Insa Korten

The nasal microbiota in infants with cystic fibrosis in the first year of life: a prospective cohort study

BACKGROUND Respiratory tract infections and subsequent airway inflammation occur early in the life of infants with cystic fibrosis. However, detailed information about the microbial composition of the respiratory tract in infants with this disorder is scarce. We aimed to undertake longitudinal in-depth characterisation of the upper respiratory tract microbiota in infants with cystic fibrosis during the first year of life. METHODS We did this prospective cohort study at seven cystic fibrosis centres in Switzerland. Between Feb 1, 2011, and May 31, 2014, we enrolled 30 infants with a diagnosis of cystic fibrosis. Microbiota characterisation was done with 16S rRNA gene pyrosequencing and oligotyping of nasal swabs collected every 2 weeks from the infants with cystic fibrosis. We compared these data with data for an age-matched cohort of 47 healthy infants. We additionally investigated the effect of antibiotic treatment on the microbiota of infants with cystic fibrosis. Statistical methods included regression analyses with a multivariable multilevel linear model with random effects to correct for clustering on the individual level. FINDINGS We analysed 461 nasal swabs taken from the infants with cystic fibrosis; the cohort of healthy infants comprised 872 samples. The microbiota of infants with cystic fibrosis differed compositionally from that of healthy infants (p=0·001). This difference was also found in exclusively antibiotic-naive samples (p=0·001). The disordering was mainly, but not solely, due to an overall increase in the mean relative abundance of Staphylococcaceae in infants with cystic fibrosis compared with healthy infants (multivariable linear regression model stratified by age and adjusted for season; second month: coefficient 16·2 [95% CI 0·6-31·9]; p=0·04; third month: 17·9 [3·3-32·5]; p=0·02; fourth month: 21·1 [7·8-34·3]; p=0·002). Oligotyping analysis enabled differentiation between Staphylococcus aureus and coagulase-negative Staphylococci. Whereas the analysis showed a decrease in S aureus at and after antibiotic treatment, coagulase-negative Staphylococci increased. INTERPRETATION Our study describes compositional differences in the microbiota of infants with cystic fibrosis compared with healthy controls, and disordering of the microbiota on antibiotic administration. Besides S aureus, coagulase-negative Staphylococci also contributed to the disordering identified in these infants. These findings are clinically important in view of the crucial role that bacterial pathogens have in the disease progression of cystic fibrosis in early life. Our findings could be used to inform future studies of the effect of antibiotic treatment on the microbiota in infants with cystic fibrosis, and could assist in the prevention of early disease progression in infants with this disorder. FUNDING Swiss National Science Foundation, Fondation Botnar, the Swiss Society for Cystic Fibrosis, and the Swiss Lung Association Bern.

False normal Lung Clearance Index in infants with cystic fibrosis due to software algorithms

Lung clearance index (LCI), a marker of ventilation inhomogeneity, is elevated early in children with cystic fibrosis (CF). However, in infants with CF, LCI values are found to be normal, although structural lung abnormalities are often detectable. We hypothesized that this discrepancy is due to inadequate algorithms of the available software package.

Air pollution during pregnancy and lung development in the child

Air pollution exposure has increased extensively in recent years and there is considerable evidence that exposure to particulate matter can lead to adverse respiratory outcomes. The health impacts of exposure to air pollution during the prenatal period is especially concerning as it can impair organogenesis and organ development, which can lead to long-term complications. Exposure to air pollution during pregnancy affects respiratory health in different ways. Lung development might be impaired by air pollution indirectly by causing lower birth weight, premature birth or disturbed development of the immune system. Exposure to air pollution during pregnancy has also been linked to decreased lung function in infancy and childhood, increased respiratory symptoms, and the development of childhood asthma. In addition, impaired lung development contributes to infant mortality. The mechanisms of how prenatal air pollution affects the lungs are not fully understood, but likely involve interplay of environmental and epigenetic effects. The current epidemiological evidence on the effect of air pollution during pregnancy on lung function and childrens respiratory health is summarized in this review. While evidence for the adverse effects of prenatal air pollution on lung development and health continue to mount, rigorous actions must be taken to reduce air pollution exposure and thus long-term respiratory morbidity and mortality.

