Revisiting Host-Pathogen Interactions in Cystic Fibrosis Lungs in the Era of CFTR Modulators.

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators, a new series of therapeutics that correct and potentiate some classes of mutations of the CFTR, have provided a great therapeutic advantage to people with cystic fibrosis (pwCF). The main hindrances of the present CFTR modulators are related to their limitations in reducing chronic lung bacterial infection and inflammation, the main causes of pulmonary tissue damage and progressive respiratory insufficiency, particularly in adults with CF. Here, the most debated issues of the pulmonary bacterial infection and inflammatory processes in pwCF are revisited. Special attention is given to the mechanisms favoring the bacterial infection of pwCF, the progressive adaptation of Pseudomonas aeruginosa and its interplay with Staphylococcus aureus, the cross-talk among bacteria, the bronchial epithelial cells and the phagocytes of the host immune defenses. The most recent findings of the effect of CFTR modulators on bacterial infection and the inflammatory process are also presented to provide critical hints towards the identification of relevant therapeutic targets to overcome the respiratory pathology of pwCF.

Cystic Fibrosis Airway Mucus Hyperconcentration Produces a Vicious Cycle of Mucin, Pathogen, and Inflammatory Interactions that Promotes Disease Persistence.

The dynamics describing the vicious cycle characteristic of cystic fibrosis (CF) lung disease, initiated by stagnant mucus and perpetuated by infection and inflammation, remain unclear. Here we determine the effect of the CF airway milieu, with persistent mucoobstruction, resident pathogens, and inflammation, on the mucin quantity and quality that govern lung disease pathogenesis and progression. The concentrations of MUC5AC and MUC5B were measured and characterized in sputum samples from subjects with CF (N = 44) and healthy subjects (N = 29) with respect to their macromolecular properties, degree of proteolysis, and glycomics diversity. These parameters were related to quantitative microbiome and clinical data. MUC5AC and MUC5B concentrations were elevated, 30- and 8-fold, respectively, in CF as compared with control sputum. Mucin parameters did not correlate with hypertonic saline, inhaled corticosteroids, or antibiotics use. No differences in mucin parameters were detected at baseline versus during exacerbations. Mucin concentrations significantly correlated with the age and sputum human neutrophil elastase activity. Although significantly more proteolytic cleavages were detected in CF mucins, their macromolecular properties (e.g., size and molecular weight) were not significantly different than control mucins, likely reflecting the role of S-S bonds in maintaining multimeric structures. No evidence of giant mucin macromolecule reflecting oxidative stress-induced cross-linking was found. Mucin glycomic analysis revealed significantly more sialylated glycans in CF, and the total abundance of nonsulfated O-glycans correlated with the relative abundance of pathogens. Collectively, the interaction of mucins, pathogens, epithelium, and inflammatory cells promotes proteomic and glycomic changes that reflect a persistent mucoobstructive, infectious, and inflammatory state.

Interventions for the eradication of meticillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

