A polymicrobial perspective of pulmonary infections exposes an enigmatic pathogen in cystic fibrosis patients

Cystic fibrosis respiratory microbiota: unraveling complexity to inform clinical practice

INTRODUCTION

Cystic fibrosis (CF) lung disease is characterized by chronic cycles of pulmonary infection, inflammation, and mucus obstruction, beginning early in life, and eventually leading to progressive lung damage and early mortality. During the past ~15 years, culture-independent analyses of CF respiratory samples have identified diverse bacterial communities in CF airways, and relationships between respiratory microbiota and clinical outcomes. Areas covered: This paper reviews recent advances in our understanding of the relationships between respiratory microbiota and CF lung disease. The paper focuses on measures of airway bacterial community diversity and estimates of the relative abundance of anaerobic species. Finally, this paper will review the opportunities for advancing patient care suggested by these studies and highlight some of the ongoing challenges and unmet needs in translating this knowledge into clinical practice. Expert commentary: Culture-independent analyses of respiratory microbiota have suggested new strategies for advancing CF care, but have also highlighted challenges in understanding the complexity of CF respiratory infections. Development of more sophisticated models and analytic approaches to better account for this complexity are needed to elucidate mechanistic links between CF respiratory microbiota and clinical outcomes, and to ultimately translate this knowledge into better patient care.

Sputum microbiota is predictive of long-term clinical outcomes in young adults with cystic fibrosis

BACKGROUND

Complex polymicrobial communities infect cystic fibrosis (CF) lower airways. Generally, communities with low diversity, dominated by classical CF pathogens, associate with worsened patient status at sample collection. However, it is not known if the microbiome can predict future outcomes. We sought to determine if the microbiome could be adapted as a biomarker for patient prognostication.

METHODS

We retrospectively assessed prospectively collected sputum from a cohort of 104 individuals aged 18-22 to determine factors associated with progression to early end-stage lung disease (eESLD; death/transplantation <25 years) and rapid pulmonary function decline (>-3%/year FEV₁ over the ensuing 5 years). Illumina MiSeq paired-end sequencing of the V3-V4 region of the 16S rRNA was used to define the airway microbiome.

RESULTS

Based on the primary outcome analysed, 17 individuals (16%) subsequently progressed to eESLD. They were more likely to have sputum with low alpha diversity, dominated by specific pathogens including Pseudomonas. Communities with abundant Streptococcus were observed to be protective. Microbial communities clustered together by baseline lung disease stage and subsequent progression to eESLD. Multivariable analysis identified baseline lung function and alpha diversity as independent predictors of eESLD. For the secondary outcomes, 58 and 47 patients were classified as rapid progressors based on absolute and relative definitions of lung function decline, respectively. Patients with low alpha diversity were similarly more likely to be classified as experiencing rapid lung function decline over the ensuing 5 years when adjusted for baseline lung function.

CONCLUSIONS

We observed that the diversity of microbial communities in CF airways is predictive of progression to eESLD and disproportionate lung function decline and may therefore represent a novel biomarker.

In vitro activity of lascufloxacin, a novel fluoroquinolone antibacterial agent, against various clinical isolates of anaerobes and Streptococcus anginosus group

The in vitro activities of lascufloxacin were evaluated by comparison with seven reference compounds using 412 clinical isolates of anaerobes and Streptococcus anginosus group. Lascufloxacin showed potent and broad antibacterial activities greater than those of existing quinolones against the clinical isolates used in this study.

Bacterial DNA patterns identified using paired-end Illumina sequencing of 16S rRNA genes from whole blood samples of septic patients in the emergency room and intensive care unit

BACKGROUND

Sepsis refers to clinical presentations ranging from mild body dysfunction to multiple organ failure. These clinical symptoms result from a systemic inflammatory response to pathogenic or potentially pathogenic microorganisms present systemically in the bloodstream. Current clinical diagnostics rely on culture enrichment techniques to identify bloodstream infections. However, a positive result is obtained in a minority of cases thereby limiting our knowledge of sepsis microbiology. Previously, a method of saponin treatment of human whole blood combined with a comprehensive bacterial DNA extraction protocol was developed. The results indicated that viable bacteria could be recovered down to 10 CFU/ml using this method. Paired-end Illumina sequencing of the 16S rRNA gene also indicated that the bacterial DNA extraction method enabled recovery of bacterial DNA from spiked blood. This manuscript outlines the application of this method to whole blood samples collected from patients with the clinical presentation of sepsis.

RESULTS

Blood samples from clinically septic patients were obtained with informed consent. Application of the paired-end Illumina 16S rRNA sequencing to saponin treated blood from intensive care unit (ICU) and emergency department (ED) patients indicated that bacterial DNA was present in whole blood. There were three clusters of bacterial DNA profiles which were distinguished based on the distribution of Streptococcus, Staphylococcus, and Gram-negative DNA. The profiles were examined alongside the patient's clinical data and indicated molecular profiling patterns from blood samples had good concordance with the primary source of infection.

CONCLUSIONS

Overall this study identified common bacterial DNA profiles in the blood of septic patients which were often associated with the patients' primary source of infection. These results indicated molecular bacterial DNA profiling could be further developed as a tool for clinical diagnostics for bloodstream infections.

Live and let die: Hydrogen peroxide production by the commensal flora and its role in maintaining a symbiotic microbiome

The majority of commensal oral streptococci are able to generate hydrogen peroxide (H₂ O₂ ) during aerobic growth, which can diffuse through the cell membrane and inhibit competing species in close proximity. Competing H₂ O₂ production is mainly dependent upon the pyruvate oxidase SpxB, and to a lesser extent the lactate oxidase LctO, both of which are important for energy generation in aerobic environments. Several studies point to a broad impact of H₂ O₂ production in the oral environment, including a potential role in biofilm homeostasis, signaling, and interspecies interactions. Here, we summarize the current research regarding oral streptococcal H₂ O₂ generation, resistance mechanisms, and the ecological impact of H₂ O₂ production. We also discuss the potential therapeutic utility of H₂ O₂ for the prevention/treatment of dysbiotic diseases as well as its potential role as a biomarker of oral health.

Airway persistence by the emerging multi-azole-resistant Rasamsonia argillacea complex in cystic fibrosis

Infections caused by Rasamsonia argillacea complex have been reported in various clinical settings. Cystic fibrosis (CF) is one of the main underlying conditions. An observational cohort study of CF patients with Rasamsonia in respiratory samples was conducted. Eight isolates from 6 patients were identified as R. argillacea complex and tested for antifungal susceptibility. All isolates had high MICs to voriconazole and posaconazole and low MECs to echinocandins. Four patients experienced lung function decline in the year preceding first Rasamsonia isolation. This continued in the year following first isolation in 3 out of 4 cases. Antifungal therapy was initiated in 2 patients, to which only one exhibited a clinical response. Three out of 6 patients died within 3 years of isolating Rasamsonia. Genotyping suggests that similar genotypes of Rasamsonia can persist in CF airways. Consistent with other fungi in CF, the clinical impact of airway colonisation by Rasamsonia is variable. In certain patients, Rasamsonia may be able to drive clinical decline. In others, though a clear impact on lung function may be difficult to determine, the appearance of Rasamsonia acts as a marker of disease severity. In others it does not appear to have an obvious clinical impact on disease progression.

