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.

Association of Pseudomonas aeruginosa incident infections with adherence to cystic fibrosis foundation care guidelines.

BACKGROUND: Care guidelines for cystic fibrosis (CF) have been developed to enhance consistent care and to improve health outcomes. We determined if adherence to CF care guidelines predicted P. aeruginosa incidence rates (Pa-IR) at U.S. CF centers in 2018. METHODS: This cross-sectional CF Foundation Patient Registry study included 82 adult and 132 pediatric centers. Adherence to 12 guidelines was defined categorically (guideline met) or as a continuous measure (proportion of patients being treated/evaluated per guideline). Association of adherence to individual guidelines with Pa-IR, accounted for center and patient characteristics relevant to Pa-IR and were modeled using random forests and weighted-least-squares (WLS) analyses. RESULTS: The mean Pa-IR was 0.2 cases/patient-years at risk (SE 0.0074) for all centers combined. Guideline adherence was lowest for ≥4 bacterial cultures/year (54% of centers) and annual oral glucose tolerance test (OGTT) (48% of centers), and highest for annual non-tuberculous mycobacteria (NTM) sputum culture (98%). The mean number of guidelines met was 6.7 and higher for pediatric (7.3) than adult (5.6) centers, (p<0.001). The number of guidelines met correlated negatively with Pa-IR (ß=-0.007, p = 0.043). Macrolide prescription and annual OGTT per guideline were associated with lower and higher Pa-IR, respectively. Centers with lower center-wide lung function, higher proportion of pwCF with low body-mass index, and location in the Southwest had higher Pa-IR. CONCLUSION: Overall adherence to guidelines was high except for performing ≥4 bacterial cultures/year and OGTT. Higher Pa-IR was associated with center characteristics and lower guideline adherence. The lower Pa-IR with greater adherence to guidelines suggests that focusing on quality care can positively impact Pa-IR.

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.

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.

Antibiotic Tolerance and Treatment Outcomes in Cystic Fibrosis Methicillin-Resistant Staphylococcus aureus Infections.

Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in U.S. cystic fibrosis (CF) patients and is associated with worse clinical outcomes in CF. These infections often become chronic despite repeated antibiotic therapy. Here, we assessed whether bacterial phenotypes, including antibiotic tolerance, can predict the clinical outcomes of MRSA infections. MRSA isolates (n = 90) collected at the incident (i.e., acute) and early infection states from 57 patients were characterized for growth rates, biofilm formation, hemolysis, pigmentation, and vancomycin tolerance. The resistance profiles were consistent with those in prior studies. Isolates from the early stage of infection were found to produce biofilms, and 70% of the isolates exhibited delta-hemolysis, an indicator of agr activity. Strong vancomycin tolerance was present in 24% of the isolates but was not associated with intermediate vancomycin susceptibility. There were no associations between these phenotypic measures, antibiotic tolerance, and MRSA clearance. Our research suggests that additional factors may be relevant for predicting the clearance of MRSA. IMPORTANCE Chronic MRSA infections remain challenging to treat in patients with cystic fibrosis (CF). The ability of the bacterial population to survive high concentrations of bactericidal antibiotics, including vancomycin, despite lacking resistance is considered one of the main reasons for treatment failures. The connection between antibiotic tolerance and treatment outcomes remains unexplored and can be crucial for prognosis and regimen design toward eradication. In this study, we measured the capacity of 90 MRSA isolates from CF patients to form vancomycin-tolerant persister cells and evaluated their correlation with the clinical outcomes. Additionally, various traits that could reflect the metabolism and/or virulence of those MRSA isolates were systematically phenotyped and included for their predictive power. Our research highlights that despite the importance of antibiotic tolerance, additional factors need to be considered for predicting the clearance of MRSA.

Eradication of early MRSA infection in cystic fibrosis: a novel study design for the STAR-ter trial.

