Diagnosing and managing infection in CF

The Binding of Pseudomonas aeruginosa to Cystic Fibrosis Bronchial Epithelial Model Cells Alters the Composition of the Exosomes They Produce Compared to Healthy Control Cells

Cystic fibrosis (CF) is a genetic disease that causes dehydration of the surface of the airways, increasing lung infections, most frequently caused by Pseudomonas aeruginosa. Exosomes are nanovesicles released by cells that play an essential role in intercellular communication, although their role during bacterial infections is not well understood. In this article, we analyze the alterations in exosomes produced by healthy bronchial epithelial and cystic fibrosis cell lines caused by the interaction with P. aeruginosa. The proteomic study detected alterations in 30% of the species analyzed. In healthy cells, they mainly involve proteins related to the extracellular matrix, cytoskeleton, and various catabolic enzymes. In CF, proteins related to the cytoskeleton and matrix, in addition to the proteasome. These differences could be related to the inflammatory response. A study of miRNAs detected alterations in 18% of the species analyzed. The prediction of their potential biological targets identified 7149 genes, regulated by up to 7 different miRNAs. The identification of their functions showed that they preferentially affected molecules involved in binding and catalytic activities, although with differences between cell types. In conclusion, this study shows differences in exosomes between CF and healthy cells that could be involved in the response to infection.

Growing emergence of drug-resistant Pseudomonas aeruginosa and attenuation of its virulence using quorum sensing inhibitors: A critical review

A perilous increase in the number of bacterial infections has led to developing throngs of antibiotics for increasing the quality and expectancy of life. Pseudomonas aeruginosa is becoming resistant to all known conventional antimicrobial agents thereby posing a deadly threat to the human population. Nowadays, targeting virulence traits of infectious agents is an alternative approach to antimicrobials that is gaining much popularity to fight antimicrobial resistance. Quorum sensing (QS) involves interspecies communication via a chemical signaling pathway. Under this mechanism, cells work in a concerted manner, communicate with each other with the help of signaling molecules called auto-inducers (AI). The virulence of these strains is driven by genes, whose expression is regulated by AI, which in turn acts as transcriptional activators. Moreover, the problem of antibiotic-resistance in case of infections caused by P. aeruginosa becomes more alarming among immune-compromised patients, where the infectious agents easily take over the cellular machinery of the host while hidden in the QS mediated biofilms. Inhibition of the QS circuit of P. aeruginosa by targeting various signaling pathways such as LasR, RhlR, Pqs, and QScR transcriptional proteins will help in blocking downstream signal transducers which could result in reducing the bacterial virulence. The anti-virulence agent does not pose an immediate selective pressure on growing bacterium and thus reduces the pathogenicity without harming the target species. Here, we review exclusively, the growing emergence of multi-drug resistant (MDR) P. aeruginosa and the critical literature survey of QS inhibitors with their potential application of blocking P. aeruginosa infections.

Treatment for chronic methicillin-sensitive Staphylococcus aureus pulmonary infection in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is an inherited life-threatening multisystem disorder with lung disease characterized by abnormally thick airway secretions and persistent bacterial infection. Chronic, progressive lung disease is the most important cause of morbidity and mortality in the condition and is therefore the main focus of clinical care and research. Staphylococcus aureus is a major cause of chest infection in people with cystic fibrosis. Early onset, as well as chronic, lung infection with this organism in young children and adults results in worsening lung function, poorer nutrition and increases the airway inflammatory response, thus leading to a poor overall clinical outcome. There are currently no evidence-based guidelines for chronic suppressive therapy for Staphylococcus aureus infection in cystic fibrosis such as those used for Pseudomonas aeruginosa infection. This is an update of a previously published review.

OBJECTIVES

To assess the evidence regarding the effectiveness of long-term antibiotic treatment regimens for chronic infection with methicillin-sensitive Staphylococcus aureus (MSSA) infection in people with cystic fibrosis and to determine whether this leads to improved clinical and microbiological outcomes.