Epidemiology of blood culture-proven bacterial sepsis in children in Switzerland: a population-based cohort study

BACKGROUND Sepsis is a leading cause of childhood mortality worldwide. We assessed population-based incidence and outcomes of blood culture-proven bacterial sepsis in children in Switzerland. METHODS We did a multicentre, prospective, cohort study at ten paediatric hospitals in Switzerland. We included neonates and children younger than 17 years with blood culture-proven bacterial sepsis. Children were eligible if they met criteria for systemic inflammatory response syndrome-according to 2005 paediatric consensus definition- at the time of blood culture sampling. Incidence was calculated by dividing the number of annual sepsis episodes in the study for the years 2012-15 by the end-of-year resident paediatric population in Switzerland. The primary outcome was in-hospital mortality in the first 30 days after sepsis onset. FINDINGS Between Sept 1, 2011, and Dec 31, 2015, we enrolled 1096 children to our study. Of 1181 episodes of blood culture-proven bacterial sepsis, 382 (32%) occurred in 379 previously healthy children, 402 (34%) in 391 neonates, and 397 (34%) in 341 children with comorbidities. Incidence was 25·1 cases per 100 000 (95% CI 23·8-26·4) in children and 146·0 cases per 100 000 (133·2-159·6) in neonates. Central line-associated bloodstream infections and primary bloodstream infections accounted for 569 (48%) of 1181 episodes, and organ dysfunction was present in 455 (39%) of 1181 episodes. Escherichia coli (242 of 1181 [20%]), Staphylococcus aureus (177 of 1181 [15%]), coagulase-negative staphylococci (135 of 1181 [11%]), and Streptococcus pneumoniae (118 of 1181 [10%]) were the most prevalent pathogens in our study, accounting for 57% of episodes. The overall case-fatality ratio was 7% (82 of 1181 episodes; 95% CI 5·6-8·6), and it was higher in neonates (11%, 45 of 402 episodes; 8·4-14·8; adjusted odds ratio [OR] 4·41, 95% CI 1·75-11·1) and children with comorbidities (7%, 27 of 397 episodes; 4·6-9·9; OR 4·97, 1·84-13·4) compared with previously healthy children (3%, ten of 382 episodes; 1·3-4·9). The case-fatality ratio was 1% (five of 726 episodes [95% CI 0·3-1·7]) for children without organ dysfunction, which increased to 17% (77 of 455 episodes [13·7-20·8]) when organ dysfunction was present (adjusted OR 4·84, 95% CI 1·40-16·7). INTERPRETATION The burden of blood culture-proven bacterial sepsis on child health remains considerable. We recorded key differences in predominant organisms, severity, and outcome between neonates, previously healthy children, and children with comorbidities. Although for most episodes of blood culture-proven bacterial sepsis, no organ dysfunction was seen, presence of organ dysfunction was strongly associated with mortality. FUNDING Swiss National Science Foundation, Swiss Society of Intensive Care, Bangerter Foundation, Vinetum and Borer Foundation, and Foundation for the Health of Children and Adolescents.

Interactions of Respiratory Viruses and the Nasal Microbiota during the First Year of Life in Healthy Infants

