Pneumococcal carriage is more common in asthmatic than in non-asthmatic young men

Bacterial antigens and asthma: a comparative study of common respiratory pathogenic bacteria

Objective: In a previous study we have shown that, in the presence of interleukin (IL)-33, repeated, per-nasal challenge of murine airways with Streptococcus pneumoniae (S. pneumoniae) organisms induces human asthma-like airways inflammation. It is not clear, however, whether this effect is unique or manifest in response to other common respiratory pathogens.Methods: To explore this, airways of BALB/c mice were repeatedly challenged per-nasally with formaldehyde-inactivated bacterial bodies in the presence or absence of murine recombinant IL-33. Serum concentrations of S.pneumoniae, Moraxella catarrhalis (M.catarrhalis) and Haemophilus influenzae (H.influenzae) lysates-specific IgE were measured in patients with asthma and control subjects.Results: We showed that in the presence of IL-33, repeated, per-nasal airways exposure to the bodies of these bacteria induced airways hyperresponsiveness (AHR) in the experimental mice. This was accompanied by cellular infiltration into bronchoalveolar lavage fluid (BALF), eosinophilic infiltration and mucous hypertrophy of the lung tissue, with elevated local expression of some type 2 cytokines and elevated, specific IgG and IgE in the serum. The precise characteristics of the inflammation evoked by exposure to each bacterial species were distinguishable.Conclusions: These results suggest that in the certain circumstances, inhaled or commensal bacterial body antigens of both Gram-positive (S. pneumoniae) and Gram-negative (M. catarrhalis and H. influenzae) respiratory tract bacteria may initiate type 2 inflammation typical of asthma in the airways. In addition, we demonstrated that human asthmatic patients manifest elevated serum concentrations of M.catarrhalis- and H.influenzae-specific IgE.

Mucus plugging on computed tomography and the sputum microbiome in patients with asthma, chronic obstructive pulmonary disease, and asthma-COPD overlap

BACKGROUND

Despite clinical implications, the pathogenesis of mucus plugging in asthma, chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap (ACO) remains unclear. We hypothesized that distinct airway microbiomes might affect mucus plugging differently among ACO, asthma, and COPD and among different extents of airway eosinophilic inflammation.

METHODS

The sputum microbiome, sputum cell differential count, and mucus plug score on computed tomography were cross-sectionally evaluated in patients with chronic airflow limitation.

RESULTS

Patients with ACO, asthma, or COPD were enrolled (n = 56, 10, and 25). Higher mucus plug scores were associated with a greater relative abundance of the phylum Proteobacteria (rho = 0.29) only in patients with ACO and a greater relative abundance of the phylum Actinobacteria (rho = 0.46) only in patients with COPD. In multivariable models including only patients with ACO, the presence of mucus plugs was associated with a greater relative abundance of the phylum Proteobacteria and the genus Haemophilus, independent of smoking status, airflow limitation, and emphysema severity. Moreover, the mucus score was associated with a greater relative abundance of the genus Streptococcus (rho = 0.46) in patients with a high sputum eosinophil count (n = 22) and with that of the genus Haemophilus (rho = 0.46) in those with a moderate sputum eosinophil count (n = 26).

CONCLUSIONS

The associations between mucus plugging and the microbiome in ACO differed from those in COPD and asthma. Greater relative abundances of the phylum Proteobacteria and genus Haemophilus may be involved in mucus plugging in patients with ACO and moderate airway eosinophilic inflammation.

Pneumococcal Colonization in Children With Persistent Asthma: A Retrospective Cohort

BACKGROUND

Asthma is the most common chronic medical condition among children ≥5 years of age with invasive pneumococcal disease. How asthma or its management affects pneumococcal colonization is not fully understood. Our objective was to compare pneumococcal colonization rates between children with persistent asthma and children without asthma, and to characterize the pneumococcal serotype distribution.

METHODS

We used nasal mid-turbinate samples obtained per routine care from 5- to 18-year-old children with upper respiratory symptoms from November to April (respiratory seasons) of 2017 to 2018 and 2018 to 2019 in Kansas City, United States. Pneumococcal immunization status, prior antibiotic use and other clinical data were collected. Samples were tested for pneumococcal colonization by real-time polymerase chain reaction targeting lytA gene. Positive samples underwent multiplex serotype-specific polymerase chain reaction assays to determine the serotype.

RESULTS

Of 363 children (120 with persistent asthma and 243 without asthma), 87.6% were 5 to 10 years old, 50.1% were female and 74.1% received ≥3 doses of a pneumococcal conjugate vaccine. The pneumococcal colonization rate was lower in children with persistent asthma than in children without asthma (10% versus 18.9%, P = 0.03). The odds of colonization were lower in children with persistent asthma [OR 0.4 (95% confidence interval: 0.2-0.9)] after adjusting for demographic and clinical data. Pneumococcal serotype was confirmed in 77.6% of positive samples; 35.6% of those samples corresponded to PCV13 serotypes and 64.4% to non-PCV13 serotypes. The most common serotypes were 19F (15%), 3 (13%) and 6C/6D (11%).

CONCLUSIONS

Children with persistent asthma had lower rates of pneumococcal colonization than children without asthma when seeking care for respiratory symptoms.

The Airway Microbiome-IL-17 Axis: a Critical Regulator of Chronic Inflammatory Disease

The respiratory tract is home to a diverse microbial community whose influence on local and systemic immune responses is only beginning to be appreciated. Increasing reports have linked changes in this microbiome to a range of pulmonary and extrapulmonary disorders, including asthma, chronic obstructive pulmonary disease and rheumatoid arthritis. Central to many of these findings is the role of IL-17-type immunity as an important driver of inflammation. Despite the crucial role played by IL-17-mediated immune responses in protection against infection, overt Th17 cell responses have been implicated in the pathogenesis of several chronic inflammatory diseases. However, our knowledge of the influence of bacteria that commonly colonise the respiratory tract on IL-17-driven inflammatory responses remains sparse. In this article, we review the current knowledge on the role of specific members of the airway microbiota in the modulation of IL-17-type immunity and discuss how this line of research may support the testing of susceptible individuals and targeting of inflammation at its earliest stages in the hope of preventing the development of chronic disease.

Asthma-associated bacterial infections: Are they protective or deleterious?

Eosinophilic, noneosinophilic, or mixed granulocytic inflammations are the hallmarks of asthma heterogeneity. Depending on the priming of lung immune and structural cells, subjects with asthma might generate immune responses that are TH2-prone or TH17-prone immune response. Bacterial infections caused by Haemophilus, Moraxella, or Streptococcus spp. induce the secretion of IL-17, which in turn recruit neutrophils into the airways. Clinical studies and experimental models of asthma indicated that neutrophil infiltration induces a specific phenotype of asthma, characterized by an impaired response to corticosteroid treatment. The understanding of pathways that regulate the TH17-neutrophils axis is critical to delineate and develop host-directed therapies that might control asthma and its exacerbation episodes that course with infectious comorbidities. In this review, we outline clinical and experimental studies on the role of airway epithelial cells, S100A9, and high mobility group box 1, which act in concert with the IL-17-neutrophil axis activated by bacterial infections, and are related with asthma that is difficult to treat. Furthermore, we report critically our view in the light of these findings in an attempt to stimulate further investigations and development of immunotherapies for the control of severe asthma.