Oral Microbiota Community Dynamics Associated With Oral Squamous Cell Carcinoma Staging

Oral squamous cell carcinoma (OSCC) is a highly aggressive cancer and the fourth leading malignancy among males in Taiwan. Some pathogenic bacteria are associated with periodontitis and oral cancer. However, the comprehensive profile of the oral microbiome during the cancer's progression from the early stage to the late stage is still unclear. We profiled the oral microbiota and identified bacteria biomarkers associated with OSCC. The microbiota of an oral rinse from 51 healthy individuals and 197 OSCC patients at different stages were investigated using 16S rRNA V3V4 amplicon sequencing, followed by bioinformatics and statistical analyses. The oral microbiota communities from stage 4 patients showed significantly higher complexity than those from healthy controls. The populations also dynamically changed with the cancer's progression from stage 1 to stage 4. The predominant phyla in the oral samples showed variation in the relative abundance of Fusobacteria, Bacteroidetes, and Actinobacteria. The abundance of Fusobacteria increased significantly with the progression of oral cancer from the healthy controls (2.98%) to OSCC stage 1 (4.35%) through stage 4 (7.92%). At the genus level, the abundance of Fusobacterium increased, while the number of Streptococcus, Haemophilus, Porphyromonas, and Actinomyces decreased with cancer progression. Fusobacterium periodonticum, Parvimonas micra, Streptococcus constellatus, Haemophilus influenza, and Filifactor alocis were associated with OSCC, and they progressively increased in abundance from stage 1 to stage 4. The abundances of Streptococcus mitis, Haemophilus parainfluenzae, and Porphyromonas pasteri were inversely associated with OSCC progression. We selected a bacterial marker panel of three bacteria (upregulated F. periodonticum, down-regulated S. mitis, and P. pasteri), which had an AUC of 0.956 (95% CI = 0.925-0.986) in discriminating OSCC stage 4 from the healthy controls. Furthermore, the functional prediction of oral bacterial communities showed that genes involved in carbohydrate-related metabolism, such as methane metabolism, and energy-metabolism-related parameters, such as oxidative phosphorylation and carbon fixation in photosynthetic organisms, were enriched in late-stage OSCC, while those responsible for amino acid metabolism, such as folate biosynthesis and valine, leucine, and isoleucine biosynthesis, were significantly associated with the healthy controls. In conclusion, our results provided evidence of oral bacteria community changes during oral cancer progression and suggested the possibility of using bacteria as OSCC diagnostic markers.

Cystic Fibrosis Airway Microbiome: Overturning the Old, Opening the Way for the New

The genetic disease cystic fibrosis (CF) is associated with chronic airway infections that are a proximal cause of death in many patients with this affliction. Classic microbiology studies focusing on canonical pathogens resulted in the development of a common set of views regarding the nature of the airway infections associated with this disease, and these ideas have influenced everything from the way infections are treated to how clinical trials for new CF-targeted antibiotics are designed and the focus of CF-related research topics. Recent culture-independent studies have prompted us to rethink, and in some cases discard, some of these long-held views. In this piece, I argue that an updated view of the complicated chronic infections associated with CF, thanks in large part to culture-independent studies of sputum and bronchoalveolar lavage fluid samples, should be leveraged to develop new strategies to treat these recalcitrant infections.

Reemergence of Lower-Airway Microbiota in Lung Transplant Patients with Cystic Fibrosis

RATIONALE

Chronic lung infections are a hallmark of cystic fibrosis; they are responsible for progressive airway destruction and ultimately lead to respiratory death or the requirement for life-saving bilateral lung transplant. Furthermore, recurrent isolation of airway pathogens such as Pseudomonas aeruginosa in the allograft after transplant is associated with adverse outcomes, including bronchiolitis obliterans syndrome and acute infections. Little information exists on the impact of bilateral lung transplant on the lower-airway microbiota.

OBJECTIVES

To compare, at a microbiome and single-pathogen level (P. aeruginosa), the bacterial communities in pre- and post-transplant samples.

METHODS

We retrospectively accessed our biobank of sputum samples and sputum-derived bacterial pathogens for patients who had matched samples, including those who were clinically stable before transplant, those who had a pulmonary exacerbation before transplant, and those who had pulmonary exacerbation after transplant. We used 16S ribosomal RNA gene sequencing to characterize the lower-airway microbiome of 14 adult transplant patients with cystic fibrosis. Genotyping and phenotyping of P. aeruginosa isolates from 12 of these patients with matched isolates was performed.

MEASUREMENTS AND MAIN RESULTS

Although α-diversity (richness and evenness) of patient microbiomes was similar before and after transplant, β- diversity (core microbiome composition) measures stratified patients evenly into two groups with more similar and more dissimilar communities. P. aeruginosa strains isolated before transplant were found to reemerge in 11 of 12 patients; however, phenotypic variation was observed.

CONCLUSIONS

These findings indicate that recolonization by P. aeruginosa after transplant is almost always strain specific, suggesting a within-host source. The polymicrobial colonization of the airways after transplant does not always reflect the pretransplant sputum microbiota.

Streptococcus Constellatus Spondylodiscitis in a Teenager: A Case Report

Streptococcus constellatus is an extremely rare cause of pyogenic spondylodiscitis. Literature search yielded only one case report in an elderly 72 years old man with spontaneous T10-T11 S. constellatus spondylodiscitis. It is virtually unheard of in young teenage. We report the case of a 14 years old male teenager who presented with worsening low back pain for one year with no neurological deficit. Imaging studies were consistent with features of L4-L5 spondylodiscitis. CT guided biopsy grew a pure culture of streptococcus constellatus sensitive to penicillin and erythromycin. He showed full recovery with six weeks of intravenous antibiotics. Due to the insidious onset, this case highlight the importance of high clinical suspicion and early diagnosis, with image guided biopsy followed by treatment with appropriate intravenous antibiotics to enable full recovery without further neurological deterioration.

Microbial Biofilms in Pulmonary and Critical Care Diseases

Microbial biofilms can colonize medical devices and human tissues, and their role in microbial pathogenesis is now well established. Not only are biofilms ubiquitous in natural and human-made environments, but they are also estimated to be associated with approximately two-thirds of nosocomial infections. This multicellular aggregated form of microbial growth confers a remarkable resistance to killing by antimicrobials and host defenses, leading biofilms to cause a wide range of subacute or chronic infections that are difficult to eradicate. We have gained tremendous knowledge on the molecular, genetic, microbiological, and biophysical processes involved in biofilm formation. These insights now shape our understanding, diagnosis, and management of many infectious diseases and direct the development of novel antimicrobial therapies that target biofilms. Bacterial and fungal biofilms play an important role in a range of diseases in pulmonary and critical care medicine, most importantly catheter-associated infections, ventilator-associated pneumonia, chronic Pseudomonas aeruginosa infections in cystic fibrosis lung disease, and Aspergillus fumigatus pulmonary infections.

