Candidaspecies in cystic fibrosis: A road less travelled

Ceragenins exhibit bactericidal properties that are independent of the ionic strength in the environment mimicking cystic fibrosis sputum

The purpose of the work was to investigate the impact of sodium chloride (NaCl) on the antimicrobial efficacy of ceragenins (CSAs) and antimicrobial peptides (AMPs) against bacterial and fungal pathogens associated with cystic fibrosis (CF) lung infections. CF-associated bacterial (Pseudomonas aeruginosa, Ochrobactrum spp., and Staphylococcus aureus), and fungal pathogens (Candida albicans, and Candida tropicalis) were used as target organisms for ceragenins (CSA-13 and CSA-131) and AMPs (LL-37 and omiganan). Susceptibility to the tested compounds was assessed using minimal inhibitory concentrations (MICs) and bactericidal concentrations (MBCs), as well as by colony counting assays in CF sputum samples supplemented with various concentrations of NaCl. Our results demonstrated that ceragenins exhibit potent antimicrobial activity in CF sputum regardless of the NaCl concentration when compared to LL-37 and omiganan. Given the broad-spectrum antimicrobial activity of ceragenins in the microenvironments mimicking the airways of CF patients, ceragenins might be promising agents in managing CF disease.

Proliferative activity of antigen-specific CD154+ T cells against bacterial and fungal respiratory pathogens in cystic fibrosis decreases after initiation of highly effective CFTR modulator therapy

Background: Together with impaired mucociliary clearance, lung disease in cystic fibrosis (CF) is driven by dysregulation of innate and adaptive immunity caused by dysfunctional CFTR (Cystic Fibrosis Transmembrane Conductance Regulator), leading to airway infection and hyperinflamma-tion. The highly effective CFTR modulator therapy (HEMT) elexacaftor/tezacaftor/ivacaftor (ETI) generates substantial improvements in clinical outcomes of people with CF (pwCF) by restoration of CFTR activity. Aberrant immune responses of lymphocytes due to CFTR dysfunction has been described in the past, but not the effects of CFTR restoration by HEMT on these cells. We aimed to examine the effect of ETI on the proliferative activity of antigen-specific CD154 (+) T cells against bacterial and fungal species relevant in CF and on total IgG and IgE as markers of B cell adaptive immunity. Methods: We performed ex vivo analyses of Ki-67 expression in antigen-specific CD154 (+) T cells against Pseudomonas aeruginosa, Staphylococcus aureus, Aspergillus fumigatus, Scedosporium apiospermum and Candida albicans from 21 pwCF by cytometric assay based on antigen-reactive T cell enrichment (ARTE), and analysis of total serum IgE and IgG before and after initiation of ETI. Results: Mean Ki-67 expression in antigen-specific CD154 (+) T cells against P. aeruginosa, A. fumigatus, S. apiospermum and C. albicans, but not S. aureus, mean total serum IgG and mean total serum IgE decreased significantly after initiation of ETI. No correlation was found to change in sputum microbiology of the examined pathogens. Mean BMI and FEV1 increased significantly. Conclusion: HEMT is associated with decreased antigen-specific CD154 (+) T cell proliferation activity in our cohort, independent of findings in sputum microbiology of the examined pathogens. Together with the observed clinical improvement and the decrease in total IgE and IgG, this indicates effects due to CFTR restoration on CD154 (+) T cells by ETI and a reduction of B cell activation with subsequent lower immunoglobulin synthesis under HEMT therapy. These results endorse earlier evidence of CFTR dysfunction in T and B cells leading directly to aberrant immune responses with hyperinflammation.

Optimizing sexual and reproductive health across the lifespan in people with cystic fibrosis

With improved therapies, people with cystic fibrosis are living longer and healthier lives and increasingly have questions surrounding their sexual and reproductive health. This article will summarize the important issues of which providers should be aware during the lifespan of people with cystic fibrosis, including puberty, adulthood, and menopause. A wide range of sexual and reproductive health topics are addressed such as puberty, transgender and gender nonbinary identities, contraception, sexually transmitted infections, hypogonadism, sexual functioning, cyclical hemoptysis, and urinary incontinence. We discuss gaps in knowledge and current evidence as well as management strategies to optimize care. Our goal is to support providers to enable them to give comprehensive care throughout the lifespan of people with cystic fibrosis.

Symbiosis and Dysbiosis of the Human Mycobiome

The influence of microbiological species has gained increased visibility and traction in the medical domain with major revelations about the role of bacteria on symbiosis and dysbiosis. A large reason for these revelations can be attributed to advances in deep-sequencing technologies. However, the research on the role of fungi has lagged. With the continued utilization of sequencing technologies in conjunction with traditional culture assays, we have the opportunity to shed light on the complex interplay between the bacteriome and the mycobiome as they relate to human health. In this review, we aim to offer a comprehensive overview of the human mycobiome in healthy and diseased states in a systematic way. The authors hope that the reader will utilize this review as a scaffolding to formulate their understanding of the mycobiome and pursue further research.

Impact of airway Exophiala spp. on children with cystic fibrosis

INTRODUCTION

Isolation of Exophiala species from sputum samples has become increasingly reported in Cystic Fibrosis (CF). However, the clinical significance of Exophiala spp. with regards to the paediatric CF population is unknown.

METHODS

A case control study was undertaken to compare CF children with and without chronic Exophiala spp. in their sputum samples. Demographic and clinical data were collected retrospectively for each case from the date of Exophiala isolation and for 12 months preceding isolation. Each case was compared to three age and year-matched controls. To determine the effect of Exophiala on clinical course, patients were then followed for 12 months post isolation.