Human matters in asthma: Considering the microbiome in pulmonary health

Microbial communities form an important symbiotic ecosystem within humans and have direct effects on health and well-being. Numerous exogenous factors including airborne triggers, diet, and drugs impact these established, but fragile communities across the human lifespan. Crosstalk between the mucosal microbiota and the immune system as well as the gut-lung axis have direct correlations to immune bias that may promote chronic diseases like asthma. Asthma initiation and pathogenesis are multifaceted and complex with input from genetic, epigenetic, and environmental components. In this review, we summarize and discuss the role of the airway microbiome in asthma, and how the environment, diet and therapeutics impact this low biomass community of microorganisms. We also focus this review on the pediatric and Black populations as high-risk groups requiring special attention, emphasizing that the whole patient must be considered during treatment. Although new culture-independent techniques have been developed and are more accessible to researchers, the exact contribution the airway microbiome makes in asthma pathogenesis is not well understood. Understanding how the airway microbiome, as a living entity in the respiratory tract, participates in lung immunity during the development and progression of asthma may lead to critical new treatments for asthma, including population-targeted interventions, or even more effective administration of currently available therapeutics.

House Dust Mite Aeroallergen Suppresses Leukocyte Phagocytosis and Netosis Initiated by Pneumococcal Lung Infection

Asthmatics are highly susceptible to developing lower respiratory tract infections caused by Streptococcus pneumoniae (SPN, the pneumococcus). It has recently emerged that underlying allergic airway disease creates a lung microenvironment that is defective in controlling pneumococcal lung infections. In the present study, we examined how house dust mite (HDM) aeroallergen exposure altered immunity to acute pneumococcal lung infection. Alveolar macrophage (AM) isolated from HDM-exposed mice expressed alternatively activated macrophage (AAM) markers including YM1, FIZZ1, IL-10, and ARG-1. In vivo, prior HDM exposure resulted in accumulation of AAMs in the lungs and 2-log higher bacterial titres in the bronchoalveolar (BAL) fluid of SPN-infected mice (Day 2). Acute pneumococcal infection further increased the expression of IL-10 and ARG1 in the lungs of HDM-exposed mice. Moreover, prior HDM exposure attenuated neutrophil extracellular traps (NETs) formation in the lungs and dsDNA levels in the BAL fluid of SPN-infected mice. In addition, HDM-SPN infected animals had significantly increased BAL fluid cellularity driven by an influx of macrophages/monocytes, neutrophils, and eosinophils. Increased lung inflammation and mucus production was also evident in HDM-sensitised mice following acute pneumococcal infection, which was associated with exacerbated airway hyperresponsiveness. Of note, PCV13 vaccination modestly reduced pneumococcal titres in the BAL fluid of HDM-exposed animals and did not prevent BAL inflammation. Our findings provide new insights on the relationship between pneumococcal lung infections and allergic airways disease, where defective AM phagocytosis and NETosis are implicated in increased susceptibility to pneumococcal infection.

Prevalence and characteristics of children with otitis media with effusion in Vietnam

PURPOSE

Otitis media with effusion (OME) commonly occurs and persists in young children. It can cause hearing impairment and damage to the tympanic membrane without treatment. We aimed to determine the prevalence and association of Streptococcus pneumoniae in the nasopharynx of healthy children before the introduction of a pneumococcal conjugate vaccine.

METHODS

In October 2016, nasopharyngeal swabs collection and otoscope examinations by an otolaryngologist were conducted in children aged less than 24 months in Nha Trang, Vietnam. OME was diagnosed as the presence of middle ear fluid using a digital otoscope equipped with a pneumatic otoscope. Quantitative PCR targeting pneumococci-specific lytA (the major autolysis gene) and bacterial culture were performed to detect S. pneumoniae. The point prevalence of OME in the study area was estimated. The association between OME and S. pneumoniae in the nasopharynx was evaluated using a multivariable logistic regression model.

RESULTS

Among the 274 children who underwent bilateral ear examinations and nasopharyngeal swab collections, 47 had OME (17.2%, 95% confidence interval [CI] 12.9-22.1%) and 96 were colonized with S. pneumoniae (35.0%, 29.4-41.0%). OME and nasopharyngeal S. pneumoniae carriage were positively associated in children aged less than 12  months (adjusted odds ratio [aOR] 3.83, 1.40-10.51). Day-care attendance and living in a rural area were independently associated with OME (aOR 5.87, 2.31-14.91, and aOR 3.77, 1.58-8.99, respectively).

CONCLUSIONS

The nasopharyngeal pneumococcal carriage was associated with OME among children aged  <12 months. A further study after introducing a pneumococcal conjugate vaccine (PCV) is required to better understand the effect of PCV and S. pneumoniae carriage on OME in young children.

Increased nasal Streptococcus pneumoniae presence in Western environment associated with allergic conditions in Chinese immigrants

BACKGROUND

Chinese immigrants living in Australia experience increased allergic conditions: asthma, eczema, hay fever and wheeze. Recently we reported diminished innate cytokine responses in long-term immigrants, potentially increasing their pathogenic viral load and microbial carriage. We hypothesise that a Western environment changes the nasal microbiome profile, and this altered profile may be associated with the development of allergic conditions. In this cross-sectional study, we aimed to examine the loading of viral and microbial respiratory pathogens in the upper airway.

METHODS

Adult Chinese immigrants were grouped depending on time spent in Australia: short-term (<6 years) or long-term (≥6 years). First, age- and gender-matched immigrants were selected for an initial screen using quantitative polymerase chain reaction (qPCR) micro-array panels. Then based on initial results the viruses, human parainfluenza 3 and rhinovirus, and the bacteria, Burkholderia spp., Staphylococcus aureus and Streptococcus pneumoniae, were validated using qPCR in the population. Associations for bacterial prevalence with atopic phenotypes were investigated.

RESULTS

Pooling the initial screen and validation subjects, S. aureus and S. pneumoniae had higher prevalence in long-term compared with short-term subjects (25.0% vs 8.1%, P = 0.012; and 76.8% vs 48.4%, P = 0.002). Those immigrants with nasal S. pneumoniae presence resided longer (average time 90.4 months) in Australia than immigrants without S. pneumoniae (52.7 months; P = 0.001). After adjusting for confounders, Chinese immigrants with S. pneumoniae carriage have a five-fold increased risk of doctor-diagnosed eczema (odds ratio, OR 5.36, 95% CI: 1.10-26.14; P = 0.038) compared to immigrants without S. pneumoniae carriage. There was a trend of S. pneumoniae abundance correlating with reduced host Toll-like receptor gene expression.

CONCLUSION

Our findings suggest that nasal S. pneumoniae may play a role in the development of allergic conditions in Chinese immigrants in a Western environment.