Introduction: Early eradication of methicillin-resistant Staphylococcus aureus (MRSA) in cystic fibrosis is desirable. Prospective studies are challenging owing to the feasibility of recruiting patients with a rare event in an orphan disease. Our prior randomised study (Staph Aureus Resistance-Treat Or Observe (STAR-too)) showed improved clearance and outcomes with aggressive therapy compared to no treatment. We present a novel trial design to guide treatment for eradicating incident infection with a focus on feasibility. Methods: Subjects with cystic fibrosis with incident MRSA infection were enrolled into the Staph Aureus Resistance-Treat Early And Repeat (STAR-ter) protocol and treated with a combination of an oral antibiotic and topical (nare and throat) decolonisation. The primary outcome was MRSA-negative respiratory culture at Day 28, i.e. 14 days after completion of oral antibiotics. What was novel about this study design was that the control/comparator group was the untreated group of the STAR-too trial. This design was developed because having a "no treatment" group would be unethical given prior findings and a superiority design would delay the time to results based on small numbers of eligible subjects. Both studies used the same inclusion and exclusion criteria and drew subjects from the same geographic regions. The main difference between the studies was the use of a single oral antibiotic, trimethoprim-sulfamethoxazole, rather than the combination with oral rifampin used in STAR-too. Discussion: An innovative approach to address a clinical question for a rare event in an orphan disease, cystic fibrosis, is presented to enhance current clinical evidence to guide cystic fibrosis care in relation to new MRSA infection.

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.

Predicting risk-adjusted incidence rates of methicillin-resistant Staphylococcus Aureus and Pseudomonas Aeruginosa in cystic fibrosis programs in the United States.

BACKGROUND: Healthcare-associated transmission of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa occurs for people with cystic fibrosis (CF), but CF programs lack a process to monitor incidence rates (IRs). We assessed predictors of incident infections and created a model to determine risk-adjusted IRs for CF programs. METHODS: Using the CF Foundation Patient Registry data for all patients from 2012 to 2015, coefficients for variables that predicted IRs were estimated. Hazard functions were then used to predict IRs of MRSA and P. aeruginosa for CF programs based on their patient and program characteristics. Predicted IRs were compared with observed IRs over multiple time intervals. RESULTS: Multiple patient and program characteristics were identified as predictors of observed IRs. Our model's predicted IRs closely aligned with observed IRs for most CF programs. Alarm values (defined as observed IR > 95% confidence interval of predicted IR) were found at 5.9%, 5.9%, 6.0% (adult, pediatric, affiliate) of programs for MRSA and 3.0%, 1.7%, 0.0% (adult, pediatric, affiliate) of programs for P. aeruginosa. CONCLUSIONS: We found patient and program characteristics that predicted MRSA and P. aeruginosa IRs. Our model accurately predicted risk-adjusted IRs of MRSA and P. aeruginosa. CF programs could use our model to monitor their IRs and potentially improve infection prevention and control.

Mucus and mucus flake composition and abundance reflect inflammatory and infection status in cystic fibrosis.

BACKGROUND: Mucus hyperconcentration in cystic fibrosis (CF) lung disease is marked by increases in both mucin and DNA concentration. Additionally, it has been shown that half of the mucins present in bronchial alveolar lavage fluid (BALF) from preschool-aged CF patients are present in as non-swellable mucus flakes. This motivates us to examine the utility of mucus flakes, as well as mucin and DNA concentrations in BALF as markers of infection and inflammation in CF airway disease. METHODS: In this study, we examined the mucin and DNA concentration, as well as mucus flake abundance, composition, and biophysical properties in BALF from three groups; healthy adult controls, and two CF cohorts, one preschool aged and the other school aged. BALFs were characterized via refractometry, PicoGreen, immunofluorescence microscopy, particle tracking microrheology, and fluorescence image tiling. RESULTS: Mucin and DNA BALF concentrations increased progressively from healthy young adult controls to preschool-aged people and school-aged people with CF. Notably, mucin concentrations were increased in bronchoalveolar lavage fluid (BALF) from preschool-aged patients with CF prior to decreased pulmonary function. Infrequent small mucus flakes were identified in normal subjects. A progressive increase in the abundance of mucus flakes in preschool and school-aged CF patients was observed. Compositionally, MUC5B dominated flakes from normal subjects, whereas an increase in MUC5AC was observed in people with CF, reflected in a reduced flaked MUC5B/MUC5AC mucin ratio. CONCLUSION: These findings suggest mucus composition and flake properties are useful markers of inflammatory and infection-based changes in CF airways.