The airway microbiota in early cystic fibrosis lung disease

Infection plays a critical role in the pathogenesis of cystic fibrosis (CF) lung disease. Over the past two decades, the application of molecular and extended culture-based techniques to microbial analysis has changed our understanding of the lungs in both health and disease. CF lung disease is a polymicrobial disorder, with obligate and facultative anaerobes recovered alongside traditional pathogens in varying proportions, with some differences observed to correlate with disease stage. While healthy lungs are not sterile, differences between the lower airway microbiota of individuals with CF and disease-controls are already apparent in childhood. Understanding the evolution of the CF airway microbiota, and its relationship with clinical treatments and outcome at each disease stage, will improve our understanding of the pathogenesis of CF lung disease and potentially inform clinical management. This review summarizes current knowledge of the early development of the respiratory microbiota in healthy children and then discusses what is known about the airway microbiota in individuals with CF, including how it evolves over time and where future research priorities lie.

Community Composition Determines Activity of Antibiotics against Multispecies Biofilms

In young cystic fibrosis (CF) patients, Staphylococcus aureus is typically the most prevalent organism, while in adults, Pseudomonas aeruginosa is the major pathogen. More recently, it was observed that also Streptococcus anginosus plays an important role in exacerbations of respiratory symptoms. These species are often coisolated from CF lungs, yet little is known about whether antibiotic killing of one species is influenced by the presence of others. In the present study, we compared the activities of various antibiotics against S. anginosus, S. aureus, and P. aeruginosa when grown in monospecies biofilms with the activity observed in a multispecies biofilm. Our results show that differences in antibiotic activity against species grown in mono- and multispecies biofilms are species and antibiotic dependent. Fewer S. anginosus cells are killed by antibiotics that interfere with cell wall synthesis (amoxicillin plus sulbactam, cefepime, imipenem, meropenem, and vancomycin) in the presence of S. aureus and P. aeruginosa, while for ciprofloxacin, levofloxacin, and tobramycin, no difference was observed. In addition, we observed that the cell-free supernatant of S. aureus, but not that of P. aeruginosa biofilms, also caused this decrease in killing. Overall, S. aureus was more affected by antibiotic treatment in a multispecies biofilm, while for P. aeruginosa, no differences were observed between growth in mono- or multispecies biofilms. The results of the present study suggest that it is important to take the community composition into account when evaluating the effect of antimicrobial treatments against certain species in mixed biofilms.

EXAMES PARA AVALIAR A SENSIBILIZAÇÃO AO ASPERGILLUS FUMIGATUS EM FIBROSE CÍSTICA

Objective:

To evaluate the results of the tests used to identify the IgE mediated sensitization to Aspergillus fumigatus in patients with cystic fibrosis.

Methods:

This is a cross-sectional descriptive study with a convenience sample of 86 patients diagnosed with cystic fibrosis in the Reference Service in Cystic Fibrosis at a tertiary teaching hospital. The following tests were performed to assess the sensitization to A. fumigatus in patients with cystic fibrosis: Total serum IgE, eosinophil count, fungus detection through oropharyngeal swab or sputum culture, serum-specific IgE, and immediate-type hypersensitivity (IgE) skin tests. We compared the results of the different tests performed.

Results:

In 33 (38.4%) patients with cystic fibrosis, with ages ranging from 1 to 33 years (median of 8 years), the IgE-mediated A. fumigatus sensitization test results were: in 16 patients, there was an increase in serum-specific IgE (>0.35 kU/L); in 23, skin tests were positive; and six had sensitization in both tests. We observed two patients with eosinophilia (>1,000 eosinophils/mm3) and seven with increasing total serum IgE (>1,000 IU/mL), all of whom obtained negative results in skin tests and had no IgE increase specific to A. fumigatus. A. fumigatus was not detected in oropharyngeal swabs and/or sputum culture of any patients.

Conclusions:

We conclude that, among the tests used to assess sensitization to A. fumigatus in cystic fibrosis patients, both serum-specific IgE and immediate-type hypersensitivity (IgE) skin tests are required. Serum eosinophilia and respiratory secretion culture were not essential in this study.

The metabolic footprint of the airway bacterial community in cystic fibrosis

BACKGROUND

Progressive, chronic bacterial infection of the airways is a leading cause of death in cystic fibrosis (CF). Culture-independent methods based on sequencing of the bacterial 16S rRNA gene describe a distinct microbial community that decreases in richness and diversity with disease progression. Understanding the functional characteristics of the microbial community may aid in identifying potential therapies and may assist in management, but current methods are cumbersome. Here, we demonstrate the use of an oxidative metabolic assay as a complement to sequencing methods to describe the microbiome in the airways of patients with CF.

METHODS

Expectorated sputum was collected from 16 CF subjects and 8 control subjects. The Biolog Gen III Microplate was used in a community-level physiological profiling (CLPP)-based assay to examine oxidative metabolic activity. 16S rRNA V4 amplicon sequencing was used to characterize the taxonomy and diversity of the samples. Correlations were then identified among the oxidative activity and taxonomy data. In an additional paired analysis, sputum from seven CF subjects were collected at two separate clinic visits and compared for oxidative activity, taxonomy, and diversity.

RESULTS

Significant differences in oxidative metabolic activity, microbial taxonomy, and diversity were found between the CF and control sputum samples. Oxidative activity correlated positively with total genera but not with other measures of diversity or taxonomy, demonstrating that the metabolic assay complements the structural aspects of the microbiome. As expected, Pseudomonas was significantly enriched in CF samples, while Streptococcus and Prevotella were similarly abundant in both CF and control samples. Paired analysis of CF samples at separate clinic visits revealed comparable oxidative activity that correlated with similar stability in taxonomy and diversity.

CONCLUSIONS

The CLPP assay used in this study complements existing sequencing methods to delineate the oxidative metabolic footprint of the CF airway bacterial community. This method may be useful to study the CF microbial community over time and with changes in disease state.

Influence of chronic azithromycin treatment on the composition of the oropharyngeal microbial community in patients with severe asthma

BACKGROUND

This study of the oropharyngeal microbiome complements the previously published AZIthromycin in Severe ASThma (AZISAST) clinical trial, where the use of azithromycin was assessed in subjects with exacerbation-prone severe asthma. Here, we determined the composition of the oropharyngeal microbial community by means of deep sequencing of the amplified 16S rRNA gene in oropharyngeal swabs from patients with exacerbation-prone severe asthma, at baseline and during and after 6 months treatment with azithromycin or placebo.

