95% CI 1.11-1.37 in MoBa and 1.21, 1.16-1.25 in the register cohort) and asthma at 13 in the register cohort (1.13, 1.03-1.23) after adjusting for maternal characteristics. In MoBa, the estimate was attenuated after adjusting for infections during pregnancy. Maternal lower and upper respiratory tract infections (aRR 1.30, 95% CI 1.07-1.57 and 1.19, 1.09-1.30, respectively) and urinary tract infections (1.26, 1.11-1.42) showed associations with asthma at 7. Register cohort also showed an increased risk of asthma in relation to maternal antibiotics before and after pregnancy. Our findings suggest that both maternal antibiotics and infections during pregnancy have a role in the risk of offspring asthma. However, results from the register cohort suggest that the effect of antibiotics may reflect the shared underlying susceptibility.

Does the timing of antibiotic exposure in pregnancy impact the risk of development of pediatric asthma?: A systematic review and meta-analysis

OBJECTIVE

Maternal exposure to antibiotics has been linked to the development of pediatric asthma. However, the impact of the timing of exposure is unclear. We aimed to explore if the risk of pediatric asthma varies with trimester-specific exposure to antibiotics through a systematic review and meta-analysis.

METHODS

PubMed, Embase, ScienceDirect, CENTRAL, and Google Scholar databases were searched for studies reporting an association between trimester-specific maternal exposure to antibiotics and risk of asthma in the offspring.

RESULTS

Eleven studies were included. The total sample size of the included studies was 2,160,216. Meta-analysis revealed a statistically significant increased risk of asthma with first (RR: 1.13 95% CI: 1.10, 1.17 I² = 59% p < 0.00001), second (RR: 1.14 95% CI: 1.07, 1.21 I² = 92% p < 0.0001), and third (RR: 1.14 95% CI: 1.08, 1.20 I²=86% p < 0.00001) trimester exposure of antibiotics. The results were stable on sensitivity analysis. On subgroup analysis, we noted that the association for the first and second trimester was significant for studies on children >5 years but not for those on children <5 years of age. The certainty of evidence based on GRADE was low.

CONCLUSION

Our results indicate that antibiotics administered during any trimester of pregnancy lead to an increased risk of childhood asthma. The overall risk is small and could be due to confounding. Further studies rigorously adjusting for important confounding variables are needed for stronger evidence.

The Role of Early Life Microbiota Composition in the Development of Allergic Diseases

Allergic diseases are becoming a major healthcare issue in many developed nations, where living environment and lifestyle are most predominantly distinct. Such differences include urbanized, industrialized living environments, overused hygiene products, antibiotics, stationary lifestyle, and fast-food-based diets, which tend to reduce microbial diversity and lead to impaired immune protection, which further increase the development of allergic diseases. At the same time, studies have also shown that modulating a microbiocidal community can ameliorate allergic symptoms. Therefore, in this paper, we aimed to review recent findings on the potential role of human microbiota in the gastrointestinal tract, surface of skin, and respiratory tract in the development of allergic diseases. Furthermore, we addressed a potential therapeutic or even preventive strategy for such allergic diseases by modulating human microbial composition.

Use of Azithromycin in Pregnancy: More Doubts than Certainties

Macrolides such as azithromycin are commonly prescribed antibiotics during pregnancy. The good oral bioavailability and transplacental transfer of azithromycin make this drug suitable for the treatment of sexually transmitted diseases, toxoplasmosis, and malaria. Moreover, azithromycin is useful both in the management of preterm pre-labor rupture of membranes and in the adjunctive prophylaxis for cesarean delivery. The aim of this comprehensive narrative review is to critically analyze and summarize the available literature on the main aspects of azithromycin use in pregnant women, with a special focus on adverse offspring outcomes associated with prenatal exposure to the drug. References for this review were identified through searches of MEDLINE, PubMed, and EMBASE. Fetal and neonatal outcomes following prenatal azithromycin exposure have been investigated in several studies, yielding conflicting results. Increased risks of spontaneous miscarriage, major congenital malformations, cardiovascular malformations, digestive system malformations, preterm birth, and low birth weight have been reported in some studies but not in others. Currently, there is no conclusive evidence to support that azithromycin use by pregnant women causes adverse outcomes in their offspring. Therefore, this agent should only be used during pregnancy when clinically indicated, if the benefits of treatment are expected to outweigh the potential risks.

Are wheezing, asthma and eczema in children associated with mother's health during pregnancy? Evidence from an Australian birth cohort

BACKGROUND

This study investigated the prevalence of wheezing, asthma, and eczema among Australian children using longitudinal data from birth to 15 years of age. This study also examined the association between maternal health status during pregnancy and their offspring's respiratory and allergic morbidities using sex-segregated data.

METHODS

This study used data from the Longitudinal Study of Australian Children (LSAC) where approximately 5000 children of a birth cohort across Australia were surveyed in 2004. These children were followed biennially in eight waves up to their age of 15 years until 2018. The status of the children's wheezing, asthma, and eczema were reported by the mothers upon doctors' diagnosis (for asthma) or self-assessment (for wheezing or eczema). Binomial logistic regression models were used to analyse associations between maternal health during pregnancy and their children's health outcomes.

RESULTS

Asthma prevalence among 0-1-year aged children was 11.7%, increased to 15.4% when the children were 10-11 years old, and then decreased to 13.6% when they were 14-15 years old. Wheezing and eczema were most prevalent when the children were 2-3 years old (26.0 and 17.8% respectively) and were least prevalent when the children were 14-15 years old (7.3 and 9.5% respectively). Maternal asthma, smoking during pregnancy, and pre-pregnancy obesity were significantly associated with an increased risk of wheezing and asthma in Australian children. Childhood eczema was associated only with maternal asthma. These associations were stronger among male children up to age 10-11 and during adolescence (12-15 years of age), female children were more prone to wheezing, asthma, and eczema.

CONCLUSION

This is a comprehensive longitudinal study of Australian children (0-15 years of age) to assess the prevalence (with sex-specific differences) of wheezing, asthma and eczema as well as the association between these respiratory and allergic morbidities and maternal health during pregnancy. The study findings suggest that careful medical and obstetric monitoring, improved specific age-sex wise risk factor prevention for children and health promotion for pregnant women would help protect child health.

