The case of drug causation of childhood asthma: antibiotics and paracetamol

Breastfeeding enrichment of B. longum subsp. infantis mitigates the effect of antibiotics on the microbiota and childhood asthma risk

BACKGROUND

Early antibiotic exposure is linked to persistent disruption of the infant gut microbiome and subsequent elevated pediatric asthma risk. Breastfeeding acts as a primary modulator of the gut microbiome during early life, but its effect on asthma development has remained unclear.

METHODS

We harnessed the CHILD cohort to interrogate the influence of breastfeeding on antibiotic-associated asthma risk in a subset of children (n = 2,521). We then profiled the infant microbiomes in a subset of these children (n = 1,338) using shotgun metagenomic sequencing and compared human milk oligosaccharide and fatty acid composition from paired maternal human milk samples for 561 of these infants.

FINDINGS

Children who took antibiotics without breastfeeding had 3-fold higher asthma odds, whereas there was no such association in children who received antibiotics while breastfeeding. This benefit was associated with widespread "re-balancing" of taxonomic and functional components of the infant microbiome. Functional changes associated with asthma protection were linked to enriched Bifidobacterium longum subsp. infantis colonization. Network analysis identified a selection of fucosylated human milk oligosaccharides in paired maternal samples that were positively associated with B. infantis and these broader functional changes.

CONCLUSIONS

Our data suggest that breastfeeding and antibiotics have opposing effects on the infant microbiome and that breastfeeding enrichment of B. infantis is associated with reduced antibiotic-associated asthma risk.

FUNDING

This work was supported in part by the Canadian Institutes of Health Research; the Allergy, Genes and Environment Network of Centres of Excellence; Genome Canada; and Genome British Columbia.

Racing against time: leveraging preclinical models to understand pulmonary susceptibility to perinatal acetaminophen exposures

Over the past decade, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce postoperative opiate burden, and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). Despite these potential benefits, APAP exposures have spread to increasingly less mature infants, a highly vulnerable population for whom robust pharmacokinetic and pharmacodynamic data for APAP are lacking. Concerningly, preclinical studies suggest that perinatal APAP exposures may result in unanticipated adverse effects that are unique to the developing lung. In this review, we discuss the clinical observations linking APAP exposures to adverse respiratory outcomes and the preclinical data demonstrating a developmental susceptibility to APAP-induced lung injury. We show how clinical observations linking perinatal APAP exposures to pulmonary injury have been taken to the bench to produce important insights into the potential mechanisms underlying these findings. We argue that the available data support a more cautious approach to APAP use in the NICU until large randomized controlled trials provide appropriate safety and efficacy data.

Paracetamol exposure and asthma: What does the evidence say? An overview of systematic reviews

OBJECTIVE

To conduct an umbrella review collating the existing evidence to determine whether there is an association between exposure of Paracetamol in-utero or in infancy and the development of childhood Asthma.

METHODS

In this review, systematic reviews with or without meta-analysis that reported the association between paracetamol and asthma in children were included. To identify relevant reviews, a search was performed in the electronic databases PubMed, the Cochrane Library, and Ovid MEDLINE. The protocol was registered in PROSPERO CRD42020156023. A separate search was conducted for primary studies from the last 5 years not yet included in systematic reviews reporting the association from January 2016 to March 2021.

RESULTS

The electronic searches identified 1966 review titles. After the removal of 493 duplicates, 1475 titles and abstracts were screened against the eligibility criteria. Full-text screening yielded six systematic reviews to be included in this review. The search for primary studies in the last 5 years yielded 1214 hits, out of which 5 studies were found suitable for inclusion. Three of them, that were not included in the systematic reviews, and have been summarised in this paper. The odds ratios (ORs) for the outcome of asthma in offspring of mothers with prenatal paracetamol consumption in any trimester were 1.28 (1.13-1.39) and 1.21 (1.02-1.44). For first trimester exposures, they were 1.12 (0.99-1.27), 1.39 (1.01-1.91), and 1.21 (1.14-1.28), for the second or third trimester, they were 1.49 (1.37-1.63) and 1.13 (1.04-1.23). For the third trimester only, the figure was 1.17 (1.04-1.31). Of the six reviews included, 1 had a low risk of bias, 2 had an unclear risk while 3 had a high risk of bias assessed using the ROBIS tool. There was no significant increased risk of asthma with early infancy exposure. The inter-study heterogeneity varied from I²  = 41% to I²  = 76% across reviews. In the primary studies, the OR for prenatal exposure ranged from 1.12 (0.25-4.98) to 4.66 (1.92-11.3) and for infancy exposure was 1.56 (1.06-2.30). All three included primary studies were adjudged to be of high quality using the Newcastle Ottawa scale.

CONCLUSIONS

There is a modest association between paracetamol exposure in-utero and the future development of asthma. Exposure in infancy has a less consistant association. All the studies done thus far are observational in nature, with their inherent biases. Further research, preferably randomized controlled trials are recommended to answer this pertinent question.

