Association of maternal snuff use and smoking with Sudden Infant Death Syndrome: a national register study

BACKGROUND

The aim was to study whether non-combustible nicotine (Swedish snuff) use in pregnancy is associated with elevated risk of post neonatal mortality, Sudden Infant Death Syndrome (SIDS), and Sudden Unexpected Infant Death (SUID) and to study how cessation before the antenatal booking influenced these risks.

METHODS

This was a population-based register study of all infants with information on tobacco exposure in early pregnancy born in Sweden 1999-2019, n = 2,061,514. Self-reported tobacco use in early pregnancy was categorized as nonuse, snuff use, and moderate and heavy smoking. Multiple logistic regression models were used to estimate crude and adjusted odds ratios (aORs) with 95% confidence intervals (CIs).

RESULTS

Maternal snuff use was associated with increased risks of post neonatal mortality, SIDS, and SUID. The risks of snuff use and moderate smoking were of similar magnitude. Heavy smoking was associated with the highest risks. Cessation of smoking and snuff use before the antenatal booking was associated with lower risks of SIDS and SUID compared to that of continuous usage.

CONCLUSIONS

Maternal snuff use was associated with increased risks of post neonatal mortality, SIDS, and SUID. Nicotine is the common substance in cigarette smoke and snuff. These findings support the hypothesis that nicotine contributes to an elevated risk of SIDS.

IMPACT

Maternal snuff use and smoking in early pregnancy were associated with increased risks of post neonatal mortality, SIDS, and SUID. Cessation of smoking and snuff use before the first antenatal visit was associated with reduced risks of SIDS and SUID. The common substance in cigarette smoke and snuff is nicotine. Our findings suggest that nicotine contributes to an elevated risk of SIDS and SUID. The implication of our findings is that all forms of nicotine should be avoided in pregnancy.

In-utero antibiotic exposure and subsequent infections in infancy: a register-based cohort study with sibling analysis

BACKGROUND

Prenatal antibiotic use, the ensuing maternal dysbiosis, and subsequent acquisition of altered microbiota in early life have been linked to the offspring's increased susceptibility to childhood infections. However, infection risks during the first year of life associated with in-utero antibiotic exposure have not been comprehensively explored.

OBJECTIVE

To investigate the associations between exposure to antibiotics in utero and subsequent infections during infancy and whether such associations differ by antibiotic class.

STUDY DESIGN

All data were retrieved from Swedish population-based registers. Singletons live-born between 2006 and 2018 were followed up from birth to their first birthday. Exposure was maternal filling of at least 1 antibiotic prescription between the last menstrual period and delivery. Outcomes were the infants' antimicrobial prescription fills, incident infections diagnosed in specialist care, and deaths with infections indicated as underlying or contributing causes ("infection-related deaths"). Birth year, birth season, maternal age, place of residence, parity, comorbidity indicator, body mass index, proxies for general health status, education level, and smoking status were considered covariates. Poisson regression was used to estimate crude and adjusted incidence rate ratios with 95% confidence intervals for the number of antimicrobial prescriptions filled to the infant. Cox regression was used to estimate crude and adjusted hazard ratios with 95% confidence intervals for incident infections diagnosed in specialist care and at death. Sibling analyses were used to account for shared familial factors. Sensitivity of the results to exposure definition and perinatal factors prognostic for the outcomes were assessed in supplementary analyses.

RESULTS

Of 1,347,018 infants in the full cohort, 294,657 (21.9%) were exposed to antibiotics in utero. There were 677,430 antimicrobial prescriptions filled (1.380 per 1000 person-days), 423,705 incident infections diagnosed in specialist care (0.870 per 1000 person-days), and 2800 infection-related deaths (0.006 deaths per 1000 person-days) during follow-up. Compared to unexposed, infants exposed to antibiotics in utero had higher rates of antimicrobial prescription fills (adjusted incidence rate ratio, 1.34; 95% confidence interval, 1.33-1.34), incident infections diagnosed in specialist care (adjusted hazard ratio, 1.28; 95% confidence interval, 1.27-1.29), and infection-related mortality (adjusted hazard ratio, 1.15; 95% confidence interval, 1.05-1.25). For antimicrobial prescriptions and infections diagnosed in specialist care, associations were consistent across most antibiotic classes but were attenuated in the sibling analyses: adjusted incidence rate ratio of 1.05 (95% confidence interval, 1.04-1.06) and adjusted hazard ratio of 1.05 (95% confidence interval, 1.03-1.07), respectively. No association with infant mortality was found in the sibling cohort (adjusted hazard ratio, 0.93; 95% confidence interval, 0.81-1.08).