RESULTS

In total, 27 of 244 eligible paediatric CF patients (11%) isolated Exophiala spp. on more than one occasion. There were no significant differences in the key clinical parameters: spirometry, mean number of intravenous (IV) antibiotic days and body mass index (BMI), between cases and controls (p = 0.91, p = 0.56 and p = 0.63 respectively). A higher proportion of cases isolated Candida spp. (67% vs 21%, p < 0.0001) and Aspergillus fumigatus (37% vs 26%, p = 0.37). There was no clinically significant difference in spirometry, mean number of IV antibiotic days and BMI in cases pre and post Exophiala spp. isolation. Posaconazole was the only drug used that successfully eradicated Exophiala.

CONCLUSION

Despite the frequent isolation of Exophiala spp. in this cohort, in most patients it is not associated with significant clinical deterioration. It does however seem to be associated with isolation of other fungi.

Respiratory Candida in Patients with Bronchitis, Mucus Plugging, and Atelectasis

Background

The significance of Candida in pulmonary secretions is unclear, and usually is regarded as colonization, not contributing to symptoms or disease. Yet, in our experience, Candida seemed associated with chronic sputum, mucus plugging, atelectasis, and poor outcome.

Objective

The aim of this study is to describe the clinical findings of patients with Candida in pulmonary (sputum or bronchoscopy) secretions and the significance of Candida.

Methods

Retrospective study of inpatients and outpatients referred for pulmonary consultation with Candida in pulmonary secretions. Clinical parameters and estimates of whether Candida was likely clinically significant, were determined.

Results

82 inpatients and 11 outpatients were identified, of which 61 (66%) had atelectasis and 68 (73%) bronchoscopies. Of patients having bronchoscopies, 56 (82%) had mucus, and 43 (63%) mucus plugging. Of the inpatients death (or probable death) occurred in 43 (63%), 42 (98%) of which were from definite or probable respiratory failure, with 13 (31%) likely related to mucus plugging, 16 (38%) possibly from mucus plugging, 6 (14%) unknown, and 7 (17%) not due to mucus plugging. Candida was felt likely clinically significant in 57 patients (61%), uncertain significance in 23 (25%), and not significant in 13 (14%). All outpatients had exacerbations, including 7 (64%) within a year.

Conclusion

Patients requiring pulmonary consultation with Candida in pulmonary secretions often have chronic sputum production, exacerbations, mucus plugging, atelectasis, and death from respiratory failure. Candida was likely clinically significant in most patients. Recommendations to consider Candida in pulmonary secretions as colonization should be reconsidered.

Respiratory Mycoses in COPD and Bronchiectasis

Chronic obstructive pulmonary disease (COPD) and bronchiectasis represent chronic airway diseases associated with significant morbidity and mortality. Bacteria and viruses are commonly implicated in acute exacerbations; however the significance of fungi in these airways remains poorly defined. While COPD and bronchiectasis remain recognized risk factors for the occurrence of Aspergillus-associated disease including chronic and invasive aspergillosis, underlying mechanisms that lead to the progression from colonization to invasive disease remain uncertain. Nonetheless, advances in molecular technologies have improved our detection, identification and understanding of resident fungi characterizing these airways. Mycobiome sequencing has revealed the complex varied and myriad profile of airway fungi in COPD and bronchiectasis, including their association with disease presentation, progression, and mortality. In this review, we outline the emerging evidence for the clinical importance of fungi in COPD and bronchiectasis, available diagnostic modalities, mycobiome sequencing approaches and association with clinical outcomes.

Thymosin alpha 1 exerts beneficial extrapulmonary effects in cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the gene encoding for the ion channel Cystic Fibrosis Transmembrane conductance Regulator (CFTR). Long considered a lung disease for the devastating impact on the respiratory function, the recent diagnostic and therapeutic advances have shed the light on the extra-pulmonary manifestations of CF, including gastrointestinal, hepatobiliary and pancreatic symptoms. We have previously demonstrated that thymosin alpha1 (Tα1), a naturally occurring immunomodulatory peptide, displays multi-sided beneficial effects in CF that concur in ameliorating the lung inflammatory pathology. In the present study, by resorting to murine models of gut inflammation with clinical relevance for CF patients, we demonstrate that Tα1 can also have beneficial effects in extrapulmonary pathology. Specifically, Tα1 restored barrier integrity and immune homeostasis in the inflamed gut of CF mice as well as in mice with the metabolic syndrome, a disorder that may arise in CF patients with high caloric intake despite pancreatic sufficiency. The protective effects of Tα1 also extended to pancreas and liver, further emphasizing the beneficial effects of Tα1 in extra-pulmonary complications of CF. By performing wide-ranging multi-organ anti-inflammatory effects, Tα1 could potentially integrate current therapeutic approaches to tackle the complex symptomatology of CF disease.

Selectively targeting key inflammatory pathways in cystic fibrosis

Cystic fibrosis (CF) is a rare genetic disorder caused by a defect in the ion channel Cystic Fibrosis Transmembrane conductance Regulator (CFTR), resulting in ionic imbalance of surface fluid. Although affecting multiple organs, the progressive deterioration of respiratory function by recurrent infections and chronic inflammation represents the main cause of morbidity and mortality in CF patients. The development of modulators targeting the basic defect of CFTR has represented a major breakthrough in CF therapy, but the impact on inflammation has remained enigmatic. The emerging scenario taking hold in the field points to inflammation as a major, somehow missed, therapeutic target for prevention of lung decline. Not surprisingly, the development of anti-inflammatory drugs is taking its share in the drug development pipeline. But the path is not straightforward and targeting inflammation should be balanced with the increased risk of infection. The strategy to restore the homeostatic regulation of inflammation to efficiently respond to infection while preventing lung damage needs to be based on identifying and targeting endogenous immunoregulatory pathways that are defective in CF. We herein provide an overview of anti-inflammatory drugs currently approved or under investigation in CF patients, and present our recent studies on how the knowledge on defective immune pathways in CF may translate into innovative and selective anti-inflammatory therapeutics. Through the discovery of naturally occurring molecules or their synthetic mimics, this review emphasizes the critical importance of selectively targeting key inflammatory pathways to preserve immunocompetence in CF patients.