Microbiome analysis of contact lens care solutions and tear fluids of contact lens wearers: Possible involvement of streptococcal antigens in allergic symptoms related to contact lens wear

The present study elucidated the pathogenesis of allergic symptoms (AS) related to contact lens (CL) wear by assaying CL care solutions in lens storage cases and tears from subjects with AS using molecular biology techniques. A total of 15 CL storage cases were collected from subjects with AS (n=9) and healthy, asymptomatic control CL wearers (n=6). Bacterial populations in CL care solutions and tears were assayed by culture and 16S rDNA sequencing. Histamine levels in tears were measured by high-performance liquid chromatography. Western blot analysis was performed to identify the bacteria recognized by tear IgE from subjects with AS. No significant differences were found in the culture results between the subjects with AS and asymptomatic subjects. Histamine was detected in 2 subjects with AS. Meta-16S rDNA sequencing identified a cluster of 4 subjects with AS that were distinguished from others by principal coordinate analysis. Detailed population analysis revealed that the abundance of Gram-positive bacteria in the microbiomes of CL care solutions used by the subjects with AS were higher than those of asymptomatic subjects (42.24±9.47 vs. 16.85±22.76% abundance). Among these, Streptococcus was the dominant genus (12.1-18.3% abundance). Tear microbiome analysis revealed that the abundance of Streptococcus in the subjects with AS was significantly higher than that in other subjects (19.02±5.50 vs. 3.08±3.35%, P<0.01). Western blot analysis demonstrated that the tear IgE in all subjects with AS reacted with Streptococcus (100%), but not with Staphylococcus. On the whole, these results provide novel insight into the pathogenesis of AS and identify Streptococcus as an important factor in AS associated with CL wear.

Novel Therapies for Pneumonia-Associated Severe Asthma Phenotypes

Distinct asthma phenotypes are emerging from well-defined cohort studies and appear to be associated with a history of pneumonia. Asthmatics are more susceptible to infections caused by Streptococcus pneumoniae; however, the mechanisms that underlie defective immunity to this pathogen are still being elucidated. Here, we discuss how alternatively activated macrophages (AAMs) in asthmatics are defective in bacterial phagocytosis and how respiratory viruses disrupt essential host immunity to cause bacterial dispersion deeper into the lungs. We also describe how respiratory pathogens instigate neutrophilic inflammation and amplify type-2 inflammation in asthmatics. Finally, we propose novel dual-acting strategies including granulocyte-colony-stimulating factor receptor (G-CSFR) antagonism and specialised pro-resolving mediators (SPMs) to suppress type-2 and neutrophilic inflammation without compromising pathogen clearance.

Why are people with asthma susceptible to pneumonia? A review of factors related to upper airway bacteria

Asthma and pneumonia are common respiratory conditions globally, affecting individuals of all ages. Streptococcus pneumoniae is the predominant bacterial cause of pneumonia, with nasopharyngeal carriage an important step towards invasive and pulmonary disease. Vaccines provide individual protection, and also prevent nasopharyngeal carriage, providing herd immunity. Asthma is associated with an increased risk of pneumonia, but there is limited information on the underlying mechanism of this predisposition. Both asthma and its treatment may conceivably alter propensity to, and density of, carriage through an altered epithelial microenvironment driven by disease-related inflammation or treatment-related immunomodulation, for example with inhaled corticosteroids. The relative importance of these factors could impact the efficacy of vaccines in this vulnerable patient population. In this review, we summarize the evidence for an increased risk of pneumonia in asthma, and discuss factors affecting nasopharyngeal carriage in the context of current guidelines for pneumococcal vaccination.

Relationship between asthma status and antibody response pattern to 23-valent pneumococcal vaccination

Objective: Asthma poses an increased risk for serious pneumococcal disease, but little is known about the influence of asthma status on the 23-valent serotype-specific pneumococcal antibody response. We examined differences in antibody titers between pre- and post-vaccination with 23-valent pneumococcal polysaccharide vaccine (PPSV-23) in relation to asthma status. Methods: Asthma status was retrospectively ascertained by the Predetermined Asthma Criteria in an existing vaccine cohort through comprehensive medical record review. Twenty-three serotype-specific pneumococcal antibody titers measured at baseline and 4-6 weeks post-vaccination were analyzed. Vaccine responses to PPSV-23 were calculated from pre- to post-vaccine titers for each of the serotypes. Results: Of the 64 eligible and enrolled subjects, 18 (28%) had asthma. Controls (i.e., subjects without asthma) demonstrated a statistically significant fold change response compared to their baseline for all serotypes, while those with asthma did not mount a significant response to serotypes 7F, 22F, and 23F. The overall vaccine response as measured by fold change over baseline was lower in subjects with asthma than controls. Conclusions: Poorer humoral immune responses to PPSV-23 as measured by fold change were more likely to be observed in subjects with asthma compared to controls. We recommend the consideration of asthma status when interpreting vaccine response for immune competence workup through larger studies. Further studies are warranted to replicate these findings.

Prevalence of Nasopharyngeal Carriage, Serotype Distribution, and Antimicrobial Resistance of Streptococcus pneumoniae among Children with Chronic Diseases

The aim of this study was to evaluate the prevalence of nasopharyngeal (NP) carriage and the serotype distribution and antimicrobial resistance of Streptococcus pneumoniae in children with chronic diseases, which predisposes them to invasive pneumococcal disease in comparison with that in healthy children. A cross-sectional prevalence study was performed between February 2015 and February 2016 in Istanbul, Turkey. We enrolled 1,024 children with chronic diseases and 394 healthy children aged 0-18 years. The overall prevalence of S. pneumoniae NP (SPNP) carriage was 9.8%, with 8.4% in healthy children and 10.3% in children with chronic diseases. The prevalence rates of SPNP carriage were 17.5%, 13.5%, 10.5%, 9.3%, 8.6%, 8.6%, 8%, 6.7%, and 4%, respectively, in each of the following risk groups: primary immunodeficiency, asthma, chronic renal failure, congenital heart disease, chronic lung disease, leukemia, nephrotic syndrome, solid organ tumors, and type 1 diabetes mellitus. In the multivariate analysis, a history of otitis media within the last year, a history of pneumonia within the last year, and more than one sibling under 8 years of age were found to be independent risk factors for SPNP carriage.

Allergic Asthma Favors Brucella Growth in the Lungs of Infected Mice

Allergic asthma is a chronic Th2 inflammatory disease of the lower airways affecting a growing number of people worldwide. The impact of infections and microbiota composition on allergic asthma has been investigated frequently. Until now, however, there have been few attempts to investigate the impact of asthma on the control of infectious microorganisms and the underlying mechanisms. In this work, we characterize the consequences of allergic asthma on intranasal (i.n.) infection by Brucella bacteria in mice. We observed that i.n. sensitization with extracts of the house dust mite Dermatophagoides farinae or the mold Alternaria alternata (Alt) significantly increased the number of Brucella melitensis, Brucella suis, and Brucella abortus in the lungs of infected mice. Microscopic analysis showed dense aggregates of infected cells composed mainly of alveolar macrophages (CD11c+ F4/80+ MHCII+) surrounded by neutrophils (Ly-6G+). Asthma-induced Brucella susceptibility appears to be dependent on CD4+ T cells, the IL-4/STAT6 signaling pathway and IL-10, and is maintained in IL-12- and IFN-γR-deficient mice. The effects of the Alt sensitization protocol were also tested on Streptococcus pneumoniae and Mycobacterium tuberculosis pulmonary infections. Surprisingly, we observed that Alt sensitization strongly increases the survival of S. pneumoniae infected mice by a T cell and STAT6 independent signaling pathway. In contrast, the course of M. tuberculosis infection is not affected in the lungs of sensitized mice. Our work demonstrates that the impact of the same allergic sensitization protocol can be neutral, negative, or positive with regard to the resistance of mice to bacterial infection, depending on the bacterial species.