CONCLUSION

The minor associations between exposure to antibiotics in utero and infections during infancy were partly explained by shared familial factors and did not differ across frequently used antibiotic classes.

Myxovirus resistance protein A for discriminating between viral and bacterial lower respiratory tract infections in children - The TREND study

OBJECTIVE

Discriminating between viral and bacterial lower respiratory tract infection (LRTI) in children is challenging, leading to an excessive use of antibiotics. Myxovirus resistance protein A (MxA) is a promising biomarker for viral infections. The primary aim of the study was to assess differences in blood MxA levels between children with viral and bacterial LRTI. Secondary aims were to assess differences in blood MxA levels between children with viral LRTI and asymptomatic controls and to assess MxA levels in relation to different respiratory viruses.

METHODS

Children with LRTI were enrolled as cases at Sachs' Children and Youth Hospital, Stockholm, Sweden. Nasopharyngeal aspirates and blood samples for analysis of viral PCR, MxA and CRP were systematically collected from all study subjects in addition to standard laboratory/radiology assessment. Aetiology was defined according to an algorithm based on laboratory and radiological findings. Asymptomatic children with minor surgical disease were enrolled as controls.

RESULTS

MxA levels were higher in children with viral LRTI (n=242) as compared to both bacterial (n=5) LRTI (p<0.01, area under the curve (AUC) 0.90, 95% confidence interval (CI):0.81-0.99) and controls (AUC 0.92, 95% CI:0.88-0.95). In the subgroup of children with pneumonia diagnosis, a cut-off of MxA 430μg/l discriminated between viral (n=29) and bacterial (n=4) aetiology with 93% (95% CI: 78%-99%) sensitivity and 100% (95% CI: 51%-100%) specificity (AUC 0.98, 95% CI: 0.94-1.00). The highest MxA levels were seen in cases PCR positive for influenza (median MxA 1699μg/l, interquartile range (IQR): 732-2996) and respiratory syncytial virus (median MxA 1115μg/l, IQR: 679-2489).

CONCLUSION

MxA accurately discriminated between viral and bacterial aetiology in children with LRTI, particularly in the group of children with pneumonia diagnosis, but the number of children with bacterial LRTI was low.

Pneumonia in Infancy and Risk for Asthma: The Role of Familial Confounding and Pneumococcal Vaccination

BACKGROUND

Studies have reported an increased risk for asthma following lower respiratory tract infections, but few studies have specifically assessed this risk in children diagnosed with pneumonia in infancy. Furthermore, it is not fully understood whether this association is indicative of a causal relationship or if certain children have a predisposition for both diseases.

RESEARCH QUESTION

Are children diagnosed with pneumonia in infancy at increased risk for asthma, and what is the role of familial confounding and pneumococcal conjugate vaccine immunization on the association?

STUDY DESIGN AND METHODS

This study was a nationwide register-based cohort analysis of > 900,000 Swedish children to assess the association between pneumonia in infancy and prevalent asthma at 4 years. A secondary aim was to assess if the association has changed after the introduction of nationwide pneumococcal conjugate vaccine (PCV) immunization as this has led to a shift in pneumonia etiology. The study controlled for important confounders, including shared environmental and familial confounding, by using sibling analyses.

RESULTS

There was a strong association between pneumonia diagnosis in infancy and prevalent asthma at 4 years (adjusted OR, 3.38; 95% CI, 3.26-3.51), as well as in the full sibling analyses (adjusted OR, 2.81; 95% CI, 2.58-3.06). The risk for asthma following pneumonia diagnosis in infancy was slightly higher for those born in the PCV period compared with the pre-PCV period (adjusted OR, 3.80 [95% CI, 3.41-4.24] vs 3.28 [95% CI, 3.15-3.42]) when the proportion of viral pneumonia etiology was also higher (14.5% vs 10.7%, respectively) and the overall asthma prevalence was lower (5.3% vs 6.6%).

INTERPRETATION

Children diagnosed with pneumonia in infancy have a highly increased risk for prevalent asthma at 4 years, which might have implications for future asthma preventive measures and needs to be considered when assessing the morbidity that can be attributed to pneumonia.

Season of birth, childhood asthma and allergy in a nationwide cohort-Mediation through lower respiratory infections

BACKGROUND

Previous studies have suggested an association between season of birth and risk of childhood asthma and allergic disease. The association may be modified by birth year and region, or mediated by respiratory tract infections.

OBJECTIVE

We aimed to estimate the association between season of birth and risk of childhood asthma/wheeze or allergic rhinoconjunctivitis in a population-based setting, and the mediating effect of lower respiratory infections.