BACKGROUND: Cystic fibrosis is an inherited recessive disorder of chloride transport that is characterised by recurrent and persistent pulmonary infections from resistant organisms that result in lung function deterioration and early mortality in sufferers. Meticillin-resistant Staphylococcus aureus (MRSA) has emerged not only as an important infection in people who are hospitalised, but also as a potentially harmful pathogen in cystic fibrosis. Chronic pulmonary infection with MRSA is thought to confer on people with cystic fibrosis a worse clinical outcome and result in an increased rate of lung function decline. Clear guidance for MRSA eradication in cystic fibrosis, supported by robust evidence, is urgently needed. This is an update of a previous review. OBJECTIVES: To evaluate the effectiveness of treatment regimens designed to eradicate MRSA and to determine whether the eradication of MRSA confers better clinical and microbiological outcomes for people with cystic fibrosis. To ascertain whether attempts at eradicating MRSA can lead to increased acquisition of other resistant organisms (including Pseudomonas aeruginosa), increased adverse effects from drugs, or both. SEARCH METHODS: We identified randomised and quasi-randomised controlled trials by searching the Cochrane Cystic Fibrosis and Genetic Disorders (CFGD) Group's Cystic Fibrosis Trials Register, PubMed, MEDLINE and three clinical trials registries; by handsearching article reference lists; and through contact with experts in the field. We last searched the CFGD Group's Cystic Fibrosis Trials Register on 4 October 2021, and the ongoing trials registries on 31 January 2022. SELECTION CRITERIA: Randomised controlled trials (RCTs) or quasi-RCTs of any combinations of topical, inhaled, oral or intravenous antimicrobials primarily aimed at eradicating MRSA compared with placebo, standard treatment or no treatment. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane and used the GRADE methodology to assess the certainty of the evidence. MAIN RESULTS: The review includes three RCTs with 135 participants with MRSA infection. Two trials compared active treatment versus observation only and one trial compared active treatment with placebo.  Active treatment versus observation In both trials (106 participants), active treatment consisted of oral trimethoprim and sulfamethoxazole combined with rifampicin. One trial administered this combination for two weeks alongside nasal, skin and oral decontamination and a three-week environmental decontamination, while the second trial administered this drug combination for 21 days with five days intranasal mupirocin. Both trials reported successful eradication of MRSA in people with cystic fibrosis, but they used different definitions of eradication. One trial (45 participants) defined MRSA eradication as negative MRSA respiratory cultures at day 28, and reported that oral trimethoprim and sulfamethoxazole combined with rifampicin may lead to a higher proportion of negative cultures compared to control (odds ratio (OR) 12.6 (95% confidence interval (CI) 2.84 to 55.84; low-certainty evidence). However, by day 168 of follow-up, there was no difference between groups in the proportion of participants who remained MRSA-negative (OR 1.17, 95% CI 0.31 to 4.42; low-certainty evidence). The second trial defined successful eradication as the absence of MRSA following treatment in at least three cultures over a period of six months. We are uncertain if the intervention led to results favouring the treatment group as the certainty of the evidence was very low (OR 2.74, 95% CI 0.64 to 11.75). There were no differences between groups in the remaining outcomes for this comparison: quality of life, frequency of exacerbations or adverse effects (all low-certainty evidence) or the change from baseline in lung function or weight (both very low-certainty evidence). The time until next positive MRSA isolate was not reported. The included trials found no differences between groups in terms of nasal colonisation with MRSA. While not a specific outcome of this review, investigators from one study reported that the rate of hospitalisation from screening through day 168 was lower with oral trimethoprim and sulfamethoxazole combined with rifampicin compared to control (rate ratio 0.22, 95% CI 0.05 to 0.72; P = 0.01). Nebulised vancomycin with oral antibiotics versus nebulised placebo with oral antibiotics The third trial (29 participants) defined eradication as a negative respiratory sample for MRSA at one month following completion of treatment. No differences were reported in MRSA eradication between treatment arms (OR 1.00, 95% CI 0.14 to 7.39; low-certainty evidence). No differences between groups were seen in lung function or adverse effects (low-certainty evidence), in quality of life (very low-certainty evidence) or nasal colonisation with MRSA. The trial did not report on the change in weight or frequency of exacerbations.  AUTHORS' CONCLUSIONS: Early eradication of MRSA is possible in people with cystic fibrosis, with one trial demonstrating superiority of active MRSA treatment compared with observation only in terms of the proportion of MRSA-negative respiratory cultures at day 28. However, follow-up at three or six months showed no difference between treatment and control in the proportion of participants remaining MRSA-negative. Moreover, the longer-term clinical consequences - in terms of lung function, mortality and cost of care - remain unclear. Using GRADE methodology, we judged the certainty of the evidence provided by this review to be very low to low, due to potential biases from the open-label design, high rates of attrition and small sample sizes. Based on the available evidence, we believe that whilst early eradication of respiratory MRSA in people with cystic fibrosis is possible, there is not currently enough evidence regarding the clinical outcomes of eradication to support the use of the interventions studied.

Initial acquisition and succession of the cystic fibrosis lung microbiome is associated with disease progression in infants and preschool children.

The cystic fibrosis (CF) lung microbiome has been studied in children and adults; however, little is known about its relationship to early disease progression. To better understand the relationship between the lung microbiome and early respiratory disease, we characterized the lower airways microbiome using bronchoalveolar lavage (BAL) samples obtained from clinically stable CF infants and preschoolers who underwent bronchoscopy and chest computed tomography (CT). Cross-sectional samples suggested a progression of the lower airways microbiome with age, beginning with relatively sterile airways in infancy. By age two, bacterial sequences typically associated with the oral cavity dominated lower airways samples in many CF subjects. The presence of an oral-like lower airways microbiome correlated with a significant increase in bacterial density and inflammation. These early changes occurred in many patients, despite the use of antibiotic prophylaxis in our cohort during the first two years of life. The majority of CF subjects older than four harbored a pathogen dominated airway microbiome, which was associated with a further increase in inflammation and the onset of structural lung disease, despite a negligible increase in bacterial density compared to younger patients with an oral-like airway microbiome. Our findings suggest that changes within the CF lower airways microbiome occur during the first years of life and that distinct microbial signatures are associated with the progression of early CF lung disease.