First 1000 Days of Life: Consequences of Antibiotics on Gut Microbiota

The developmental origin of health and disease highlights the importance of the period of the first 1000 days (from conception to 2 years) of life. In particular, the process of gut microbiota establishment occurs within this time window. Therefore, determinants interfering with neonatal gut establishment may disrupt its physiological functions and potentially lead to negative health outcomes. Antibiotics are among perinatal determinants that can directly or indirectly affect the pattern of gut bacterial colonization, with a long-lasting impact on intestinal ecosystem functions. In this review, we will examine the impact of antibiotics on the intestinal microbiota during the perinatal period and first years of life, a key interval for development of an individual’s health capital. Further, we will discuss the role of antibiotics during short- and long-term dysbiosis and their associated health consequences.

Early life microbial exposures and allergy risks: opportunities for prevention

Allergies, including asthma, food allergy and atopic dermatitis, are increasing in prevalence, particularly in westernized countries. Although a detailed mechanistic explanation for this increase is lacking, recent evidence indicates that, in addition to genetic predisposition, lifestyle changes owing to modernization have an important role. Such changes include increased rates of birth by caesarean delivery, increased early use of antibiotics, a westernized diet and the associated development of obesity, and changes in indoor and outdoor lifestyle and activity patterns. Most of these factors directly and indirectly impact the formation of a diverse microbiota, which includes bacterial, viral and fungal components; the microbiota has a leading role in shaping (early) immune responses. This default programme is markedly disturbed under the influence of environmental and lifestyle risk factors. Here, we review the most important allergy risk factors associated with changes in our exposure to the microbial world and the application of this knowledge to allergy prevention strategies.

E-Synthesis: A Bayesian Framework for Causal Assessment in Pharmacosurveillance

Background: Evidence suggesting adverse drug reactions often emerges unsystematically and unpredictably in form of anecdotal reports, case series and survey data. Safety trials and observational studies also provide crucial information regarding the (un-)safety of drugs. Hence, integrating multiple types of pharmacovigilance evidence is key to minimising the risks of harm.

Methods: In previous work, we began the development of a Bayesian framework for aggregating multiple types of evidence to assess the probability of a putative causal link between drugs and side effects. This framework arose out of a philosophical analysis of the Bradford Hill Guidelines. In this article, we expand the Bayesian framework and add “evidential modulators,” which bear on the assessment of the reliability of incoming study results. The overall framework for evidence synthesis, “E-Synthesis”, is then applied to a case study.

Results: Theoretically and computationally, E-Synthesis exploits coherence of partly or fully independent evidence converging towards the hypothesis of interest (or of conflicting evidence with respect to it), in order to update its posterior probability. With respect to other frameworks for evidence synthesis, our Bayesian model has the unique feature of grounding its inferential machinery on a consolidated theory of hypothesis confirmation (Bayesian epistemology), and in allowing any data from heterogeneous sources (cell-data, clinical trials, epidemiological studies), and methods (e.g., frequentist hypothesis testing, Bayesian adaptive trials, etc.) to be quantitatively integrated into the same inferential framework.

Conclusions: E-Synthesis is highly flexible concerning the allowed input, while at the same time relying on a consistent computational system, that is philosophically and statistically grounded. Furthermore, by introducing evidential modulators, and thereby breaking up the different dimensions of evidence (strength, relevance, reliability), E-Synthesis allows them to be explicitly tracked in updating causal hypotheses.

Long-term adverse effects of paracetamol - a review

Paracetamol (acetaminophen) is the most commonly used drug in the world, with a long record of use in acute and chronic pain. In recent years, the benefits of paracetamol use in chronic conditions has been questioned, notably in the areas of osteoarthritis and lower back pain. Over the same period, concerns over the long-term adverse effects of paracetamol use have increased, initially in the field of hypertension, but more recently in other areas as well. The evidence base for the adverse effects of chronic paracetamol use consists of many cohort and observational studies, with few randomized controlled trials, many of which contradict each other, so these studies must be interpreted with caution. Nevertheless, there are some areas where the evidence for harm is more robust, and if a clinician is starting paracetamol with the expectation of chronic use it might be advisable to discuss these side effects with patients beforehand. In particular, an increased risk of gastrointestinal bleeding and a small (~4 mmHg) increase in systolic blood pressure are adverse effects for which the evidence is particularly strong, and which show a degree of dose dependence. As our estimation of the benefits decreases, an accurate assessment of the harms is ever more important. The present review summarizes the current evidence on the harms associated with chronic paracetamol use, focusing on cardiovascular disease, asthma and renal injury, and the effects of in utero exposure.

A population-based prospective cohort study examining the influence of early-life respiratory tract infections on school-age lung function and asthma

BACKGROUND

Early-life respiratory tract infections could affect airway obstruction and increase asthma risk in later life. However, results from previous studies are inconsistent.

OBJECTIVE

We examined the associations of early-life respiratory tract infections with lung function and asthma in school-aged children.

METHODS

This study among 5197 children born between April 2002 and January 2006 was embedded in a population-based prospective cohort study. Information on physician-attended upper and lower respiratory tract infections until age 6 years (categorised into ≤ 3 and >3-6 years) was obtained by annual questionnaires. Spirometry measures and physician-diagnosed asthma were assessed at age 10 years.