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.

Barriers implementing infection prevention and control experienced by healthcare workers, people with CF and parents.

BACKGROUND: Barriers to implementing infection prevention and control (IP&C) practices may be experienced by healthcare workers (HCWs) caring for people with CF (PwCF), PwCF, and their families. We hypothesized that these stakeholders from CF centers with early adoption of the updated 2013 IP&C guideline would experience fewer barriers implementing selected recommendations compared to stakeholders from CF centers with delayed adoption. METHODS: In 2018-2019 we surveyed HCWs and PwCF/parents from 25 CF centers to identify knowledge, attitude, and practice barriers. Each center recruited five HCWs with different occupations. Pediatric centers recruited five parents of children <18 years old and five young adults 18-21 years old. Adult centers recruited 10 adults ≥18 years old. We determined respondents' knowledge scores, the proportion who agreed with or perceived health benefits from recommendations, and reported adherence to recommendations. RESULTS: Knowledge scores, perception of health benefits, and adherence to selected practices were similar among participants from centers with early vs. delayed adoption, yet generally lower for inpatient nurses. IP&C practitioners were less likely to perceive health benefits from PwCF wearing masks and HCWs wearing gowns and gloves. Among HCWs, 57% educated >75% of PwCF/parents about IP&C and 43% advised >75% of PwCF/parents to avoid socializing with other PwCF. Among PwCF/parents, 69%, 53%, and 56% reported discussions with their care teams about performing hand hygiene, avoiding socialization, or the 2013 IP&C guideline, respectively. CONCLUSIONS: Our findings suggest opportunities for targeted education for specific HCW occupations and for PwCF and their families.

Longitudinal changes and regional variation of incident infection rates at cystic fibrosis centers, United States 2010-2016.

BACKGROUND: Multiple factors affect incident infection rates (IIR) for Pseudomonas aeruginosa (PA) and methicillin resistant Staphylococcus aureus (MRSA) at CF care centers. We assessed changes in IIR across CF centers temporally associated with the 2013 Infection/Prevention & Control guidelines controlling for center-specific factors. METHODS: Using the CF Foundation Patient Registry we defined and measured changes in IIR between 2010-2012 and 2014-2016. Data were compared to non-CF rates of MRSA and resistant PA in geographically similar regions. Characteristics of each CF center (n centers: Adult 54 in 2010 to 82 in 2016. Pediatric ∼106) and their respective population were evaluated for associations with IIR and with changes in IIR between the study periods. RESULTS: Across the years 35613 patients were included. Incident-infection rates for PA (mean 19.2±0.04% Pediatric, 21.2±0.07% Adult centers) were higher than for MRSA (mean 9.4±0.03% Pediatric, 7.8±0.03% Adult). The IIR decreased for MRSA (-1.54±0.54%, p<0.001) and PA (-4.77±0.63%, p<0.001) at Pediatric but only for PA (-3.20±1.31, p=0.02) at Adult centers. Except for Adult CF, MRSA rates (CF and non-CF) were highest in the South. In 2014-2016, private insurance and a higher proportion of LatinX patients at a center were associated with lower MRSA IIR while larger center size, higher proportion of LatinX, and lower mean center-wide lung function were associated with higher PA IIR. Higher IIR in 2010-2012, were predictive of a more pronounced decrease in IIR in 2014-2016 for MRSA and PA (p<0.001). Different factors indicative of lower social status (smoking, insurance, education) in 2010-2012 predicted decreases in MRSA or PA IIR. CONCLUSION: Comparisons of IIR across U.S. CF centers should consider location, ethnic background and socio-economic variables of a center's population.