Chronic E-Cigarette Use Increases Neutrophil Elastase and Matrix Metalloprotease Levels in the Lung.

Rationale: Proteolysis is a key aspect of the lung's innate immune system. Proteases, including neutrophil elastase and MMPs (matrix metalloproteases), modulate cell signaling, inflammation, tissue remodeling, and leukocyte recruitment via cleavage of their target proteins. Excessive proteolysis occurs with chronic tobacco use and is causative for bronchiectasis and emphysema. The effect of e-cigarettes (vaping) on proteolysis is unknown.Objectives: We used protease levels as biomarkers of harm to determine the impact of vaping on the lung.Methods: We performed research bronchoscopies on healthy nonsmokers, cigarette smokers, and e-cigarette users (vapers), and determined protease levels in BAL. In parallel, we studied the effects of e-cigarette components on protease secretion in isolated human blood neutrophils and BAL-derived macrophages. We also analyzed the nicotine concentration in induced sputum and BAL.Measurements and Main Results: Neutrophil elastase, MMP-2, and MMP-9 activities and protein levels were equally elevated in both vapers' and smokers' BAL relative to nonsmokers. In contrast, antiprotease levels were unchanged. We also found that exposure of isolated neutrophils and macrophages to nicotine elicited dose-dependent increases in protease release. After vaping, measurable levels of nicotine were detectable in sputum and BAL, which corresponded to the half-maximal effective concentration values for protease release seen in immune cells.Conclusions: We conclude that vaping induces nicotine-dependent protease release from resident pulmonary immune cells. Thus, chronic vaping disrupts the protease-antiprotease balance by increasing proteolysis in lung, which may place vapers at risk of developing chronic lung disease. These data indicate that vaping may not be safer than tobacco smoking.

Anaerobic bacteria cultured from cystic fibrosis airways correlate to milder disease: a multisite study.

Anaerobic and aerobic bacteria were quantitated in respiratory samples across three cystic fibrosis (CF) centres using extended culture methods. Subjects aged 1-69 years who were clinically stable provided sputum (n=200) or bronchoalveolar lavage (n=55). 18 anaerobic and 39 aerobic genera were cultured from 59% and 95% of samples, respectively; 16 out of 57 genera had a ≥5% prevalence across centres.Analyses of microbial communities using co-occurrence networks in sputum samples showed groupings of oral, including anaerobic, bacteria, whereas typical CF pathogens formed distinct entities. Pseudomonas was associated with worse nutrition and F508del genotype, whereas anaerobe prevalence was positively associated with pancreatic sufficiency, better nutrition and better lung function. A higher total anaerobe/total aerobe CFU ratio was associated with pancreatic sufficiency and better nutrition. Subjects grouped by factor analysis who had relative dominance of anaerobes over aerobes had milder disease compared with a Pseudomonas-dominated group with similar proportions of subjects that were homozygous for F508del.In summary, anaerobic bacteria occurred at an early age. In sputum-producing subjects anaerobic bacteria were associated with milder disease, suggesting that targeted eradication of anaerobes may not be warranted in sputum-producing CF subjects.

Interventions for the eradication of meticillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