RESULTS

Upper respiratory tract infections were not associated with adverse respiratory outcomes. Compared with children without lower respiratory tract infections ≤3 years, children with lower respiratory tract infections ≤3 years had a lower FEV₁, FVC, FEV₁:FVC and forced expiratory flow at 75% of FVC (FEF₇₅) (Z-score (95% CI): ranging from -0.22 (-0.31 to -0.12) to -0.12 (-0.21 to -0.03)) and an increased risk of asthma (OR (95% CI): 1.79 (1.19 to 2.59)). Children with lower respiratory tract infections >3-6 years had an increased risk of asthma (3.53 (2.37 to 5.17)) only. Results were not mediated by antibiotic or paracetamol use and not modified by inhalant allergic sensitisation. Cross-lagged modelling showed that results were not bidirectional and independent of preschool wheezing patterns.

CONCLUSION

Early-life lower respiratory tract infections ≤3 years are most consistently associated with lower lung function and increased risk of asthma in school-aged children.

A population-based prospective cohort study examining the influence of early-life respiratory tract infections on school-age lung function and asthma

BACKGROUND

Early-life respiratory tract infections could affect airway obstruction and increase asthma risk in later life. However, results from previous studies are inconsistent.

OBJECTIVE

We examined the associations of early-life respiratory tract infections with lung function and asthma in school-aged children.

METHODS

This study among 5197 children born between April 2002 and January 2006 was embedded in a population-based prospective cohort study. Information on physician-attended upper and lower respiratory tract infections until age 6 years (categorised into ≤ 3 and >3-6 years) was obtained by annual questionnaires. Spirometry measures and physician-diagnosed asthma were assessed at age 10 years.

RESULTS

Upper respiratory tract infections were not associated with adverse respiratory outcomes. Compared with children without lower respiratory tract infections ≤3 years, children with lower respiratory tract infections ≤3 years had a lower FEV₁, FVC, FEV₁:FVC and forced expiratory flow at 75% of FVC (FEF₇₅) (Z-score (95% CI): ranging from -0.22 (-0.31 to -0.12) to -0.12 (-0.21 to -0.03)) and an increased risk of asthma (OR (95% CI): 1.79 (1.19 to 2.59)). Children with lower respiratory tract infections >3-6 years had an increased risk of asthma (3.53 (2.37 to 5.17)) only. Results were not mediated by antibiotic or paracetamol use and not modified by inhalant allergic sensitisation. Cross-lagged modelling showed that results were not bidirectional and independent of preschool wheezing patterns.

CONCLUSION

Early-life lower respiratory tract infections ≤3 years are most consistently associated with lower lung function and increased risk of asthma in school-aged children.

Is acetaminophen safe in pregnancy?

Acetaminophen is thought to be the safest analgesic and antipyretic medicine for pregnant women, and it is widely used all over the world. However, prenatal acetaminophen was reported to be associated with asthma, lower performance intelligence quotient (IQ), shorter male infant anogenital distance (predicting poor male reproductive potential), autism spectrum disorder, neurodevelopmental problems (gross motor development, communication), attention-deficit/hyperactivity disorder, poorer attention and executive function, and behavioral problems in childhood. Each article has poor power to show risks of acetaminophen, however, the integration of the articles that showed adverse effects of acetaminophen may have power to show them. Acetaminophen use in childhood was associated with autism spectrum disorder, asthma symptoms, wheezing, and allergic disease. Acetaminophen is the safest medicine as analgesics for nociceptive pain and antipyretics in childhood and pregnancy. There is no alternative medication of acetaminophen. Acetaminophen should not be withheld from children or pregnant women for fears it might develop adverse effects. Acetaminophen should be used at the lowest effective dosage and for the shortest time. When we know the possible, rare but serious complications, we should use acetaminophen in pregnancy only when needed and no safer option for pain or fever relief is available. Health care providers should help inform the general lay public about this difficult dilemma.

Clinical update on benefit versus risks of oral paracetamol alone or with codeine: still a good option?

BACKGROUND

After decades of worldwide use of paracetamol/acetaminophen as a popular and apparently safe prescription and over-the-counter medicine, the future role of this poorly understood analgesic has been seriously questioned by recent concerns about prenatal, cardiovascular (CV) and hepatic safety, and also about its analgesic efficacy. At the same time the usefulness of codeine in combination products has come under debate.

METHODS

Based on a PubMed database literature search on the terms efficacy, safety, paracetamol, acetaminophen, codeine and their combinations up to and including June 2016, this clinical update reviews the current evidence of the benefit and risks of oral paracetamol alone and with codeine for mild-to-moderate pain in adults, and compares the respective efficacy and safety profiles with those of nonsteroidal anti-inflammatory drugs (NSAIDs).

RESULTS

Whereas there is a clear strong association of NSAID use and gastrointestinal (GI) and CV morbidity and mortality, evidence for paracetamol with and without codeine supports the recommended use even in most vulnerable individuals, such as the elderly, pregnant women, alcoholics, and compromised GI and CV patients. The controversies and widespread misconceptions about the complex hepatic metabolism and potential hepatotoxicity have been corrected by recent reviews, and paracetamol remains the first-line nonopioid analgesic in patients with liver diseases if notes of caution are applied.