Dangerous liaisons: Bacteria, antimicrobial therapies, and allergic diseases

Microbiota composition and associated metabolic activities are essential for the education and development of a healthy immune system. Microbial dysbiosis, caused by risk factors such as diet, birth mode, or early infant antimicrobial therapy, is associated with the inception of allergic diseases. In turn, allergic diseases increase the risk for irrational use of antimicrobial therapy. Microbial therapies, such as probiotics, have been studied in the prevention and treatment of allergic diseases, but evidence remains limited due to studies with high heterogeneity, strain-dependent effectiveness, and variable outcome measures. In this review, we sketch the relation of microbiota with allergic diseases, the overuse and rationale for the use of antimicrobial agents in allergic diseases, and current knowledge concerning the use of bacterial products in allergic diseases. We urgently recommend 1) limiting antibiotic therapy in pregnancy and early childhood as a method contributing to the reduction of the allergy epidemic in children and 2) restricting antibiotic therapy in exacerbations and chronic treatment of allergic diseases, mainly concerning asthma and atopic dermatitis. Future research should be aimed at antibiotic stewardship implementation strategies and biomarker-guided therapy, discerning those patients that might benefit from antibiotic therapy.

Machine Learning for Predicting the Risk for Childhood Asthma Using Prenatal, Perinatal, Postnatal and Environmental Factors

The prevalence rate for childhood asthma and its associated risk factors vary significantly across countries and regions. In the case of Morocco, the scarcity of available medical data makes scientific research on diseases such as asthma very challenging. In this paper, we build machine learning models to predict the occurrence of childhood asthma using data from a prospective study of 202 children with and without asthma. The association between different factors and asthma diagnosis is first assessed using a Chi-squared test. Then, predictive models such as logistic regression analysis, decision trees, random forest and support vector machine are used to explore the relationship between childhood asthma and the various risk factors. First, data were pre-processed using a Chi-squared feature selection, 19 out of the 36 factors were found to be significantly associated (p-value < 0.05) with childhood asthma; these include: history of atopic diseases in the family, presence of mites, cold air, strong odors and mold in the child's environment, mode of birth, breastfeeding and early life habits and exposures. For asthma prediction, random forest yielded the best predictive performance (accuracy = 84.9%), followed by logistic regression (accuracy = 82.57%), support vector machine (accuracy = 82.5%) and decision trees (accuracy = 75.19%). The decision tree model has the advantage of being easily interpreted. This study identified important maternal and prenatal risk factors for childhood asthma, the majority of which are avoidable. Appropriate steps are needed to raise awareness about the prenatal risk factors.

Maternal health and health-related behaviours and their associations with child health: Evidence from an Australian birth cohort

Objective

This study investigates the associations between maternal health and health-related behaviours (nutrition, physical activity, alcohol consumption and smoking) both during pregnancy and up to 15 months from childbirth and children’s health outcomes during infancy and adolescence (general health, presence of a chronic illness, and physical health outcome index).

Methods

This study used Wave 1 (2004) and Wave 7 (2016) data from the Longitudinal Survey of Australian Children (LSAC). We measured mothers’ general health, presence of a medical condition during pregnancy and mental health during pregnancy or in the year after childbirth. We subsequently measured the children’s general health, presence of a medical condition, and physical health outcome index at ages 0–1 (infancy) and 12–13 (adolescence). Binary logistic and linear regression analyses were performed to examine the association between the mothers’ health-related variables and their children’s health.

Results

Our results showed that poor general health of the mother in the year after childbirth was associated with higher odds of poor health in infants and adolescents in all three dimensions: poor general health (OR: 3.13, 95% CI: 2.16–4.52 for infants; OR: 1.39, 95% CI: 0.95–2.04 for adolescents), presence of a chronic condition (OR: 1.47, 95% CI: 1.19–1.81 for adolescents) and lower physical health score (b = −0.94, p-value <0.05 for adolescents). Our study also revealed that the presence of a chronic condition in mothers during pregnancy significantly increased the likelihood of the presence of a chronic condition in their offspring during infancy (OR: 1.31, 95% CI: 1.12–1.54) and during adolescence (OR: 1.45, 95% CI: 1.20–1.75). The study found that stressful life events faced by mothers increase the odds of poor general health or any chronic illness during adolescence, while stress, anxiety or depression during pregnancy and psychological distress in the year after childbirth increase the odds of any chronic illness during infancy.

Conclusions

The present study found evidence that poor maternal physical and mental health during pregnancy or up to 15 months from childbirth has adverse health consequences for their offspring as measured by general health, presence of chronic health conditions, and physical health index scores. This suggests that initiatives to improve maternal physical and mental health would not only improve child health but would also reduce the national health burden.

Evaluation of Risk Scores to Predict Pediatric Severe Asthma Exacerbations

BACKGROUND

Asthma exacerbations commonly lead to unplanned health care utilization and are costly. Early identification of children at increased risk of asthma exacerbations would allow a proactive management approach.

OBJECTIVE

We evaluated common asthma risk factors to predict the probability of exacerbation for individual children aged 0-21 years using data from the electronic medical record (EMR).

METHODS

We analyzed longitudinal EMR data for over 3000 participants with asthma seen at Cincinnati Children's Hospital Medical Center over a 7-year period. The study population was divided into 3 age groups: 0-4, 5-11, and 12-21 years. Each age group was divided into a derivation cohort and a validation cohort, which were used to build a risk score model. We predicted risk of exacerbation in the next 12 months, validated the scores by risk stratum, and developed a clinical tool to determine the risk level based on this model.

RESULTS

Risk model results were confirmed with validation cohorts by calendar year and age groups. Race, allergic sensitization, and smoke exposure were each important risk factors in the 0-4 age group. Abnormal spirometry and obesity were more sensitive predictors of exacerbation in children >12 years. For each age group, a higher expanded score was associated with a higher predicted probability of an asthma exacerbation in the subsequent year.

CONCLUSION

This asthma exacerbation prediction model, and the associated clinical tool, may assist clinicians in identifying children at high risk for exacerbation that may benefit from more aggressive management and targeted risk mitigation.

Antibiotic exposure during pregnancy and childhood asthma: a national birth cohort study investigating timing of exposure and mode of delivery

OBJECTIVE

To investigate whether antibiotic exposure during pregnancy was associated with childhood asthma and if this relationship was conditional on timing of exposure and mode of delivery.

DESIGN

A cohort study using multivariable logistic regression models adjusting for a priori defined confounders. Pregnant women were recruited from 1996 to 2002.

SETTING

The Danish National Birth Cohort.

PATIENTS

Of the 96 832 children in the cohort, 32 651 children were included in the study population.

MAIN OUTCOME MEASURE

Parent-reported childhood asthma at 11 years.

RESULTS

A total of 5522 (17%) children were born to mothers exposed to antibiotics during pregnancy. In adjusted analyses, children born to exposed mothers had higher odds of asthma (OR 1.14, 95% CI 1.05 to 1.24). There was no association with antibiotic exposure in the first trimester (OR 1.02, 95% CI 0.83 to 1.26), but higher odds were observed for antibiotic exposure in the second to third trimester (OR 1.17, 95% CI 1.06 to 1.28), compared with unexposed children. The overall association between antibiotics during pregnancy and childhood asthma was only observed in vaginally born children (OR 1.17, 95% CI 1.07 to 1.28) but not in caesarean section born children (planned caesarean section: OR 0.95, 95% CI 0.66 to 1.37; caesarean emergency: OR 0.96, 95% CI 0.73 to 1.28). In exposed vaginally born children, the odds for childhood asthma requiring treatment during the preceding year were 34% higher (OR 1.34, 95% CI 1.21 to 1.49), compared with unexposed vaginally born children.