RESULTS

A total of 1429 OTUs were observed, of which only 59 were represented by more than 0.02% of the reads. Firmicutes, Bacteroidetes, Fusobacteria, Proteobacteria and Actinobacteria were the most abundant phyla and Streptococcus and Prevotella were the most abundant genera in all the samples. Thirteen species only accounted for two thirds of the reads and two species only, i.e. Prevotella melaninogenica and Streptococcus mitis/pneumoniae, accounted for one fourth of the reads. We found that the overall composition of the oropharyngeal microbiome in patients with severe asthma is comparable to that of the healthy population, confirming the results of previous studies. Long term treatment (6 months) with azithromycin increased the species Streptococcus salivarius approximately 5-fold and decreased the species Leptotrichia wadei approximately 5-fold. This was confirmed by Boruta feature selection, which also indicated a significant decrease of L. buccalis/L. hofstadtii and of Fusobacterium nucleatum. Four of the 8 treated patients regained their initial microbial composition within one month after cessation of treatment.

CONCLUSIONS

Despite large diversity of the oropharyngeal microbiome, only a few species predominate. We confirm the absence of significant differences between the oropharyngeal microbiomes of people with and without severe asthma. Possibly, long term azithromycin treatment may have long term effects on the composition of the oropharygeal microbiome in half of the patients.

Swimming bacteria promote dispersal of non-motile staphylococcal species

Swimming motility is considered a beneficial trait among bacterial species as it enables movement across fluid environments and augments invasion of tissues within the host. However, non-swimming bacteria also flourish in fluid habitats, but how they effectively spread and colonize distant ecological niches remains unclear. We show that non-motile staphylococci can gain motility by hitchhiking on swimming bacteria, leading to extended and directed motion with increased velocity. This phoretic interaction was observed between Staphylococcus aureus and Pseudomonas aeruginosa, Staphylococcus epidermidis and P. aeruginosa, as well as S. aureus and Escherichia coli, suggesting hitchhiking as a general translocation mechanism for non-motile staphylococcal species. By leveraging the motility of swimming bacteria, it was observed that staphylococci can colonize new niches that are less available in the absence of swimming carriers. This work highlights the importance of considering interactions between species within polymicrobial communities, in which bacteria can utilize each other as resources.

Differential responses of human dendritic cells to metabolites from the oral/airway microbiome

Small molecule metabolites that are produced or altered by host-associated microbial communities are emerging as significant immune response modifiers. However, there is a key gap in our knowledge of how oral microbial metabolites affect the immune response. Here, we examined the effects of metabolites from five bacterial strains found commonly in the oral/airway microbial communities of humans. The five strains, each isolated from cystic fibrosis patient sputum, were Pseudomonas aeruginosa FLR01 non-mucoid (P1) and FLR02 mucoid (P2) forms, Streptococcus pneumoniae (Sp), S. salivarius (Ss) and Rothia mucilaginosa (Rm). The effect of bacterial metabolites on dendritic cell (DC) activation, T cell priming and cytokine secretion was determined by exposing DCs to bacterial supernatants and individual metabolites of interest. Supernatants from P1 and P2 induced high levels of tumour necrosis factor (TNF)-α, interleukin (IL)-12 and IL-6 from DCs and primed T cells to secrete interferon (IFN)-γ, IL-22 compared to supernatants from Sp, Ss and Rm. Investigations into the composition of supernatants using gas chromatography-mass spectroscopy (GC-MS) revealed signature metabolites for each of the strains. Supernatants from P1 and P2 contained high levels of putrescine and glucose, while Sp and Ss contained high levels of 2,3-butanediol. The individual metabolites replicated the results of whole supernatants, although the magnitudes of their effects were reduced significantly. Altogether, our data demonstrate for the first time that the signature metabolites produced by different bacteria have different effects on DC functions. The identification of signature metabolites and their effects on the host immune system can provide mechanistic insights into diseases and may also be developed as biomarkers.

Modulation of behaviour and virulence of a high alginate expressing Pseudomonas aeruginosa strain from cystic fibrosis by oral commensal bacterium Streptococcus anginosus

Cystic fibrosis (CF) airways harbour complex and dynamic polymicrobial communities that include many oral bacteria. Despite increased knowledge of CF airway microbiomes the interaction between established CF pathogens and other resident microbes and resulting impact on disease progression is poorly understood. Previous studies have demonstrated that oral commensal streptococci of the Anginosus group (AGS) can establish chronic pulmonary infections and become numerically dominant in CF sputa indicating that they play an important role in CF microbiome dynamics. In this study a strain of Pseudomonas aeruginosa (DWW2) of the mucoid alginate overproducing phenotype associated with chronic CF airway infection and a strain of the oral commensal AGS species Streptococcus anginosus (3a) from CF sputum were investigated for their ability to co-exist and their responses to biofilm co-culture. Bacteria in biofilms were quantified, pyocyanin expression by DWW2 was measured and the effect of AGS strain 3a on reversion of DWW2 to a non-mucoidal phenotype investigated. The virulence of DWW2, 3a and colony variant phenotypes of DWW2 in mono- and co-culture were compared in a Galleria mellonella infection model. Co-culture biofilms were formed in normoxic, hypercapnic (10% CO₂) and anoxic atmospheres with the streptococcus increasing in number in co-culture, indicating that these bacteria would be able to co-exist and thrive within the heterogeneous microenvironments of the CF airway. The streptococcus caused increased pyocyanin expression by DWW2 and colony variants by stimulating reversion of the mucoid phenotype to the high pyocyanin expressing non-mucoid phenotype. The latter was highly virulent in the infection model with greater virulence when in co-culture with the streptococcus. The results of this study demonstrate that the oral commensal S. anginosus benefits from interaction with P. aeruginosa of the CF associated mucoid phenotype and modulates the behaviour of the pseudomonad in ways that may be clinically relevant.

Bacterial infections in patients with primary ciliary dyskinesia: Comparison with cystic fibrosis

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder associated with severely impaired mucociliary clearance caused by defects in ciliary structure and function. Although recurrent bacterial infection of the respiratory tract is one of the major clinical features of this disease, PCD airway microbiology is understudied. Despite the differences in pathophysiology, assumptions about respiratory tract infections in patients with PCD are often extrapolated from cystic fibrosis (CF) airway microbiology. This review aims to summarize the current understanding of bacterial infections in patients with PCD, including infections with Pseudomonas aeruginosa, Staphylococcus aureus, and Moraxella catarrhalis, as it relates to bacterial infections in patients with CF. Further, we will discuss current and potential future treatment strategies aimed at improving the care of patients with PCD suffering from recurring bacterial infections.

Longitudinal sampling of the lung microbiota in individuals with cystic fibrosis

Cystic fibrosis (CF) manifests in the lungs resulting in chronic microbial infection. Most morbidity and mortality in CF is due to cycles of pulmonary exacerbations-episodes of acute inflammation in response to the lung microbiome-which are difficult to prevent and treat because their cause is not well understood. We hypothesized that longitudinal analyses of the bacterial component of the CF lung microbiome may elucidate causative agents within this community for pulmonary exacerbations. In this study, 6 participants were sampled thrice-weekly for up to one year. During sampling, sputum, and data (antibiotic usage, spirometry, and symptom scores) were collected. Time points were categorized based on relation to exacerbation as Stable, Intermediate, and Treatment. Retrospectively, a subset of were interrogated via 16S rRNA gene sequencing. When samples were examined categorically, a significant difference between the lung microbiota in Stable, Intermediate, and Treatment samples was observed in a subset of participants. However, when samples were examined longitudinally, no correlations between microbial composition and collected data (antibiotic usage, spirometry, and symptom scores) were observed upon exacerbation onset. In this study, we identified no universal indicator within the lung microbiome of exacerbation onset but instead showed that changes to the CF lung microbiome occur outside of acute pulmonary episodes and are patient-specific.