BACKGROUND: Cystic fibrosis is an inherited recessive disorder of chloride transport that is characterised by recurrent and persistent pulmonary infections from resistant organisms that result in lung function deterioration and early mortality in sufferers.Meticillin-resistant Staphylococcus aureus (MRSA) has emerged as, not only an important infection in people who are hospitalised, but also as a potentially harmful pathogen in cystic fibrosis. Chronic pulmonary infection with MRSA is thought to confer people with cystic fibrosis with a worse clinical outcome and result in an increased rate of lung function decline. Clear guidance for MRSA eradication in cystic fibrosis, supported by robust evidence, is urgently needed. This is an update of a previous review. OBJECTIVES: To evaluate the effectiveness of treatment regimens designed to eradicate MRSA and to determine whether the eradication of MRSA confers better clinical and microbiological outcomes for people with cystic fibrosis. To ascertain whether attempts at eradicating MRSA can lead to increased acquisition of other resistant organisms (including P aeruginosa) or increased adverse effects from drugs, or both. SEARCH METHODS: Randomised and quasi-randomised controlled trials were identified by searching the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, PubMed, MEDLINE, clinical trial registries (Clinicaltrials.gov, WHO ICTRP, ISRCTN Registry), handsearching article reference lists and through contact with experts in the field.Date of the last search of the Group's Cystic Fibrosis Trials Register: 27 July 2017.Ongoing trials registries were last searched: 07 August 2017. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing any combinations of topical, inhaled, oral or intravenous antimicrobials with the primary aim of eradicating MRSA compared with placebo, standard treatment or no treatment. DATA COLLECTION AND ANALYSIS: The authors independently assessed all search results for eligibility. They used the GRADE methodology to assess the quality of the evidence. MAIN RESULTS: The review includes two trials with a total of 106 participants with MRSA infection. In both trials the active treatment was oral trimethoprim and sulfamethoxazole combined with rifampicin; however, one trial administered this combination for two weeks alongside nasal, skin and oral decontamination and a three-week environmental decontamination, while the second trial administered this drug combination for 21 days with five days intranasal mupirocin. In both trials the control arm was observation only.Both trials reported successful eradication of MRSA in people with CF as an outcome; however, the definition used for MRSA eradication differed. The first trial (n = 45) defined MRSA eradication as negative MRSA respiratory cultures at day 28, and reported that, when compared to control, oral trimethoprim and sulfamethoxazole combined with rifampicin may lead to a higher proportion of negative cultures, odds ratio (OR) 12.6 (95% confidence interval (CI) 2.84 to 55.84; low-certainty evidence); however, by day 168 of follow-up there was no difference in the proportion of participants who remained MRSA-negative in either treatment arm, OR 1.17 (95% CI 0.31 to 4.42) (low-quality evidence). In the second trial, successful eradication was defined as the absence of MRSA following treatment (oral co-trimoxazole and rifampicin with intranasal mupirocin or observation) in at least three cultures over a period of six months. At the time of reporting, 40 out of 61 participants had completed follow-up, but results showed no difference between groups. Eradication was achieved in 12 out 29 participants (41%) receiving active treatment, and in 9 out of 32 participants (28%) on the observation arm, OR 1.80 (95% CI 0.62 to 5.25) (very low-quality evidence).With regards to this review's secondary outcomes, these were reported in the first trial only. The trial reports that no differences were observed between the two arms in terms of pulmonary exacerbations (from screening to day 28), nasal colonisation, lung function, weight or participant-reported outcomes. While not a specific outcome of this review, investigators reported that the rate of hospitalisation from screening through day 168 was lower with oral trimethoprim and sulfamethoxazole combined with rifampicin compared to control, rate ratio 0.22 (95% CI 0.05 to 0.72) (P = 0.0102). AUTHORS' CONCLUSIONS: Early eradication of MRSA is possible in people with cystic fibrosis, with one trial demonstrating superiority of active MRSA treatment compared with observation only in terms of the proportion of MRSA-negative respiratory cultures at day 28. However, by six months, the proportion of participants who remained MRSA-negative did not differ between treatment arms in either trial. Moreover, the longer-term clinical consequences in terms of lung function, mortality and cost of care, remain unclear.Using GRADE methodology, we judged the quality of the evidence provided by this review to be very low to low, due to potential biases from the open-label design and unclear detail reported in one trial. Based on the available evidence, it is the opinion of the authors that whilst early eradication of respiratory MRSA in people with cystic fibrosis is possible, there is not currently enough evidence regarding the clinical outcomes of eradication to support the use of the interventions studied.

Methicillin-resistant Staphylococcus aureus in cystic fibrosis: how should it be managed?

PURPOSE OF REVIEW: Methicillin-resistant Staphylococcus aureus (MRSA) remains prevalent in people with cystic fibrosis (CF). As chronic infection is often associated with worse pulmonary outcomes, the organism is concerning to CF providers and patients. This review describes current epidemiology, our understanding of risk factors for MRSA infection, and relevant aspects of treatment with review of new and ongoing trials. RECENT FINDINGS: Prevalence ranges from a low of 3 to 4% in some European countries to a high of approximately 26% in the United States. Risk factors for chronic MRSA infection include patient-specific factors such as genotype, pancreatic insufficiency, diabetes and antibiotic use; however, warmer climate also contributes to increased MRSA rates in CF and non-CF. In addition to retrospective reviews, a few clinical trials are being conducted or have been performed showing the successful short-term eradication of incident MRSA. Chronic MRSA remains challenging to eradicate and antibiotics should be dosed to adjust for CF-specific pharmacokinetics. SUMMARY: As chronic MRSA will remain a long-term challenge to treat, ongoing effort should focus on the prevention of transmission with a need to better understand patient's environmental and modifiable risk factors. Early treatment appears successful; however, protocols to achieve long-term clearance are lacking.

Metabolomic biomarkers predictive of early structural lung disease in cystic fibrosis.