CONCLUSIONS

Antibiotic exposure in mid-to-late pregnancy is associated with higher odds of childhood asthma in vaginally born children. Mode of delivery may modify the association.

The maternal gut microbiome during pregnancy and offspring allergy and asthma

Environmental exposures during pregnancy that alter both the maternal gut microbiome and the infant's risk of allergic disease and asthma include a traditional farm environment and consumption of unpasteurized cow's milk, antibiotic use, dietary fiber and psychosocial stress. Multiple mechanisms acting in concert may underpin these associations and prime the infant to acquire immune competence and homeostasis following exposure to the extrauterine environment. Cellular and metabolic products of the maternal gut microbiome can promote the expression of microbial pattern recognition receptors, as well as thymic and bone marrow hematopoiesis relevant to regulatory immunity. At birth, transmission of maternally derived bacteria likely leverages this in utero programming to accelerate postnatal transition from a Th2 to Th1 and Th17 dominant immune phenotypes and maturation of regulatory immune mechanisms, which in turn reduce the child's risk of allergic disease and asthma. Although our understanding of these phenomena is rapidly evolving, the field is relatively nascent, and we are yet to translate existing knowledge into interventions that substantially reduce disease risk in humans. Here we review evidence that the maternal gut microbiome impacts the offspring's risk of allergic disease and asthma, discuss challenges and future directions for the field, and propose the hypothesis that maternal carriage of Prevotella copri during pregnancy decreases the offspring's risk of allergic disease via production of succinate which in turn promotes bone marrow myelopoiesis of dendritic cell precursors in the fetus.

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.

Dose, Timing, and Spectrum of Prenatal Antibiotic Exposure and Risk of Childhood Asthma

BACKGROUND

The potential for prenatal antibiotic exposure to influence asthma risk is not clear. We aimed to determine the effect of timing, dose, and spectrum of prenatal antibiotic exposure on the risk of childhood asthma.

METHODS

We conducted a population-based cohort study of 84 214 mother-child dyads to examine the association of prenatal antibiotic exposure and childhood asthma using multivariable logistic regression models.

RESULTS

Sixty-four percent of pregnant women received antibiotics. Prenatal antibiotic exposure was associated dose-dependently with increased odds of childhood asthma (adjusted odds ratio [aOR] for interquartile increase of 2 courses [interquartile range, 0-2], 1.26 [95% confidence interval {CI}, 1.20-1.33]). Among children exposed to at least 1 course in utero, the effect of timing at the first course was moderated by total maternal courses. Among pregnant women receiving a single antibiotic course, timing of exposure had no effect on childhood asthma risk. Among women receiving > 1 course, early exposure of the first course was associated with greater childhood asthma risk. Compared to narrow spectrum-only antibiotic use, broad spectrum-only antibiotic exposure was associated with increased odds of asthma (aOR, 1.14 [95% CI, 1.05-1.24]). There were effect modifications (P < .001) by maternal asthma on total courses, and on timing of the first course, significant only among those without maternal asthma.

CONCLUSIONS

Increased cumulative dose, early pregnancy first course, and broad-spectrum antibiotic exposure were associated with childhood asthma risk. Our study provides important evidence supporting judicious prenatal antibiotic use, particularly timing of use and choice of antibiotics, in preventing subsequent childhood asthma.

The Association Between Intestinal Bacteria and Allergic Diseases-Cause or Consequence?

The incidence of allergic disorders has been increasing over the past few decades, especially in industrialized countries. Allergies can affect people of any age. The pathogenesis of allergic diseases is complex and involves genetic, epigenetic, and environmental factors, and the response to medication is very variable. For some patients, avoidance is the sole effective therapy, and only when the triggers are identifiable. In recent years, the intestinal microbiota has emerged as a significant contributor to the development of allergic diseases. However, the precise mechanisms related to the effects of the microbiome on the pathogenesis of allergic diseases are unknown. This review summarizes the recent association between allergic disorders and intestinal bacterial dysbiosis, describes the function of gut microbes in allergic disease development from both preclinical and clinical studies, discusses the factors that influence gut microbial diversity and advanced techniques used in microbial analysis. Ultimately, more studies are required to define the host-microbial relationship relevant to allergic disorders and amenable to new therapeutic interventions.

Maternal antibiotic exposure during pregnancy and the risk of allergic diseases in childhood: A meta-analysis

BACKGROUND

Increasing studies suggest that antibiotic exposure during pregnancy may increase the risk of childhood allergic diseases; however, controversy still exists. Thus, we conducted this meta-analysis to evaluate the association between antibiotic use during pregnancy and childhood asthma/wheeze, eczema/atopic dermatitis, and food allergy.

METHODS

CENTRAL, EMBASE, and PubMed were searched for studies up to July 20, 2020. Cohort studies and case-control studies that estimated the association of antibiotic exposure in pregnancy with the risk of childhood asthma/wheeze, eczema/atopic dermatitis, and food allergy were included. A random-effects model or fixed-effects model was used to calculate the pooled estimates. The quality of the included studies was assessed by the Newcastle-Ottawa Scale (NOS). Stata12.0 software was used to analyze the association through a meta-analysis.

RESULTS

A total of 26 studies were included in the meta-analysis. The results showed that maternal antibiotic exposure in pregnancy and the summary OR for the risk of childhood asthma/wheeze was 1.29 (95% CI = 1.16-1.43), the summary OR for eczema/atopic dermatitis was 1.62 (95% CI = 1.16-2.27), and the pooled OR for food allergy was 1.36 (95% CI = 0.94-1.96).

CONCLUSIONS

Our results indicated that maternal antibiotic use during pregnancy might increase the risk of asthma/wheeze and eczema/atopic dermatitis but not food allergy in children. Further studies with larger sample size and robust multivariable adjustment are needed to confirm our findings. Nevertheless, the appropriate use of antibiotics during pregnancy is incredibly important, and healthcare professionals should be selective when prescribing antibiotics for pregnant women.

