Prevalence of cystic fibrosis pathogens in the oropharynx of healthy children and implications for cystic fibrosis care

Clinical outcomes at 9-10 years of age in children born with cystic fibrosis transmembrane conductance regulator related metabolic syndrome

BACKGROUND AND OBJECTIVES

There are limited data on cystic fibrosis (CF) transmembrane conductance regulator-related metabolic syndrome (CRMS) outcomes beyond infancy. The goal of this study was to analyze outcomes of infants with CRMS up to the age of 9-10 years using the CF Foundation Patient Registry (CFFPR).

METHODS

We analyzed data from the CFFPR for individuals with CF and CRMS born between 2010 and 2020. We classified all patients based on the clinical diagnosis reported by the CF care center and the diagnosis using CFF guideline definitions for CF and CRMS, classifying children into groups based on agreement between clinical report and guideline criteria. Descriptive statistics for the cohort were calculated for demographics, nutritional outcomes, and microbiology for the first year of life and lung function and growth outcomes were summarized for ages 6-10 years.

RESULTS

From 2010 to 2020, there were 8765 children with diagnosis of CF or CRMS entered into the CFFPR with sufficient diagnostic data for classification, of which 7591 children had a clinical diagnosis of CF and 1174 had a clinical diagnosis of CRMS. CRMS patients exhibited normal nutritional indices and pulmonary function up to age 9-10 years. The presence of respiratory bacteria associated with CF, such as Pseudomonas aeruginosa from CRMS patients ranged from 2.1% to 9.1% after the first year of life.

CONCLUSIONS

Children with CRMS demonstrate normal pulmonary and nutritional outcomes into school age. However, a small percentage of children continue to culture CF-associated respiratory pathogens after infancy.

Cystic Fibrosis Foundation Evidence-Based Guideline for the Management of CRMS/CFSPID

A multidisciplinary committee developed evidence-based guidelines for the management of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen-positive, inconclusive diagnosis (CRMS/CFSPID). A total of 24 patient, intervention, comparison, and outcome questions were generated based on surveys sent to people with CRMS/CFSPID and clinicians caring for these individuals, previous recommendations, and expert committee input. Four a priori working groups (genetic testing, monitoring, treatment, and psychosocial/communication issues) were used to provide structure to the committee. A systematic review of the evidence was conducted, and found numerous case series and cohort studies, but no randomized clinical trials. A total of 30 recommendations were graded using the US Preventive Services Task Force methodology. Recommendations that received ≥80% consensus among the entire committee were approved. The resulting recommendations were of moderate to low certainty for the majority of the statements because of the low quality of the evidence. Highlights of the recommendations include thorough evaluation with genetic sequencing, deletion/duplication analysis if <2 disease-causing variants were noted in newborn screening; repeat sweat testing until at least age 8 but limiting further laboratory testing, including microbiology, radiology, and pulmonary function testing; minimal use of medications, which when suggested, should lead to shared decision-making with families; and providing communication with emphasis on social determinants of health and shared decision-making to minimize barriers which may affect processing and understanding of this complex designation. Future research will be needed regarding medication use, antibiotic therapy, and the use of chest imaging for monitoring the development of lung disease.

Children with cystic fibrosis are still receiving inconclusive diagnosis despite undergoing newborn screening

AIM

We aimed to familiarise clinicians with the terms cystic fibrosis transmembrane conductance regulator related metabolic syndrome (CRMS) and cystic fibrosis screen positive inconclusive diagnosis (CFSPID). We also sought to highlight the monitoring and outcomes of children that match these designations.

METHODS

A literature review was performed by searching PubMed from its inception until 30 November 2022. All relevant articles were included in this narrative review.

RESULTS

Despite the implementation of newborn screening programmes for cystic fibrosis (CF), the diagnosis remains uncertain in some newborn infants with elevated immunoreactive trypsinogen. In 2016, a unified definition for CRMS/CFSPID was established to categorise these children. While many of them remain healthy, a portion of these children may develop CF. As a result, it is crucial to monitor them regularly.