Neutrophilic airway inflammation plays a role in early structural lung disease in cystic fibrosis, but the mechanisms underlying this pathway are incompletely understood.Metabolites associated with neutrophilic inflammation were identified by discovery metabolomics on bronchoalveolar lavage fluid supernatant from 20 preschool children (2.9±1.3 years) with cystic fibrosis. Targeted mass-spectrometric detection of relevant metabolites was then applied to 34 children (3.5±1.5 years) enrolled in the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) who underwent chest computed tomography and bronchoalveolar lavage from two separate lobes during 42 visits. Relationships between metabolites and localised structural lung disease were assessed using multivariate analyses.Discovery metabolomics identified 93 metabolites associated with neutrophilic inflammation, including pathways involved in metabolism of adenyl purines, amino acids and small peptides, cellular energy and lipids. In targeted mass spectrometry, products of adenosine metabolism, protein catabolism and oxidative stress were associated with structural lung disease and predicted future bronchiectasis, and activities of enzymes associated with adenosine metabolism were elevated in the samples with early disease.Metabolomics analyses revealed metabolites and pathways altered with neutrophilic inflammation and destructive lung disease. These pathways can serve as biomarkers and potential therapeutic targets for early cystic fibrosis lung disease.

Population pharmacokinetics of meropenem administered as a prolonged infusion in children with cystic fibrosis.

OBJECTIVES: Meropenem is frequently used to treat pulmonary exacerbations in children with cystic fibrosis (CF) in the USA. Prolonged-infusion meropenem improves the time that free drug concentrations remain above the MIC (fT> MIC) in adults, but data in CF children are sparse. We describe the population pharmacokinetics, tolerability and treatment burden of prolonged-infusion meropenem in CF children. METHODS: Thirty children aged 6-17 years with a pulmonary exacerbation received 40 mg/kg meropenem every 8 h; each dose was administered as a 3 h infusion. Pharmacokinetics were determined using population methods in Pmetrics. Monte Carlo simulation was employed to compare 0.5 with 3 h infusions to estimate the probability of pharmacodynamic target attainment (PTA) at 40% fT> MIC. NCT#01429259. RESULTS: A two-compartment model fitted the data best with clearance and volume predicted by body weight. Clearance and volume of the central compartment were 0.41 ±â€Š0.23 L/h/kg and 0.30 ±â€Š0.17 L/kg, respectively. Half-life was 1.11 ±â€Š0.38 h. At MICs of 1, 2 and 4 mg/L, PTAs for the 0.5 h infusion were 87.6%, 70.1% and 35.4%, respectively. The prolonged infusion increased PTAs to >99% for these MICs and achieved 82.8% at 8 mg/L. Of the 30 children, 18 (60%) completed treatment with prolonged infusion; 5 did so at home without any reported burden. Nine patients were changed to a 0.5 h infusion when discharged home. CONCLUSIONS: In these CF children, meropenem clearance was greater compared with published values from non-CF children. Prolonged infusion provided an exposure benefit against pathogens with MICs ≥1 mg/L, was well tolerated and was feasible to administer in the hospital and home settings, the latter depending on perception and family schedule.

The Role of Short-Chain Fatty Acids, Produced by Anaerobic Bacteria, in the Cystic Fibrosis Airway.

RATIONALE: Anaerobic bacteria are present in large numbers in the airways of people with cystic fibrosis (PWCF). In the gut, anaerobes produce short-chain fatty acids (SCFAs) that modulate immune and inflammatory processes. OBJECTIVES: To investigate the capacity of anaerobes to contribute to cystic fibrosis (CF) airway pathogenesis via SCFAs. METHODS: Samples of 109 PWCF were processed using anaerobic microbiological culture with bacteria present identified by 16S RNA sequencing. SCFA levels in anaerobic supernatants and bronchoalveolar lavage (BAL) were determined by gas chromatography. The mRNA and/or protein expression of two SCFA receptors, GPR41 and GPR43, in CF and non-CF bronchial brushings and 16HBE14o(-) and CFBE41o(-) cells were evaluated using reverse transcription polymerase chain reaction, Western blot analysis, laser scanning cytometry, and confocal microscopy. SCFA-induced IL-8 secretion was monitored by ELISA. MEASUREMENTS AND MAIN RESULTS: Fifty-seven (52.3%) of 109 PWCF were anaerobe positive. Prevalence increased with age, from 33.3% to 57.7% in PWCF younger (n = 24) and older (n = 85) than 6 years of age. All evaluated anaerobes produced millimolar concentrations of SCFAs, including acetic, propionic, and butyric acids. SCFA levels were higher in BAL samples of adults than in those of children. GPR41 levels were elevated in CFBE41o(-) versus 16HBE14o(-) cells; CF versus non-CF bronchial brushings; and 16HBE14o(-) cells after treatment with cystic fibrosis transmembrane conductance regulator inhibitor CFTR(inh)-172, CF BAL, or inducers of endoplasmic reticulum stress. SCFAs induced a dose-dependent and pertussis toxin-sensitive IL-8 response in bronchial epithelial cells, with a higher production of IL-8 in CFBE41o(-) than in 16HBE14o(-) cells. CONCLUSIONS: This study illustrates that SCFAs contribute to excessive production of IL-8 in CF airways colonized with anaerobes via up-regulated GPR41.