Maternal antibiotic use during pregnancy and asthma in children: population-based cohort study and sibling design

Antibiotic use during pregnancy may affect asthma risk in offspring. However, epidemiological studies yielded conflicting findings, with an observed association possibly confounded by shared familial factors. We sought to assess the association between maternal antibiotic use during pregnancy and childhood asthma in the offspring, by accounting for time-stable familial factors.We conducted a population-based cohort study and sibling study using data from Danish nationwide registers, which comprised 407 804 liveborn singletons from 2005 to 2011. Antibiotic use during pregnancy was defined as at least one antibiotic prescription filled by the mother from 1 month prior to pregnancy up until delivery, identified in the National Prescription Registry. First-time asthma in the offspring was determined by hospital treatment or asthma medication treatment after age 5 years. We estimated hazard ratios (HRs) of asthma using Cox regression in the population-based cohort and stratified Cox regression in the sibling cohort.Approximately 36.5% of pregnant women redeemed antibiotic prescriptions. Antibiotic use during pregnancy was associated with childhood asthma in cohort analyses (HR 1.21, 95% CI 1.18-1.24), but not in sibling analyses (HR 0.96, 95% CI 0.90-1.03). In the population-based analyses, higher risks of asthma were seen with longer duration of maternal antibiotic use, a higher number of prescriptions and prescriptions of multiple types of antibiotics. All these associations disappeared in the sibling analyses.The associations observed by previous studies for prenatal exposure to antibiotics and offspring asthma risk are likely to be due to confounding factors shared within families.

Antibiotic use during pregnancy increases offspring asthma severity in a dose-dependent manner

BACKGROUND

The use of antibiotics during pregnancy is associated with increased allergic asthma risk in the offspring, and given that approximately 25% of pregnant women are prescribed antibiotics, it is important to understand the mechanisms contributing to this phenomenon. Currently, there are no studies that directly test this association experimentally. Our objective was to develop a mouse model in which antibiotic treatment during pregnancy results in increased offspring asthma susceptibility.

METHODS

Pregnant mice were treated daily from gestation day 8-17 with an oral solution of the antibiotic vancomycin, and three concentrations were tested. At weaning, offspring were subjected to an adjuvant-free experimental asthma protocol using ovalbumin as an allergen. The composition of the gut microbiome was determined in mothers and offspring with samples collected from five different time points; short-chain fatty acids were also analyzed in allergic offspring.

RESULTS

We found that maternal antibiotic treatment during pregnancy was associated with increased offspring asthma severity in a dose-dependent manner. Furthermore, maternal vancomycin treatment during pregnancy caused marked changes in the gut microbiome composition in both mothers and pups at several different time points. The increased asthma severity and intestinal microbiome changes in pups were also associated with significantly decreased cecal short-chain fatty acid concentrations.

CONCLUSION

Consistent with the "Developmental Origins Hypothesis," our results confirm that exposure to antibiotics during pregnancy shapes the neonatal intestinal environment and increases offspring allergic lung inflammation.

Gut Microbiota and Lung Injury

Gut microbiota are known to impact multiple organs including the lung. The cross talk between gut microbes and lungs, termed as the "gut-lung axis," is vital for immune response and homeostasis in the airways. In this chapter, we summarized the coordinated development of microorganisms in the gut and lung, exogenous and endogenous factors related to the cross talk, the mechanisms of the gut-lung axis and their dysbiosis in lung diseases. Although the current understanding of the gut-lung axis is in its infancy, several gut microbiota-associated strategies have been designed to treat and prevent lung diseases.

The relationship of prenatal antibiotic exposure and infant antibiotic administration with childhood allergies: a systematic review

Background

Early antibiotic exposure may be contributing to the onset of childhood allergies. The main objective of this study was to conduct a systematic review on the relationship between early life antibiotic exposure and childhood asthma, eczema and hay fever.

Methods

Pubmed and Embase were searched for studies published between 01-01-2008 and 01-08-2018, examining the effects of (1) prenatal antibiotic exposure and (2) infant antibiotic administration (during the first 2 years of life) on childhood asthma, eczema and hay fever from 0 to 18 years of age. These publications were assessed using the Newcastle Ottawa Scale (NOS) and analysed narratively.

Results

(1) Prenatal antibiotics: Asthma (12 studies): The majority of studies (9/12) reported significant relationships (range OR 1.13 (1.02–1.24) to OR 3.19 (1.52–6.67)). Three studies reported inconsistent findings. Eczema (3 studies): An overall significant effect was reported in one study and in two other studies only when prenatal antibiotic exposure was prolonged. (2) Infant antibiotics: Asthma (27 studies): 17/27 studies reported overall significant findings (range HR 1.12 (1.08–1.16) to OR 3.21 (1.89–5.45)). Dose-response effects and stronger effects with broad-spectrum antibiotic were often reported. 10/27 studies reported inconsistent findings depending on certain conditions and types of analyses. Of 19 studies addressing reverse causation or confounding by indication at least somewhat, 11 reported overall significant effects. Eczema (15 studies): 6/15 studies reported overall significant effects; 9 studies had either insignificant or inconsistent findings. Hay fever (9 studies): 6/9 reported significant effects, and the other three insignificant or inconsistent findings. General: Multiple and broad-spectrum antibiotics were more strongly associated with allergies. The majority of studies scored a 6 or 7 out of 9 based on the NOS, indicating they generally had a medium risk of bias. Although most studies showed significant findings between early antibiotic exposure and asthma, the actual effects are still unclear as intrapartum antibiotic administration, familial factors and confounding by maternal and child infections were often not addressed.

Conclusions

This review points to a moderate amount of evidence for a relationship between early life antibiotics (especially prenatal) and childhood asthma, some evidence for a relationship with hay fever and less convincing evidence for a relationship with eczema. More studies are still needed addressing intra-partum antibiotics, familial factors, and possible confounding by maternal and childhood infections. Children exposed to multiple, broad-spectrum antibiotics early in life appear to have a greater risk of allergies, especially asthma; these effects should be investigated further.

Maternal exposure to antibiotics increases the risk of infant eczema before one year of life: a meta-analysis of observational studies

BACKGROUND

There are some conflicting evidences showing that maternal exposure to antibiotics may increase the risk of infant eczema. The present study aims to estimate the effect of prenatal antibiotics administration on infant eczema.

METHODS

According to the established inclusion criteria, eligible observational studies were collected by comprehensive database search. The qualities of the included studies were assessed using the Newcastle-Ottawa Scale. Effect sizes that were adjusted by multivariable models were extracted and combined. Publication bias was evaluated by visual inspection of funnel plot.

RESULTS

A total of seven observational studies were included. The qualities of the included studies were at moderate or high level. Prenatal antibiotics use was positively associated with eczema before one year of age [odds ratio (OR) = 1.93, 95% confidence interval (CI) 1.35-2.76]. In addition, antibiotics exposure in utero was likely to be related to eczema after one year of age (OR 1.21, 95% CI 0.98-1.49). The exposure to antibiotics during third trimester was not associated with infant eczema (OR 0.97, 95% CI 0.86-1.09).

CONCLUSIONS

Maternal exposure to antibiotics is associated with eczema by one-year age and may have a prolonged effect on eczema after 1-year age. The influence of timing of antibiotics exposure during pregnancy needs more studies to clarify.