SEARCH METHODS

Trials were identified by searching the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, MEDLINE, Embase, handsearching article reference lists and through contact with local and international experts in the field. Date of the last search of the Group's Cystic Fibrosis Trials Register: 09 February 2018.We also searched ongoing trials databases. Date of latest search: 20 May 2018.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any combinations of topical, inhaled, oral or intravenous antimicrobials used as suppressive therapy for chronic infection with methicillin-sensitive Staphylococcus aureus compared with placebo or no treatment.

DATA COLLECTION AND ANALYSIS

The authors independently assessed all search results for eligibility. No eligible trials were identified.

MAIN RESULTS

The searches identified 58 trials, but none were eligible for inclusion in the current version of this review.

AUTHORS' CONCLUSIONS

No randomised controlled trials were identified which met the inclusion criteria for this review. Although methicillin-sensitive Staphylococcus aureus is an important and common cause of lung infection in people with cystic fibrosis, there is no agreement on how best to treat long-term infection. The review highlights the need to organise well-designed trials that can provide evidence to support the best management strategy for chronic methicillin-sensitive Staphylococcus aureus infection in people with cystic fibrosis.

Oral anti-pseudomonal antibiotics for cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa is the most common bacterial pathogen causing lung infections in people with cystic fibrosis and appropriate antibiotic therapy is vital. Antibiotics for pulmonary exacerbations are usually given intravenously, and for long-term treatment, via a nebuliser. Oral anti-pseudomonal antibiotics with the same efficacy and safety as intravenous or nebulised antibiotics would benefit people with cystic fibrosis due to ease of treatment and avoidance of hospitalisation. This is an update of a previous review.

OBJECTIVES

To determine the benefit or harm of oral anti-pseudomonal antibiotic therapy for people with cystic fibrosis, colonised with Pseudomonas aeruginosa, in the:1. treatment of a pulmonary exacerbation; and2. long-term treatment of chronic infection.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.We contacted pharmaceutical companies and checked reference lists of identified trials.Date of last search: 08 July 2016.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any dose of oral anti-pseudomonal antibiotics, to other combinations of inhaled, oral or intravenous antibiotics, or to placebo or usual treatment for pulmonary exacerbations and long-term treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the trials, extracted data and assessed quality. We contacted trial authors to obtain missing information.

MAIN RESULTS

We included three trials examining pulmonary exacerbations (171 participants) and two trials examining long-term therapy (85 participants). We regarded the most important outcomes as quality of life and lung function. The analysis did not identify any statistically significant difference between oral anti-pseudomonal antibiotics and other treatments for these outcome measures for either pulmonary exacerbations or long-term treatment. One of the included trials reported significantly better lung function when treating a pulmonary exacerbation with ciprofloxacin when compared with intravenous treatment; however, our analysis did not confirm this finding. We found no evidence of difference between oral anti-pseudomonal antibiotics and other treatments regarding adverse events or development of antibiotic resistance, but trials were not adequately powered to detect this. None of the studies had a low risk of bias from blinding which may have an impact particularly on subjective outcomes such as quality of life. The risk of bias for other criteria could not be clearly stated across the studies.

AUTHORS' CONCLUSIONS

We found no conclusive evidence that an oral anti-pseudomonal antibiotic regimen is more or less effective than an alternative treatment for either pulmonary exacerbations or long-term treatment of chronic infection with P. aeruginosa. Until results of adequately-powered future trials are available, treatment needs to be selected on a pragmatic basis, based upon any available non-randomised evidence, the clinical circumstances of the individual, the known effectiveness of drugs against local strains and upon individual preference.

Treatment for chronic methicillin-sensitive Staphylococcus aureus pulmonary infection in people with cystic fibrosis

BACKGROUND

Cystic fibrosis is an inherited life-threatening multisystem disorder with lung disease characterized by abnormally thick airway secretions and persistent bacterial infection. Chronic, progressive lung disease is the most important cause of morbidity and mortality in the condition and is therefore the main focus of clinical care and research. Staphylococcus aureus is a major cause of chest infection in people with cystic fibrosis. Early onset, as well as chronic, lung infection with this organism in young children and adults results in worsening lung function, poorer nutrition and increases the airway inflammatory response, thus leading to a poor overall clinical outcome. There are currently no evidence-based guidelines for chronic suppressive therapy for Staphylococcus aureus infection in cystic fibrosis such as those used for Pseudomonas aeruginosa infection.