Does concomitant bacteraemia hide the fungi in blood cultures? An in vitro study

Introduction. Polymicrobial infections including yeasts and bacteria are not rare and patients with polymicrobial bloodstream infection have higher early and overall case fatality rates. The diagnosis of invasive fungal and bacterial infections is mainly based on blood culture.Aim. The aim was to reveal the effect of concomitant bacteraemia on the detection of fungi from blood cultures in the presence of polymicrobial bloodstream infections involving Candida and non-Candida fungi and to show the superiority of blood culture bottles including selective fungal media in such situations.Methodology. Twenty-four polymicrobial bloodstream infection models - involving one fungus and one bacterium - were constituted by using clinical blood culture isolates (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Candida glabrata, Fusarium solani and Trichosporon asahii). The Plus Aerobic/F (PAF) and Mycosis IC/F (MICF) culture bottles were used with the BACTEC 9240 device. After a bottle signalled positive, direct microscopic examination and subcultures on agar plates were performed.Results. All of fungi that were inoculated alone and in combination were detected by both direct microscopic examination and subcultures on agar plates from MICF bottles, whereas direct microscopic examination only revealed the bacterial agents from PAF bottles including combinations. Furthermore, fungal growth was hidden by bacterial growth on blood agar subcultures from PAF bottles including combinations of F. solani, C. glabrata or T. asahii with bacteria.Conclusion. Blood culture bottles including selective fungal media that can allow selective growth of fungi and earlier detection of some species should be preferred in addition to non-selective blood culture bottles, especially in specific patient populations. Further, the use of selective agar plates such as inhibitory mould agar may contribute to the solution of this problem in clinical laboratories.

A 16-year retrospective study on fungal prevalence and diversity in patients with cystic fibrosis: Candida dubliniensis was associated with a decline in lung function

OBJECTIVES

To study the prevalence of fungal species in cystic fibrosis (CF) patients over a 16 years period. To examine the impact of Candida albicans (C. albicans), Candida dubliniensis (C. dubliniensis) and Aspergillus fumigatus (A. fumigatus) on lung function.

METHODS

Observational single-center cohort study (2000-2015) including 133 CF patients (ages 6-66 years). Linear mixed models with autoregressive covariance matrix were used.

RESULTS

The most common fungus was C. albicans (prevalence 62%) followed by A. fumigatus (22%) and C. dubliniensis (11%). In the initial year of detection, there was no impact of C. albicans, C. dubliniensis or A. fumigatus on lung function. However, one and two years after detection of C. dubliniensis a reduction in percent predicted forced expiratory volume in the first second (ppFEV1) was observed of 3.8% (p = 0.022) and 4.1% (p = 0.017), respectively, compared with CF patients without these findings. Furthermore, patients with positive cultures for any of these fungal species for three consecutive years exhibited a decline in lung function: C. dubliniensis, 7.6% reduction in ppFEV1 (p = 0.001); A. fumigatus, 4.9% (p = 0.007); C. albicans, 2.6% (p = 0.014). The results were adjusted for age, CFTR genotype, chronic and intermittent P. aeruginosa colonization, and numbers of intravenous antibiotic treatments per year. Persistence of C. dubliniensis for three consecutive years was positively correlated to age and erythrocyte sedimentation rate (ESR) (both p = 0.001).

CONCLUSIONS

Cystic fibrosis patients who were cultured positive for C. dubliniensis, C. albicans or A. fumigatus in sputum exhibited a decline in ppFEV1 over time. The effect was most pronounced for C. dubliniensis.

Respiratory Fungal Diseases in Adult Patients With Cystic Fibrosis

Clinical manifestations of respiratory fungal diseases in adult cystic fibrosis (CF) patients are very heterogeneous, ranging from asymptomatic colonization to chronic infections, allergic disorders, or invasive diseases in immunosuppressed CF patients after lung transplantation. In this narrative review, mainly addressed to clinicians without expertise in CF who may nonetheless encounter adult CF patients presenting with acute and chronic respiratory syndromes, we briefly summarize the most representative clinical aspects of respiratory fungal diseases in adult CF patients.

Fungal-Bacterial Interactions in Health and Disease

Fungi and bacteria encounter each other in various niches of the human body. There, they interact directly with one another or indirectly via the host response. In both cases, interactions can affect host health and disease. In the present review, we summarized current knowledge on fungal-bacterial interactions during their commensal and pathogenic lifestyle. We focus on distinct mucosal niches: the oral cavity, lung, gut, and vagina. In addition, we describe interactions during bloodstream and wound infections and the possible consequences for the human host.