CONCLUSION

CRMS/CFSPID is a designation and not a diagnosis. Longer longitudinal studies are needed to shed light on the most appropriate follow-up of these children. Paediatricians need to be knowledgeable about this condition in order to administer proper care, and children should be in contact with their local CF centre.

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.

Different management approaches and outcome for infants with an inconclusive diagnosis following newborn screening for cystic fibrosis (CRMS/CFSPID) and Pseudomonas aeruginosa isolation

INTRODUCTION

Evidence is currently lacking to guide the management of cystic fibrosis (CF) transmembrane conductance regulator-related metabolic syndrome CF screen-positive inconclusive diagnosis (CRMS/CFSPID) with Pseudomonas aeruginosa (Pa)-positive respiratory culture. This study assessed the clinical data, management, and outcomes of an Italian cohort of CRMS/CFSPID infants with Pa isolated from their airways.

METHODS

Data of Pa-positive CRMS/CFSPID infants born between January 2011 and August 2018 and followed at five CF Italian centres were retrospectively extracted. Further data were collected until June 2021 to assess outcomes, prevalence of subjects treated with antimicrobials, and treatment type and duration.

RESULTS

Forty-three asymptomatic CRMS/CFSPID patients (median age on 30 June 2021, 82 months; interquartile range [IQR], 63-98 months) with at least one positive airway culture for non-mucoid Pa (median age at first isolation, 18.7 months; IQR, 7-25 months) were enrolled. Of them, 24 (55.8%) underwent anti-Pa therapy. Pa clearance occurred in 22 (91.6%) of 24 patients versus spontaneous clearance in 16 of 19 (84.2%) untreated patients (chi-square, 0.5737; p = 0.44878). After a median follow-up of 6.2 years (IQR, 3.0-9.9), 7 (16.3%) were diagnosed with CF after a pathological sweat test (median age, 43 months; IQR, 28-77 months), 3 (7%) developed recurrent pancreatitis or isolated bronchiectasis consistent with CFTR-related disorder, and the CRMS/CFSPID classification remained in 33 (76.7%).

CONCLUSIONS

Pa detection frequently occurs in asymptomatic infants with CRMS/CFSPID but tends to clear spontaneously. More studies are needed to determine if Pa isolation can predict evolution.

Curating and comparing 114 strain-specific genome-scale metabolic models of Staphylococcus aureus

Staphylococcus aureus is a high-priority pathogen causing severe infections with high morbidity and mortality worldwide. Many S. aureus strains are methicillin-resistant (MRSA) or even multi-drug resistant. It is one of the most successful and prominent modern pathogens. An effective fight against S. aureus infections requires novel targets for antimicrobial and antistaphylococcal therapies. Recent advances in whole-genome sequencing and high-throughput techniques facilitate the generation of genome-scale metabolic models (GEMs). Among the multiple applications of GEMs is drug-targeting in pathogens. Hence, comprehensive and predictive metabolic reconstructions of S. aureus could facilitate the identification of novel targets for antimicrobial therapies. This review aims at giving an overview of all available GEMs of multiple S. aureus strains. We downloaded all 114 available GEMs of S. aureus for further analysis. The scope of each model was evaluated, including the number of reactions, metabolites, and genes. Furthermore, all models were quality-controlled using MEMOTE, an open-source application with standardized metabolic tests. Growth capabilities and model similarities were examined. This review should lead as a guide for choosing the appropriate GEM for a given research question. With the information about the availability, the format, and the strengths and potentials of each model, one can either choose an existing model or combine several models to create models with even higher predictive values. This facilitates model-driven discoveries of novel antimicrobial targets to fight multi-drug resistant S. aureus strains.