OBJECTIVES

To assess the evidence regarding the effectiveness of long-term antibiotic treatment regimens for chronic infection with methicillin-sensitive Staphylococcus aureus (MSSA) infection in people with cystic fibrosis and to determine whether this leads to improved clinical and microbiological outcomes.

SEARCH METHODS

Trials were identified by searching the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, MEDLINE, Embase, handsearching article reference lists and through contact with local and international experts in the field. We also searched ongoing trials databases.Date of the last search of the Group's Cystic Fibrosis Trials Register: 03 March 2016.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any combinations of topical, inhaled, oral or intravenous antimicrobials used as suppressive therapy for chronic infection with methicillin-sensitive Staphylococcus aureus compared with placebo or no treatment.

DATA COLLECTION AND ANALYSIS

The authors independently assessed all search results for eligibility. No eligible trials were identified.

MAIN RESULTS

The searches identified 55 trials, but none were eligible for inclusion in the current version of this review.

AUTHORS' CONCLUSIONS

No randomised controlled trials were identified which met the inclusion criteria for this review. Although methicillin-sensitive Staphylococcus aureus is an important and common cause of lung infection in people with cystic fibrosis, there is no agreement on how best to treat long-term infection. The review highlights the need to organise well-designed trials that can provide evidence to support the best management strategy for chronic methicillin-sensitive Staphylococcus aureus infection in people with cystic fibrosis.

Pseudomonas aeruginosa infection in patients with cystic fibrosis: scientific evidence regarding clinical impact, diagnosis, and treatment

Evidence-based techniques have been increasingly used in the creation of clinical guidelines and the development of recommendations for medical practice. The use of levels of evidence allows the reader to identify the quality of scientific information that supports the recommendations made by experts. The objective of this review was to address current concepts related to the clinical impact, diagnosis, and treatment of Pseudomonas aeruginosa infections in patients with cystic fibrosis. For the preparation of this review, the authors defined a group of questions that would be answered in accordance with the principles of PICO-an acronym based on questions regarding the Patients of interest, Intervention being studied, Comparison of the intervention, and Outcome of interest. For each question, a structured review of the literature was performed using the Medline database in order to identify the studies with the methodological design most appropriate to answering the question. The questions were designed so that each of the authors could write a response. A first draft was prepared and discussed by the group. Recommendations were then made on the basis of the level of scientific evidence, in accordance with the classification system devised by the Oxford Centre for Evidence-Based Medicine, as well as the level of agreement among the members of the group.

Oral anti-pseudomonal antibiotics for cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa is the most common bacterial pathogen causing lung infections in people with CF and appropriate antibiotic therapy is vital. Antibiotics for pulmonary exacerbations are usually given intravenously, and for long-term treatment, via a nebuliser. Oral anti-pseudomonal antibiotics with the same efficacy and safety as intravenous or nebulised antibiotics would benefit people with CF due to ease of treatment and avoidance of hospitalisation.

OBJECTIVES

To determine the benefit or harm of oral anti-pseudomonal antibiotic therapy for people with CF, colonised with Pseudomonas aeruginosa, in the:1. treatment of a pulmonary exacerbation; and 2. long-term treatment of chronic infection.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.We contacted pharmaceutical companies and checked reference lists of identified trials.Date of last search: 28 June 2013.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any dose of oral anti-pseudomonal antibiotics, to other combinations of inhaled, oral or intravenous antibiotics, or to placebo or usual treatment for pulmonary exacerbations and long-term treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the trials, extracted data and assessed quality. We contacted trial authors to obtain missing information.