Airway colonisation by Candida and Aspergillus species in Iranian cystic fibrosis patients

Cystic fibrosis (CF) is associated with increased rates of morbidity and mortality due to fungal and bacterial colonisation of the airways or respiratory infections. The prevalence of fungi in Iranian CF population has been underestimated. Therefore, the current study was conducted to define the frequency of fungi in respiratory specimens obtained from Iranian CF patients based on conventional and molecular assays. Furthermore, in vitro antifungal susceptibility testing was performed on the obtained isolates according to the guidelines from the Clinical and Laboratory Standards Institute. A cohort of 42 CF patients, including 29 males and 13 females, were categorised according to the referenced diagnostic criteria. Candida albicans (n = 24, 80%), C. dubliniensis (n = 2, 6.6%), C. parapsilosis (n = 2, 6.6%), C. tropicalis (n = 1, 3.3%), C. glabrata (n = 1, 3.3%) and Meyerozyma caribbica (n = 1, 3.3%) were isolated from 73.8% of the CF patients. Aspergillus terreus (n = 3, 42.8%) was identified as the most common Aspergillus species, followed by A. fumigatus (n = 2, 28.5%), A. oryzae (n = 1, 14.2%) and A. flavus (n = 1, 14.2%). Bacterial and fungal co-colonisation was detected in 7 (16.6%) and 22 (52.3%) samples that were positive for Aspergillus and Candida species, respectively. However, Scedosporium species and Exophiala dermatitidis never were detected. In terms of geometric mean (GM) minimum inhibitory concentrations (MICs), posaconazole (0.018 μg/mL) and caspofungin (0.083 μg/mL) exhibited the highest antifungal activities against all Candida species. In addition, posaconazole exhibited the lowest MIC range (0.008-0.063 μg/mL) against all Aspergillus species, followed by caspofungin (0.016-0.125 μg/mL) and voriconazole (0.125-0.25 μg/mL). To conclude, it is essential to adopt a consistent method for the implementation of primary diagnosis and determination of treatment regimen for the CF patients. However, further studies are still needed to better define the epidemiology of fungal organisms in CF patients from the Middle East and the clinical significance of their isolation.

Iron at the Centre of Candida albicans Interactions

Iron is an absolute requirement for both the host and most pathogens alike and is needed for normal cellular growth. The acquisition of iron by biological systems is regulated to circumvent toxicity of iron overload, as well as the growth deficits imposed by iron deficiency. In addition, hosts, such as humans, need to limit the availability of iron to pathogens. However, opportunistic pathogens such as Candida albicans are able to adapt to extremes of iron availability, such as the iron replete environment of the gastrointestinal tract and iron deficiency during systemic infection. C. albicans has developed a complex and effective regulatory circuit for iron acquisition and storage to circumvent iron limitation within the human host. As C. albicans can form complex interactions with both commensal and pathogenic co-inhabitants, it can be speculated that iron may play an important role in these interactions. In this review, we highlight host iron regulation as well as regulation of iron homeostasis in C. albicans. In addition, the review argues for the need for further research into the role of iron in polymicrobial interactions. Lastly, the role of iron in treatment of C. albicans infection is discussed.

Pathogenesis, imaging and clinical characteristics of CF and non-CF bronchiectasis

Bronchiectasis is a common feature of severe inherited and acquired pulmonary disease conditions. Among inherited diseases, cystic fibrosis (CF) is the major disorder associated with bronchiectasis, while acquired conditions frequently featuring bronchiectasis include post-infective bronchiectasis and chronic obstructive pulmonary disease (COPD). Mechanistically, bronchiectasis is driven by a complex interplay of inflammation and infection with neutrophilic inflammation playing a predominant role. The clinical characterization and management of bronchiectasis should involve a precise diagnostic workup, tailored therapeutic strategies and pulmonary imaging that has become an essential tool for the diagnosis and follow-up of bronchiectasis. Prospective future studies are required to optimize the diagnostic and therapeutic management of bronchiectasis, particularly in heterogeneous non-CF bronchiectasis populations.

Fungus-Specific CD4 T Cells as Specific Sensors for Identification of Pulmonary Fungal Infections

Patients with cystic fibrosis (CF) suffer from chronic lung infections, caused by bacterial, viral or fungal pathogens, which determine morbidity and mortality. The contribution of individual pathogens to chronic disease and acute lung exacerbations is often difficult to determine due to the complex composition of the lung microbiome in CF. In particular, the relevance of fungal pathogens in CF airways remains poorly understood due to limitations of current diagnostics to identify the presence of fungal pathogens and to resolve the individual host-pathogen interaction status. T-lymphocytes play an essential role in host defense against pathogens, but also in inappropriate immune reactions such as allergies. They have the capacity to specifically recognize and discriminate the different pathogens and orchestrate a diverse array of effector functions. Thus, the analysis of the fungus-specific T cell status of an individual can in principle provide detailed information about the identity of the fungal pathogen(s) encountered and the actual fungus-host interaction status. This may allow to classify patients, according to appropriate (protective) or inappropriate (pathology-associated) immune reactions against individual fungal pathogens. However, T cell-based diagnostics are currently not part of the clinical routine. The identification and characterization of fungus-specific T cells in health and disease for diagnostic purposes are associated with significant challenges. Recent technological developments in the field of fungus-specific T helper cell detection provide new insights in the host T cell-fungus interaction. In this review, we will discuss basic principles and the potential of T cell-based diagnostics, as well as the perspectives and further needs for use of T cells for improved clinical diagnostics of fungal diseases.

Susceptibility of Candida albicans from Cystic Fibrosis Patients

Candida albicans is a common microbe, colonizer and potential pathogen found in respiratory cultures of cystic fibrosis (CF) patients. Because of possible development of resistance in patient isolates resulting from residence in the abnormal milieu of CF patient airways, or from exposure to antifungals, and considering the possibility of patient-to-patient spread of microbes and reports of elevated resistance to other fungal pathogens, it was important to assay the susceptibility of isolates of Candida and compare that profile to isolates from the community. In our center, and unlike another fungal pathogen, no increase in resistance of Candida isolates of the CF cohort was found.