Sustained Coinfections with Staphylococcus aureus and Pseudomonas aeruginosa in Cystic Fibrosis

Rationale: Staphylococcus aureus and Pseudomonas aeruginosa often infect the airways in cystic fibrosis (CF). Because registry studies show higher prevalence of P. aeruginosa versus S. aureus in older patients with CF, a common assumption is that P. aeruginosa replaces S. aureus over time. In vitro, P. aeruginosa can outgrow and kill S. aureus. However, it is unknown how rapidly P. aeruginosa replaces S. aureus in patients with CF.Methods: We studied a longitudinal cohort of children and adults with CF who had quantitative sputum cultures. We determined the abundance of P. aeruginosa and S. aureus in cfu/ml. We determined the duration and persistence of infections and measured longitudinal changes in culture positivity and abundance for each organism.Measurements and Main Results: Between 2004 and 2017, 134 patients had ≥10 quantitative cultures, with median observation time of 10.15 years. One hundred twenty-four patients had at least one positive culture for P. aeruginosa, and 123 had at least one positive culture for S. aureus. Both species had median abundance of >10⁶ cfu/ml. Culture abundance was stable over time for both organisms. There was an increase in the prevalence of S. aureus/P. aeruginosa coinfection but no decrease in S. aureus prevalence within individuals over time.Conclusions: S. aureus and P. aeruginosa are abundant in CF sputum cultures. Contrary to common assumption, we found no pattern of replacement of S. aureus by P. aeruginosa. Many patients with CF have durable long-term coinfection with these organisms. New strategies are needed to prevent and treat these infections.

Phenotype of children with inconclusive cystic fibrosis diagnosis after newborn screening

OBJECTIVE

To characterize the phenotypic expression of children with conductance regulator-related metabolic syndrome (CRMS)/cystic fibrosis screen positive inconclusive diagnosis (CFSPID) designation after positive newborn screening, reassign labeling if applicable and better define these children's prognosis.

METHODS

A multicenter cohort with CRMS/CFSPID designation was matched with cystic fibrosis (CF)-diagnosed cohort. Cohorts were prospectively compared on baseline characteristics, cumulative data and when they reached 6 to 7 years at endpoint assessment.

RESULTS

Compared to infants with CF (n = 63), the CRMS/CFSPID cohort (n = 63) had initially lower immunoreactive trypsinogen (IRT) and sweat chloride (SC) values, delayed visits, less symptoms, and better nutritional status; during follow-up, they had fewer hospitalizations, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus identification, CF comorbidities, and treatment burden. At endpoint assessment, they presented a milder pulmonary phenotype on Brody computed tomography scores (0.0[0.0; 2.0] vs 13[2.0; 31.0]; P < .0001, respectively), Wisconsin and Brasfield chest radiograph scores, pulmonary function tests, and improved nutritional status. Among the inconclusive CF diagnosis cohort, 28 cases (44%) converted to CF diagnosis based on genotype (44%), SC (28%) or both (28%); yet, comparing those with or without final CF diagnosis, we found no differences, possibly related to their young age and mild degree of lung disease. In the total cohort, we found significant associations between Brody scores and IRT, SC values, genotype, Wisconsin and Brasfield score and spirometry.

CONCLUSIONS

The matched CRMS/CFSPID and CF cohorts showed differences in outcomes. By a mean age of 7.6 years, a high proportion of the CRMS/CFSPID cohort converted to CF. Our results highlight that monitoring at CF clinics until at least 6 years is needed as well as further studies.

Acute and Chronic Infection Management in CF

CFTR protein malfunction results in thick, copious mucus, causes poor mucociliary clearance and, ultimately, structural lung damage such as bronchiectasis. All of these manifestations of cystic fibrosis contribute to a rich milieu for lower respiratory pathogens in patients affected by the disease. CF patients are, therefore, highly susceptible to chronic colonization with many pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. They are also uniquely prone to acute infections with respiratory pathogens, which tend to persist longer and cause more impairment in lung function than in patients without CF. Tailored strategies for managing infectious complications of CF patients include chronic prophylactic antibiotics, use of systemic as well as inhaled antibiotics, mechanical assistance with mucus clearance, and scrupulous infection control measures.