METHODS

Two population-based cohorts were identified from the nationwide Swedish Medical Birth, Patient and Prescribed Drug Registers. The association between birth month/season and asthma/wheeze incidence was analysed using Cox proportional regression in the younger cohort born 2005-2010 (n = 582 494) and asthma/allergic rhinoconjunctivitis prevalence during the 7th year of life using log-binomial models in the older cohort born 2001-2004 (n = 367 583). Interactions were formally tested. Mediation analyses to address the effect of lower respiratory infections were performed in the older cohort using the R package "medflex."

RESULTS

Children born during fall and winter had an increased risk of asthma/wheeze after 2 years of age in the younger cohort: hazard ratio 1.24 (95% confidence interval, CI 1.17, 1.33) for winter and risk of prevalent asthma during their 7th year of life in the older cohort; prevalence ratio (PR) 1.12 (95% CI 1.08, 1.16) for winter. These estimates were partly mediated by lower respiratory infections; the indirect effect for winter compared with summer was PR 1.03 (95% CI 1.03, 1.04). The association was similar for allergic rhinoconjunctivitis in the 7th year of life, but not mediated by respiratory infections.

CONCLUSION

We found that the association between season of birth and risk of childhood asthma/wheeze, but not allergic rhinoconjunctivitis, is partly mediated through lower respiratory infections.

CLINICAL RELEVANCE

This has important implications for patient care, such as asthma management programmes to notify timing of seasonality for viral respiratory tract infections.

Adenoviral detection by recombinase polymerase amplification and vertical flow paper microarray

Respiratory viral infections often mimic the symptoms of infections caused by bacteria; however, restricted and targeted administration of antibiotics is needed to combat growing antimicrobial resistance. This is particularly relevant in low-income settings. In this work, we describe the use of isothermal amplification of viral DNA at 37 °C coupled to a paper-based vertical flow microarray (VFM) setup that utilizes a colorimetric detection of amplicons using functionalized gold nanoparticles. Two oligonucleotide probes, one in-house designed and one known adenoviral probe were tested and validated for microarray detection down to 50 nM using a synthetic target template. Furthermore, primers were shown to function in a recombinase polymerase amplification reaction using both synthetic template and viral DNA. As a proof-of-concept, we demonstrate adenoviral detection with four different adenoviral species associated with respiratory infections using the paper-based VFM format. The presented assay was validated with selected adenoviral species using the in-house probe, enabling detection at 1 ng of starting material with intra- and inter-assay %CV of ≤ 9% and ≤ 13%. Finally, we validate our overall method using clinical samples. Based on the results, the combination of recombinase polymerase amplification, paper microarray analysis, and nanoparticle-based colorimetric detection could thus be a useful strategy towards rapid and affordable multiplexed viral diagnostics.

Frequent Respiratory Viral Infections in Children with Febrile Neutropenia - A Prospective Follow-Up Study

OBJECTIVE

Febrile neutropenia is common in children undergoing chemotherapy for the treatment of malignancies. In the majority of cases, the cause of the fever is unknown. Although respiratory viruses are commonly associated with this condition, the etiologic significance of this finding remains unclear and is therefore the subject of this study.

STUDY DESIGN

Nasopharyngeal aspirates were collected during 87 episodes of febrile neutropenia in children age 0-18 years, being treated at a children's oncology unit between January 2013 and June 2014. Real-time polymerase chain reaction was used to determine the presence of 16 respiratory viruses. Follow-up samples were collected from children who tested positive for one or more respiratory viruses. Rhinoviruses were genotyped by VP4/VP2 sequencing. Fisher's exact test and Mann-Whitney U test were used for group comparisons.

RESULTS

At least one respiratory virus was detected in samples from 39 of 87 episodes of febrile neutropenia (45%), with rhinoviruses the most frequently detected. Follow-up samples were collected after a median of 28 days (range, 9-74 days) in 32 of the 39 virus-positive episodes. The respiratory viral infection had resolved in 25 episodes (78%). The same virus was detected at follow-up in one coronavirus and six rhinovirus episodes. Genotyping revealed a different rhinovirus species in two of the six rhinovirus infections.

CONCLUSION

The frequency of respiratory viral infections in this group of patients suggests an etiologic role in febrile neutropenia. However, these findings must be confirmed in larger patient cohorts.

Respiratory viruses associated with community-acquired pneumonia in children: matched case-control study

BACKGROUND

Community-acquired pneumonia (CAP) is the leading cause of death in children worldwide and a substantial proportion of childhood CAP is caused by viruses. A better understanding of the role of virus infections in this condition is needed to improve clinical management and preventive measures. The aim of the study was therefore to assess the association between specific respiratory viruses and childhood CAP.