Update on host-pathogen interactions in cystic fibrosis lung disease

Bacterial and fungal infections are hallmarks of cystic fibrosis (CF) lung disease. In the era of long-term inhaled antibiotics and increasing CF patient survival, new "emerging" pathogens are detected in CF airways, yet their pathophysiological disease relevance remains largely controversial and incompletely defined. As a response to chronic microbial triggers, innate immune cells, particularly neutrophils, are continuously recruited into CF airways where they combat pathogens but also cause tissue injury through release of oxidants and proteases. The coordinated interplay between host immune cell activation and pathogens is essential for the outcome of CF lung disease. Here, we provide a concise overview and update on host-pathogen interactions in CF lung disease.

Microbial colonization and lung function in adolescents with cystic fibrosis

With intensified antibiotic therapy and longer survival, patients with cystic fibrosis (CF) are colonized with a more complex pattern of bacteria and fungi. However, the clinical relevance of these emerging pathogens for lung function remains poorly defined. The aim of this study was to assess the association of bacterial and fungal colonization patterns with lung function in adolescent patients with CF. Microbial colonization patterns and lung function parameters were assessed in 770 adolescent European (German/Austrian) CF patients in a retrospective study (median follow-up time: 10years). Colonization with Pseudomonas aeruginosa and MRSA were most strongly associated with loss of lung function, while mainly colonization with Haemophilus influenzae was associated with preserved lung function. Aspergillus fumigatus was the only species that was associated with an increased risk for infection with P. aeruginosa. Microbial interaction analysis revealed three distinct microbial clusters within the longitudinal course of CF lung disease. Collectively, this study identified potentially protective and harmful microbial colonization patterns in adolescent CF patients. Further studies in different patient cohorts are required to evaluate these microbial patterns and to assess their clinical relevance.

Iron acquisition in the cystic fibrosis lung and potential for novel therapeutic strategies

Iron acquisition is vital to microbial survival and is implicated in the virulence of many of the pathogens that reside in the cystic fibrosis (CF) lung. The multifaceted nature of iron acquisition by both bacterial and fungal pathogens encompasses a range of conserved and species-specific mechanisms, including secretion of iron-binding siderophores, utilization of siderophores from other species, release of iron from host iron-binding proteins and haemoproteins, and ferrous iron uptake. Pathogens adapt and deploy specific systems depending on iron availability, bioavailability of the iron pool, stage of infection and presence of competing pathogens. Understanding the dynamics of pathogen iron acquisition has the potential to unveil new avenues for therapeutic intervention to treat both acute and chronic CF infections. Here, we examine the range of strategies utilized by the primary CF pathogens to acquire iron and discuss the different approaches to targeting iron acquisition systems as an antimicrobial strategy.

Association of chronic Candida albicans respiratory infection with a more severe lung disease in patients with cystic fibrosis

BACKGROUND

Despite the increase in fungal isolates, the significance of chronic Candida albicans airway colonization in CF is unclear.

AIM

To investigate the impact of C. albicans airway colonization on CF disease severity.

METHODS

Longitudinal analysis of clinical data from CF patients followed during 2003-2009 at our CF center. Patients were stratified based on their C. albicans colonization status--chronic, intermittent, and none.

RESULTS

A total of 4,244 cultures were obtained from 91 patients (mean age 19.7 years, range 5-68). The three colonization groups were similar in age, gender,and body mass index (BMI). Compared to the non-colonized group (n = 27, 30%), the chronic C. albicans colonization group (n = 34, 37%), had a significantly lower FEV1 percent predicted (74.3 ± 23.1% vs. 93.9% ± 22.2) with a higher annual rate of FEV1 decline (-1.9 ± 4.2% vs. 0.7 ± 4.5%). The patients who were intermittently colonized with C. albicans had intermediate values.

CONCLUSIONS

Chronic respiratory colonization of C. albicans is associated with worsening of FEV1 in CF. Prospective studies are needed to confirm this finding and to corroborate whether indeed C. albicans drives a deleterious lung phenotype.

Co-occurence of filamentation defects and impaired biofilms in Candida albicans protein kinase mutants

Pathogenicity of Candida albicans is linked with its developmental stages, notably the capacity switch from yeast-like to hyphal growth, and to form biofilms on surfaces. To better understand the cellular processes involved in C. albicans development, a collection of 63 C. albicans protein kinase mutants was screened for biofilm formation in a microtitre plate assay. Thirty-eight mutants displayed some degree of biofilm impairment, with 20 categorised as poor biofilm formers. All the poor biofilm formers were also defective in the switch from yeast to hyphae, establishing it as a primary defect. Five genes, VPS15, IME2, PKH3, PGA43 and CEX1, encode proteins not previously reported to influence hyphal development or biofilm formation. Network analysis established that individual components of some processes, most interestingly MAP kinase pathways, are not required for biofilm formation, most likely indicating functional redundancy. Mutants were also screened for their response to bacterial supernatants and it was found that Pseudomonas aeruginosa supernatants inhibited biofilm formation in all mutants, regardless of the presence of homoserine lactones (HSLs). In contrast, Candida morphology was only affected by supernatant containing HSLs. This confirms the distinct HSL-dependent inhibition of filamentation and the HSL-independent impairment of biofilm development by P. aeruginosa.