CONCLUSION

Due to its safety and tolerability profile paracetamol remained a first-line treatment in many international guidelines. Alone and with codeine it is a safe and effective option in adults, whilst NSAIDs are obviously less safe as alternatives, given the risk of potentially fatal GI and CV adverse effects.

2016 Update of the Italian Pediatric Society Guidelines for Management of Fever in Children

OBJECTIVE

To review new scientific evidence to update the Italian guidelines for managing fever in children as drafted by the panel of the Italian Pediatric Society.

STUDY DESIGN

Relevant publications in English and Italian were identified through search of MEDLINE and the Cochrane Database of Systematic Reviews from May 2012 to November 2015.

RESULTS

Previous recommendations are substantially reaffirmed. Antipyretics should be administered with the purpose to control the child's discomfort. Antipyretics should be administered orally; rectal administration is discouraged except in the setting of vomiting. Combined use of paracetamol and ibuprofen is discouraged, considering risk and benefit. Antipyretics are not recommended preemptively to reduce the incidence of fever and local reactions in children undergoing vaccination, or in attempt to prevent febrile convulsions in children. Ibuprofen and paracetamol are not contraindicated in children who are febrile with asthma, with the exception of known cases of paracetamol- or nonsteroidal anti-inflammatory drug-induced asthma.

CONCLUSIONS

Recent medical literature leads to reaffirmation of previous recommendations for use of antipyretics in children who are febrile.

Acetaminophen Attenuates House Dust Mite-Induced Allergic Airway Disease in Mice

Epidemiologic evidence suggests that N-acetyl-para-aminophenol (APAP) may play a role in the pathogenesis of asthma, likely through pro-oxidant mechanisms. However, no studies have investigated the direct effects of APAP on the development of allergic inflammation. To determine the likelihood of a causal relationship between APAP and asthma pathogenesis, we explored the effects of APAP on inflammatory responses in a murine house dust mite (HDM) model of allergic airway disease. We hypothesized that APAP would enhance the development of HDM-induced allergic inflammation. The HDM model consisted of once daily intranasal instillations for up to 2 weeks with APAP or vehicle administration 1 hour prior to HDM during either week 1 or 2. Primary assessment of inflammation included bronchoalveolar lavage (BAL), cytokine expression in lung tissue, and histopathology. Contrary to our hypothesis, the effects of HDM treatment were substantially diminished in APAP-treated groups compared with controls. APAP-treated groups had markedly reduced airway inflammation: including decreased inflammatory cells in the BAL fluid, lower cytokine expression in lung tissue, and less perivascular and peribronchiolar immune cell infiltration. The anti-inflammatory effect of APAP was not abrogated by an inhibitor of cytochrome P450 (P450) metabolism, suggesting that the effect was due to the parent compound or a non-P450 generated metabolite. Taken together, our studies do not support the biologic plausibility of the APAP hypothesis that APAP use may contribute to the causation of asthma. Importantly, we suggest the mechanism by which APAP modulates airway inflammation may provide novel therapeutic targets for asthma.

Effects of Acetaminophen on Oxidant and Irritant Respiratory Tract Responses to Environmental Tobacco Smoke in Female Mice

BACKGROUND

Although it is known that acetaminophen causes oxidative injury in the liver, it is not known whether it causes oxidative stress in the respiratory tract. If so, this widely used analgesic may potentiate the adverse effects of oxidant air pollutants.

OBJECTIVES

The goal of this study was to determine if acetaminophen induces respiratory tract oxidative stress and/or potentiates the oxidative stress and irritant responses to an inhaled oxidant: environmental tobacco smoke (ETS).

METHODS

Acetaminophen [100 mg/kg intraperitoneal (ip)] and/or sidestream tobacco smoke (as a surrogate for ETS, 5 mg/m3 for 10 min) were administered to female C57Bl/6J mice, and airway oxidative stress was assessed by loss of tissue antioxidants [estimated by nonprotein sulfhydryl (NPSH) levels] and/or induction of oxidant stress response genes. In addition, the effects of acetaminophen on airway irritation reflex responses to ETS were examined by plethysmography.

RESULTS

Acetaminophen diminished NPSH in nasal, thoracic extrapulmonary, and lung tissues; it also induced the oxidant stress response genes glutamate-cysteine ligase, catalytic subunit, and NAD(P)H dehydrogenase, quinone 1, in these sites. ETS produced a similar response. The response to acetaminophen plus ETS was equal to or greater than the sum of the responses to either agent alone. Although it had no effect by itself, acetaminophen greatly increased the reflex irritant response to ETS.

CONCLUSIONS

At supratherapeutic levels, acetaminophen induced oxidative stress throughout the respiratory tract and appeared to potentiate some responses to environmentally relevant ETS exposure in female C57Bl/6J mice. These results highlight the potential for this widely used drug to modulate responsiveness to oxidant air pollutants.

CITATION

Smith GJ, Cichocki JA, Doughty BJ, Manautou JE, Jordt SE, Morris JB. 2016. Effects of acetaminophen on oxidant and irritant respiratory tract responses to environmental tobacco smoke in female mice. Environ Health Perspect 124:642-650; http://dx.doi.org/10.1289/ehp.1509851.