Interventions for the eradication of meticillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

BACKGROUND: Cystic fibrosis is an inherited recessive disorder of chloride transport that is characterised by recurrent and persistent pulmonary infections from resistant organisms that result in lung function deterioration and early mortality in sufferers.Meticillin-resistant Staphylococcus aureus (MRSA) has emerged as, not only an important infection in long-term hospitalised patients, but also as a potentially harmful pathogen in cystic fibrosis, and has been increasing steadily in prevalence internationally. Chronic pulmonary infection with MRSA is thought to confer cystic fibrosis patients with a worse overall clinical outcome and, in particular, result in an increased rate of decline in lung function. Clear guidance for the eradication of MRSA in cystic fibrosis, supported by robust evidence from good quality trials, is urgently needed. OBJECTIVES: To evaluate the effectiveness of treatment regimens designed to eradicate MRSA and to determine whether the eradication of MRSA confers better clinical and microbiological outcomes for people with cystic fibrosis. SEARCH METHODS: Randomised and quasi-randomised controlled trials were identified by searching the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, PUBMED, 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: 04 September 2014. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing any combinations of topical, inhaled, oral or intravenous antimicrobials with the primary aim of eradicating MRSA compared with placebo, standard treatment or no treatment. DATA COLLECTION AND ANALYSIS: The authors independently assessed all search results for eligibility. No eligible trials were identified for inclusion. MAIN RESULTS: No current published eligible trials were identified, although three ongoing clinical trials are likely to be eligible for inclusion in future updates of this review. AUTHORS' CONCLUSIONS: We did not identify any randomised trials which would allow us to make any evidence-based recommendations. Although the results of several non-randomised studies would suggest that, once isolated, the eradication of MRSA is possible; whether this has a significant impact on clinical outcome is still unclear. Further research is required to guide clinical decision making in the management of MRSA infection in cystic fibrosis.

Inter-α-inhibitor blocks epithelial sodium channel activation and decreases nasal potential differences in ΔF508 mice.

Increased activity of lung epithelial sodium channels (ENaCs) contributes to the pathophysiology of cystic fibrosis (CF) by increasing the rate of epithelial lining fluid reabsorption. Inter-α-inhibitor (IαI), a serum protease inhibitor, may decrease ENaC activity by preventing its cleavage by serine proteases. High concentrations of IαI were detected in the bronchoalveolar lavage fluid (BALF) of children with CF and lower airway diseases. IαI decreased amiloride-sensitive (IENaC) but not cAMP-activated Cl(-) currents across confluent monolayers of rat ATII, and mouse nasal epithelial cells grew in primary culture by 45 and 25%, respectively. Changes in IENaC by IαI in ATII cells were accompanied by increased levels of uncleaved (immature) surface α-ENaC. IαI increased airway surface liquid depth overlying murine nasal epithelial cells to the same extent as amiloride, consistent with ENaC inhibition. Incubation of lung slices from C57BL/6, those lacking phenylalanine at position 508 (∆F508), or CF transmembrane conductance regulator knockout mice with IαI for 3 hours decreased the open probability of their ENaC channels by 50%. ∆F508 mice had considerably higher levels the amiloride-sensitive fractions of ENaC nasal potential difference (ENaC-NPD) than wild-type littermates and only background levels of IαI in their BALF. A single intranasal instillation of IαI decreased their ENaC-NPD 24 hours later by 25%. In conclusion, we show that IαI is present in the BALF of children with CF, is an effective inhibitor of ENaC proteolysis, and decreases ENaC activity in lung epithelial cells of ∆F508 mice.

Mechanisms of reduced susceptibility and genotypic prediction of antibiotic resistance in Prevotella isolated from cystic fibrosis (CF) and non-CF patients.