Noisy neighbourhoods: quorum sensing in fungal-polymicrobial infections

Quorum sensing was once considered a way in which a species was able to sense its cell density and regulate gene expression accordingly. However, it is now becoming apparent that multiple microbes can sense particular quorum-sensing molecules, enabling them to sense and respond to other microbes in their neighbourhood. Such interactions are significant within the context of polymicrobial disease, in which the competition or cooperation of microbes can alter disease progression. Fungi comprise a small but important component of the human microbiome and are in constant contact with bacteria and viruses. The discovery of quorum-sensing pathways in fungi has led to the characterization of a number of interkingdom quorum-sensing interactions. Here, we review the recent developments in quorum sensing in medically important fungi, and the implications these interactions have on the host's innate immune response.

Pseudomonas aeruginosa inhibits the growth of Scedosporium aurantiacum, an opportunistic fungal pathogen isolated from the lungs of cystic fibrosis patients

The filamentous fungus Scedosporium aurantiacum and the bacterium Pseudomonas aeruginosa are opportunistic pathogens isolated from lungs of the cystic fibrosis (CF) patients. P. aeruginosa has been known to suppress the growth of a number of CF related fungi such as Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans. However, the interactions between P. aeruginosa and S. aurantiacum have not been investigated in depth. Hence we assessed the effect of P. aeruginosa reference strain PAO1 and two clinical isolates PASS1 and PASS2 on the growth of two clinical S. aurantiacum isolates WM 06.482 and WM 08.202 using solid plate assays and liquid cultures, in a synthetic medium mimicking the nutrient condition in the CF sputum. Solid plate assays showed a clear inhibition of growth of both S. aurantiacum strains when cultured with P. aeruginosa strains PASS1 and PAO1. The inhibitory effect was confirmed by confocal microscopy. In addition to using chemical fluorescent stains, strains tagged with yfp (P. aeruginosa PASS1) and mCherry (S. aurantiacum WM 06.482) were created to facilitate detailed microscopic observations on strain interaction. To our knowledge, this is the first study describing successful genetic transformation of S. aurantiacum. Inhibition of growth was observed only in co-cultures of P. aeruginosa and S. aurantiacum; the cell fractions obtained from independent bacterial monocultures failed to initiate a response against the fungus. In the liquid co-cultures, biofilm forming P. aeruginosa strains PASS1 and PAO1 displayed higher inhibition of fungal growth when compared to PASS2. No change was observed in the inhibition pattern when direct cell contact between the bacterial and fungal strains was prevented using a separation membrane suggesting the involvement of extracellular metabolites in the fungal inhibition. However, one of the most commonly described bacterial virulence factors, pyocyanin, had no effect against either of the S. aurantiacum strains. This study shows that P. aeruginosa has a substantial inhibitory effect on the growth of the recently described CF fungal pathogen S. aurantiacum. The findings also highlighted that P. aeruginosa biofilm formation is important but not crucial for inhibiting the growth of S. aurantiacum in a lung- mimicking environment.

Candida albicans chronic colonisation in cystic fibrosis may be associated with inhaled antibiotics

Candida albicans is increasingly recognised as a coloniser of the respiratory tract in cystic fibrosis (CF) patients. Yet, the potential role, if any, of the micro-organism in the progress of the disease remains unclear. In this study, we investigated the association between inhaled antibiotics and C. albicans chronic colonisation in patients with CF. A cohort of 121 CF patients born from 1988 to 1996 was, respectively, studied. The medical records of each patient were reviewed from the first time they attended the CF Centre until the occurrence of C. albicans chronic colonisation or their last visit for the year 2010. Chronic colonisation was defined as the presence of C. albicans in more than 50% of cultures in a given year. A number of possible confounders were included in the multivariate logistic regression analysis to identify an independent association between inhaled antibiotics and C. albicans chronic colonisation. Fifty-four (44.6%) of the 121 patients enrolled in the study developed chronic colonisation by the micro-organism. Multivariate logistic regression analysis determined the independent effect of inhaled antibiotic treatment on the odds of chronic colonisation (OR 1.112, 95% CI [1.007-1.229], P = 0.036). Candida albicans chronic colonisation may be associated with the duration of inhaled antibiotic treatment.

Antibiotic management of lung infections in cystic fibrosis. II. Nontuberculous mycobacteria, anaerobic bacteria, and fungi

Airway infections are a key component of cystic fibrosis (CF) lung disease. Whereas the approach to common pathogens such as Pseudomonas aeruginosa is guided by a significant body of evidence, other infections often pose a considerable challenge to treating physicians. In Part I of this series on the antibiotic management of difficult lung infections, we discussed bacterial organisms including methicillin-resistant Staphylococcus aureus, gram-negative bacterial infections, and treatment of multiple bacterial pathogens. Here, we summarize the approach to infections with nontuberculous mycobacteria, anaerobic bacteria, and fungi. Nontuberculous mycobacteria can significantly impact the course of lung disease in patients with CF, but differentiation between colonization and infection is difficult clinically as coinfection with other micro-organisms is common. Treatment consists of different classes of antibiotics, varies in intensity, and is best guided by a team of specialized clinicians and microbiologists. The ability of anaerobic bacteria to contribute to CF lung disease is less clear, even though clinical relevance has been reported in individual patients. Anaerobes detected in CF sputum are often resistant to multiple drugs, and treatment has not yet been shown to positively affect patient outcome. Fungi have gained significant interest as potential CF pathogens. Although the role of Candida is largely unclear, there is mounting evidence that Scedosporium species and Aspergillus fumigatus, beyond the classical presentation of allergic bronchopulmonary aspergillosis, can be relevant in patients with CF and treatment should be considered. At present, however there remains limited information on how best to select patients who could benefit from antifungal therapy.