Adverse consequences of neonatal antibiotic exposure

PURPOSE OF REVIEW

Antibiotics have not only saved lives and improved outcomes, but they also influence the evolving microbiome. This review summarizes reports on neonatal infections and variation in antibiotic utilization, discusses the emergence of resistant organisms, and presents data from human neonates and animal models demonstrating the impact of antibiotics on the microbiome, and how microbiome alterations impact health. The importance of antibiotic stewardship is also discussed.

RECENT FINDINGS

Infections increase neonatal morbidity and mortality. Furthermore, the clinical presentation of infections can be subtle, prompting clinicians to empirically start antibiotics when infection is a possibility. Antibiotic-resistant infections are a growing problem. Cohort studies have identified extensive center variations in antibiotic usage and associations between antibiotic exposures and outcomes. Studies of antibiotic-induced microbiome alterations and downstream effects on the developing immune system have increased our understanding of the mechanisms underlying the associations between antibiotics and adverse outcomes. The emergence of resistant microorganisms and recent evidence linking antibiotic practice variations with health outcomes has led to the initiation of antibiotic stewardship programs.

SUMMARY

The review encourages practitioners to assess local antibiotic use with regard to local microbiology, and to adopt steps to reduce infections and use antibiotics wisely.

The association between paracetamol use and asthma: causation or coincidence?

A better understanding of the causation of asthma and allergic disorders could potentially lead to intervention strategies that reduce their prevalence and severity. One potential causative factor is the use of paracetamol. Most of the evidence for the link with asthma is from non-experimental studies of paracetamol exposure in utero, infancy, childhood and adult life; however, it has been difficult to rule out confounding and bias in the associations observed. The two randomized clinical trials of the effect of paracetamol in patients with asthma have been difficult to interpret, due to methodological issues. There have been no randomized controlled trials of paracetamol use and the development of asthma. Both asthma and paracetamol use are common, and so even if there is a relatively small effect of paracetamol exposure on the development of asthma or its severity, then such an effect would be of major public health significance. It is proposed that randomized controlled trials of the effect of paracetamol on the development of asthma and its severity are a high research priority.

Prenatal Paracetamol Exposure and Wheezing in Childhood: Causation or Confounding?

Background

Several studies have reported an increased risk of wheezing in the children of mothers who used paracetamol during pregnancy. We evaluated to what extent this association is explained by confounding.

Methods

We investigated the association between maternal paracetamol use in the first and third trimester of pregnancy and ever wheezing or recurrent wheezing/asthma in infants in the NINFEA cohort study. Risks ratios (RR) and 95% confidence intervals (CI) were estimated after adjustment for confounders, including maternal infections and antibiotic use during pregnancy.

Results

The prevalence of maternal paracetamol use was 30.6% during the first and 36.7% during the third trimester of pregnancy. The prevalence of ever wheezing and recurrent wheezing/asthma was 16.9% and 5.6%, respectively. After full adjustment, the RR for ever wheezing decreased from 1.25 [1.07–1.47] to 1.10 [0.94–1.30] in the first, and from 1.26 [1.08–1.47] to 1.10 [0.93–1.29] in the third trimester. A similar pattern was observed for recurrent wheezing/asthma. Duration of maternal paracetamol use was not associated with either outcome. Further analyses on paracetamol use for three non-infectious disorders (sciatica, migraine, and headache) revealed no increased risk of wheezing in children.

Conclusion

The association between maternal paracetamol use during pregnancy and infant wheezing is mainly, if not completely explained by confounding.

Prevalence, Severity, and Treatment of Recurrent Wheezing During the First Year of Life: A Cross-Sectional Study of 12,405 Latin American Infants

PURPOSE

This study aimed to determine the prevalence and severity of recurrent wheezing (RW) defined as ≥3 episodes of wheezing, risk factors, and treatments prescribed during the first year of life in Latin American infants.

METHODS

In this international, cross-sectional, and community-based study, parents of 12,405 infants from 11 centers in 6 South American countries (Argentina, Brazil, Chile, Colombia, Peru, and Uruguay) completed a questionnaire about wheezing and associated risk/protective factors, asthma medications, and the frequency of and indications for the prescription of antibiotics and paracetamol during the first year of life.

RESULTS

The prevalence of RW was 16.6% (95% CI 16.0-17.3); of the 12,405 infants, 72.7% (95% CI 70.7-74.6) visited the Emergency Department for wheezing, and 29.7% (27.7-31.7) was admitted. Regarding treatment, 49.1% of RW infants received inhaled corticosteroids, 55.7% oral corticosteroids, 26.3% antileukotrienes, 22.9% antibiotics ≥4 times mainly for common colds, wheezing, and pharyngitis, and 57.5% paracetamol ≥4 times. Tobacco smoking during pregnancy, household income per month <1,000 USD, history of parental asthma, male gender, and nursery school attendance were significant risk factors for higher prevalence and severity of RW, whereas breast-feeding for at least 3 months was a significant protective factor. Pneumonia and admissions for pneumonia were significantly higher in infants with RW as compared to the whole sample (3.5-fold and 3.7-fold, respectively).