Candida Species Biofilms' Antifungal Resistance

Candida infections (candidiasis) are the most prevalent opportunistic fungal infection on humans and, as such, a major public health problem. In recent decades, candidiasis has been associated to Candida species other than Candida albicans. Moreover, biofilms have been considered the most prevalent growth form of Candida cells and a strong causative agent of the intensification of antifungal resistance. As yet, no specific resistance factor has been identified as the sole responsible for the increased recalcitrance to antifungal agents exhibited by biofilms. Instead, biofilm antifungal resistance is a complex multifactorial phenomenon, which still remains to be fully elucidated and understood. The different mechanisms, which may be responsible for the intrinsic resistance of Candida species biofilms, include the high density of cells within the biofilm, the growth and nutrient limitation, the effects of the biofilm matrix, the presence of persister cells, the antifungal resistance gene expression and the increase of sterols on the membrane of biofilm cells. Thus, this review intends to provide information on the recent advances about Candida species biofilm antifungal resistance and its implication on intensification of the candidiasis.

The sil Locus in Streptococcus Anginosus Group: Interspecies Competition and a Hotspot of Genetic Diversity

The Streptococcus Invasion Locus (Sil) was first described in Streptococcus pyogenes and Streptococcus pneumoniae, where it has been implicated in virulence. The two-component peptide signaling system consists of the SilA response regulator and SilB histidine kinase along with the SilCR signaling peptide and SilD/E export/processing proteins. The presence of an associated bacteriocin region suggests this system may play a role in competitive interactions with other microbes. Comparative analysis of 42 Streptococcus Anginosus/Milleri Group (SAG) genomes reveals this to be a hot spot for genomic variability. A cluster of bacteriocin/immunity genes is found adjacent to the sil system in most SAG isolates (typically 6–10 per strain). In addition, there were two distinct SilCR peptides identified in this group, denoted here as SilCR_SAG-A and SilCR_SAG-B, with corresponding alleles in silB. Our analysis of the 42 sil loci showed that SilCR_SAG-A is only found in Streptococcus intermedius while all three species can carry SilCR_SAG-B. In S. intermedius B196, a putative SilA operator is located upstream of bacteriocin gene clusters, implicating the sil system in regulation of microbe–microbe interactions at mucosal surfaces where the group resides. We demonstrate that S. intermedius B196 responds to its cognate SilCR_SAG-A, and, less effectively, to SilCR_SAG-B released by other Anginosus group members, to produce putative bacteriocins and inhibit the growth of a sensitive strain of S. constellatus.

Host-microbiome interactions in acute and chronic respiratory infections

Respiratory infection is a leading cause of global morbidity and mortality. Understanding the factors that influence risk and outcome of these infections is essential to improving care. We increasingly understand that interactions between the microbial residents of our mucosal surfaces and host regulatory systems is fundamental to shaping local and systemic immunity. These mechanisms are most well defined in the gastrointestinal tract, however analogous systems also occur in the airways. Moreover, we now appreciate that the host-microbiota interactions at a given mucosal surface influence systemic host processes, in turn, affecting the course of infection at other anatomical sites. This review discusses the mechanisms by which the respiratory microbiome influences acute and chronic airway disease and examines the contribution of cross-talk between the gastrointestinal and respiratory compartments to microbe-mucosa interactions.

Pathogenesis of Fungal Infections in Cystic Fibrosis

For a long time, the microbiology of cystic fibrosis has been focussed on Pseudomonas aeruginosa and associated Gram-negative pathogens. An increasing body of evidence has been compiled demonstrating an important role for moulds and yeasts within this complex patient group. Whether or not fungi are active participants, spectators or transient passersby remain to be elucidated. However, functionally, they do appear to play a contributory role in pathogenesis, albeit we do not know if this is a direct or indirect effect. The following review examines some of the key evidence for the role of fungi in CF pathogenesis.

A comparison of intestinal microbiota in a population of low-risk infants exposed and not exposed to intrapartum antibiotics: The Baby & Microbiota of the Intestine cohort study protocol

Background

The intestinal microbiota influences metabolic, nutritional, and immunologic processes and has been associated with a broad range of adverse health outcomes including asthma, obesity and Type 2 diabetes. Early life exposures may alter the course of gut microbial colonization leading to differences in metabolic and immune regulation throughout life. Although approximately 50 % of low-risk full-term infants born in Canada are exposed to intrapartum antibiotics, little is known about the influence of this common prophylactic treatment on the developing neonatal intestinal microbiota. The purpose of this study is to describe the intestinal microbiome over the first 3 years of life among healthy, breastfed infants born to women with low-risk pregnancies at full term gestation and to determine if at 1 year of age, the intestinal microbiome of infants exposed to intrapartum antibiotics differs in type and quantity from the infants that are not exposed.

Methods

A prospectively followed cohort of 240 mother-infant pairs will be formed by enrolling eligible pregnant women from midwifery practices in the City of Hamilton and surrounding area in Ontario, Canada. Participants will be followed until the age of 3 years. Women are eligible to participate in the study if they are considered to be low-risk, planning a vaginal birth and able to communicate in English. Women are excluded if they have a multiple pregnancy or a preterm birth. Study questionnaires are completed, anthropometric measures are taken and biological samples are acquired including eight infant stool samples between 3 days and 3 years of age.

Discussion

Our experience to date indicates that midwifery practices and clients are keen to participate in this research. The midwifery client population is likely to have high rates of breastfeeding and low rates of intervention, allowing us to examine the comparative development of the microbiome in a relatively healthy and homogenous population. Results from this study will make an important contribution to the growing understanding of the patterns of intestinal microbiome colonization in the early years of life and may have implications for best practices to support the establishment of the microbiome at birth.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0724-5) contains supplementary material, which is available to authorized users.