Staphylococcus aureus in cystic fibrosis: pivotal role or bit part actor?

PURPOSE OF REVIEW

The cystic fibrosis (CF) lung has long been appreciated as a competitive niche for complex interactions between bacterial species. The individual relationships between effects on the host, and thereafter clinical outcomes, has been poorly understood. We aim to describe the role of Staphyloccus aureus, one of the most commonly encountered bacteria cultured from the respiratory tracts of people with CF, and it's complex interplay with other organisms, with particular attention to Pseudomonas aeruginosa.

RECENT FINDINGS

We describe the challenges posed in understanding the role that S. aureus plays in the CF lung, including the difficulties in interpreting culture results depending upon sampling technique, relationships with P. aeruginosa and the rest of the microbiome, as well as discussing the relative merits and potential harms of antibiotic prophylaxis. Finally, we describe the particular challenge of methicillin-resistant S. aureus.

SUMMARY

We describe research underway that will address the long-held contentious issues of antibiotic prophylaxis. We also describe the emerging research interest in determining whether, at differences phases in the evolution of CF airways infection, S. aureus infection can have both harmful and protective effects for the host.

Early Respiratory Bacterial Detection and Antistaphylococcal Antibiotic Prophylaxis in Young Children with Cystic Fibrosis

RATIONALE

Consensus is lacking regarding antistaphylococcal antibiotic prophylaxis use for young children with cystic fibrosis. Prophylaxis is recommended in the United Kingdom, but it is recommended against in the United States.

OBJECTIVES

To test the hypothesis that antistaphylococcal antibiotic prophylaxis is associated with a decreased risk of Staphylococcus aureus acquisition but no increased risk of Pseudomonas aeruginosa acquisition.

METHODS

We undertook a longitudinal observational study of children with cystic fibrosis who were recruited from birth (or from their first registry entry in the period) and followed until the age of 4 years (1,500 d) using 2000-2009 data from the UK Cystic Fibrosis Trust and Cystic Fibrosis Foundation registries. Children were excluded if they had a positive culture result for S. aureus or P. aeruginosa, or if they were receiving inhaled antibiotics, at the first encounter. Time to first S. aureus and P. aeruginosa detection in the UK/U.S. cohorts was compared using a Cox proportional hazards model. A UK-based analysis compared the same for those receiving flucloxacillin with those who received no prophylaxis. We included the following covariates: sex, age at registry entry, dornase alfa use, genotype, and center size.

RESULTS

The primary analysis comprised 1,074 UK and 3,677 U.S. children. The risk of first detection was greater in U.S. children than in UK children for S. aureus (hazard ratio [HR], 5.79; 95% confidence interval [CI], 4.85, 6.90; P < 0.001) and P. aeruginosa (HR, 1.92; 95% CI, 1.65, 2.24; P < 0.001). In the UK analysis, we compared 278 children receiving flucloxacillin and 306 receiving no prophylaxis. Flucloxacillin was not associated with a reduced risk of S. aureus detection (HR, 1.22; 95% CI, 0.74, 2.0; P = 0.43), but it was associated with an increased risk of P. aeruginosa detection (HR, 2.53; 95% CI, 1.71, 3.74; P < 0.001). None of the covariates significantly affected the risk estimate in either analysis.

CONCLUSIONS

The risk of first detection of S. aureus and P. aeruginosa was greater in the United States than in the United Kingdom. In the United Kingdom, the risk of first P. aeruginosa detection was increased among those receiving flucloxacillin compared with those who received no prophylaxis. These observational findings should be examined in randomized controlled trials.

Staphylococcus aureus in cystic fibrosis: problem bug or an innocent bystander?