CONCLUSIONS

RW affects 1.6 out of 10 infants during the first year of life, with a high prevalence of severe episodes, frequent visits to the Emergency Department, and frequent admissions for wheezing. Besides the elevated prescription of asthma medications, there is an excessive use of antibiotics and paracetamol in infants with RW and also in the whole sample, which is mainly related to common colds.

The gut microbiota and inflammatory noncommunicable diseases: associations and potentials for gut microbiota therapies

Rapid environmental transition and modern lifestyles are likely driving changes in the biodiversity of the human gut microbiota. With clear effects on physiologic, immunologic, and metabolic processes in human health, aberrations in the gut microbiome and intestinal homeostasis have the capacity for multisystem effects. Changes in microbial composition are implicated in the increasing propensity for a broad range of inflammatory diseases, such as allergic disease, asthma, inflammatory bowel disease (IBD), obesity, and associated noncommunicable diseases (NCDs). There are also suggestive implications for neurodevelopment and mental health. These diverse multisystem influences have sparked interest in strategies that might favorably modulate the gut microbiota to reduce the risk of many NCDs. For example, specific prebiotics promote favorable intestinal colonization, and their fermented products have anti-inflammatory properties. Specific probiotics also have immunomodulatory and metabolic effects. However, when evaluated in clinical trials, the effects are variable, preliminary, or limited in magnitude. Fecal microbiota transplantation is another emerging therapy that regulates inflammation in experimental models. In human subjects it has been successfully used in cases of Clostridium difficile infection and IBD, although controlled trials are lacking for IBD. Here we discuss relationships between gut colonization and inflammatory NCDs and gut microbiota modulation strategies for their treatment and prevention.

Antibiotic stewardship: reassessment of guidelines for management of neonatal sepsis

In 2010, the Centers for Disease Control and Prevention (CDC) provided updated guidelines for prevention of perinatal group B streptococcus disease. In 2012, the American Academy of Pediatrics' Committee on the Fetus and Newborn (COFN) provided a clinical report which suggested approaches to infants with risk factors for EOS which would increase empirical antibiotic use beyond the CDC guidelines. This Clinics article reviews the CDC guidelines and 2012 COFN report, summarizes the 2014 commentary provided by COFN members which provided a revised clinical algorithm, and discusses mechanisms which could reduce the number of well-appearing term infants exposed to empirical antibiotics.

The role of the early-life environment in the development of allergic disease

A consensus has been reached that the development of allergic disorders is strongly influenced by early life exposures. An overview of several prenatal and early life factors that have been investigated for their associations with development of childhood allergy is presented. Delivery mode, the gut microbiome, vitamin D, folate, breastfeeding, pets, antibiotics, environmental tobacco smoke, and airborne traffic pollutants are discussed. Although many studies suggest an effect, overall, no risk factors clearly increase or reduce the risk of allergic outcomes.

Relationship between prenatal antibiotic use and asthma in at-risk children

BACKGROUND

Asthma prevalence has doubled in developed countries during the past 30 years. Pre- and perinatal events are essential in shaping the development of the immune system and systemic antibiotic use during this time could alter the maternal or placental microbiome, leading to an increase in the child's risk of developing asthma.

OBJECTIVE

To determine whether prenatal antibiotic use is associated with asthma and wheezing in children at risk for asthma.

METHODS

Using data from a randomized education intervention of families at risk for asthma from 1998 followed through 2009 in urban Chicago, asthma was defined as ever having a physician asthma diagnosis by year 3 and wheezing in the third year. Logistic regression models controlling for confounders investigated the effect of antibiotic use during pregnancy on these outcomes.

RESULTS

After adjustment, prenatal antibiotic use was a risk factor for asthma (odds ratio 3.1, 95% confidence interval 1.4-6.8) but was only weakly associated with wheezing (odds ratio 1.8, 95% confidence interval 0.9-3.3). Analyses of the effects of timing of prenatal antibiotic use on asthma and wheezing showed the relation remained consistent for antibiotic use later in pregnancy, but the outcomes were not associated with antibiotic use in the first trimester.

CONCLUSION

This study suggests prenatal antibiotic use might be associated with the development of asthma in children at risk for asthma. Although the relation with prenatal antibiotics does not hold for wheezing in this study, there might be a trend that could be delineated further within a larger cohort study.

Antibiotics in fetal and early life and subsequent childhood asthma: nationwide population based study with sibling analysis

OBJECTIVE

To investigate the association between exposure to antibiotics in fetal and early life and asthma in childhood, with adjustment for confounding factors.

DESIGN

Nationwide prospective population based cohort study, including sibling control design.

SETTING

Swedish population identified from national demographic and health registers.

PARTICIPANTS

493,785 children born 2006-10; 180,894 of these were eligible for sibling analyses.

MAIN OUTCOME MEASURE

Asthma defined as having both an asthma diagnosis and dispensed asthma drugs. The association between antibiotic exposure and asthma was investigated in the whole cohort with Cox proportional hazard regression. A stratified proportional hazards model conditional on sibling group was used to adjust for shared factors within families. Confounding by respiratory infections was assessed by investigating whether specific groups of antibiotics were associated with asthma.