ATS Core Curriculum 2021. Pediatric Pulmonary Medicine: Pulmonary Infections.

The following is a concise review of the Pediatric Pulmonary Medicine Core reviewing pediatric pulmonary infections, diagnostic assays, and imaging techniques presented at the 2021 American Thoracic Society Core Curriculum. Molecular methods have revolutionized microbiology. We highlight the need to collect appropriate samples for detection of specific pathogens or for panels and understand the limitations of the assays. Considerable progress has been made in imaging modalities for detecting pediatric pulmonary infections. Specifically, lung ultrasound and lung magnetic resonance imaging are promising radiation-free diagnostic tools, with results comparable with their radiation-exposing counterparts, for the evaluation and management of pulmonary infections. Clinicians caring for children with pulmonary disease should ensure that patients at risk for nontuberculous mycobacteria disease are identified and receive appropriate nontuberculous mycobacteria screening, monitoring, and treatment. Children with coronavirus disease (COVID-19) typically present with mild symptoms, but some may develop severe disease. Treatment is mainly supportive care, and most patients make a full recovery. Anticipatory guidance and appropriate counseling from pediatricians on social distancing and diagnostic testing remain vital to curbing the pandemic. The pediatric immunocompromised patient is at risk for invasive and opportunistic pulmonary infections. Prompt recognition of predisposing risk factors, combined with knowledge of clinical characteristics of microbial pathogens, can assist in the diagnosis and treatment of specific bacterial, viral, or fungal diseases.

Impact of the SARS-CoV-2 pandemic on cystic fibrosis centres and care: survey results from US centres.

Lessons learnt from the pandemic show that telehealth for cystic fibrosis allows multidisciplinary visits but better means for monitoring of lung function and microbiology are needed https://bit.ly/2V7g09x.

Phenotypic characteristics of incident and chronic MRSA isolates in cystic fibrosis.

BACKGROUND: Chronic methicillin resistant Staphylococcus aureus (MRSA) in CF is associated with worse outcomes compared to early or intermittent infection. This observation could be related to adaptive bacterial changes such as biofilm formation or anaerobic growth. METHODS: MRSA isolates stored from incident and during chronic (>2 years) infection were included at two study sites. MRSA isolates were characterised by spa-typing, antimicrobial susceptibility testing, biofilm formation and haemolysis under aerobic and anaerobic culture conditions. RESULTS: Paired MRSA isolates from 49 patients were included. Mean age at incident infection was 9.7±1.2 years with mild to moderate lung disease (FEV1 74±4% predicted). Twenty-five subjects showed progression of disease/symptoms after onset of MRSA with significantly increased use of antibiotics. Most isolates belonged to t002 (38%) and t008 (36%) spa-types and 8 patients had a change in spa-type over time. Antimicrobial susceptibility testing showed few differences between incident and late isolates but significantly lower MIC under anaerobic vs. aerobic conditions for vancomycin, fusidic acid, rifampin but higher MIC for trimethoprim-sulfamethoxazole. Biofilm formation and haemolysis did not differ by stage of infection or disease course but both were lower under anaerobic conditions (biofilm p=0.018; haemolysis p=0.002) in multi-variate analyses that included study site, growth condition and stage of infection. CONCLUSIONS: Persistent MRSA infection is frequently associated with clinical decline. Anaerobic growth conditions, which occur in CF airways, affect the expression of virulence factors and antibiotic susceptibility of MRSA more than duration of infection.

Antimicrobial resistance: Concerns of healthcare providers and people with CF.