Staphylococcus aureus in cystic fibrosis: problem bug or an innocent bystander? The jury requires more evidence http://ow.ly/HQjk30j3nmL.

Guidelines for the clinical management and follow-up of infants with inconclusive cystic fibrosis diagnosis through newborn screening

Neonatal screening for cystic fibrosis (CF) can detect infants with elevated immunoreactive trypsinogen (IRT) levels and inconclusive sweat tests and/or CFTR DNA results. These cases of uncertain diagnosis are defined by (1) either the presence of at most one CF-associated cystic fibrosis transmembrane conductance regulator (CFTR) mutation with sweat chloride values between 30 and 59mmol/L or (2) two CFTR mutations with at least one of unknown pathogenic potential and a sweat chloride concentration below 60mmol/L. This encompasses various clinical situations whose progression cannot be predicted. In these cases, a sweat chloride test has to be repeated at 12 months, and if possible at 6 and 24 months of life along with extended CFTR sequencing to detect rare mutations. When the diagnosis is not definite, CFTR functional explorations may provide a better understanding of CFTR dysfunction. The initial evaluation of these infants must be conducted in dedicated CF reference centers and should include bacteriological sputum analysis, chest radiology, and fecal elastase assay. The primary care physicians in charge of these patients should be familiar with the current management of CF and should work in collaboration with CF centers. A follow-up should be performed in a CF reference center at 3, 6, and 12 months of life and every year thereafter. Any symptom indicative of CF requires immediate reevaluation of the diagnosis. These guidelines were established by the "neonatal screening and difficult diagnoses" working group of the French CF society. Their objective is to standardize the management of infants with unclear diagnosis.

Progression of Lung Disease in Preschool Patients with Cystic Fibrosis

RATIONALE

Implementation of intervention strategies to prevent lung damage in early cystic fibrosis (CF) requires objective outcome measures that capture and track lung disease.

OBJECTIVES

To define the utility of the Lung Clearance Index (LCI), measured by multiple breath washout, as a means to track disease progression in preschool children with CF.

METHODS

Children with CF between the ages of 2.5 and 6 years with a confirmed diagnosis of CF and age-matched healthy control subjects were enrolled at three North American CF centers. Multiple breath washout tests were performed at baseline, 1, 3, 6, and 12 months to mimic time points chosen in clinical care and interventional trials; spirometry was also conducted. A generalized linear mixed-effects model was used to distinguish LCI changes associated with normal growth and development (i.e., healthy children) from the progression of CF lung disease.

MEASUREMENTS AND MAIN RESULTS

Data were collected on 156 participants with 800 LCI measurements. Although both LCI and spirometry discriminated health from disease, only the LCI identified significant deterioration of lung function in CF over time. The LCI worsened during cough episodes and pulmonary exacerbations, whereas similar symptoms in healthy children were not associated with increased LCI values.

CONCLUSIONS

LCI is a useful marker to track early disease progression and may serve as a tool to guide therapies in young patients with CF.

Early Lung Disease in Infants and Preschool Children with Cystic Fibrosis. What Have We Learned and What Should We Do about It?

The past decade has seen significant advances in understanding of the pathogenesis and progression of lung disease in cystic fibrosis (CF). Pulmonary inflammation, infection, and structural lung damage manifest very early in life and are prevalent among preschool children and infants, often in the absence of symptoms or signs. Early childhood represents a pivotal period amenable to intervention strategies that could delay or prevent the onset of lung damage and alter the longer-term clinical trajectory for individuals with CF. This review summarizes what we have learned about early lung disease in children with CF and discusses the implications for future clinical practice and research.