Respiratory viral infections are very frequent in infancy and of importance in acute and chronic disease development. Infections with human rhinovirus (HRV) are, e.g., associated with the later development of asthma. We found that only symptomatic HRV infections were associated with acute changes in the nasal microbiota, mainly characterized by a loss of microbial diversity. Infants with more frequent symptomatic HRV infections had a lower bacterial diversity at the end of the first year of life. Whether the interaction between viruses and the microbiota is one pathway contributing to asthma development will be assessed in the follow-ups of these children. Independent of that, measurements of microbial diversity might represent a potential marker for risk of later lung disease or monitoring of early life interventions. ABSTRACT Traditional culture techniques have shown that increased bacterial colonization is associated with viral colonization; however, the influence of viral colonization on the whole microbiota composition is less clear. We thus aimed to understand the interaction of viral infections and the nasal microbiota in early life to appraise their roles in disease development. Thirty-two healthy, unselected infants were included in this prospective longitudinal cohort study within the first year of life. Biweekly nasal swabs (n = 559) were taken, and the microbiota was analyzed by 16S rRNA pyrosequencing, and 10 different viruses and 2 atypical bacteria were characterized by real-time PCR (combination of seven duplex samples). In contrast to asymptomatic human rhinovirus (HRV) colonization, symptomatic HRV infections were associated with lower alpha diversity (Shannon diversity index [SDI]), higher bacterial density (PCR concentration), and a difference in beta diversities (Jaccard and Bray-Curtis index) of the microbiota. In addition, infants with more frequent HRV infections had a lower SDI at the end of the study period. Overall, changes in the microbiota associated with symptomatic HRV infections were characterized by a loss of microbial diversity. The interaction between HRV infections and the nasal microbiota in early life might be of importance for later disease development and indicate a potential approach for future interventions. IMPORTANCE Respiratory viral infections are very frequent in infancy and of importance in acute and chronic disease development. Infections with human rhinovirus (HRV) are, e.g., associated with the later development of asthma. We found that only symptomatic HRV infections were associated with acute changes in the nasal microbiota, mainly characterized by a loss of microbial diversity. Infants with more frequent symptomatic HRV infections had a lower bacterial diversity at the end of the first year of life. Whether the interaction between viruses and the microbiota is one pathway contributing to asthma development will be assessed in the follow-ups of these children. Independent of that, measurements of microbial diversity might represent a potential marker for risk of later lung disease or monitoring of early life interventions.

Novel magnetic resonance technique for functional imaging of cystic fibrosis lung disease

Lung function tests are commonly used to monitor lung disease in cystic fibrosis (CF). While practical, they cannot locate the exact origin of functional impairment. Contemporary magnetic resonance imaging (MRI) techniques provide information on the location of disease but the need for contrast agents constrains their repeated application. We examined the correlation between functional MRI, performed without administration of contrast agent, and lung clearance index (LCI) from nitrogen multiple-breath washout (N2-MBW). 40 children with CF (median (range) age 12.0 (6–18) years) and 12 healthy age-matched controls underwent functional and structural MRI and lung function tests on the same day. Functional MRI provided semiquantitative measures of perfusion (RQ) and ventilation (RFV) impairment as percentages of affected lung volume. Morphological MRI was evaluated using CF-specific scores. LCI measured global ventilation inhomogeneity. MRI detected functional impairment in CF: RFV 19–38% and RQ 16–35%. RFV and RQ correlated strongly with LCI (r=0.76, p<0.0001 and r=0.85, p<0.0001, respectively), as did total morphology score (r=0.81, p<0.0001). All indices differed significantly between patients with CF and healthy controls (p<0.001). Noninvasive functional MRI is a promising method to detect and visualise perfusion and ventilation impairment in CF without the need for contrast agents. New functional MRI without the need for contrast agents correlates strongly with ventilation inhomogeneity in CF http://ow.ly/emo930eQJ67

Altered renal functions in patients with occlusion of an accessory renal artery after endovascular stenting of an infrarenal aneurysm

Objective: Coverage of an accessory renal artery (ARA) during endovascular aneurysm repair (EVAR) may result in renal infarction (RI) or decline in renal function. Until now, it remains vague which patients are at risk to develop these complications. We therefore analyzed the effect of ARA sealing by EVAR with respect to the occurrence of RI and renal function. Methods: A retrospective analysis of the medical records and computed tomographic scans of patients who underwent EVAR within a period of 5 years was performed. Particular attention was paid to the presence or absence of accessory renal arteries and renal function before EVAR. Thirty‐four patients with ARA were matched 1:3 to 102 patients without ARA. The results after EVAR were analyzed in patients with and without ARA. In patients with ARA, we further examined the results after EVAR in patients with an estimated glomerular filtration rate (eGFR) ≥ 60 mL/min and eGFR < 60 mL/min before EVAR. Results: Before EVAR, the median eGFR was 74 mL/min (25th/75th percentiles, 57/89) in patients with ARA and 72 mL/min (25th/75th percentiles, 63/87) in patients without ARA. Alterations in eGFR were significantly pronounced in patients with ARA when compared with patients without ARA 1 week after EVAR (ARA, −10.7 ± 16.9 mL/min vs without ARA, 1.2 ± 13.3 mL/min; P = .002) and after 6 months (ARA, −10.8 ± 17.4 mL/min vs without ARA, 1.2 ± 13.3 mL/min; P = .001). RI only occurred in patients with ARA. Within the group of patients with ARA, patients with normal renal function (NF) showed a more pronounced decline in eGFR preoperatively when compared with patients with impaired renal function (IF) 1 week after EVAR (NF, −14.3 ± 18.0 mL/min vs IF, −1.3 ± 10.8 mL/min; P = .02) and after 6 months (NF, −15.8 ± 17.9 mL/min vs IF, 0.1 ± 15.2 mL/min; P = .007). Conclusions: The decrease in renal function was more pronounced in patients with ARA after EVAR when compared with patients without ARA undergoing EVAR. In patients with ARA, the observed decline in renal function was significantly distinct in patients presenting NF preoperatively. Consequently, the risk of IF after EVAR seems to be increased in patients with ARA and normal preoperative renal function.