Effects of procalcitonin-guided treatment on antibiotic use and need for mechanical ventilation in patients with acute asthma exacerbation: Meta-analysis of randomized controlled trials

OBJECTIVE

The primary outcome was to determine whether serum procalcitonin-guided antibiotic therapy can reduce antibiotic exposure in patients with an acute exacerbation of asthma presenting to the primary care facility or emergency department, or during hospital admission. The secondary outcome was the need for mechanical ventilation.

METHODS

An extensive literature search was performed to identify randomized controlled clinical trials (published in English) that compared serum procalcitonin-guided antibiotic therapy versus antibiotic use according to physician's discretion for adult participants with mild, moderate, or severe acute asthma exacerbations.

RESULTS

Four randomized controlled trials evaluating 457 patients were included in this meta-analysis, with significant homogeneity observed among these studies. Procalcitonin-based protocols decreased antibiotic prescriptions (relative risk 0.58, 95% confidence interval 0.50-0.67). The conclusion regarding the difference between the two groups in the need for mechanical ventilation (relative risk 1.10, 95% confidence interval 0.62-1.94) was guarded due to inadequate power and the potential for type II error. The overall quality of evidence was also limited by the lack of double-blinding.

CONCLUSIONS

These data suggest a potential benefit for the use of serum procalcitonin in guiding antibiotic therapy in patients with an acute asthma exacerbation and advocates the need for more randomized controlled trials.

Addressing unmet needs in understanding asthma mechanisms: From the European Asthma Research and Innovation Partnership (EARIP) Work Package (WP)2 collaborators

Asthma is a heterogeneous, complex disease with clinical phenotypes that incorporate persistent symptoms and acute exacerbations. It affects many millions of Europeans throughout their education and working lives and puts a heavy cost on European productivity. There is a wide spectrum of disease severity and control. Therapeutic advances have been slow despite greater understanding of basic mechanisms and the lack of satisfactory preventative and disease modifying management for asthma constitutes a significant unmet clinical need. Preventing, treating and ultimately curing asthma requires co-ordinated research and innovation across Europe. The European Asthma Research and Innovation Partnership (EARIP) is an FP7-funded programme which has taken a co-ordinated and integrated approach to analysing the future of asthma research and development. This report aims to identify the mechanistic areas in which investment is required to bring about significant improvements in asthma outcomes.

Nasopharyngeal Microbiome Diversity Changes over Time in Children with Asthma

BACKGROUND

The nasopharynx is a reservoir for pathogens associated with respiratory illnesses such as asthma. Next-generation sequencing (NGS) has been used to characterize the nasopharyngeal microbiome of infants and adults during health and disease; less is known, however, about the composition and temporal dynamics (i.e., longitudinal variation) of microbiotas from children and adolescents. Here we use NGS technology to characterize the nasopharyngeal microbiomes of asthmatic children and adolescents (6 to 18 years) and determine their stability over time.

METHODS

Two nasopharyngeal washes collected 5.5 to 6.5 months apart were taken from 40 children and adolescents with asthma living in the Washington D.C. area. Sequence data from the 16S-V4 rRNA gene region (~250 bp) were collected from the samples using the MiSeq platform. Raw data were processed in mothur (SILVA123 reference database) and Operational Taxonomic Units (OTU)-based alpha- and beta-diversity metrics were estimated. Relatedness among samples was assessed using PCoA ordination and Procrustes analyses. Differences in microbial diversity and taxon mean relative proportions were assessed using linear mixed effects models. Core microbiome analyses were also performed to identify stable and consistent microbes of the nasopharynx.

RESULTS AND DISCUSSION

A total of 2,096,584 clean 16S sequences corresponding to an average of 167 OTUs per sample were generated. Representatives of Moraxella*, Staphylococcus*, Dolosigranulum, Corynebacterium, Prevotella, Streptococcus*, Haemophilus*, Fusobacterium* and a Neisseriaceae genus accounted for 86% of the total reads. These nine genera have been previously found in the nasopharynxes of both infants and adults, but in different proportions. OTUs from the five genera highlighted (*) above defined the nasopharyngeal core microbiome at the 95% level. No significant differences in alpha- and beta-diversity were observed between seasons, but bacterial mean relative proportions of Haemophilus, Moraxella, Staphylococcus and Corynebacterium varied significantly between summer-fall and age groups (inter-patient variation). Additionally, OTUs varied significantly within patients between time points in 35 of the 40 patients analyzed. Future cross-sectional studies should be mindful of the temporal dynamics of the nasopharyngeal microbiota.

Azithromycin for Acute Exacerbations of Asthma : The AZALEA Randomized Clinical Trial

IMPORTANCE

Guidelines recommend against antibiotic use to treat asthma attacks. A study with telithromycin reported benefit, but adverse reactions limit its use.

OBJECTIVE

To determine whether azithromycin added to standard care for asthma attacks in adults results in clinical benefit.

DESIGN, SETTING, AND PARTICIPANTS

The Azithromycin Against Placebo in Exacerbations of Asthma (AZALEA) randomized, double-blind, placebo-controlled clinical trial, a United Kingdom-based multicenter study in adults requesting emergency care for acute asthma exacerbations, ran from September 2011 to April 2014. Adults with a history of asthma for more than 6 months were recruited within 48 hours of presentation to medical care with an acute deterioration in asthma control requiring a course of oral and/or systemic corticosteroids.

INTERVENTIONS

Azithromycin 500 mg daily or matched placebo for 3 days.

MAIN OUTCOMES AND MEASURES

The primary outcome was diary card symptom score 10 days after randomization, with a hypothesized treatment effect size of -0.3. Secondary outcomes were diary card symptom score, quality-of-life questionnaires, and lung function changes, all between exacerbation and day 10, and time to a 50% reduction in symptom score.

RESULTS

Of 4582 patients screened at 31 centers, 199 of a planned 380 were randomized within 48 hours of presentation. The major reason for nonrecruitment was receipt of antibiotics (2044 [44.6%] screened patients). Median time from presentation to drug administration was 22 hours (interquartile range, 14-28 hours). Exacerbation characteristics were well balanced across treatment arms and centers. The primary outcome asthma symptom scores were mean (SD), 4.14 (1.38) at exacerbation and 2.09 (1.71) at 10 days for the azithromycin group and 4.18 (1.48) and 2.20 (1.51) for the placebo group, respectively. Using multilevel modeling, there was no significant difference in symptom scores between azithromycin and placebo at day 10 (difference, -0.166; 95% CI, -0.670 to 0.337), nor on any day between exacerbation and day 10. No significant between-group differences were observed in quality-of-life questionnaires or lung function between exacerbation and day 10, or in time to 50% reduction in symptom score.

CONCLUSIONS AND RELEVANCE

In this randomized population, azithromycin treatment resulted in no statistically or clinically significant benefit. For each patient randomized, more than 10 were excluded because they had already received antibiotics.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01444469.