[Management of infants whose diagnosis is inconclusive at neonatal screening for cystic fibrosis]

Neonatal screening for cystic fibrosis (CF) may detect infants with elevated immunoreactive trypsinogen (IRT) levels but with inconclusive sweat tests and/or DNA results. This includes cases associating (1) either the presence of at most one CF-causing mutation and sweat chloride values between 30 and 59mmol/L or (2) two CFTR mutations with at least one of unknown pathogenicity and a sweat chloride below 60mmol/L. This encompasses different clinical situations whose progression cannot be predicted. These cases require redoing the sweat test at 12 months and if possible at 6 and 24 months of life. This must be associated with extended genotyping. CFTR functional explorations can also help by investigating CFTR dysfunction. These infants must be initially evaluated in dedicated CF centers including bacteriological sputum analysis, chest radiology and fecal elastase dosage. A home practitioner must be informed of the specificity of follow-up. These infants will be reviewed in the CF center at 3, 6 and 12 months and every year. Any CF-related symptom requires reevaluation of the diagnosis. These guidelines were established by the "neonatal screening and difficult diagnoses" working group of the French CF Society. They aim to standardize management of infants with unclear diagnosis in French CF centers.

Cystic Fibrosis Transmembrane Conductance Regulator-Related Metabolic Syndrome and Cystic Fibrosis Screen Positive, Inconclusive Diagnosis

OBJECTIVE

An unintended consequence of cystic fibrosis (CF) newborn screening (NBS) is the identification of infants with a positive NBS test but inconclusive diagnostic testing. These infants are classified as CF transmembrane conductance regulator-related metabolic syndrome (CRMS) in the US and CF screen positive, inconclusive diagnosis (CFSPID) in other countries. Diagnostic and management decisions of these infants are challenges for CF healthcare professionals and stressful situations for families. As CF NBS has become more widespread across the world, increased information about the epidemiology and outcomes of these infants is becoming available. These data were reviewed at the 2015 CF Foundation Diagnosis Consensus Conference, and a harmonized definition of CRMS and CFSPID was developed.

STUDY DESIGN

At the consensus conference, participants reviewed published and unpublished studies of CRMS/CFSPID and used a modified Delphi methodology to develop a harmonized approach to the definition of CRMS/CFSPID.

RESULTS

Several studies of CRMS/CFSPID from populations around the world have been published in the past year. Although the studies vary in the number of infants studied, study design, and outcome measures, there have been some consistent findings. CRMS/CFSPID occurs relatively frequently, with CF:CRMS that ranges from 3 to 5 cases of CF for every 1 case of CRMS/CFSPID in regions where gene sequencing is not used. The incidence varies by NBS protocol used, and in some regions more cases of CRMS/CFSPID are detected than cases of CF. The majority of individuals with CRMS/CFSPID do not develop CF disease or progress to a diagnosis of CF. However, between 10% and 20% of asymptomatic infants can develop clinical features concerning for CF, such as a respiratory culture positive for Pseudomonas aeruginosa. Most studies have only reported short-term outcomes in the first 1-3 years of life; the long-term outcomes of CRMS/CFSPID remain unknown. The European CF Society definition of CFSPID and the CF Foundation definition of CRMS differ only slightly, and the consensus conference was able to create a unified definition of CRMS/CFSPID.

CONCLUSIONS

CRMS/CFSPID is a relatively common outcome of CF NBS, and clinicians need to be prepared to counsel families whose NBS test falls into this classification. The vast majority of infants with CRMS/CFSPID will remain free from disease manifestations early in life. However, a small proportion may develop clinical features concerning for CF or demonstrate progression to a clinical phenotype compatible with a CF diagnosis, and their long-term outcomes are not known. A consistent international definition of CRMS/CFSPID will allow for better data collection for study of outcomes and result in improved patient care.

Phenotypes of California CF Newborn Screen-Positive Children with CFTR 5T Allele by TG Repeat Length

BACKGROUND

At the cystic fibrosis transmembrane conductance regulator (CFTR) gene (IVS8)-(TG)m(T)n locus, a lower number of thymidines (legacy names 9T vs. 7T vs. 5T) and a higher number of (TG) repeats (TG-11 vs. 12 vs. 13) are associated with decreasing translation of functional CFTR protein in vitro.