Infant wheezing and prenatal antibiotic exposure and mode of delivery: a prospective birth cohort study

Introduction: Assessments on whether prenatal antibiotic exposure and mode of delivery increase the risk of wheezing in infants and toddlers are inconsistent. Our goal is to evaluate the association between prenatal antibiotic use and Cesarean section with three subtypes of wheezing in infancy.Methods: An ongoing prospective three generations cohort study provides data on prenatal antibiotic use and mode of delivery. Respective questionnaire data was used to distinguish three subtypes of wheezing: any wheezing, infectious wheezing, and noninfectious wheezing. Repeated measurements of wheezing at 3, 6, and 12 months were analyzed using generalized estimation equations. Latent transition analysis assessed patterns of infant wheezing development in the first year of life.Results: The prevalence of any wheezing was highest at 12 months (40.1%). The prevalence of infectious wheezing was higher (3 months 23.8%, 6 months 33.5%, 12 months 38.5%) than of noninfectious wheezing (3 months 13.0%, 6 months 14.0%, 12 months 11.1%). About 11-13% of children had both infectious and noninfectious wheezing at 3, 6, and 12 months (3 months 10.7%, 6 months 13.9%, 12 months 13.1%). Children born via Cesarean section have approximately a 70-80% increase in the risk of any wheezing (RR = 1.83, 95% CI 1.29-2.60) and of infectious wheezing (RR = 1.72, 95% CI 1.18-2.50).Conclusions: Analyses of infectious and noninfectious wheezing subtypes suggests that children born by Cesarean sections may be more susceptible to infectious wheezing, warranting investigations into microbial factors of infectious wheezing. No significant associations were found between prenatal antibiotic exposure and wheezing types.

Childhood inflammatory and metabolic disease following exposure to antibiotics in pregnancy, antenatally, intrapartum and neonatally

Background: There are concerns that the use of antibiotics before, during or immediately after pregnancy may have adverse effects on the neonatal gut microbiome and adversely affect the development of the infant immune system, leading to the development of childhood allergy, asthma, atopic disease and obesity. Methods: In this narrative review, we have explored a number of hypotheses, including the "Barker hypothesis", the "hygiene hypothesis", the link between inflammation and metabolic disease, and the influence of the neonatal gut microbiota on the development of the immune system in infants. Results: We found evidence to link the use of antibiotics before, during or immediately after pregnancy with an increased risk of childhood allergy, asthma, atopy and obesity. Conclusions: Although we found robust evidence to link antibiotic use in pregnancy with obesity and an "allergic triad" of asthma, eczema and hay fever, care must be taken when interpreting the findings because of the lack of adjustment for confounding variables in published studies. These may be (i) whether or not the mother had the same outcome variable (for example, asthma) as the infant, for which the mother may have received the antibiotics; (ii) the indication, timing or number of antibiotic courses given; (iii) the use of broad-spectrum or narrow-range antibiotics; (iv) the dose-dependent nature of the effector; and (v) the class of antibiotics used.

Dysbiosis of the gut and lung microbiome has a role in asthma

Worldwide 300 million children and adults are affected by asthma. The development of asthma is influenced by environmental and other exogenous factors synergizing with genetic predisposition, and shaping the lung microbiome especially during birth and in very early life. The healthy lung microbial composition is characterized by a prevalence of bacteria belonging to the phyla Bacteroidetes, Actinobacteria, and Firmicutes. However, viral respiratory infections are associated with an abundance of Proteobacteria with genera Haemophilus and Moraxella in young children and adult asthmatics. This dysbiosis supports the activation of inflammatory pathways and contributes to bronchoconstriction and bronchial hyperresponsiveness. Exogenous factors can affect the natural lung microbiota composition positively (farming environment) or negatively (allergens, air pollutants). It is evident that also gut microbiota dysbiosis has a high influence on asthma pathogenesis. Antibiotics, antiulcer medications, and other drugs severely impair gut as well as lung microbiota. Resulting dysbiosis and reduced microbial diversity dysregulate the bidirectional crosstalk across the gut-lung axis, resulting in hypersensitivity and hyperreactivity to respiratory and food allergens. Efforts are undertaken to reconstitute the microbiota and immune balance by probiotics and engineered bacteria, but results from human studies do not yet support their efficacy in asthma prevention or treatment. Overall, dysbiosis of gut and lung seem to be critical causes of the increased emergence of asthma.

Influence of age on real-life effects of doxycycline for acute exacerbations among COPD outpatients: a population-based cohort study

INTRODUCTION

Although bacteria contribute significantly to acute exacerbations of chronic obstructive pulmonary disease (AECOPD), the added value of antibiotics remains controversial, especially in outpatient settings. Age may affect antibiotic effectiveness, but real-world evidence is lacking. We aimed to assess the influence of age on the effectiveness of doxycycline for AECOPD.

METHODS

A retrospective cohort study among outpatients with the first recorded AECOPD treated with oral corticosteroids was conducted using a large pharmacy dispensing database. The primary outcome was treatment failure within 15-31 days after treatment start. Secondary outcome was time to second exacerbation. All analyses were stratified by age groups.

RESULTS

We identified 6300 outpatients with the first AECOPD. 2261 (36%) received doxycycline and 4039 (64%) did not receive any antibiotic (reference group). Overall, there was no difference in treatment failure (adjusted OR: 0.97, 95% CI: 0.84 to 1.12) between two groups. Similarly, no difference in treatment failure was observed in younger groups. However, in patients with advanced age (≥75 years), treatment failure was significantly reduced by doxycycline compared with reference (16% vs 20%, adjusted OR: 0.77, 95% CI: 0.62 to 0.97). Overall, median time to second exacerbation was 169 days (95% CI: 158 to 182 days) in doxycycline group compared with 180 days (95% CI: 169 to 191 days) in reference group (adjusted HR: 1.06, 95% CI: 0.99 to 1.12). Although in older patients there was a trend within 3 months towards longer time of next exacerbation by doxycycline, it did not achieve statistical significance.

CONCLUSIONS

Our findings showed short-term treatment benefit of doxycycline added to oral corticosteroids for chronic obstructive pulmonary disease patients with advanced age. This value remains unclear for persons aged under 75 years in current primary care. Long-term preventive benefits of doxycycline for the next exacerbation were not observed, irrespective of age.