STAT6 Signaling Attenuates Interleukin-17-Producing γδ T Cells during Acute Klebsiella pneumoniae Infection

γδ T cells are prevalent at mucosal and epithelial surfaces and are a critical first line of defense against bacterial and fungal pathogens. γδ17 cells are a subset of γδ T cells which, in the presence of IL-23 and IL-1β, produce large quantities of interleukin-17A (IL-17A), a cytokine crucial to these cells' antibacterial and antifungal function. STAT6, an important transcription factor in Th2 differentiation and inhibition of Th1 differentiation, is expressed at high levels in the T cells of people with parasitic infections and asthma. Our group and others have shown that STAT6 attenuates IL-17A protein expression by CD4(+) T cells. By extension, we hypothesized that STAT6 activation also inhibits innate γδ17 cell cytokine secretion. We show here that γδ17 cells expressed the type I IL-4 receptor (IL-4R), and IL-4 increased STAT6 phosphorylation in γδ T cells. IL-4 inhibited γδ17 cell production of IL-17A. IL-4 also decreased γδ17 cell expression of IL-23R as well as Sgk1. To determine whether STAT6 signaling regulates γδ17 cell numbers in vivo, we used a model of Klebsiella pneumoniae in mice deficient in STAT6. We chose K. pneumoniae for our in vivo model, since K. pneumoniae increases IL-17A expression and γδ17 numbers. K. pneumoniae infection of STAT6 knockout mice resulted in a statistically significant increase in the number of γδ17 cells compared to that of wild-type mice. These studies are the first to demonstrate that γδ17 cells express the type I IL-4R and that STAT6 signaling negatively regulates γδ17 cells, a cell population that plays a front-line role in mucosal immunity.

Pneumococcal disease in adult solid organ transplantation recipients

In solid organ transplant (SOT) recipients, Streptococcus pneumoniae can cause substantial morbidity and mortality ranging from non-invasive to invasive diseases, including pneumonia, bacteremia, and meningitis, with a risk of invasive pneumococcal disease 12 times higher than that observed in non-immunocompromised patients. Moreover, pneumococcal infection has been related to graft dysfunction. Several factors have been involved in the risk of pneumococcal disease in SOT recipients, such as type of transplant, time since transplantation, influenza activity, and nasopharyngeal colonization. Pneumococcal vaccination is recommended for all SOT recipients with 23-valent pneumococcal polysaccharides vaccine. Although immunological rate response is appropriate, it is lower than in the rest of the population, decreases with time, and its clinical efficacy is variable. Booster strategy with 7-valent pneumococcal conjugate vaccine has not shown benefit in this population. Despite its relevance, there are few studies focused on invasive pneumococcal disease in SOT recipients. Further studies addressing clinical, microbiological, and epidemiological data of pneumococcal disease in the transplant setting as well as new strategies for improving the protection of SOT recipients are warranted.

Eotaxin-3 (CCL26) exerts innate host defense activities that are modulated by mast cell proteases

BACKGROUND

During bacterial infections of the airways, a Th1-profiled inflammation promotes the production of several host defense proteins and peptides with antibacterial activities including β-defensins, ELR-negative CXC chemokines, and the cathelicidin LL-37. These are downregulated by Th2 cytokines of the allergic response. Instead, the eosinophil-recruiting chemokines eotaxin-1/CCL11, eotaxin-2/CCL24, and eotaxin-3/CCL26 are expressed. This study set out to investigate whether these chemokines could serve as innate host defense molecules during allergic inflammation.

METHODS

Antibacterial activities of the eotaxins were investigated using viable count assays, electron microscopy, and methods assessing bacterial permeabilization. Fragments generated by mast cell proteases were characterized, and their potential antibacterial, receptor-activating, and lipopolysaccharide-neutralizing activities were investigated.

RESULTS

CCL11, CCL24, and CCL26 all showed potent bactericidal activity, mediated through membrane disruption, against the airway pathogens Streptococcus pneumoniae, Staphylococcus aureus, Nontypeable Haemophilus influenzae, and Pseudomonas aeruginosa. CCL26 retained bactericidal activity in the presence of salt at physiologic concentrations, and the region holding the highest bactericidal activity was the cationic and amphipathic COOH-terminus. Proteolysis of CCL26 by chymase and tryptase, respectively, released distinct fragments of the COOH- and NH2 -terminal regions. The COOH-terminal fragment retained antibacterial activity while the NH2 -terminal had potent LPS-neutralizing properties in the order of CCL26 full-length protein. An identical fragment to NH2 -terminal fragment generated by tryptase was obtained after incubation with supernatants from activated mast cells. None of the fragments activated the CCR3-receptor.

CONCLUSIONS

Taken together, the findings show that the eotaxins can contribute to host defense against common airway pathogens and that their activities are modulated by mast cell proteases.

[Prevalence of nasal carriage of Staphylococcus aureus and Streptococcus pneumoniae in Primary Care and factors associated with colonization]

OBJECTIVE

To determine (i) the prevalence of Staphylococcus aureus (S.aureus) and Streptococcus pneumoniae (S.pneumoniae) nasal carriage in Primary Health Care patients in area of Barcelona, and (ii) the factors associated with S.aureus and S.pneumoniae colonization.

METHODS

Multi-center cross-sectional study conducted in 2010-2011 with the participation of 27 Primary Health Care professionals. Nasopharyngeal swabs were obtained from 3,969 patients over 4 years of age who did not present with any sign of infection.

DEPENDENT VARIABLES

S.aureus and/or S.pneumoniae carrier state.

INDEPENDENT VARIABLES

socio-demographic characteristics, health status, vaccination status, occupation, and living with children. A descriptive analysis was performed. The prevalence of carriers of S.aureus and/or S.pneumoniae was calculated and logistic regression models were adjusted by age.

RESULTS

In children from 4 to 14 years old, the prevalence of S.aureus carriers was 35.7%, of S.pneumoniae 27.1%, and 5.8% were co-colonized. In adults older than 14 years old, the prevalence was 17.8%, 3.5%, and 0.5%, respectively. In children, S.aureus carrier state was inversely associated with S.pneumoniae carrier state; S.pneumoniae was associated with younger age, and inversely associated with S.aureus carrier state. In adults, being a carrier of S.aureus was associated with male gender, younger age, and a health-related occupation, whereas S.pneumoniae carrier state was associated with living with children under 6 years of age. The proportion of co-colonized carriers was low (1.0%).

CONCLUSIONS

The proportion of S.aureus and S.pneumoniae carriers was higher in children than in adults. Age was the only factor associated with healthy carrier status for S.aureus and for S.pneumoniae.

Pneumococcal pneumonia suppresses allergy development but preserves respiratory tolerance in mice

Colonization with Streptococcus pneumoniae (S. pneumoniae) is associated with an increased risk for recurrent wheeze and asthma. Killed S. pneumoniae showed some potential as an effective immunomodulatory therapy in a murine model of asthma. Murine studies demonstrated protection against allergic asthma by symbiotic bacteria via triggering regulatory T cell response: treatment with killed S. pneumoniae resulted in suppressed levels of allergen-specific Th2 cytokines, while early immunization generated a protective Th1 response. We investigated the impact of lung infection with live S. pneumoniae on both the development and maintenance of allergic airway inflammation and respiratory tolerance in mice. BALB/c mice were infected intratracheally with S. pneumoniae either prior to or after tolerance or allergy were induced, using ovalbumin (OVA) as model allergen. Infection of mice with S. pneumoniae prior to sensitization or after manifestation of allergic airway inflammation suppressed the development of an allergic phenotype as judged by reduced eosinophil counts in bronchoalveolar lavage fluid, decreased IgE serum levels and Th2 cytokines, relative to non-infected allergic control mice. In contrast, infection of mice with S. pneumoniae after manifestation of allergic airway inflammation combined with late mucosal re-challenge did not affect the allergic response. Moreover, induction and maintenance of respiratory tolerance to OVA challenge were not altered in S. pneumoniae-infected mice, demonstrating that mice remained tolerant to the model allergen and were protected from the development of allergic airway inflammation regardless of the time point of infection. Our results suggest that a bacterial infection may decrease the manifestation of an allergic phenotype not only prior to sensitization but also after manifestation of allergic airway inflammation in mice, whereas both, induction and maintenance of respiratory tolerance are not affected by pneumococcal pneumonia. These data may point to a role for undisturbed development and maintenance of mucosal tolerance for the prevention of allergic inflammation also in humans.