METHODS

Retrospective cohort study comparing phenotypes of California CF newborn screen-positive children (followed 2-8 years) who had two CF-causing mutations (diagnosed as CF) with those who had one mutation from a panel of 40 CF-causing mutations (CF40mut) and one (IVS8)-(TG)11, 12, or 13-5T mutation detected by sequencing (diagnosed as CFTR-related metabolic syndrome [cRMS]).

RESULTS

The study included 428 children, of which 234 had two CF-causing mutations, and were used to compare with the other 194 children with one CF-causing mutation and one isolated 5T allele [CF40mut/(TG)13-5T = 21, CF40mut/(TG)12-5T = 85, and CF40mut/(TG)11-5T = 88]. Among children with CF40mut/(TG)13-5T, 38% were diagnosed with CF by 8 years, based on sweat chloride results and clinical presentation. Six percent of those with CF40mut/(TG)12-5T, and none with CF40mut/(TG)11-5T, reached diagnostic criteria.

CONCLUSIONS

CFTR (IVS8)-(TG)m-5T allele (TG) tract length determination provides valuable information in predicting the risk of developing a CF phenotype. Of the three types of 5T alleles evaluated, screen-positive children with genotype CF40mut/(TG)13-5T progressed from CRMS to CF at a high rate, while there was little evidence of clinical disease in those with CF40mut/(TG)11-5T. Additional data from longer follow-up intervals are needed to fully understand the natural history of individuals with a CF40mut/(TG)m-5T genotype.

Benign and Deleterious Cystic Fibrosis Transmembrane Conductance Regulator Mutations Identified by Sequencing in Positive Cystic Fibrosis Newborn Screen Children from California

Background

Of the 2007 Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutations, 202 have been assigned disease liability. California’s racially diverse population, along with CFTR sequencing as part of newborn screening model, provides the opportunity to examine the phenotypes of children with uncategorized mutations to help inform disease liability and penetrance.

Methods

We conducted a retrospective cohort study based on children screened from 2007 to 2011 and followed for two to six years. Newborns that screened positive were divided into three genotype groups: those with two CF-causing mutations (CF-C); those with one mutation of varying clinic consequence (VCC); and those with one mutation of unknown disease liability (Unknown). Sweat chloride tests, pancreatic sufficiency status, and Pseudomonas aeruginosa colonization were compared.

Results

Children with two CF-causing mutations had a classical CF phenotype, while 5% of VCC (4/78) and 11% of Unknown (27/244) met diagnostic criteria of CF. Children carrying Unknown mutations 2215insG with D836Y, and T1036N had early and classical CF phenotype, while others carrying 1525-42G>A, L320V, L967S, R170H, and 296+28A>G had a benign clinical presentation, suggesting that these are non-CF causing.

Conclusions

While most infants with VCC and Unknown CFTR mutations do not meet diagnostic criteria for CF, a small proportion do. These findings highlight the range of genotypes and phenotypes in the first few years of life following CF newborn screening when CFTR sequencing is performed.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

The 2013 Infection Prevention and Control (IP&C) Guideline for Cystic Fibrosis (CF) was commissioned by the CF Foundation as an update of the 2003 Infection Control Guideline for CF. During the past decade, new knowledge and new challenges provided the following rationale to develop updated IP&C strategies for this unique population:

1.The need to integrate relevant recommendations from evidence-based guidelines published since 2003 into IP&C practices for CF. These included guidelines from the Centers for Disease Control and Prevention (CDC)/Healthcare Infection Control Practices Advisory Committee (HICPAC), the World Health Organization (WHO), and key professional societies, including the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). During the past decade, new evidence has led to a renewed emphasis on source containment of potential pathogens and the role played by the contaminated healthcare environment in the transmission of infectious agents. Furthermore, an increased understanding of the importance of the application of implementation science, monitoring adherence, and feedback principles has been shown to increase the effectiveness of IP&C guideline recommendations.