RESULTS

Antibiotic exposure in fetal life was associated with an increased risk of asthma in cohort analyses (hazard ratio 1.28, 95% confidence interval 1.25 to 1.32), but not in sibling analyses (0.99, 0.92 to 1.07). In cohort analyses, antibiotics used to treat respiratory infections in childhood were associated with a more pronounced increased risk of asthma (4.12, 3.78 to 4.50) than antibiotics used for urinary tract and skin infections (1.54, 1.24 to 1.92). In sibling analyses, the excess risks after exposure to antibiotics for respiratory infections decreased (2.36, 1.78 to 3.13) and disappeared for antibiotics for urinary tract and skin (0.85, 0.47 to 1.55).

CONCLUSIONS

Previous positive associations between exposure to antibiotics in fetal and early life and subsequent childhood asthma could have been caused by confounding by shared familial factors, in addition to confounding by respiratory infections.

A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years

OBJECTIVES

Childhood asthma is a complex condition where many environmental factors are implicated in causation. The aim of this study was to complete a systematic review of the literature describing associations between environmental exposures and the development of asthma in young children.

SETTING

A systematic review of the literature up to November 2013 was conducted using key words agreed by the research team. Abstracts were screened and potentially eligible papers reviewed. Papers describing associations between exposures and exacerbation of pre-existing asthma were not included. Papers were placed into the following predefined categories: secondhand smoke (SHS), inhaled chemicals, damp housing/mould, inhaled allergens, air pollution, domestic combustion, dietary exposures, respiratory virus infection and medications.

PARTICIPANTS

Children aged up to 9 years.

PRIMARY OUTCOMES

Diagnosed asthma and wheeze.

RESULTS

14,691 abstracts were identified, 207 papers reviewed and 135 included in the present review of which 15 were systematic reviews, 6 were meta-analyses and 14 were intervention studies. There was consistent evidence linking exposures to SHS, inhaled chemicals, mould, ambient air pollutants, some deficiencies in maternal diet and respiratory viruses to an increased risk for asthma (OR typically increased by 1.5-2.0). There was less consistent evidence linking exposures to pets, breast feeding and infant dietary exposures to asthma risk, and although there were consistent associations between exposures to antibiotics and paracetamol in early life, these associations might reflect reverse causation. There was good evidence that exposures to house dust mites (in isolation) was not associated with asthma risk. Evidence from observational and intervention studies suggest that interactions between exposures were important to asthma causation, where the effect size was typically 1.5-3.0.

CONCLUSIONS

There are many publications reporting associations between environmental exposures and modest changes in risk for asthma in young children, and this review highlights the complex interactions between exposures that further increase risk.

Microbiome diversity and asthma and allergy risk

The prevalence of asthma and allergy has been constantly increasing in Westernized countries in the last decades. Asthma and allergies are complex diseases with a local tissue inflammation that are determined by genetic and environmental factors. Because the commensal microflora is crucial to maintain inflammatory homeostasis and to induce immune regulation, the microbiome may play an important role for the development of allergic conditions. New techniques such as next-generation sequencing methods give the opportunity to explore the microbial community structure of the human body comprehensively. In this review, we will discuss the available literature concerning the human microbiota and asthma and allergy development and occurrence. The focus is on studies of the local microbiome of the place of inflammation, the gastrointestinal microbiome, and the influence of intrinsic factors relating to the host and extrinsic factors relating to the external environment on the microbiome.

New problems arising from old drugs: second-generation effects of acetaminophen

Acetaminophen (APAP)/paracetamol is one of the most commonly used over-the-counter drugs taken worldwide for treatment of pain and fever. Although considered as safe when taken in recommended doses not higher than 4 g/day, APAP overdose is currently the most important cause of acute liver failure (ALF). ALF may require liver transplantation and can be fatal. The reasons for APAP-related ALF are mostly intentional (suicidal) or unintentional overdose. However, results from large scale epidemiological studies provide increasing evidence for second generation effects of APAP, even when taken in pharmacological doses. Most strikingly, APAP medication during pregnancy has been associated with health problems including neurodevelopmental and behavioral disorders such as attention deficit hyperactivity disorder and increase in the risk of wheezing and incidence of asthma among offspring. This article reviews the epidemiological findings and aims to shed light into the molecular and cellular mechanisms responsible for APAP-mediated prenatal risk for asthma.

Acetaminophen and/or antibiotic use in early life and the development of childhood allergic diseases

BACKGROUND

Our understanding of whether the use of acetaminophen and/or antibiotics in early life can cause allergic diseases in later childhood remains inconclusive. The objective of this study was to investigate the temporal relationship between exposure to acetaminophen and/or antibiotics in early life and the development of allergic diseases in later childhood, using two independent birth cohorts derived from the National Health Insurance Research Database (NHIRD) in Taiwan.

METHODS

The authors conducted a prospective birth cohort study of 263 620 children born in 1998 and 9910 children born in 2003, separately, from the NHIRD. Exposure status of acetaminophen and/or antibiotics and potential confounding factors were included in the analyses. Cox proportional hazards models were applied to determine the temporal relationship between acetaminophen and/or antibiotic exposure and the development of allergic diseases.