Exposing the Three-Dimensional Biogeography and Metabolic States of Pathogens in Cystic Fibrosis Sputum via Hydrogel Embedding, Clearing, and rRNA Labeling

Physiological resistance to antibiotics confounds the treatment of many chronic bacterial infections, motivating researchers to identify novel therapeutic approaches. To do this effectively, an understanding of how microbes survive in vivo is needed. Though much can be inferred from bulk approaches to characterizing complex environments, essential information can be lost if spatial organization is not preserved. Here, we introduce a tissue-clearing technique, termed MiPACT, designed to retain and visualize bacteria with associated proteins and nucleic acids in situ on various spatial scales. By coupling MiPACT with hybridization chain reaction (HCR) to detect rRNA in sputum samples from cystic fibrosis (CF) patients, we demonstrate its ability to survey thousands of bacteria (or bacterial aggregates) over millimeter scales and quantify aggregation of individual species in polymicrobial communities. By analyzing aggregation patterns of four prominent CF pathogens, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus sp., and Achromobacter xylosoxidans, we demonstrate a spectrum of aggregation states: from mostly single cells (A. xylosoxidans), to medium-sized clusters (S. aureus), to a mixture of single cells and large aggregates (P. aeruginosa and Streptococcus sp.). Furthermore, MiPACT-HCR revealed an intimate interaction between Streptococcus sp. and specific host cells. Lastly, by comparing standard rRNA fluorescence in situ hybridization signals to those from HCR, we found that different populations of S. aureus and A. xylosoxidans grow slowly overall yet exhibit growth rate heterogeneity over hundreds of microns. These results demonstrate the utility of MiPACT-HCR to directly capture the spatial organization and metabolic activity of bacteria in complex systems, such as human sputum.

The advent of metagenomic and metatranscriptomic analyses has improved our understanding of microbial communities by empowering us to identify bacteria, calculate their abundance, and profile gene expression patterns in complex environments. We are still technologically limited, however, in regards to the many questions that bulk measurements cannot answer, specifically in assessing the spatial organization of microbe-microbe and microbe-host interactions. Here, we demonstrate the power of an enhanced optical clearing method, MiPACT, to survey important aspects of bacterial physiology (aggregation, host interactions, and growth rate), in situ, with preserved spatial information when coupled to rRNA detection by HCR. Our application of MiPACT-HCR to cystic fibrosis patient sputum revealed species-specific aggregation patterns, yet slow growth characterized the vast majority of bacterial cells regardless of their cell type. More broadly, MiPACT, coupled with fluorescent labeling, promises to advance the direct study of microbial communities in diverse environments, including microbial habitats within mammalian systems.

NAS agar is more suitable than McKay agar for primary culture of Streptococcus milleri group (SMG) fastidious bacteria, S. intermedius in particular

Streptococcus milleri group (SMG) is a group of three streptococcal species (S. anginosus, intermedius and constellatus) that act as opportunist pathogens, among others in cystic fibrosis. Due to their fastidious character, they are both difficult to cultivate and to differentiate from less pathogenic streptococcal species, therefore being most probably underdiagnosed. Semi-selective McKay agar and NAS agar were developed to facilitate SMG recovery from clinical samples; however, direct comparison of recovery rates has not been published yet. We tested the performance of both media on 123 patient samples and demonstrated general superiority of NAS agar for SMG recovery during primary cultivation convincingly. This observation was also confirmed by quantitative drop tests during subculture. Despite the undisputed overall superiority of NAS agar over McKay agar, a smaller fraction of strains grew better on McKay agar. Inter-strain differences were the most probable explanation. Therefore, when economic conditions are not limiting and maximum recovery rate is desirable, both plates are advised to be used in parallel for primary cultivation of clinical samples.

Clinical Insights into Pulmonary Exacerbations in Cystic Fibrosis from the Microbiome. What Are We Missing?

Pulmonary exacerbations account for much of the decrease in lung function and consequently most of the morbidity and mortality in patients with cystic fibrosis. These events are driven by an acute inflammatory response to infection. Recent technological advancements in molecular profiling techniques have allowed for a proliferation of microbiome studies of the lower airways of patients with cystic fibrosis. But these methods may not provide a comprehensive and unbiased measure of the lung microbiota in these patients and molecular profiles do not always translate to quantitative microbiology. Furthermore, these studies have not yet been able to provide much in the way of mechanistic insights into exacerbations or to guide patient therapy. We propose a model in which pulmonary exacerbations may be driven by an active subpopulation of the lung microbiota, which may represent only a small portion of the microbiota measured in a clinical sample. Methodology should be focused on the ultimate goal, which is to use the best available approaches to provide accurate quantitative measures of the microbiome to inform clinical decisions and provide rapid assessment of treatment efficacy. These strategies would be relevant to other chronic lung diseases such as chronic obstructive pulmonary disease and neutrophilic asthma.

Chelation of Membrane-Bound Cations by Extracellular DNA Activates the Type VI Secretion System in Pseudomonas aeruginosa

Pseudomonas aeruginosa employs its type VI secretion system (T6SS) as a highly effective and tightly regulated weapon to deliver toxic molecules to target cells. T6SS-secreted proteins of P. aeruginosa can be detected in the sputum of cystic fibrosis (CF) patients, who typically present a chronic and polymicrobial lung infection. However, the mechanism of T6SS activation in the CF lung is not fully understood. Here we demonstrate that extracellular DNA (eDNA), abundant within the CF airways, stimulates the dynamics of the H1-T6SS cluster apparatus in Pseudomonas aeruginosa PAO1. Addition of Mg(2+) or DNase with eDNA abolished such activation, while treatment with EDTA mimicked the eDNA effect, suggesting that the eDNA-mediated effect is due to chelation of outer membrane-bound cations. DNA-activated H1-T6SS enables P. aeruginosa to nonselectively attack neighboring species regardless of whether or not it was provoked. Because of the importance of the T6SS in interspecies interactions and the prevalence of eDNA in the environments that P. aeruginosa inhabits, our report reveals an important adaptation strategy that likely contributes to the competitive fitness of P. aeruginosa in polymicrobial communities.

Pyrosequencing Unveils Cystic Fibrosis Lung Microbiome Differences Associated with a Severe Lung Function Decline

Chronic airway infection is a hallmark feature of cystic fibrosis (CF) disease. In the present study, sputum samples from CF patients were collected and characterized by 16S rRNA gene-targeted approach, to assess how lung microbiota composition changes following a severe decline in lung function. In particular, we compared the airway microbiota of two groups of patients with CF, i.e. patients with a substantial decline in their lung function (SD) and patients with a stable lung function (S). The two groups showed a different bacterial composition, with SD patients reporting a more heterogeneous community than the S ones. Pseudomonas was the dominant genus in both S and SD patients followed by Staphylococcus and Prevotella. Other than the classical CF pathogens and the most commonly identified non-classical genera in CF, we found the presence of the unusual anaerobic genus Sneathia. Moreover, the oligotyping analysis revealed the presence of other minor genera described in CF, highlighting the polymicrobial nature of CF infection. Finally, the analysis of correlation and anti-correlation networks showed the presence of antagonism and ecological independence between members of Pseudomonas genus and the rest of CF airways microbiota, with S patients showing a more interconnected community in S patients than in SD ones. This population structure suggests a higher resilience of S microbiota with respect to SD, which in turn may hinder the potential adverse impact of aggressive pathogens (e.g. Pseudomonas). In conclusion, our findings shed a new light on CF airway microbiota ecology, improving current knowledge about its composition and polymicrobial interactions in patients with CF.