A cross-sectional observational study of pneumococcal carriage in children, their parents, and older adults following the introduction of the 7-valent pneumococcal conjugate vaccine

Using nasopharyngeal carriage as a marker of vaccine impact, pneumococcal colonization and its relation to invasive disease were examined in children, their parents, and older adults in the United Kingdom following introduction of 7-valent pneumococcal conjugate vaccine (PCV7) and prior to 13-valent pneumococcal conjugate vaccine (PCV13).A cross-sectional observational study was conducted, collecting nasopharyngeal swabs from children aged 25 to 55 months who had previously received 3 doses of PCV7, their parents, and adults aged ≥65 years. Pneumococcal serotyping was conducted according to World Health Organization guidelines with nontypeable isolates further analyzed by molecular serotyping. A national invasive disease surveillance program was conducted throughout the corresponding period.Pneumococcus was isolated from 47% of children, 9% of parents, and 2.2% of older adults. For these groups, the percentage of serotypes covered by PCV7 were 1.5%, 0.0%, and 15.4%, with a further 20.1%, 44.4%, and 7.7% coverage added by those in PCV13. In each group, the percentage of disease due to serotypes covered by PCV7 were 1.0%, 7.4% and 5.1% with a further 65.3%, 42.1%, and 61.4% attributed to those in PCV13.The prevalence of carriage is the highest in children, with direct vaccine impact exemplified by low carriage and disease prevalence of PCV7 serotypes in vaccinated children, whereas the indirect effects of herd protection are implied by similar observations in unvaccinated parents and older adults.

The association between asthma and invasive pneumococcal disease: a nationwide study in Korea

The purpose of this study was to investigate the association between asthma and invasive pneumococcal disease (IPD) in Korea. A retrospective population-based cohort study was conducted using the Korean Health Insurance Review and Assessment database 2010-2011. The subjects included 935,106 (2010) and 952,295 (2011), of whom 398 (2010) and 428 (2011) patients with IPD were identified. There was significant difference in the prevalence of IPD in patients with and without asthma (0.07% vs. 0.02% in 2010 and 0.08% vs. 0.01% in 2011; P<0.001). After adjusting for age and gender, patients with asthma showed over a three-fold increased risk of IPD compared with patients without asthma (adjusted odds ratio [aOR] 3.90, 95% confidence interval [CI] 3.02-5.03 in 2010 / aOR, 5.44; 95% CI, 4.10-7.22 in 2011; P<0.001). These findings were also significant in children (aOR, 2.08; 95% CI, 1.25-3.45 in 2010; P=0.005 / aOR, 3.26; 95% CI, 1.74-6.11 in 2011; P<0.001). Although diabetes mellitus was also significantly associated with IPD, relatively low ORs compared with those of asthma were noted (aOR, 1.85; 95% CI, 1.35-2.54 in 2010 / aOR, 2.40; 95% CI, 1.78-3.24 in 2011; P<0.001). Both children and adults with asthma are at increased risk of developing IPD.

Clinical characteristics of adults with chronic rhinosinusitis and specific antibody deficiency

BACKGROUND

Specific antibody deficiency (SAD) involves a deficient response to a polysaccharide vaccine in the setting of normal immunoglobulin G (IgG) levels and chronic infections. Patients with chronic rhinosinusitis (CRS) are often evaluated for SAD. There are limited data that describe patients with CRS and SAD.

OBJECTIVE

The objective of this study was to better characterize the role of SAD in CRS.

METHODS

We reviewed electronic records of adults with CRS who were evaluated for immunodeficiency with quantitative Ig levels and pre- and postantibody titers to a pneumococcal polysaccharide vaccine (PPV).

RESULTS

Fourteen pneumococcal serotypes were determined in 239 subjects from 2002 to 2009. Of these subjects, 64 had adequate protective titers of 1.3 μg/mL or higher in 7 or more serotypes of the 14 serotypes checked; 56 (23%) had less than 7 protective titers post-PPV and were diagnosed with SAD; and 119 had an adequate response to the vaccine with 7 or more serotypes being higher than 1.3 μg/mL (>50% response) and were characterized as "responders." Subjects with SAD received more antibiotic courses relative to responders in the 2 years after immunization (3.19 ± 2.64 vs 2.19 ± 2.24, P < .05). Of 56 subjects with SAD, 10 (17.9%) received Ig replacement therapy. Subjects who received Ig had fewer numbers of protective pneumococcal titers post-PPV and had more pneumonia (40.0%) versus subjects with SAD who did not receive Ig (10.9%).

CONCLUSIONS

Of the 239 patients with CRS with normal IgG levels evaluated for immunodeficiency, 56 (23.4%) had SAD. A majority of patients with SAD may not need Ig replacement; however, a subset of patients with SAD benefit from Ig replacement.

The FACT score in predicting pneumococcal antibody levels in asthmatics

BACKGROUND

There is no measure currently available to identify asthmatics with potential immune incompetence.

OBJECTIVE

We propose use of a novel scoring system called the FACT score, which is formulated based on four parameters: (1) Family history of asthma, (2) Atopic conditions, (3) Bacterial colonization and (4) Th1 versus Th2 immune profile.

METHODS

This was a cross-sectional study involving 16 asthmatics and 14 non-asthmatics. The first two parameters of the FACT score were obtained via a chart review and interview. For the third parameter, nasopharyngeal swab samples were cultured. The ratio of interleukin-5 to interferon-gamma for each patient was measured by peripheral blood mononuclear cells cultured with house dust mite. Antibodies to 23 pneumococcal antigens were used for humoral immunity.

RESULTS

The FACT scores for asthmatics (mean ± SD: 5.2 ± 1.87) were higher than those for non-asthmatics (mean ± SD: 3.3 ± 1.5) (p = 0.008). Of the 16 asthmatics, 7 (44%) had 12 or more positive serotype-specific polysaccharide antibodies, whereas 12 of 14 (86%) of non-asthmatics subjects had 12 or more positive serotype-specific polysaccharide antibodies (p = 0.014). Overall, the FACT score was inversely correlated with the number of positive serotype-specific antibody levels [rho (ρ) = -0.38, p = 0.04]. The proportions of subjects with 12 or more positive serotype-specific antibodies among non-asthmatics and asthmatics below and above the median of the FACT scores were 86, 50 and 38%, respectively (p = 0.052).

CONCLUSIONS

The FACT score may help us identify a subset of asthmatics with immune incompetence. Study findings need to be replicated in a larger study.

What does tympanostomy tube placement in children teach us about the association between atopic conditions and otitis media?