RESULTS

We observed a positive relationship between acetaminophen and/or antibiotic exposure during the 1st year of life and the subsequent development of the three examined allergic diseases (atopic dermatitis, asthma and allergic rhinitis) in the 1998 birth cohort, but the observed relationship of drug exposure in the 2003 cohort, especially for atopic dermatitis and asthma, was lower than for those in the 1998 cohort and was not statistically significant.

CONCLUSIONS

Our findings provide suggestive evidence that the temporal effect of exposure to acetaminophen and/or antibiotics influences the development of common allergic diseases in later childhood. Further functional studies and/or animal studies are needed to better understand the underlying regulatory mechanisms driving this important clinical and public health issue.

Trends in the prevalence of asthma

The asthma epidemic of the last few decades may have peaked; studies suggest that the incidence and prevalence of asthma has decreased in some countries in the last few years, although other studies suggest continuing small increases in prevalence. Increasing awareness and changing diagnostic habits make precise evaluation of epidemiologic trends difficult in the absence of a gold-standard test for asthma, and on a global basis uncertainty persists. Trends in prevalence in some populations (eg, immigrants, farming communities) suggest both adverse and beneficial effects of specific environmental factors. Although the effects of indoor allergens, dampness, and mold and of outdoor air pollutants, especially traffic related, have traditionally dominated risk-factor research, more recent epidemiologic and clinical studies have focused on metabolic and nutritional factors, including maternal obesity and vitamin D levels, mode of delivery and its effect on the infant microbiome, fetal and infant growth, the psychosocial environment, and medication use by mother and infant. It is likely that changes in incidence and prevalence are due to multiple factors, each contributing a relatively small effect. Longitudinal studies from pregnancy through childhood to adulthood will yield greater insights into the complex pathways leading to asthma.

Randomized Controlled Trials and real life studies. Approaches and methodologies: a clinical point of view

Randomized Controlled Trials (RCTs) are the "gold standard" for evaluating treatment outcomes providing information on treatments "efficacy". They are designed to test a therapeutic hypothesis under optimal setting in the absence of confounding factors. For this reason they have high internal validity. The strict and controlled conditions in which they are conducted, leads to low generalizability because they are performed in conditions very different from real life usual care. Conversely, real life studies inform on the "effectiveness" of a treatment, that is, the measure of the extent to which an intervention does what is intended to do in routine circumstances. At variance to RCTs, real life trials have high generalizability, but low internal validity. Recently the number of real life studies has been rapidly growing in different areas of respiratory medicine, particularly in asthma and COPD. The role of such studies is becoming a hot topic in respiratory medicine, attracting research interest and debate. In the first part of this review we discuss some of the advantages and disadvantages of different types of RCTs and analyze the strengths and weaknesses of real life trials, considering the recent examples of some studies conducted in COPD. We then discuss methodological approaches and options to overcome some of the limitations of real life studies. Comparing the conclusions of effectiveness and efficacy trials can provide important pieces of information. Indeed, these approaches can result complementary, and they can guide the interpretation of each other results.

Developmental Immunotoxicity, Perinatal Programming, and Noncommunicable Diseases: Focus on Human Studies

Developmental immunotoxicity (DIT) is a term given to encompass the environmentally induced disruption of normal immune development resulting in adverse outcomes. A myriad of chemical, physical, and psychological factors can all contribute to DIT. As a core component of the developmental origins of adult disease, DIT is interlinked with three important concepts surrounding health risks across a lifetime: (1) the Barker Hypothesis, which connects prenatal development to later-life diseases, (2) the hygiene hypothesis, which connects newborns and infants to risk of later-life diseases and, (3) fetal programming and epigenetic alterations, which may exert effects both in later life and across future generations. This review of DIT considers: (1) the history and context of DIT research, (2) the fundamental features of DIT, (3) the emerging role of DIT in risk of noncommunicable diseases (NCDs) and (4) the range of risk factors that have been investigated through human research. The emphasis on the human DIT-related literature is significant since most prior reviews of DIT have largely focused on animal research and considerations of specific categories of risk factors (e.g., heavy metals). Risk factors considered in this review include air pollution, aluminum, antibiotics, arsenic, bisphenol A, ethanol, lead (Pb), maternal smoking and environmental tobacco smoke, paracetamol (acetaminophen), pesticides, polychlorinated biphenyls, and polyfluorinated compounds.

Prenatal and childhood infections: implications for the development and treatment of childhood asthma

Bacterial and viral infections occur early and recurrently in life and thereby impose a substantial disease burden. Besides causing clinical symptoms, a potential role of infection in the development of the asthma syndrome later in life has also been suggested. However, whether bacterial and viral infections unmask host factors in children at risk of asthma or whether they directly cause asthma remains unclear; both viewpoints could be justified, but the underlying mechanisms are complex and poorly understood. Recently, the role of the bacterial microbiome has been emphasised. But data are still sparse and future studies are needed for definitive conclusions to be made. In this Review, we discuss present knowledge of viruses and bacteria that infect and colonise the respiratory tract and mucosal surfaces, including their timepoint of action, host factors related to infection, and their effect on childhood asthma. Childhood asthma could be the result of a combination of altered host susceptibility and infectious agents.