Fungal allergy in asthma-state of the art and research needs

Sensitization to fungi and long term or uncontrolled fungal infection are associated with poor control of asthma, the likelihood of more severe disease and complications such as bronchiectasis and chronic pulmonary aspergillosis. Modelling suggests that >6.5 million people have severe asthma with fungal sensitizations (SAFS), up to 50% of adult asthmatics attending secondary care have fungal sensitization, and an estimated 4.8 million adults have allergic bronchopulmonary aspergillosis (ABPA). There is much uncertainty about which fungi and fungal allergens are relevant to asthma, the natural history of sensitisation to fungi, if there is an exposure response relationship for fungal allergy, and the pathogenesis and frequency of exacerbations and complications. Genetic associations have been described but only weakly linked to phenotypes. The evidence base for most management strategies in ABPA, SAFS and related conditions is weak. Yet straightforward clinical practice guidelines for management are required. The role of environmental monitoring and optimal means of controlling disease to prevent disability and complications are not yet clear. In this paper we set out the key evidence supporting the role of fungal exposure, sensitisation and infection in asthmatics, what is understood about pathogenesis and natural history and identify the numerous areas for research studies.

Fungi in the cystic fibrosis lung: bystanders or pathogens?

Improvement to the life expectancy of people with cystic fibrosis (PWCF) brings about novel challenges including the need for evaluation of the role of fungi in the cystic fibrosis (CF) lung. To determine if such organisms represent bystanders or pathogens affecting clinical outcomes we review the existing knowledge from a clinical, biochemical, inflammatory and immunological perspective. The prevalence and importance of fungi in the CF airway has likely been underestimated with the most frequently isolated filamentous fungi being Aspergillus fumigatus and Scedosporium apiospermum and the major yeast Candida albicans. Developing non-culture based microbiological methods for fungal detection has improved both our classification and understanding of their clinical consequences including localized, allergic and systemic infections. Cross-kingdom interaction between bacteria and fungi are discussed as is the role of biofilms further affecting clinical outcome. A combination of host and pathogen-derived factors determines if a particular fungus represents a commensal, colonizer or pathogen in the setting of CF. The underlying immune state, disease severity and treatment burden represent key host variables whilst fungal type, form, chronicity and virulence including the ability to evade immune recognition determines the pathogenic potential of a specific fungus at a particular point in time. Further research in this emerging field is warranted to fully elucidate the spectrum of disease conferred by the presence of fungi in the CF airway and the indications for therapeutic interventions.

Development of IgG antibodies to Exophiala dermatitidis is associated with inflammatory responses in patients with cystic fibrosis

BACKGROUND

The clinical importance of airway colonisation by the fungus Exophiala dermatitidis in patients with cystic fibrosis (CF) is unclear. We have previously shown that E. dermatitidis frequently colonises the airways of patients with CF. The aims of the present study were to determine whether patients who are colonised by E. dermatitidis have detectable fungal antigens in the circulation, develop anti-fungal antibodies, and show signs of inflammation and impaired respiratory function.

METHODS

We collected sputum and serum samples consecutively from 98 sputum-producing patients with CF aged more than 12 years. The serum samples were subjected to bacterial and fungal culturing and analyses for fungal antigens and inflammatory factors.

RESULTS

E. dermatitidis was recovered from 17 (17%) patients, the same isolation rate as for Aspergillus fumigatus. There were no difference regarding the levels of β-glucan in the sera from E. dermatitidis culture-positive and culture-negative patients with CF. Serological analysis revealed significantly higher levels of IgG antibodies to E. dermatitidis cell wall fragments in the E. dermatitidis culture-positive patients. Patients with higher level of E. dermatitidis IgG antibodies were more often colonised with non-tuberculous Mycobacteria, and less often with Staphylococcus aureus. The increased levels of IgG antibodies directed against E. dermatitidis were positively associated with higher white blood cell counts, increased erythrocyte sedimentation rate, pancreatic insufficiency, intravenous antibiotic treatment, and they were negatively associated with respiratory function (FEV1 % predicted). Overall, 4/17 Exophiala-positive patients were diagnosed as having symptomatic infection with E. dermatitidis and were treated with broad-spectrum azoles.

CONCLUSION

E. dermatitidis triggers antibody production and may cause significant airway infection in patients with cystic fibrosis.

The effect of Aspergillus fumigatus infection on vitamin D receptor expression in cystic fibrosis

RATIONALE

Aspergillus fumigatus (A. fumigatus) in cystic fibrosis (CF) is increasingly recognized. Although allergic bronchopulmonary aspergillosis (ABPA) leads to deterioration of pulmonary function, the effect of A. fumigatus colonization in the absence of ABPA remains unclear.

OBJECTIVES

To address this, we examined individuals with CF with A. fumigatus who were ABPA negative to identify the effects of itraconazole therapy on Aspergillus-induced lung inflammation.

METHODS

The effect of A. fumigatus on nuclear vitamin D receptor (VDR) expression was investigated using qRT-PCR and Western blotting. IL-5 and IL-13 levels were quantified by ELISA. The effect of itraconazole was assessed by a combination of high-resolution computed tomography, lung function test, and microbiological analysis.