Influence of maternal microbiota during pregnancy on infant immunity

Microbiota from various maternal sites, including the gut, vagina and breast milk, are known to influence colonization in infants. However, emerging evidence suggests that these sites may exert their influence prior to delivery, in turn influencing fetal immune development. The dogma of a sterile womb continues to be challenged. Regardless, there is convincing evidence that the composition of the maternal gut prior to delivery influences neonatal immunity. Therefore, while the presence and function of placental microbiome is not clear, there is consensus that the gut microbiota during pregnancy is a critical determinant of offspring health. Data supporting the notion of bacterial translocation from the maternal gut to extra-intestinal sites during pregnancy are emerging, and potentially explain the presence of bacteria in breast milk. Much evidence suggests that the maternal gut microbiota during pregnancy potentially determines the development of atopy and autoimmune phenotypes in offspring. Here, we highlight the role of the maternal microbiota prior to delivery on infant immunity and predisposition to diseases. Moreover, we discuss potential mechanisms that underlie this phenomenon.

The "envirome" and what the practitioner needs to know about it

OBJECTIVE

This review on the "envirome" focuses on pollution, microbial, and social stressor elements of the environment that may impact development or expression of allergic diseases.

DATA SOURCES

Peer-reviewed publications on the impact of environmental factors indexed in PubMed were the primary data source for this review.

STUDY SELECTIONS

The primary search strategy for this review employed cross-referencing asthma, atopic dermatitis, and immunoglobulin E (IgE) against pollution (ozone, particulate matter, nitrogen oxides, tobacco smoke), microbial exposures (farm exposure, microbiome, infection, antibiotic use) and psychosocial stressors, with emphasis on results in the past 5 years, with inclusion of key seminal articles or comprehensive reviews.

RESULTS

Air pollution is a clear cause of allergic disease exacerbation, with increasing recognition that pollutant exposure increases risk of allergic disease. Microbial exposures and maternal and child stress also modulate development and expression of allergic disease. Early life exposures are especially critical periods during which all of these factors have notable impacts on allergic disease.

CONCLUSION

Nonallergenic environmental factors are important modulators and adjuvants for development of allergic disease, with early life exposures being especially important. Development and validation of interventions directed toward these factors during early life is a significant opportunity for primary prevention of allergic disease.

The safety of amoxicillin and clavulanic acid use during the first trimester of pregnancy

AIMS

The goal of the current study was to assess the risk for major congenital malformations following first-trimester exposure to amoxicillin, or amoxicillin and clavulanic acid (ACA).

METHODS

A population-based retrospective cohort study was conducted, by linking 4 computerized databases: maternal and infant hospitalization records, drug dispensing database of Clalit Health Services in Israel and data concerning pregnancy terminations. Multivariate negative-binomial regression was used to assess the risk for major malformations following first-trimester exposure, adjusted for mother's age, ethnicity (Bedouin vs Jewish), parity, diabetes mellitus, lack of perinatal care, and the year of birth.

RESULTS

The study included 101 615 pregnancies, of which 6919 (6.8%) were exposed to amoxicillin: 1045 (1.0%) to amoxicillin only and 6041 (5.9%) to ACA. No significant association was found, in the univariate and multivariate analyses, between first-trimester exposure to amoxicillin or ACA and major malformations in general (crude relative risk, 1.05 95% confidence interval 0.95-1.16; adjusted relative risk 1.09, 95% confidence interval 0.98-1.20), or for major malformations according to organ systems. No dose-response relationship was found between exposure in terms of the defined daily dose and major malformations.

CONCLUSION

Exposure to amoxicillin and ACA during the first trimester of pregnancy was not associated with an increased risk of major congenital malformations.

Specific class of intrapartum antibiotics relates to maturation of the infant gut microbiota: a prospective cohort study

OBJECTIVE

To evaluate the potential impact of intrapartum antibiotics, and their specific classes, on the infant gut microbiota in the first year of life.

DESIGN

Prospective study of infants in the New Hampshire Birth Cohort Study (NHBCS).

SETTINGS

Rural New Hampshire, USA.

POPULATION OR SAMPLE

Two hundred and sixty-six full-term infants from the NHBCS.

METHODS

Intrapartum antibiotic use during labour and delivery was abstracted from medical records. Faecal samples collected at 6 weeks and 1 year of age were characterised by 16S rRNA sequencing, and metagenomics analysis in a subset of samples.

EXPOSURES

Maternal exposure to antibiotics during labour and delivery.

MAIN OUTCOME MEASURE

Taxonomic and functional profiles of faecal samples.

RESULTS

Infant exposure to intrapartum antibiotics, particularly to two or more antibiotic classes, was independently associated with lower microbial diversity scores as well as a unique bacterial community at 6 weeks (GUnifrac, P = 0.02). At 1 year, infants in the penicillin-only group had significantly lower α diversity scores than infants not exposed to intrapartum antibiotics. Within the first year of life, intrapartum exposure to penicillins was related to a significantly lower increase in several taxa including Bacteroides, use of cephalosporins was associated with a significantly lower rise over time in Bifidobacterium and infants in the multi-class group experienced a significantly higher increase in Veillonella dispar.

CONCLUSIONS

Our findings suggest that intrapartum antibiotics alter the developmental trajectory of the infant gut microbiome, and specific antibiotic types may impact community composition, diversity and keystone immune training taxa.

TWEETABLE ABSTRACT

Class of intrapartum antibiotics administered during delivery relates to maturation of infant gut microbiota.

The role of antimicrobial treatment during pregnancy on the neonatal gut microbiome and the development of atopy, asthma, allergy and obesity in childhood

INTRODUCTION

The use of antibiotics prenatally, during pregnancy, or neonatally may have adverse effects on the neonatal gut microbiome, and adversely affect the development of the infant immune system, leading to childhood atopy, asthma, allergy and obesity.

AREAS COVERED

Vaginal eubiosis and dysbiosis from molecular-based, cultivation-independent techniques, and how this affects the neonatal gut microbiome and early development of the immune system, the association between maternal antibiotics and the beneficial role of vitamin D in the development of atopy, asthma, allergy and obesity, efforts to reduce the use of antibiotics in pregnancy and therapeutic interventions such as vaginal 'seeding', probiotics, breastfeeding and neonatal dietary supplementation.

EXPERT OPINION

Currently available research gives insufficient attention to confounding variables. There remains uncertainty as to whether it is relevant that the mother suffered from the same condition as the purported infant outcome variable, for which she may have received antibiotics. In most studies, there is a lack of control for the number of antibiotic courses administered, the timing of use, the use of broad spectrum or narrow range antibiotics, the indication for antibiotics, the dose-dependent nature of the effect, the class of antibiotics used, or a varying degree of risk.

Trimester-specific association between antibiotics exposure during pregnancy and childhood asthma or wheeze: the role of confounding

PURPOSE

We conducted the meta-analysis to respectively evaluate the risk of prenatal antibiotics use during specific trimesters (first, second, and third trimester) on childhood asthma or wheeze and to explore whether the association was biased by potential confounding.

METHODS

The quality of included articles was assessed according to Newcastle-Ottawa Quality Assessment Scale and the Strengthening the Reporting of Observational Studies in Epidemiology. A random effects model was used to calculate pooled risk ratios and corresponding 95% confidence interval (CI), and publication bias was tested by Egger statistical test.