The fermentation product 2,3-butanediol alters P. aeruginosa clearance, cytokine response and the lung microbiome

Diseases that favor colonization of the respiratory tract with Pseudomonas aeruginosa are characterized by an altered airway microbiome. Virulence of P. aeruginosa respiratory tract infection is likely influenced by interactions with other lung microbiota or their products. The bacterial fermentation product 2,3-butanediol enhances virulence and biofilm formation of P. aeruginosa in vitro. This study assessed the effects of 2,3-butanediol on P. aeruginosa persistence, inflammatory response, and the lung microbiome in vivo. Here, P. aeruginosa grown in the presence of 2,3-butanediol and encapsulated in agar beads persisted longer in the murine respiratory tract, induced enhanced TNF-α and IL-6 responses and resulted in increased colonization in the lung tissue by environmental microbes. These results led to the following hypothesis that now needs to be tested with a larger study: fermentation products from the lung microbiota not only have a role in P. aeruginosa virulence and abundance, but also on the increased colonization of the respiratory tract with environmental microbes, resulting in dynamic shifts in microbiota diversity and disease susceptibility.

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.

The cystic fibrosis lower airways microbial metagenome

Chronic airway infections determine most morbidity in people with cystic fibrosis (CF). Herein, we present unbiased quantitative data about the frequency and abundance of DNA viruses, archaea, bacteria, moulds and fungi in CF lower airways.

Induced sputa were collected on several occasions from children, adolescents and adults with CF. Deep sputum metagenome sequencing identified, on average, approximately 10 DNA viruses or fungi and several hundred bacterial taxa.

The metagenome of a CF patient was typically found to be made up of an individual signature of multiple, lowly abundant species superimposed by few disease-associated pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, as major components. The host-associated signatures ranged from inconspicuous polymicrobial communities in healthy subjects to low-complexity microbiomes dominated by the typical CF pathogens in patients with advanced lung disease. The DNA virus community in CF lungs mainly consisted of phages and occasionally of human pathogens, such as adeno- and herpesviruses. The S. aureus and P. aeruginosa populations were composed of one major and numerous minor clone types.

The rare clones constitute a low copy genetic resource that could rapidly expand as a response to habitat alterations, such as antimicrobial chemotherapy or invasion of novel microbes.

The CF lung metagenome is composed of few viruses and fungi and hundreds of bacterial species, clones and subcloneshttp://ow.ly/ZiqUE

Episodic oral antibiotic use in CF: Discordance between the electronic medical record and self-report

BACKGROUND

Accurate accounting of antibiotic use is necessary for studies comparing the CF airway microbiota across clinically relevant disease states. While poor adherence to chronic therapies is well described for individuals with CF, use patterns of episodic oral antibiotics are less clear.

METHODS

Eleven individuals with CF completed daily questionnaires regarding antibiotic use for a mean of 458days. Self-report of episodic oral antibiotic use was compared to antibiotic prescription data in the electronic medical record (EMR).

RESULTS

Self-reported use of episodic oral antibiotics differed from EMR data an average of 8.3% of days per subject. The majority of these discrepancies were due to self-reported use of oral antibiotics outside of the EMR-documented dates of antibiotic prescription.

CONCLUSIONS

Discrepancies exist between self-reported use of episodic oral antibiotics and EMR data that have implications for studies of the CF airway microbiota.

The clinical importance of fungal biofilms

Fungal biofilms have become an increasingly important clinical problem. The widespread use of antibiotics, frequent use of indwelling medical devices, and a trend toward increased patient immunosuppression have resulted in a creation of opportunity for clinically important yeasts and molds to form biofilms. This review will discuss the diversity and importance of fungal biofilms in the context of clinical medicine, provide novel insights into the clinical management of fungal biofilm infection, present evidence why these structures are recalcitrant to antifungal therapy, and discuss how our knowledge and understanding may lead to novel therapeutic intervention.

Drug interactions and treatment burden as survival improves

PURPOSE OF REVIEW

With our growing understanding of the pathophysiology of cystic fibrosis, the pace of drug discovery is accelerating. Newer agents and therapies have traditionally been added to available medications, given the urgency in treating the disease. As the cystic fibrosis population ages, the number of associated comorbidities increases, requiring additional therapeutic approaches. Thus, while current management strategies have dramatically extended projected life expectancy, the treatment burden of the disease in adulthood has become onerous, and there is increasing concern over unintended effects and drug-drug interactions of new and existing therapies.

RECENT FINDINGS

A number of recent studies have sought to quantify the treatment burden of cystic fibrosis care, and to identify ways to reduce this burden. Mechanistic studies have identified the potential for a number of cystic fibrosis medications to impair the host response, or to interfere with the efficacy of other agents.

SUMMARY

As the cystic fibrosis formulary grows, a primary emphasis will be for providers to develop personalized treatment plans, with a goal to reduce unnecessary treatment burden and an awareness of potential unanticipated effects of medications.

Assessment of the Microbial Constituents of the Home Environment of Individuals with Cystic Fibrosis (CF) and Their Association with Lower Airways Infections

INTRODUCTION

Cystic fibrosis (CF) airways are colonized by a polymicrobial community of organisms, termed the CF microbiota. We sought to define the microbial constituents of the home environment of individuals with CF and determine if it may serve as a latent reservoir for infection.

METHODS

Six patients with newly identified CF pathogens were included. An investigator collected repeat sputum and multiple environmental samples from their homes. Bacteria were cultured under both aerobic and anaerobic conditions. Morphologically distinct colonies were selected, purified and identified to the genus and species level through 16S rRNA gene sequencing. When concordant organisms were identified in sputum and environment, pulsed-field gel electrophoresis (PFGE) was performed to determine relatedness. Culture-independent bacterial profiling of each sample was carried out by Illumina sequencing of the V3 region of the 16s RNA gene.

RESULTS

New respiratory pathogens prompting investigation included: Mycobacterium abscessus(2), Stenotrophomonas maltophilia(3), Pseudomonas aeruginosa(3), Pseudomonas fluorescens(1), Nocardia spp.(1), and Achromobacter xylosoxidans(1). A median 25 organisms/patient were cultured from sputum. A median 125 organisms/home were cultured from environmental sites. Several organisms commonly found in the CF lung microbiome were identified within the home environments of these patients. Concordant species included members of the following genera: Brevibacterium(1), Microbacterium(1), Staphylococcus(3), Stenotrophomonas(2), Streptococcus(2), Sphingomonas(1), and Pseudomonas(4). PFGE confirmed related strains (one episode each of Sphinogomonas and P. aeruginosa) from the environment and airways were identified in two patients. Culture-independent assessment confirmed that many organisms were not identified using culture-dependent techniques.

CONCLUSIONS

Members of the CF microbiota can be found as constituents of the home environment in individuals with CF. While the majority of isolates from the home environment were not genetically related to those isolated from the lower airways of individuals with CF suggesting alternate sources of infection were more common, a few genetically related isolates were indeed identified. As such, the home environment may rarely serve as either the source of infection or a persistent reservoir for re-infection after clearance.