OBJECTIVES: To investigate mechanisms of reduced susceptibility to commonly used antibiotics in Prevotella cultured from patients with cystic fibrosis (CF), patients with invasive infection and healthy control subjects and to determine whether genotype can be used to predict phenotypic resistance. METHODS: The susceptibility of 157 Prevotella isolates to seven antibiotics was compared, with detection of resistance genes (cfxA-type gene, ermF and tetQ), mutations within the CfxA-type ß-lactamase and expression of efflux pumps. RESULTS: Prevotella isolates positive for a cfxA-type gene had higher MICs of amoxicillin and ceftazidime compared with isolates negative for this gene (P < 0.001). A mutation within the CfxA-type ß-lactamase (Y239D) was associated with ceftazidime resistance (P = 0.011). The UK CF isolates were 5.3-fold, 2.7-fold and 5.7-fold more likely to harbour ermF compared with the US CF, UK invasive and UK healthy control isolates, respectively. Higher concentrations of azithromycin (P < 0.001) and clindamycin (P < 0.001) were also required to inhibit the growth of the ermF-positive isolates compared with ermF-negative isolates. Furthermore, tetQ-positive Prevotella isolates had higher MICs of tetracycline (P = 0.001) and doxycycline (P < 0.001) compared with tetQ-negative isolates. Prevotella spp. were also shown, for the first time, to express resistance nodulation division (RND)-type efflux pumps. CONCLUSIONS: This study has demonstrated that Prevotella isolated from various sources harbour a common pool of resistance genes and possess RND-type efflux pumps, which may contribute to tetracycline resistance. The findings indicate that antibiotic resistance is common in Prevotella spp., but the genotypic traits investigated do not reflect phenotypic antibiotic resistance in every instance.

Longitudinal changes in the cystic fibrosis airway microbiota with time and treatment.

BACKGROUND: Whether there is any benefit in integrating culture-independent molecular analysis of the lower airway microbiota of people with cystic fibrosis into clinical care is unclear. This study determined the longitudinal trajectory of the microbiota and if there were microbiota characteristics that corresponded with response to treatment or predicted a future pulmonary exacerbation. METHODS: At least one sputum sample was collected from 149 participants enrolled in this prospective longitudinal multi-centre study and total bacterial density and microbiota community measurements were determined and compared with clinical parameters. RESULTS: In 114 participants with paired samples when clinically stable, ∼8 months apart, the microbiota remained conserved between timepoints, regardless of whether participants received acute intravenous antibiotic treatment or not. In 62 participants, who presented with an acute exacerbation, a decrease in community richness correlated best with patient response to antibiotic treatment. Analysis of baseline samples from 30 participants who exacerbated within 4 months of their stable sample being collected and 72 participants who remained stable throughout the study showed that community characteristics such as lower richness at baseline may be predictive of an exacerbation in addition to several clinical parameters. However, lasso regression analysis indicated that only lung function (p = 0.014) was associated with a future exacerbation. CONCLUSIONS: The airway microbiota remains stable over periods <1 year with modest shifts related to treatment apparent which might provide some additional insights to patient-level measurements.

Antibiotic resistance in Prevotella species isolated from patients with cystic fibrosis.

OBJECTIVES: To compare the antimicrobial susceptibility of Prevotella spp. isolated from cystic fibrosis (CF) and non-CF patients and analyse the impact of antibiotic prescribing in the preceding year on resistance amongst CF isolates. METHODS: The susceptibility of 80 CF Prevotella isolates to 12 antibiotics was compared with that of 50 Prevotella isolates from invasive infections in people who did not have CF and 27 Prevotella isolates from healthy controls. RESULTS: All isolates were susceptible to chloramphenicol, meropenem and piperacillin/tazobactam, with only four isolates resistant to metronidazole. However, resistance to amoxicillin, ceftazidime and tetracycline was apparent in all groups. Significant differences in clindamycin resistance (UK CF, 56%; UK invasive, 10%) and co-amoxiclav non-susceptibility (UK CF, 32%; UK invasive, 12%) were observed between UK CF and UK invasive isolates. The likelihood of non-susceptibility to clindamycin and co-amoxiclav in UK CF isolates was 5.5-fold and 2.5-fold higher relative to that in UK invasive isolates, respectively. Azithromycin MICs were also significantly higher for CF isolates (P < 0.001), which was associated with current prescription of azithromycin. More than 50% of clinical isolates tested in this study were ß-lactamase positive. CONCLUSIONS: This study profiles antibiotic susceptibility in Prevotella spp. in CF and demonstrates that meropenem, piperacillin/tazobactam, chloramphenicol and metronidazole are likely to be the most effective antibiotics if treatment is indicated.

Relationship of sleep to pulmonary function in mucopolysaccharidosis II.