MEASUREMENTS AND MAIN RESULTS

We demonstrate that A. fumigatus down-regulates VDR in macrophages and airway epithelial cells and that the fungal metabolite gliotoxin (Gt) is the main causative agent. Gt overcame the positive effect of 1,25-OH vitamin D(3) on VDR expression in vitro, resulting in increased IL-5 and IL-13 production. In vivo, A. fumigatus positivity was associated with increased Gt in CF bronchoalveolar lavage fluid and increased bronchoalveolar lavage fluid levels of IL-5 and IL-13. After airway eradication of A. fumigatus with itraconazole, we observed decreased Gt, IL-5 and IL-13, improved respiratory symptoms, and diminished high-resolution computed tomography mosaic pattern consistent with sustained pulmonary function.

CONCLUSIONS

This study provides a rationale for the therapeutic effect of itraconazole and implied that the therapeutic potential of vitamin D supplementation in preventing ABPA is only feasible with concurrent elimination of A. fumigatus to permit VDR expression and its positive functional consequences.

Frequency of fungi in respiratory samples from Turkish cystic fibrosis patients

An increased isolation of fungi from the respiratory tract of patients with cystic fibrosis (CF) has been reported. The prevalence of different fungi in CF patients from Turkey is not known. Our aim was to determine the frequency of fungi in the respiratory tract of Turkish CF patients. We investigated a total of 184 samples from 48 patients. Samples were inoculated on Medium B+ and CHROMagar Candida. Candida albicans was the predominant yeast isolated [30 patients (62.5%)], followed by C. parapsilosis [6 (12.5%)] and C. dubliniensis 5 (10.4%). Aspergillus fumigatus was the most common filamentous fungus [5 (10.4%)] and non-fumigatus Aspergillus species were isolated from four (8.3%) patients. Staphylococcus aureus was the most frequently detected bacterium in C. albicans positive samples (53.57%). A. fumigatus and Pseudomonas aeruginosa or S. aureus were detected together in 75% of A. fumigatus positive samples each. No statistically significant relationship was detected between growth of yeast and moulds and age, gender, the use of inhaled corticosteroids or tobramycin. No significant correlation was found between the isolation of C. albicans, A. fumigatus and P. aeruginosa, Stenotrophomonas maltophilia or S. aureus, and the isolation of C. albicans and Haemophilus influenzae. Other factors which may be responsible for the increased isolation of fungi in CF need to be investigated.

Effect of Aspergillus fumigatus and Candida albicans on pro-inflammatory response in cystic fibrosis epithelium

BACKGROUND

The identification of filamentous fungi and/or yeasts in the airway secretions of individuals with cystic fibrosis (CF) is becoming increasingly prevalent; yet the importance of these organisms in relation to underlying inflammation is poorly defined.

METHODS

Cystic fibrosis bronchial epithelial cells (CFBE) and human bronchial epithelial cells (HBE) were co-incubated with Candida albicans whole cells or Aspergillus fumigatus conidia for 24 h prior to the measurement of pro-inflammatory cytokines IL-6 and IL-8 by ELISA.

RESULTS

Treatment of HBE or CFBE with C. albicans whole cells did not alter cytokine secretion. However treatment of CFBE with A. fumigatus conidia resulted in a 1.45-fold increase in IL-6 and a 1.65-fold increase in IL-8 secretion in comparison to basal levels; in contrast there was far less secretion from HBE cells.

CONCLUSION

Our data indicate that A. fumigatus infection modulates a pro-inflammatory response in CF epithelial cells while C. albicans does not.

Colonization by Candida in children with cancer, children with cystic fibrosis, and healthy controls

A longitudinal, prospective study was conducted intermittently in Norway, from 1999 to 2008, to investigate the Candida colonization rates and species distributions in the tonsillopharyngeal and faecal flora in: (i) children with cancer; (ii) children with cystic fibrosis (CF); and (iii) healthy children. The effect of antibiotic treatment on Candida colonization was also studied, and we looked for changes in antifungal susceptibility over time within each child and between the different groups of children. In total, 566 tonsillopharyngeal swabs and 545 faecal samples were collected from 45 children with cancer, 37 children with CF, and 71 healthy, age-matched controls. The overall colonization rate with Candida was not significantly higher in the two groups of children undergoing extensive treatment with broad-spectrum antibiotics than in healthy controls. Approximately one-third of the cancer patients had a total lack of Candida colonization or had only one Candida-positive sample, despite multiple samples being taken, treatment with broad-spectrum antibiotics, long hospital stays, and periods with neutropenia. Children with CF had the highest prevalence of Candida albicans. Amoxycillin, azithromycin, third-generation cephalosporins and oral vancomycin resulted in a significantly increased Candida colonization rate. Phenoxymethylpenicillin, second-generation cephalosporins, metronidazole, trimethoprim-sulphamethoxazole, ciprofloxacin, penicillinase-resistant penicillins and inhaled tobramycin or colistin showed minimal effects on the Candida colonization rate. We found no evidence of development of antifungal resistance over time.

Implications of interspecies signaling for virulence of bacterial and fungal pathogens

Despite the broad armory of vaccines, antibiotics and other weapons at our disposal, pathogenic bacteria and fungi continue to present a serious threat to human health. These pathogens have proved very versatile and many are associated with infections of vulnerable individuals, often in hospital settings. Evidence is accumulating that certain infections, for example, of medical devices, the cystic fibrosis lung, the oral cavity, the GI tract and wounds, are in fact polymicrobial, with more than one microbe involved. To understand diseases and formulate intervention strategies, it is necessary to know the extent of contact and communication between microbes in these mixed infections. It is now emerging that the signals that microbes use to coordinate expression of viruence factors within a species may also be perceived by other microbes in the community. This article addresses such interspecies signaling and examines the consequences of such signaling between bacterial and fungal pathogens for expression of virulence traits.