Development and Validation of a PCR Assay To Detect the Prairie Epidemic Strain of Pseudomonas aeruginosa from Patients with Cystic Fibrosis

The monitoring of epidemic Pseudomonas aeruginosa is important for cystic fibrosis (CF) infection control. The prairie epidemic strain (PES) is common in western Canadian CF clinics. Using whole-genome sequencing, we identified a novel genomic island and developed a PCR assay for PES. Against a collection of 186 P. aeruginosa isolates, the assay had 98% sensitivity and 100% specificity.

Aspergillus Biofilms in Human Disease

The biofilm phenotype of Aspergillus species is an important and accepted clinical entity. While industrially these biofilms have been used extensively in important biofermentations, their role in clinical infection is less well defined. A recent flurry of activity has demonstrated that these interesting filamentous moulds have the capacity to form biofilms both in vitro and in vivo, and through various investigations have shown that these are exquisitely resistant to antifungal therapies through a range of adaptive resistance mechanisms independent of defined genetic changes. This review will explore the clinical importance of these biofilms and provide contemporary information with respect to their clinical management.

Culture-Based and Culture-Independent Bacteriologic Analysis of Cystic Fibrosis Respiratory Specimens

Cystic fibrosis (CF) is characterized by chronic infection and inflammation of the airways. In vitro culture of select bacterial species from respiratory specimens has been used to guide antimicrobial therapy in CF for the past few decades. More recently, DNA sequence-based, culture-independent approaches have been used to assess CF airway microbiology, although the role that these methods will (or should) have in routine microbiologic analysis of CF respiratory specimens is unclear. We performed DNA sequence analyses to detect bacterial species in 945 CF sputum samples that had been previously analyzed by selective CF culture. We determined the concordance of results based on culture and sequence analysis, highlighting the comparison of the results for the most prevalent genera. Although overall prevalence rates were comparable between the two methods, results varied by genus. While sequence analysis was more likely to detect Achromobacter, Stenotrophomonas, and Burkholderia, it was less likely to detect Staphylococcus. Streptococcus spp. were rarely reported in culture results but were the most frequently detected species by sequence analysis. A variety of obligate and facultative anaerobic species, not reported by culture, was also detected with high prevalence by sequence analysis. Sequence analysis indicated that in a considerable proportion of samples, taxa not reported by selective culture constituted a relatively high proportion of the total bacterial load, suggesting that routine CF culture may underrepresent significant segments of the bacterial communities inhabiting CF airways.

Nitrite reductase is critical for Pseudomonas aeruginosa survival during co-infection with the oral commensal Streptococcus parasanguinis

Pseudomonas aeruginosa is the major aetiological agent of chronic pulmonary infections in cystic fibrosis (CF) patients. However, recent evidence suggests that the polymicrobial community of the CF lung may also harbour oral streptococci, and colonization by these micro-organisms may have a negative impact on P. aeruginosa within the CF lung. Our previous studies demonstrated that nitrite abundance plays an important role in P. aeruginosa survival during co-infection with oral streptococci. Nitrite reductase is a key enzyme involved in nitrite metabolism. Therefore, the objective of this study was to examine the role nitrite reductase (gene nirS) plays in P. aeruginosa survival during co-infection with an oral streptococcus, Streptococcus parasanguinis. Inactivation of nirS in both the chronic CF isolate FRD1 and acute wound isolate PAO1 reduced the survival rate of P. aeruginosa when co-cultured with S. parasanguinis. Growth of both mutants was restored when co-cultured with S. parasanguinis that was defective for H2O2 production. Furthermore, the nitrite reductase mutant was unable to kill Drosophila melanogaster during co-infection with S. parasanguinis. Taken together, these results suggest that nitrite reductase plays an important role for survival of P. aeruginosa during co-infection with S. parasanguinis.

Precision respiratory medicine and the microbiome

A decade of rapid technological advances has provided an exciting opportunity to incorporate information relating to a range of potentially important disease determinants in the clinical decision-making process. Access to highly detailed data will enable respiratory medicine to evolve from one-size-fits-all models of care, which are associated with variable clinical effectiveness and high rates of side-effects, to precision approaches, where treatment is tailored to individual patients. The human microbiome has increasingly been recognised as playing an important part in determining disease course and response to treatment. Its inclusion in precision models of respiratory medicine, therefore, is essential. Analysis of the microbiome provides an opportunity to develop novel prognostic markers for airways disease, improve definition of clinical phenotypes, develop additional guidance to aid treatment selection, and increase the accuracy of indicators of treatment effect. In this Review we propose that collaboration between researchers and clinicians is needed if respiratory medicine is to replicate the successes of precision medicine seen in other clinical specialties.

Clinical implications and characterization of Group A Streptoccoccus infections in adults with cystic fibrosis

BACKGROUND

Persistent airway infection is a hallmark feature of cystic fibrosis (CF). However, increasingly it has been observed that non-classical pathogens may transiently infect CF lower airways. Streptococcus pyogenes (Group A Streptococcus; (GAS)) is an uncommon but potentially dangerous cause of community-acquired pneumonia. Our aim was to determine the incidence, natural history, and clinical impact of GAS infections in CF and phenotypically and genotypically characterize the isolates.

METHODS

We retrospectively evaluated the Calgary Adult CF Clinic biobank to identify adults with at least one GAS isolate. Patient demographics, medical and pulmonary exacerbation (PEx) histories were evaluated. The primary outcome was PEx occurrence at incident GAS culture. Secondary outcomes evaluated were changes in lung function and PEx frequency following GAS isolation. Isolates were assessed for extra-cellular virulence factor production capacity and ability to produce quorum sensing (AI-2). Isolates were genotyped using pulse-field gel electrophoresis (PFGE).

RESULTS

Fifteen individuals who cultured GAS twenty times were identified. At the time of GAS isolation, 47% (7/15) of subjects experienced a PEx and half of these (4/7) were severe. Individuals were more likely to have a PEx at the time of the index GAS isolate compared to the preceding visit (RR = 6.0, 95% CI 0.82-43.0, p = 0.08), particularly if GAS was the numerically dominant sputum pathogen (RR = 6.5, 95% CI 1.00-43.0, p = 0.009). There were no changes in PEx frequency or rate of lung function decline following GAS. None of the patients developed chronic airways infection, bacteremia, necrotizing pneumonia or empyema. Susceptibility was universal to common anti-Streptococcal antibiotics and anti-Pseudomonal antibiotics commonly used in CF, with the exception of azithromycin. GAS isolates varied in their production of protease, DNase, and AI-2 but these did not correlate with PEx, and none produced elastase, chrondrotin sulfatase or H202. One patient had prolonged carriage with the same isolate and two patients had isolates with similar PFGE patterns.

CONCLUSIONS

GAS was an uncommon lower respiratory pathogen of adults with CF. Identification of GAS in sputum was frequently associated with PEx, particularly when numerically dominant. However, transient GAS infection did not result in chronic infection nor appreciably change long-term disease trajectory.