OBJECTIVE: To study the sleep characteristics, pulmonary function, and their relationships in an enzyme naive population of patients with mucopolysaccharidoses (MPS) II (Hunter syndrome). STUDY DESIGN: The analyzed subjects (30 patients with MPS II with a median age of 9 years) had been enrolled in an MPS II natural history study and a phase I/II enzyme replacement clinical study in which they underwent standard polysomnography including spirometry and plethysmography, if cooperative. Descriptive statistics and nonparametric correlation were performed for demographic, sleep, and pulmonary function variables. RESULTS: Median apnea-hypopnea index was 6.4, with obstructive sleep apnea observed in 27/30 subjects. Sleep architecture was characterized by diminished rapid-eye movement sleep duration (median 13%), and decline in sleep efficiency and slow-wave sleep duration in older individuals. Oxygen desaturation below 90% occurred in 26/30 subjects, and hypoventilation above 50 Torr occurred in 11/23 subjects with accurate end-tidal carbon dioxide recordings. Of 15 subjects with reliable spirometry, median forced expiratory volume in 1 second was below 80% predicted in 12/15 subjects. Forced expiratory volume in 1 second in percent-predicted was inversely related to apnea-hypopnea index and increase from baseline end-tidal carbon dioxide (P=.023, rs=-0.58), (P<.001, rs=-0.82). CONCLUSION: Sleep in MPS II is characterized by obstructive sleep apnea, altered sleep architecture, and impaired gas exchange. Sleep disruption is related to daytime pulmonary function, thus both systems should be evaluated when sleep abnormalities are suspected.

Interventions for the eradication of methicillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

BACKGROUND: Cystic fibrosis is an inherited recessive disorder of chloride transport that is characterised by recurrent and persistent pulmonary infections from resistant organisms that result in lung function deterioration and early mortality in sufferers.Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as, not only an important infection in long-term hospitalised patients, but also as a potentially harmful pathogen in cystic fibrosis, and has been increasing steadily in prevalence internationally. Chronic pulmonary infection with MRSA is thought to confer cystic fibrosis patients with a worse overall clinical outcome and, in particular, result in an increased rate of decline in lung function. Clear guidance for the eradication of MRSA in cystic fibrosis, supported by robust evidence from good quality trials, is urgently needed. OBJECTIVES: To evaluate the effectiveness of treatment regimens designed to eradicate MRSA and to determine whether the eradication of MRSA confers better clinical and microbiological outcomes for people with cystic fibrosis. SEARCH METHODS: Randomised and quasi-randomised controlled 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: 24 January 2013. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials comparing any combinations of topical, inhaled, oral or intravenous antimicrobials with the primary aim of eradicating MRSA compared with placebo, standard treatment or no treatment. DATA COLLECTION AND ANALYSIS: The authors independently assessed all search results for eligibility. No eligible trials were identified. MAIN RESULTS: No current published eligible trials were identified, although two ongoing clinical trials are likely to be eligible for inclusion in future updates of this review. AUTHORS' CONCLUSIONS: We did not identify any randomised trials which would allow us to make any evidence-based recommendations. Although the results of several non-randomised studies would suggest that, once isolated, the eradication of MRSA is possible; whether this has a significant impact on clinical outcome is still unclear. Further research is required to guide clinical decision making in the management of MRSA infection in cystic fibrosis.

Airway Findings in Patients with Hunter Syndrome Treated with Intravenous Idursulfase.

People with Hunter syndrome are known to be affected by a variety of airway pathologies. Treatment of Hunter syndrome with the enzyme replacement therapy (ERT) idursulfase is now the standard of care. However, it is not known how ERT changes the progression of airway involvement. To evaluate this, we performed a retrospective analysis of bronchoscopies performed on children with Hunter syndrome who were part of intrathecal ERT trials. Findings for airway pathology were extracted from bronchoscopy reports and analyses were performed for cross-sectional and longitudinal changes in airway disease. One-hundred and thirty bronchoscopies from 23 subjects were analyzed. Upper airway disease (adenoid hypertrophy and/or pharyngomalacia) was reported in 93% and 87% of bronchoscopies, respectively. Laryngeal abnormalities were recognized in 46% of cases. There were lower airway (tracheal and or bronchial) findings in 64% of all bronchoscopies and prevalence increased with age. Evaluations over time adjusted for repeat evaluations showed that increasing airway involvement was associated with older age (p = 0.0007) despite ongoing ERT. No association was discovered between age of intravenous ERT initiation and progression of airway disease. Individuals with Hunter syndrome who are receiving intravenous enzyme replacement therapy showed the progression of airways disease supporting the need for regular airway monitoring and intervention.