“Lung sparing growth”: is the lung not affected by malnutrition?

Malnutrition is a major cause of mortality and morbidity in developing countries [1]. It has been reported to play a role in different acute and chronic disease conditions [2–4], including respiratory diseases and lung development [5, 6]. Starting in utero, maternal malnutrition during pregnancy may influence postnatal lung function directly (e.g. through decreased alveolar number), or indirectly (e.g. through intrauterine growth retardation, prematurity or low birth weight) [7]. There is clear evidence of detrimental effects of vitamin A deficiency in pregnancy on lung function in childhood [8]. Early postnatal malnutrition was associated with several adverse pulmonary effects and lung injury in animal models, e.g. decreased lung protein and DNA synthesis in the lungs [9], whereas breastfeeding and balanced nutrition is thought to be protective [10, 11]. Furthermore, Vitamin D and C deficiency have been reported to cause deficits in lung function and structure [12, 13]. To summarise, malnutrition potentially influences respiratory health and lung function on multiple levels. “Lung sparing growth”: intriguing hypothesis to explain why the lung is not affected by severe acute malnutrition http://ow.ly/9V5d309M1ho

Elevated lung clearance index in infants with cystic fibrosis shortly after birth

It is not known at what age lung function impairment may arise in children with cystic fibrosis (CF). We assessed lung function shortly after birth in infants with CF diagnosed by newborn screening. We performed infant lung function measurements in a prospective cohort of infants with CF and healthy controls. We assessed lung clearance index (LCI), functional residual capacity (FRC) and tidal breathing parameters. The primary outcome was prevalence and severity of abnormal lung function (±1.64 z-scores) in CF. We enrolled 53 infants with CF (mean age 7.8 weeks) and 57 controls (mean age 5.2 weeks). Compared to controls, LCI and FRC were elevated (mean difference 0.30, 95% CI 0.02–0.60; p=0.034 and 14.5 mL, 95% CI 7.7–21.3 mL; p<0.001, respectively), while ratio of time to peak tidal expiratory flow to expiratory time was decreased in infants with CF. In 22 (41.5%) infants with CF, either LCI or FRC exceeded 1.64 z-scores; three infants had both elevated LCI and FRC. Shortly after birth, abnormal lung function is prevalent in CF infants. Ventilation inhomogeneity or hyperinflation may serve as noninvasive markers to monitor CF lung disease and specific treatment effects, and could thus be used as outcome parameters for future intervention studies in this age group. Altered lung function in infants with cystic fibrosis shortly after birth http://ow.ly/qPxq30eFOkW

Lower exhaled nitric oxide in infants with Cystic Fibrosis compared to healthy controls

Exhaled nitric oxide (FENO) is a well-known, non-invasive airway biomarker. In patients with Cystic Fibrosis (CF) FENO is decreased. To understand if reduced FENO is primary related to Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) dysfunction or an epiphenomenon of chronic inflammation, we measured FENO in 34 infants with CF prior to clinical symptoms and in 68 healthy controls. FENO was lower in CF compared to controls (p=0.0006) and the effect was more pronounced in CF infants without residual CFTR function (p<0.0001). This suggests that FENO is reduced in CF early in life, possibly associated with underlying CFTR dysfunction.