RESULTS

Eight studies were included finally. We found a crude positive association of prenatal antibiotics use during each pregnancy trimester and risk of childhood asthma or wheeze with RRs of 1.28 (95% CI, 1.09-1.51) for the first trimester of pregnancy, 1.25 (95% CI, 1.02-1.52) for the second trimester, and 1.25 (95% CI, 1.05-1.49) for the third trimester. However, when considering potential factors of maternal infections and presence of siblings, the relationship for each trimester was insignificant.

CONCLUSIONS

This systemic review and meta-analysis proposed a crude positive association between prenatal antibiotic use in every specific trimester and risk of childhood asthma or wheeze. However, adjustment for confounders decreased the relative risk estimates, supporting the concept that these associations are, at least in part, because of confounding by indication.

Relationship between Maternal and First Year of Life Dispensations of Antibiotics and Antiasthmatics

Antibiotics are the most frequent prescription drugs used by pregnant women. Our objective was to investigate if the dispensation of antibiotics and antiasthmatics in children less than 1 year of age is associated with prenatal antibiotic exposure. A secondary aim was to explore the incidence of dispensed antibiotics in pregnancy and dispensed antibiotics and antiasthmatics in children. We conducted an observational study using the Peer Academic Detailing study database to select patients eligible for match in the Medical Birth Registry of Norway, a total of 7747 mother-and-child pairs. Details on antibiotic and antiasthmatic pharmacy dispensations were obtained from the Norwegian Prescription Database. One quarter (1948 of 7747) of the mothers in the study had been dispensed antibiotics during pregnancy. In their first year of life, 17% (1289) of the children had had an antibiotic dispensation, 23% (1747) an antiasthmatic dispensation, and 8% (619) of the children had had both. We found a significant association between dispensed antibiotics in pregnancy and dispensed antibiotics to the child during their first year of life; OR = 1.16 (95% CI: 1.002⁻1.351). The association was stronger when the mothers were dispensed antibiotics at all, independent of the pregnancy period; OR = 1.60 (95% CI: 1.32⁻1.94). We conclude that the probability for dispensation of antibiotics was increased in children when mothers were dispensed antibiotics, independent of pregnancy. Diagnostic challenges in the very young and parental doctor-seeking behavior may, at least in part, contribute to the association between dispensations in mothers and children below the age of one year.

The effect of breastfeeding on the risk of asthma in high-risk children: a case-control study in Shanghai, China

BACKGROUND

Increasing evidence shows that antibiotic use in pregnancy may increase the risk of childhood asthma but epidemiologic studies are still limited and findings are inconsistent. Meanwhile, exclusive and prolonged breastfeeding may prevent children from allergic diseases. We aimed to assess the association between prenatal antibiotic use and the risk of childhood asthma, and explore whether breastfeeding modifies the risk.

METHODS

We conducted a case-control study in Shanghai, China, from June 2015 to January 2016. A total of 634 asthma cases and 864 controls aged 3-12 years were included. Multiple logistic regressions were used to estimate crude and adjusted odds ratios (aOR).

RESULTS

The prevalence of antibiotic use in pregnancy in the cases and controls was 7.1 and 3.5%, respectively. A significant association between prenatal antibiotic use and childhood asthma was observed (aOR: 1.7, 95% CI: 1.0-2.9), particularly in boys (aOR: 2.2, 95% CI: 1.1-4.4) and children with family history of allergic disorders (aOR: 3.1, 95% CI: 1.2-8.4). However, this association existed only in children who were not breastfed exclusively in the first six months of life (aOR 2.6, 95% CI 1.3-5.1) but not in children who were exclusively breastfed (aOR 0.9, 95% CI 0.4-2.1). Likewise, exclusive breastfeeding also decreased the association between antibiotic use in pregnancy and asthma in boys and in children with family histories of allergic diseases.

CONCLUSIONS

Antibiotic use in pregnancy was a risk factor for childhood asthma. However, this risk may be attenuated by exclusive breastfeeding in the first six months of life, especially among high-risk children.

Gut Microbiota and Mucosal Immunity in the Neonate

Gut microbiota colonization is a complex, dynamic, and step-wise process that is in constant development during the first years of life. This microbial settlement occurs in parallel with the maturation of the immune system, and alterations during this period, due to environmental and host factors, are considered to be potential determinants of health-outcomes later in life. Given that host–microbe interactions are mediated by the immune system response, it is important to understand the close relationship between immunity and the microbiota during birth, lactation, and early infancy. This work summarizes the evidence to date on early gut microbiota colonization, and how it influences the maturation of the infant immune system and health during the first 1000 days of life. This review will also address the influence of perinatal antibiotic intake and the importance of delivery mode and breastfeeding for an appropriate development of gut immunity.

Prenatal antibiotic exposure and childhood asthma: a population-based study

Antibiotic use during infancy alters gut microbiota and immune development and is associated with an increased risk of childhood asthma. The impact of prenatal antibiotic exposure is unclear. We sought to characterise the association between prenatal antibiotic exposure and childhood asthma.We performed a population-based cohort study using prescription records, hospitalisation records and physician billing claims from 213 661 mother-child dyads born in Manitoba, Canada between 1996 and 2012. Associations were determined using Cox regression, adjusting for maternal asthma, postnatal antibiotics and other potential confounders. Sensitivity analyses evaluated maternal antibiotic use before and after pregnancy.36.8% of children were exposed prenatally to antibiotics and 10.1% developed asthma. Prenatal antibiotic exposure was associated with an increased risk of asthma (adjusted hazard ratio (aHR) 1.23, 95% CI 1.20-1.27). There was an apparent dose response (aHR 1.15, 95% CI 1.11-1.18 for one course; aHR 1.26, 95% CI 1.21-1.32 for two courses; and aHR 1.51, 95% CI 1.44-1.59 for three or more courses). Maternal antibiotic use during 9 months before pregnancy (aHR 1.27, 95% CI 1.24-1.31) and 9 months postpartum (aHR 1.32, 95% CI 1.28-1.36) were similarly associated with asthma.Prenatal antibiotic exposure was associated with a dose-dependent increase in asthma risk. However, similar associations were observed for maternal antibiotic use before and after pregnancy, suggesting the association is either not directly causal, or not specific to pregnancy.