MAIN RESULTS

We included three trials examining pulmonary exacerbations (171 participants) and two trials examining long-term therapy (85 participants). We regarded the most important outcomes as quality of life and lung function. The analysis did not identify any statistically significant difference between oral anti-pseudomonal antibiotics and other treatments for these outcome measures for either pulmonary exacerbations or long-term treatment. One of the included trials reported significantly better lung function when treating a pulmonary exacerbation with ciprofloxacin when compared with intravenous treatment; however, our analysis did not confirm this finding. We found no evidence of difference between oral anti-pseudomonal antibiotics and other treatments regarding adverse events or development of antibiotic resistance, but trials were not adequately powered to detect this. None of the studies had a low risk of bias from blinding which may have an impact particularly on subjective outcomes such as quality of life. The risk of bias for other criteria could not be clearly stated across the studies.

AUTHORS' CONCLUSIONS

We found no conclusive evidence that an oral anti-pseudomonal antibiotic regimen is more or less effective than an alternative treatment for either pulmonary exacerbations or long-term treatment of chronic infection with P. aeruginosa. Until results of adequately-powered future trials are available, treatment needs to be selected on a pragmatic basis, based upon any available non-RCT evidence, the clinical circumstances of the individual, the known effectiveness of drugs against local strains and upon individual preference.

Induced sputum compared to bronchoalveolar lavage in young, non-expectorating cystic fibrosis children

BACKGROUND

Induced sputum (IS) is feasible and safe in young CF children and is a readily accessible, non-invasive technique. However, it has not been compared to bronchoalveolar lavage (BAL), the gold standard for diagnosing lower airway infection.

METHODS

We compared bacterial yield from IS and BAL in 11 non-expectorating CF children, aged 3 to 7.4 years. IS samples were obtained in 10/11 cases.

RESULTS

Eight out of ten had the same predominant bacteria cultured from IS and BAL: Pseudomonas aeruginosa and Stenotrophomonas maltophilia[1], Staphylococcus aureus[3], and upper respiratory tract flora [4]. In one, Serratia marcescens and Haemophilus parainfluenzae were cultured from IS alone, whereas in one, non-group B Haemophilus influenzae was cultured from BAL alone.

CONCLUSIONS

As proof of principle, IS samples showed good bacteriologic correlation with BAL. Larger studies are recommended to confirm IS as a clinically valuable tool and measure for early intervention studies in young CF children.

Soluble inflammation markers in nasal lavage from CF patients and healthy controls

BACKGROUND

CF sinonasal and bronchial mucosa reveal identical ion channel defects. Nasal Lavage (NL) allows non-invasive repeated sampling of airway surface liquid. We compared inflammatory mediators in NL from CF-patients and healthy controls, and in CF in relation to sinonasal pathogen colonization.

METHODS

From 40 CF-patients (mean age 21.8yrs, SD 11.8yrs.) and 52 healthy controls (mean age 31.9yrs., SD 13.7yrs.) NL-fluid (10ml/nostril) concentrations of MPO, IL-8, IL-17A, sICAM-1, IL-1β, IL-6, TNF-α, IL-10 and IL-5 were determined using cytometric bead arrays for flow cytometry.

RESULTS

CF-patients showed significantly higher MPO-concentrations in NL-fluid and higher IL-8-levels (n.s.) than controls. MPO, IL-8, IL-17A, sICAM-1, IL-1β and IL-6 were significantly more often detectable in CF-patients than in controls. CF-patients with S. aureus colonization in both upper and lower airways had significantly elevated MPO and IL-8 levels in NL-fluid compared to S. aureus negatives.

CONCLUSION

NL-fluid differed substantially between CF-patients and healthy controls with most promising results for IL-8 and MPO, a primarily in CF-NL assessed mediator. Further studies are required to assess effects of sample collection and processing on concentrations of inflammatory markers and to evaluate potentials of NL analysis in research and clinical routine.

Innate immunity in cystic fibrosis lung disease

Chronic lung disease determines the morbidity and mortality of cystic fibrosis (CF) patients. The pulmonary immune response in CF is characterized by an early and non-resolving activation of the innate immune system, which is dysregulated at several levels. Here we provide a comprehensive overview of innate immunity in CF lung disease, involving (i) epithelial dysfunction, (ii) pathogen sensing, (iii) leukocyte recruitment, (iv) phagocyte impairment, (v) mechanisms linking innate and adaptive immunity and (iv) the potential clinical relevance. Dissecting the complex network of innate immune regulation and associated pro-inflammatory cascades in CF lung disease may pave the way for novel immune-targeted therapies in CF and other chronic infective lung diseases.

