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Pseudomonas aeruginosa is the main cause of chronic airway infection in cystic fibrosis (CF). However, for unclear reasons some patients are never colonized by P. aeruginosa. The objectives of this study were to better define the clinical, genetic, and microbiological characteristics of such a subpopulation and to identify predictive factors of non-colonization with P. aeruginosa. The French CF patient registry 2013-2014 was used to identify CF patients aged ≥ 20 years. The clinical outcomes, CF Transmembrane conductance Regulator (CFTR) genotypes, and microbiological data of patients reported positive at least once for P. aeruginosa ("Pyo" group, n = 1,827) were compared to those of patients with no history of P. aeruginosa isolation ("Never" group, n = 303). Predictive factors of non-colonization by P. aeruginosa were identified by multivariate logistic regression model with backward selection. Absence of aspergillosis (odds ratio (OR) [95% CI] = 1.64 [1.01-2.66]), absence of diabetes (2.25 [1.21-4.18]), pancreatic sufficiency (1.81 [1.30-2.52]), forced expiratory volume 1 (FEV1) ≥ 80% (3.03 [2.28-4.03]), older age at CF diagnosis (1.03 [1.02-1.04]), and absence of F508del/F508del genotype (2.17 [1.48-3.19]) were predictive clinical factors associated with absence of infection ("Never" group). Microbiologically, this same group was associated with more frequent detection of Haemophilus influenzae and lower rates of Stenotrophomonas maltophilia, Achromobacter xylosoxidans and Aspergillus spp. (all p<0.01) in sputum. This study strongly suggests that the absence of pulmonary colonization by P. aeruginosa in a minority of CF adults (14.2%) is associated with a milder form of the disease. Recent progress in the development of drugs to correct CFTR deficiency thus may be decisive in the control of P. aeruginosa lung infection., Competing Interests: The authors have declared that no competing interests exist.

Cystic fibrosis (CF) is a genetic inherited disease due to mutations in the gene cystic fibrosis transmembrane conductance regulator (CFTR). Because of the huge diversity of CFTR mutations, the CF phenotypes are highly heterogeneous, varying from typical to mild form of CF, also called atypical CF. These atypical features are more frequently diagnosed at adolescence or adulthood, and among clinical signs and symptoms leading to suspect a mild form of CF, colonization or infection of the respiratory tract due to well-known CF pathogens should be a warning signal. Exophiala dermatitidis is a melanized dimorphic fungus commonly detected in respiratory specimens from CF patients, but only very rarely from respiratory specimens from non-CF patients. We described here two cases of chronic colonization of the airways by E. dermatitidis, with recurrent pneumonia and hemoptysis in one patient, which led clinicians to diagnose mild forms of CF in these elderly patients who were 68- and 87-year-old. These cases of late CF diagnosis suggest that airway colonization or respiratory infections due to E. dermatitidis in patients with bronchiectasis should led to search for a mild form of CF, regardless of the age and associated symptoms. On a broader level, in patients with chronic respiratory disease and recurrent pulmonary infections, an allergic bronchopulmonary mycosis or an airway colonization by CF-related fungi like E. dermatitidis or some Aspergillus, Scedosporium or Rasamsonia species, should be considered as potential markers of atypical CF and should led clinicians to conduct investigations for CF diagnosis.

Very few studies have been conducted on cystic fibrosis (CF) patients' exposure to the indoor environment and, to our knowledge, there are no studies dealing with the link between specific fungal environmental exposure at home and fungal colonization resulting in allergic bronchopulmonary aspergillosis (ABPA). Fungal exposure of CF adult patients with ABPA (n=4) with fungal sensitization (n=7) and with no ABPA (n=5) was assessed in 16 homes by dust sampling with electrostatic dust fall collectors (EDCs). Aspergillus fumigatus was specifically quantified by real-time quantitative polymerase chain reactions (qPCRs), and A. fumigatus DNA concentrations were significantly higher in homes of ABPA patients (p<0.001). Results indicate that indoor fungal contamination could be a factor favoring ABPA and suggest that environmental surveys could help in preventing fungal risk in CF patients., (Copyright © 2015 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

We have studied the characteristics of 202 cystic fibrosis adult patients, all with chronic respiratory symptoms, with a median age of 27 yrs (18 to 55 yrs) and a male predominance (56%). At genetic analysis, delta F508 homozygotes were 41%, delta F508 heterozygotes 42% and 17% had no delta F508. The respiratory disease was more severe and complications were more frequent in adults: hemoptysis in 14%, pneumothorax in 15%, lung transplantation in 25 patients. Chronic bronchial colonisation with Pseudomonas aeruginosa, in 76% of patients, contributed to making treatments more severe because of antibiotic i.v. courses and nebulised antibiotics. Respiratory function showed a mean FVC of 62 +/- 22% and a mean FEVI of 48 +/- 94%. External pancreatic insufficiency was found in 83%, diabetes in 14%. Intestinal occlusion syndromes were observed in 11% of patients and hepatic cirrhosis in 8%. In spite of the severity of the respiratory disease, theses patients succeeded in social and occupational insertion; 62% were independent, 18% had children and 77% were working or studying. Analysis of the patients according to age at diagnosis showed that, in 38 patients diagnosed after the age of 18 yrs, the respiratory disease was less severe, pancreatic insufficiency and non-respiratory complications were less frequent (34% had pancreatic insufficiency, 5% had diabetes and none had cirrhosis). This may partly be due to the presence of milder CFTR mutations. In conclusion, cystic fibrosis in adulthood frequently looks like an evolutive form of cystic fibrosis in childhood. Nevertheless, some late diagnosed forms in adults, with better prognosis, have been recently identified.

This study investigated the relations between nasal transepithelial electric potential difference (PD) and the phenotype and genotype of cystic fibrosis (CF) adult patients. Basal nasal PD was measured in 95 adult CF patients who were classified into three groups of nasal PD (expressed as absolute values) according to the 10th and the 90th percentiles (28.3 and 49.2 mV, respectively), which defined group 1 (nasal PD < or =28.3 mV), group 2 (nasal PD 28.3-49.2 mV) and group 3 (nasal PD > or =49.2 mV). Patients from group 1 had a higher forced vital capacity (FVC) than patients from groups 2 and 3 (76.5+/-22.4 versus 57.4+/-21.2 and 55.7+/-21.1% predicted, respectively, p<0.05) and a higher forced expiratory volume in one second (FEV1) (69.3+/-24.0 versus 42.5+/-22.4 and 42.2+/-21.4% pred, respectively, p<0.01). Among patients with severe mutations (deltaF508 homozygotes, or one deltaF508 mutation plus another "severe" mutation, or two "severe" mutations), patients from group 1 had a higher FVC, FEV1 and arterial oxygen tension than patients from groups 2 and 3 (p<0.05 for each comparison). The results show that in adult cystic fibrosis patients a normal basal nasal potential difference is related to milder respiratory disease, irrespective of the severity of the genotype.