Microbiome-driven allergic lung inflammation is ameliorated by short-chain fatty acids

The mammalian gastrointestinal tract harbors a microbial community with metabolic activity critical for host health, including metabolites that can modulate effector functions of immune cells. Mice treated with vancomycin have an altered microbiome and metabolite profile, exhibit exacerbated T helper type 2 cell (Th2) responses, and are more susceptible to allergic lung inflammation. Here we show that dietary supplementation with short-chain fatty acids (SCFAs) ameliorates this enhanced asthma susceptibility by modulating the activity of T cells and dendritic cells (DCs). Dysbiotic mice treated with SCFAs have fewer interleukin-4 (IL4)-producing CD4⁺ T cells and decreased levels of circulating immunoglobulin E (IgE). In addition, DCs exposed to SCFAs activate T cells less robustly, are less motile in response to CCL19 in vitro, and exhibit a dampened ability to transport inhaled allergens to lung draining nodes. Our data thus demonstrate that gut dysbiosis can exacerbate allergic lung inflammation through both T cell- and DC-dependent mechanisms that are inhibited by SCFAs.

Effect of antibiotic use for acute bronchiolitis on new-onset asthma in children

Early-life use of antibiotics is associated with asthma. We examined the effect of antibiotic use for early-life bronchiolitis on the development of new-onset asthma in children from Taiwan between 2005 and 2010. Data were from the National Health Insurance Research Database 2010, and diseases were coded using the International Classification of Disease (ICD). We classified the patients, all of whom had bronchiolitis, as having asthma or not having asthma. Asthma was diagnosed using ICD criteria and by use of an inhaled bronchodilator and/or corticosteroid twice in one year. We identified age at asthma onset, sex, residential area, history of atopy and NSAID use, age at first use of antibiotics, and the specific antibiotic, and adjusted for these factors using conditional logistic regression analysis. Among all individuals, there was a relationship between risk of new-onset asthma with use of a high dose of an antibiotic (adjusted odds ratio [aOR] = 3.33, 95% confidence interval [CI] = 2.67–4.15). Among the different antibiotics, macrolides (aOR = 2.87, 95% CI = 1.99–4.16), and azithromycin specifically (aOR = 3.45, 95% CI = 1.62–7.36), had the greatest effect of development of asthma.

The effect of medical treatments on the bacterial microbiome in patients with chronic rhinosinusitis: a pilot study

BACKGROUND

Antibiotics and corticosteroids are prescribed to patients with chronic rhinosinusitis (CRS) to reduce bacterial burden and mucosal inflammation. Unfortunately, clinical improvement is often short-lived and symptoms frequently recur following cessation of treatment. The impact of these systemic therapies on bacterial communities is not well understood. Improved knowledge of how medical therapies influence the intranasal ecosystem may allow for more effective prescribing and the development of more targeted treatments.

METHODS

Twenty patients with CRS were randomized to receive either doxycycline 100 mg twice daily or prednisone 30 mg once daily for 7 days. A further 6 patients with CRS were recruited as untreated controls. Swabs were taken immediately before and after the study period. Symptom scores (22-item Sino-Nasal Outcome Test [SNOT-22]) were recorded. Bacterial communities were characterized using 16S ribosomal RNA (rRNA) gene-targeted amplicon sequencing. Bacterial abundance was estimated using quantitative polymerase chain reaction (PCR) of 16S rRNA gene copies.

RESULTS

Bacterial profiles were dominated by members of the genera Corynebacterium and Staphylococcus. Patients treated with either doxycycline or prednisone had variable and unpredictable changes in communities. The average relative abundance of Propionibacterium increased after treatment in the doxycycline treatment group, and Corynebacterium reduced in the prednisone group. Significant differences in clinical scores, bacterial community richness, diversity, and bacterial abundance were not seen after treatment.

CONCLUSION

The short-term response of bacterial communities to antibiotic or corticosteroid therapy is unpredictable. This study suggests that the use of systemic therapy in patients with stable CRS should be rationalized to minimize antibiotic-associated morbidity and bacterial dysbiosis.

Beta-2 receptor agonist exposure in the uterus associated with subsequent risk of childhood asthma

BACKGROUND

Although the beta-2 receptor agonist (B2RA) is occasionally prescribed in the prenatal period for women with preterm labor, few studies have referred to the long-term effects of intrauterine exposure to B2RA on fetus. We examined the association between intrauterine exposure to B2RA and asthma in the offspring.

METHODS

We obtained data from a hospital-based birth cohort study conducted in Tokyo, Japan. The outcomes of interest were three indicators, consisting of current wheeze, current asthma, and ever asthma at 5 years of age, based on the International Study of Asthma and Allergies in Childhood questionnaire. Logistic regression analysis was used to evaluate the association between intrauterine B2RA exposure and outcomes. To evaluate dose-dependent risk, we categorized children into three groups according to both the cumulative dose and duration (days) and conducted trend analysis.

RESULTS

Of 1158 children, 94 (8.1%) were exposed to B2RA in utero, and 191 (16.5%), 111 (9.6%), and 168 (14.5%) children experienced current wheeze, current asthma, and ever asthma, respectively. After adjusting for confounders, we found an increased risk of current asthma caused by B2RA exposure with an adjusted odds ratio of 2.04 (95% confidence interval: 1.02-4.05). Trend analysis showed that B2RA exposure in utero was associated with a dose-dependent increased risk of current asthma in terms of both cumulative dose and duration (P values for trend were .015 and .017, respectively). These results were similar to those for other outcome measures.

CONCLUSION

Exposure to B2RA in utero could be a risk for childhood asthma.

Developments in the field of allergy in 2016 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2016. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis, and clinical allergy are all covered.

Intestinal barrier and gut microbiota: Shaping our immune responses throughout life

The gastrointestinal (GI) tract is considered the largest immunological organ in the body having a central role in regulating immune homeostasis. Contrary to earlier belief, the intestinal epithelial barrier is not a static physical barrier but rather strongly interacts with the gut microbiome and cells of the immune system. This intense communication between epithelial cells, immune cells and microbiome will shape specific immune responses to antigens, balancing tolerance and effector immune functions. Recent studies indicate that composition of the gut microbiome affects immune system development and modulates immune mediators, which in turn affect the intestinal barrier. Moreover, dysbiosis may favor intestinal barrier disruption and could be related to increased susceptibility to certain diseases. This review will be focused on the development of the intestinal barrier and its function in host immune defense and how gut microbiome composition throughout life can affect this role.

Contributions of the intestinal microbiome in lung immunity

The intestine is a critical site of immune cell development that not only controls intestinal immunity but extra-intestinal immunity as well. Recent findings have highlighted important roles for gut microbiota in shaping lung inflammation. Here, we discuss interactions between the microbiota and immune system including T cells, protective effects of microbiota on lung infections, the role of diet in shaping the composition of gut microbiota and susceptibility to asthma, epidemiologic evidence implicating antibiotic use and microbiota in asthma and clinical trials investigating probiotics as potential treatments for atopy and asthma. The systemic effects of gut microbiota are partially attributed to their generating metabolites including short chain fatty acids, which can suppress lung inflammation through the activation of G protein-coupled receptors. Thus, studying the interactions between microbiota and immune cells can lead to the identification of therapeutic targets for chronic lower respiratory diseases.