High-Dose Ibuprofen in Cystic Fibrosis

Cystic Fibrosis (CF) is the most common lethal genetic disorder in North America and Europe. Most patients succumb to progressive lung disease characterized by an exaggerated neutrophilic inflammation. In animal models of chronic infection, high-dose ibuprofen was demonstrated to reduce inflammation without hindering bacterial clearance. This led to two clinical trials, which demonstrated a benefit in slowing the progression of lung disease in CF. However, concerns about potential adverse effects have limited the use of high-dose ibuprofen in CF patients. There are a variety of potential mechanisms to account for the observed clinical benefit. A better understanding of these mechanisms could potentially lead to more targeted and better-tolerated anti-inflammatory therapies.

Bugs, biofilms, and resistance in cystic fibrosis

Bacteria infect the respiratory tract early in the course of cystic fibrosis disease, often fail to be eradicated, and together with an aggressive host inflammatory response, are thought to be key players in the irreversible airway damage from which most patients ultimately die. Although incompletely understood, certain aspects of the cystic fibrosis airway itself appear to favor the development of chronic modes of survival, in particular biofilm formation; this and the development of antibiotic resistance following exposure to multiple antibiotic courses lead to chronic, persistent infection. In addition to the common cystic fibrosis pathogens, such as Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa, several newer species are becoming more common. Furthermore, new molecular techniques have led to the identification of multiple different organisms within respiratory secretions, many of which are not cultured with conventional tools. Future work should aim to develop clinically applicable methods to identify these and to determine which have the potential to impact pulmonary health. We outline the basic tenets of infection control and treatment.

Oral anti-pseudomonal antibiotics for cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa is the most common bacterial pathogen causing infection in the lungs of people with CF and appropriate antibiotic therapy is vital. Antibiotics for exacerbations are usually given intravenously, and for long-term treatment, via a nebuliser. Oral anti-pseudomonal antibiotics with the same efficacy and safety as intravenous or nebulised antibiotics would benefit the quality of life of people with CF due to ease of treatment and avoidance of hospitalisation.

OBJECTIVES

To determine the benefit or harm of oral anti-pseudomonal antibiotic therapy for people with CF, colonised with Pseudomonas aeruginosa, in the: (1) treatment of an exacerbation of respiratory tract infection; and (2) long-term treatment in chronic infection.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We contacted pharmaceutical companies for information on relevant trials and checked reference lists of identified trials. Most recent search: March 2007.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any dose of oral anti-pseudomonal antibiotics, with other combinations of inhaled, oral or intravenous antibiotics, or with placebo or usual treatment for exacerbations and long-term treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently selected the trials, extracted data and assessed quality. We contacted trialists to obtain missing information.

MAIN RESULTS

We included four trials examining exacerbations (197 participants) and two trials examining long-term therapy (85 participants). We regarded the most important outcomes as quality of life and lung function. In our analysis, we were unable to identify any statistically significant difference between oral anti-pseudomonal antibiotics and other treatments for these outcome measures for either exacerbations or long-term treatment. One of the included trials reported significantly better lung function when treating an exacerbation with ciprofloxacin when compared with intravenous treatment; however, our analysis did not confirm this finding. We found no evidence of difference between oral anti-pseudomonal antibiotics and other treatments regarding adverse events or development of antibiotic resistance, but trials were not adequately powered to detect this.

AUTHORS' CONCLUSIONS

We found no conclusive evidence that an oral anti-pseudomonal antibiotic regimen is more or less effective than an alternative treatment for either exacerbations or long-term treatment of chronic infection with P. aeruginosa. Until results of adequately-powered future trials are available, treatment needs to be selected on a pragmatic basis, based upon known effectiveness against local strains and upon individual preference.

Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium

Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.