2.Experience with emerging pathogens in the non-CF population has expanded our understanding of droplet transmission of respiratory pathogens and can inform IP&C strategies for CF. These pathogens include severe acute respiratory syndrome coronavirus and the 2009 influenza A H1N1. Lessons learned about preventing transmission of methicillin-resistantStaphylococcus aureus(MRSA) and multidrug-resistant gram-negative pathogens in non-CF patient populations also can inform IP&C strategies for CF.

Microbiological yield from induced sputum compared to oropharyngeal swab in young children with cystic fibrosis

BACKGROUND

Standard respiratory sampling in young children with cystic fibrosis (CF) is by oropharyngeal swab (OPS) as they cannot spontaneously expectorate. Sputum induction (IS) has been poorly investigated in this population. We aimed to compare the bacteriological yield of OPS vs. IS in young children with CF.

METHODS

Sequentially paired OPS followed by IS samples was collected in children <5years of age attending a CF clinic in Cape Town, South Africa.

RESULTS

IS was successfully paired with OPS in 98/113 (85%) attempts in 32 children (mean±SD 19±16months), with no serious adverse events. IS culture yield for any CF-associated bacteria from IS was 46% vs. 28% from OPS (p=0.01). The sensitivity, specificity, PPV and NPV of OPS compared to IS in isolating CF-associated bacteria were 56%, 96%, 93%, and 72% respectively.

CONCLUSION

Sputum induction is feasible, safe and superior to OPS for detecting CF-associated bacteria in young children with CF.

Bacterial colonization status of cystic fibrosis children's toothbrushes: A pilot study

BACKGROUND

Pseudomonas aeruginosa and Staphylococcus aureus toothbrush contamination in cystic fibrosis (CF) is unknown. This pilot study aimed to determine their prevalence and the potential involvement of toothbrushes in pulmonary infection.

METHODS

Toothbrush bacteriological analysis for children aged 8-18 years was conducted on 27 CF patients, 15 healthy siblings, and 15 healthy children from the general population.

RESULTS

S. aureus was detected on 22% of the patients' toothbrushes, and 13% of healthy children's toothbrushes and P. aeruginosa on 15% of patients' toothbrushes and 0-13% of healthy children's toothbrushes. There was no statistical correlation between pulmonary colonization and toothbrush contamination. P. aeruginosa genotyping showed two identical clones on the patients' toothbrushes and in their sputum, and between one patient's sputum and his sibling's toothbrush.

CONCLUSION

S. aureus and P. aeruginosa can colonize CF patients' toothbrushes. The impact on pulmonary colonization remains unknown. Toothbrush decontamination methods need to consider these bacteria in CF patients.

Benign outcome among positive cystic fibrosis newborn screen children with non-CF-causing variants

BACKGROUND

The Clinical and Functional Translation of CFTR project (CFTR2) classified some cystic fibrosis transmembrane conductance regulator (CFTR) gene variants as non-cystic fibrosis (CF)-causing. To evaluate this, the clinical status of children carrying these mutations was examined.

METHODS

We analyzed CF disease-defining variables over 2-6 years in two groups of California CF screen- positive neonates born from 2007 to 2011: (1) children with two CF-causing variants and (2) children with one CF-causing and one non-CF-causing variant, as defined by CFTR2.

RESULTS

Children carrying non-CF-causing variants had significantly higher birth weight, lower immunoreactive trypsinogen and sweat chloride values, higher first year growth curves, and a lower rate of persistent Pseudomonas aeruginosa colonization compared to children with two CF-causing variants.

CONCLUSIONS

The outcomes in children 2-6 years of age with the L997F, G576A, R1162L, V754M, R668C, R31C, and S1235R variants are consistent with the CFTR2 non-CF-causing classification.