METHODS

A case-control study was conducted during 3 years in Stockholm, Sweden. Cases were children aged ≤5 years with radiological CAP. Healthy controls were consecutively enrolled at child health units during routine visits and matched to cases on age and calendar time. Nasopharyngeal aspirates were obtained and analysed by real-time PCR for 15 viruses. Multivariate conditional logistic regression was used to account for coinfections with other viruses and baseline characteristics.

RESULTS

A total of 121 cases, of which 93 cases met the WHO criteria for radiological pneumonia, and 240 controls were included in the study. Viruses were detected in 81% of the cases (n=98) and 56% of the controls (n=134). Influenza virus, metapneumovirus and respiratory syncytial virus were detected in 60% of cases and were significantly associated with CAP with ORs >10. There was no association with parainfluenza virus, human enterovirus or rhinovirus and coronavirus and bocavirus were negatively associated with CAP.

CONCLUSIONS

Our study indicates viral CAP is an underestimated disease and points out hMPV as a new important target for the prevention of childhood CAP.

Clinical utility of PCR for common viruses in acute respiratory illness

BACKGROUND

Acute respiratory illness (ARI) accounts for a large proportion of all visits to pediatric health facilities. Quantitative real-time polymerase chain reaction (qPCR) analyses allow sensitive detection of viral nucleic acids, but it is not clear to what extent specific viruses contribute to disease because many viruses have been detected in asymptomatic children. Better understanding of how to interpret viral findings is important to reduce unnecessary use of antibiotics.

OBJECTIVE

To compare viral qPCR findings from children with ARI versus asymptomatic control subjects.

METHODS

Nasopharyngeal aspirates were collected from children aged ≤5 years with ARI and from individually matched, asymptomatic, population-based control subjects during a noninfluenza season. Samples were analyzed by using qPCR for 16 viruses.

RESULTS

Respiratory viruses were detected in 72.3% of the case patients (n = 151) and 35.4% of the control subjects (n = 74) (P = .001). Rhinovirus was the most common finding in both case patients and control subjects (47.9% and 21.5%, respectively), with a population-attributable proportion of 0.39 (95% confidence interval: 0.01 to 0.62). Metapneumovirus, parainfluenza viruses, and respiratory syncytial virus were highly overrepresented in case patients. Bocavirus was associated with ARI even after adjustment for coinfections with other viruses and was associated with severe disease. Enterovirus and coronavirus were equally common in case patients and control subjects.

CONCLUSIONS

qPCR detection of respiratory syncytial virus, metapneumovirus, or parainfluenza viruses in children with ARI is likely to be causative of disease; detection of several other respiratory viruses must be interpreted with caution due to high detection rates in asymptomatic children.

HIV-neutralizing activity of cationic polypeptides in cervicovaginal secretions of women in HIV-serodiscordant relationships

Background

HIV exposed seronegative (HESN) women represent the population most in need of a prophylactic antiviral strategy. Mucosal cationic polypeptides can potentially be regulated for this purpose and we here aimed to determine their endogenous expression and HIV neutralizing activity in genital secretions of women at risk of HIV infection.

Methodology/Principal Findings

Cervicovaginal secretions (CVS) of Kenyan women in HIV-serodiscordant relationships (HESN, n = 164; HIV seropositive, n = 60) and low-risk controls (n = 72) were assessed for the cationic polypeptides HNP1–3, LL-37 and SLPI by ELISA and for HIV neutralizing activity by a PBMC-based assay using an HIV primary isolate. Median levels of HNP1–3 and LL-37 in CVS were similar across study groups. Neither HSV-2 serostatus, nor presence of bacterial vaginosis, correlated with levels of HNP1–3 or LL-37 in the HESN women. However, an association with their partner's viral load was observed. High viral load (>10,000 HIV RNA copies/ml plasma) correlated with higher levels of HNP1–3 and LL-37 (p = 0.04 and 0.03, respectively). SLPI was most abundant in the low-risk group and did not correlate with male partner's viral load in the HESN women. HIV neutralizing activity was found in CVS of all study groups. In experimental studies, selective depletion of cationic polypeptides from CVS rendered the remaining CVS fraction non-neutralizing, whereas the cationic polypeptide fraction retained the activity. Furthermore, recombinant HNP1–3 and LL-37 could induce neutralizing activity when added to CVS lacking intrinsic activity.

Conclusions/Significance

These findings show that CVS from HESN, low-risk, and HIV seropositive women contain HIV neutralizing activity. Although several innate immune proteins, including HNP1–3 and LL-37, contribute to this activity these molecules can also have inflammatory properties. This balance is influenced by hormonal and environmental factors and in the present HIV serodiscordant couple cohort study we show that a partner's viral load is associated with levels of such molecules.