Otitis media is the most common infection second only to viral upper respiratory infection in the outpatient setting. Tympanostomy tube insertion (TTI) is the most common ambulatory surgical procedure in the USA. While many risk factors for otitis media have been identified, atopic conditions have been underrecognized as risk factors for recurrent and persistent otitis media. Given that asthma and other atopic conditions are the most common chronic conditions during childhood, it is worth examining the association between atopic conditions and risk of otitis media, which can provide insight into how atopic conditions influence the risk of microbial infections. This paper focuses its discussion on otitis media; however, it is important that the association between atopic conditions and risk of otitis media be interpreted in the context of the association of atopic conditions with increased risks of various microbial infections.

Asthma and the immune response to MMR vaccine viruses in Somali immigrant children: a cross-sectional retrospective cohort study

Background:

According to the ‘hygiene hypothesis’, an increase in microbial exposure in childhood leads to a T-helper cell 1 (Th1) predominant immune response and protection against asthma and atopic conditions.

Aims:

To assess the prevalence of asthma and other atopic conditions in Somali immigrants and to determine the humoral immune response to the measles, mumps, and rubella (MMR) vaccine viruses in Somali immigrants with asthma.

Methods:

A retrospective cohort study was conducted in Olmsted County, Minnesota. Study subjects were Somali immigrants who were born and lived in Africa during childhood and immigrated to the USA. The subjects had participated in a previous MMR vaccine study. Asthma was ascertained using predetermined asthma criteria after a thorough medical record review. An atopic condition was determined from physician-diagnosed ICD codes. Virus-specific IgG levels in response to the MMR vaccine viruses were determined using an enzyme immunoassay.

Results:

Of the 62 eligible subjects, 33 (53%) were female and 29 (47%) were male; 10 (16%) had asthma and 22 (35%) had other atopic conditions. There was no difference in the rubella (p=0.150) and measles (p=0.715) virus-specific IgG levels between the subjects with and without asthma. Mumps virus-specific IgG antibody levels were lower in those with asthma than in those without asthma (mean±SE 2.08±0.28 vs. 3.06±0.14, p=0.005).

Conclusions:

Our study results may not support the hygiene hypothesis. In addition, the previously reported abnormal T-cell development in Caucasian children with atopy can be considered even in Somali immigrants.

Asthma and Microbes: A New Paradigm

Asthma is worldwide at pandemic levels for the past 30 years but is increasing at a greater rate in more affluent societies. It is a heterogeneous disorder caused by interaction between genetic predisposition, atopy, and environmental factors, including allergens, air pollution, and respiratory infections. The pathological aspects and pathophysiological mechanisms are reviewed in this chapter. Allergens or infectious agents may stimulate Th-2 inflammation which causes activation of IL-13, eosinophils, and increase IgE levels, subsequently leading to bronchial smooth muscle hypercontraction. Respiratory viral infections are well-known causes of precipitation of acute asthma exacerbations in 50–60 % of attacks. There is also increasing evidence that bacterial infections, Chlamydia pneumoniae, and Mycoplasma pneumoniae, may contribute to the onset and course of asthma. The two main hypothesis of microbial genesis of asthma that has arisen in the past 20–30 years appears to be incongruous, but are not, are the hygiene hypothesis of asthma, and the virus-related asthma, early onset of viral bronchiolitis in the susceptible hosts being responsible for later development of asthma. The clinical and experimental evidences to support these contentions are reviewed and critiqued.

Asthma and severity of 2009 novel H1N1 influenza: a population-based case-control study

BACKGROUND

Asthma has been shown to be associated with an increased risk of the 2009 novel H1N1 influenza (H1N1) infection among children. However, little is known about the role of asthma in severity of H1N1 infection.

OBJECTIVE

To determine the association between asthma and other atopic conditions and severity of H1N1 infection.

PATIENTS AND METHODS

We conducted a population-based case-control study. Cases were all Olmsted County, MN residents admitted to the hospital within a week of a positive test for H1N1. Controls who had a positive H1N1 but were not admitted to hospital were individually matched to cases with regard to birth day, gender, clinic registration date, diagnostic method, and calendar month of influenza testing. Asthma was ascertained using predetermined criteria. Data were fit to conditional logistic regression models.

RESULTS

There were 46 eligible individuals admitted to hospitals with H1N1 infection during the study period. Ninety-seven controls were individually matched to their corresponding cases. Among cases, 23 (50%) were male and 29 (63.0%) were Caucasians. The median age at hospitalization was 20.7 years. Twenty-five (54.4%) cases had asthma before the date of hospitalization, compared to 33 (34.0%) controls (matched OR: 2.31; 95% CI, 1.13-4.73; p = 0.02). This association approached statistical significance after adjusting for all pertinent covariates (adjusted matched OR: 2.55; 95% CI, 0.98-6.64; p = 0.055).

CONCLUSION

Asthma may be associated with severe H1N1 infection. In addition to timely influenza vaccination for asthmatics, consideration for prophylactic treatment for unimmunized asthmatics with significant exposure to influenza and immunized asthmatics with early flu-like symptoms should be given.

Nasopharyngeal carriage and antimicrobial susceptibility pattern of Streptococcus pneumoniae among pediatric outpatients at Gondar University Hospital, North West Ethiopia

BACKGROUND

Pneumonia caused by Streptococcus pneumoniae is the leading cause of death among children in Ethiopia. S. pneumoniae nasopharyngeal carriage can result in endogenous infections and bacterial spread in the community. S. pneumoniae drug resistance is rapidly increasing worldwide. The aim of the study was to assess the nasopharyngeal carriage and antimicrobial susceptibility pattern of S. pneumoniae among pediatric outpatients.

METHODS

A cross-sectional study was conducted on children aged ≤10 years from February to May of 2012. Data on potential risk factors were gathered using an interview-based questionnaire. Nasopharyngeal specimens were collected with a sterile plastic cotton tip swab. Bacteria were characterized by colony appearance, Gram staining, and optochin susceptibility and bile solubility tests. An antimicrobial susceptibility test was performed using the disk diffusion method. A logistic regression analysis was used to examine the possible risk factors. All tests with p value less than 0.05 were considered statistically significant.

RESULTS

Of the 234 children screened, 41.03% carried S. pneumoniae. Age-related downward trend for S. pneumoniae carriages (50.9% in <3-year-olds, 40.7% in 3- to 5-year-olds, 40.0% in 5- to <8-year-olds, and 33.3% in 8- to 10-year-olds) were observed. Children living with siblings < 5 years old (p = 0.003) and in a house having one room (p = 0.004) were associated with higher S. pneumoniae carriage. S. pneumoniae showed 33.2% resistance to erythromycin and tetracycline, 29.2% to cotrimoxazole, 14.6% to chloramphenicol and ciprofloxacin, and 10.4% to penicillin.

CONCLUSION

The S. pneumoniae carriage rate was higher among younger children. High antimicrobial resistance of S. pneumoniae against erythromycin, tetracycline, and cotrimoxazole was observed. Being in the young age group and living with younger children are risk factors for pneumococcal carriage.