BACKGROUND: Chronic lung infections and their treatment pose risks for the development of antimicrobial resistance (AMR) in people with cystic fibrosis (PWCF). In this study, we evaluated the attitudes of healthcare providers' (HCP) and PWCF or their parents' toward AMR within the international CF community. METHODS: HCP and PWCF identified through listservs and CF-related organizations were asked to complete an AMR centered survey, with additional questions on antimicrobial stewardship (AMS) for HCP. Descriptive analyses are reported. RESULTS: The responding 443 HCP and 464 PWCF/Parents were from 30 and 25 countries, respectively. Sixty-two percent of HCP and 56% of PWCF stated they were "very concerned" about AMR, with Pseudomonas spp. and Burkholderia spp. considered the most concerning organisms for both HCP and PWCF/Parents. Non-tuberculous mycobacteria were of greater concern to HCP compared to PWCF/Parents. There was a discrepancy regarding AMR education to PWCF, with 80% of HCP stating having discussed this with PWCF/Parents, but only 50% of PWCF recalling such discussions. CONCLUSION: These results highlight that AMR is relevant to CF HCP and PWCF internationally, indicating that educational tools and research are warranted.

Highlights from the 2019 North American Cystic Fibrosis Conference.

This review briefly summarizes presentations in several major topic areas at the conference: pathophysiology and basic science of cystic fibrosis lung disease, clinical trials, clinical quality improvement, microbiology and treatment of infection, and transition, advanced lung disease and transplant, mental health and psychosocial concerns. The review is intended to highlight several areas and is not a comprehensive summary of the conference. Citations from the conference are by the first author and abstract number or symposium number, as designated in the supplement.

Finding the relevance of antimicrobial stewardship for cystic fibrosis.

Antimicrobials have undoubtedly improved the lives of people with CF, but important antimicrobial-related toxicities and the emergence of antimicrobial-resistant bacteria associated with their use must be considered. Antimicrobial stewardship (AMS) is advocated across the spectrum of healthcare to promote the appropriate use of antimicrobials to preserve their current effectiveness and to optimise treatment, and it is clear that AMS strategies are applicable to and can benefit both non-CF and CF populations. This perspective explores the definition and components of an AMS program, the current evidence for AMS, and the reasons why AMS is a challenging concept in the provision of CF care. We also discuss the elements of CF care which align with AMS programs and principles and propose research priorities for AMS in CF.

Utilizing centralized biorepository samples for biomarkers of cystic fibrosis lung disease severity.

BACKGROUND: Circulating biomarkers reflective of lung disease activity and severity have the potential to improve patient care and accelerate drug development in CF. The objective of this study was to leverage banked specimens to test the hypothesis that blood-based biomarkers discriminate CF children segregated by lung disease severity. METHODS: Banked serum samples were selected from children who were categorized into two extremes of phenotype associated with lung function ('mild' or 'severe') based on CF-specific data and were matched on age, gender, CFTR genotype, and P. aeruginosa infection status. Targeted inflammatory proteins, lipids, and discovery metabolite profiles were measured in these serum samples. RESULTS: The severe cohort, characterized by a lower CF-specific FEV1 percentile, had significantly higher circulating concentrations of high sensitivity C-reactive protein, serum amyloid A, granulocyte colony stimulating factor, and calprotectin compared to the mild cohort. The mild cohort tended to have higher serum linoleic acid concentrations. The metabolite arabitol was lower in the severe cohort while other CF relevant metabolic pathways showed non-significant differences after adjusting for multiple comparisons. A sensitivity analysis to correct for biased estimates that may result from selecting subjects using an extremes of phenotype approach confirmed the protein biomarker findings. CONCLUSIONS: Circulating inflammatory proteins differ in CF children segregated by lung function. These findings serve to demonstrate the value of maintaining centralized, high quality patient derived samples for future research, with linkage to clinical information to answer testable hypotheses in biomarker development.

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.