Atopic conditions other than asthma and risk of the 2009 novel H1N1 infection in children: a case-control study

A recent study showed an increased risk of 2009 novel H1N1 influenza (H1N1) infection among asthmatic children. Little is known whether this is true for other atopic conditions. This study was designed to determine the association between atopic dermatitis and/or allergic rhinitis and the risk of H1N1 infection among children. We conducted a case-control study in Olmsted County, MN. We randomly selected children ≤18 years of age with a positive test for H1N1. Controls were randomly selected from a pool of residents with negative H1N1 tests and were matched to cases with regard to birthday, gender, clinic registration date, diagnostic test, and month of influenza testing using frequency matching. We compared the frequency of atopic conditions other than asthma between cases and their matched controls. We enrolled 168 cases and 172 controls. Among cases, 91 (54.2%) were male patients, and 106 (63.1%) were white. The median age of cases was 6.3 years (interquartile range, 3.1-11.5). Among cases, 79 (47.0%) had atopic dermatitis and/or allergic rhinitis diagnosed before or after the index date, whereas 54 (31.4%) controls had such conditions (odds ratio [OR], 1.89; 95% CI, 1.15-3.12; p = 0.012, adjusting for asthma status, 2008-2009 seasonal influenza vaccine, time of illness at index date, and other comorbid conditions). History of receiving 2008-2009 seasonal influenza vaccine was associated with H1N1 infection (adjusted OR, 2.06; 95% CI, 1.32-3.28; p = 0.002). Our results suggest an association between H1N1 infection and atopic conditions other than asthma. The association between 2008-2009 seasonal influenza vaccinations and the risk of H1N1 requires further investigation.

Inhaled corticosteroids increase the risk of oropharyngeal colonization by Streptococcus pneumoniae in children with asthma

BACKGROUND AND OBJECTIVE

Recent studies have raised concerns about the link between use of inhaled corticosteroids (ICS) and risk of pneumonia in patients with chronic obstructive pulmonary disease. This cross-sectional study aimed to investigate the association between ICS and oropharyngeal colonization by Streptococcus pneumoniae (S. pneumoniae) among children (up to 18 years old) with asthma.

METHODS

Two age-matched groups of patients were consecutively recruited: (i) exposed group: children who had persistent asthma and were being treated with daily ICS for at least 30 days and (ii) non-exposed group: children who had asthma and were not being treated with ICS at study entry. Oropharyngeal specimens from the tonsillar area and posterior pharyngeal wall were collected. S. pneumoniae was identified according to National Committee for Clinical Laboratory Standards recommendations.

RESULTS

A total of 200 consecutive patients were recruited and 192 (96 in each group) were included in the analysis. In the exposed group, the mean daily dose of ICS was 400 µg of beclomethasone or equivalent and the mean duration of treatment was 8.6 months. The prevalence of oropharyngeal colonization by S. pneumoniae was higher in the exposed group compared with the non-exposed group (27.1% vs 8.3%, P = 0.001). After adjusting for potential confounders, use of ICS was an independent risk factor for oropharyngeal carriage of S. pneumoniae, with an adjusted prevalence ratio of 3.75 (95% confidence interval: 1.72-8.18, P = 0.001).

CONCLUSIONS

Regular use of ICS is associated with an increased risk of having oropharyngeal colonization by S. pneumoniae in children with asthma.

Bacterial superinfection following lung inflammatory disorders

The lung environment is designed to prevent innate responses to harmless commensal microorganisms and environmental antigens. Features of an intact respiratory epithelium are critical to this process. A damaged or altered lung epithelial surface will therefore remove or alter the suppressive signals delivered to local innate immune cells, and inflammation ensues. Timely resolution of inflammation is important to prevent bystander tissue damage. However, if resolving pathways themselves are prolonged or repeated, they too can cause undesirable consequences, including bacterial superinfections, which we discuss here.

Expression of Streptococcus pneumoniae Virulence-Related Genes in the Nasopharynx of Healthy Children

Colonization and persistence in the human nasopharynx are prerequisites for Streptococcus pneumoniae disease and carriage acquisition, which normally occurs during early childhood. Animal models and in vitro studies (i.e. cell adhesion and cell cytotoxicity assays) have revealed a number of colonization and virulence factors, as well as regulators, implicated in nasopharyngeal colonization and pathogenesis. Expression of genes encoding these factors has never been studied in the human nasopharynx. Therefore, this study analyzed expression of S. pneumoniae virulence-related genes in human nasopharyngeal samples. Our experiments first demonstrate that a density of ≥10(4) CFU/ml of S. pneumoniae cells in the nasopharynx provides enough DNA and RNA to amplify the lytA gene by conventional PCR and to detect the lytA message, respectively. A panel of 21 primers that amplified S. pneumoniae sequences was designed, and their specificity for S. pneumoniae sequences was analyzed in silico and validated against 20 related strains inhabitants of the human upper respiratory tract. These primers were utilized in molecular reactions to find out that all samples contained the genes ply, pavA, lytC, lytA, comD, codY, and mgrA, whereas nanA, nanB, pspA, and rrgB were present in ∼91-98% of the samples. Gene expression studies of these 11 targets revealed that lytC, lytA, pavA and comD were the most highly expressed pneumococcal genes in the nasopharynx whereas the rest showed a moderate to low level of expression. This is the first study to evaluate expression of virulence- and, colonization-related genes in the nasopharynx of healthy children and establishes the foundation for future gene expression studies during human pneumococcal disease.

Influence of bacterial interactions on pneumococcal colonization of the nasopharynx

Streptococcus pneumoniae (the pneumococcus) is a common commensal inhabitant of the nasopharynx and a frequent etiologic agent in serious diseases such as pneumonia, otitis media, bacteremia, and meningitis. Multiple pneumococcal strains can colonize the nasopharynx, which is also home to many other bacterial species. Intraspecies and interspecies interactions influence pneumococcal carriage in important ways. Co-colonization by two or more pneumococcal strains has implications for vaccine serotype replacement, carriage detection, and pneumonia diagnostics. Interactions between the pneumococcus and other bacterial species alter carriage prevalence, modulate virulence, and affect biofilm formation. By examining these interactions, this review highlights how the bacterial ecosystem of the nasopharynx changes the nature and course of pneumococcal carriage.

Altered regulation of Toll-like receptor responses impairs antibacterial immunity in the allergic lung

The lung is colonized by commensal bacteria, some of which are associated with asthma exacerbations. Using the intranasal house-dust mite-sensitized mouse model of allergic airway disease, we show an imbalance in novel antibacterial pathways that culminates in a reduction in neutrophil recruitment to the airspaces and leads to bacterial invasion and dissemination. The expression of TREM (Triggering Receptor Expressed on Myeloid cells)-1 that amplifies Toll-like receptor (TLR) signaling and TREM-2 that inhibits this process is reversed. Furthermore, endogenous TLR inhibitors (A20, Tollip, SOCS1, and IRAK-M) and proteins involved in receptor recycling (TRIAD3) are raised. Consequently, the production of neutrophil chemoattractants is reduced. Intranasal administration of either chemokine restores the ability to recruit neutrophils, which prevents bacterial invasion. A background of allergic airway disease therefore exacerbates bacterial infection by altering key antibacterial innate immune pathways that are amenable to therapeutic intervention.

The microbiology of asthma

Asthma remains an important human disease that is responsible for substantial worldwide morbidity and mortality. The causes of asthma are multifactorial and include a complex mix of environmental, immunological and host genetic factors. In addition, epidemiological studies show strong associations between asthma and infection with respiratory pathogens, including common respiratory viruses such as rhinoviruses, human respiratory syncytial virus, adenoviruses, coronaviruses and influenza viruses, as well as bacteria (including atypical bacteria) and fungi. In this Review, we describe the many roles of microorganisms in the risk of developing asthma and in the pathogenesis of and protection against the disease, and we discuss the mechanisms by which infections affect the severity and prevalence of asthma.