Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
Cystic fibrosis [keywords]
- Colour Doppler ultrasound findings in the nail in cystic fibrosis. [LETTER]
- J Eur Acad Dermatol Venereol 2014 Jul 30.
- Inactivation of thyA in Staphylococcus aureus Attenuates Virulence and Has a Strong Impact on Metabolism and Virulence Gene Expression. [Journal Article]
- MBio 2014; 5(4)
Staphylococcus aureus thymidine-dependent small-colony variants (TD-SCVs) are frequently isolated from patients with chronic S. aureus infections after long-term treatment with trimethoprim-sulfamethoxazole (TMP-SMX). While it has been shown that TD-SCVs were associated with mutations in thymidylate synthase (TS; thyA), the impact of such mutations on protein function is lacking. In this study, we showed that mutations in thyA were leading to inactivity of TS proteins, and TS inactivity led to tremendous impact on S. aureus physiology and virulence. Whole DNA microarray analysis of the constructed ΔthyA mutant identified severe alterations compared to the wild type. Important virulence regulators (agr, arlRS, sarA) and major virulence determinants (hla, hlb, sspAB, and geh) were downregulated, while genes important for colonization (fnbA, fnbB, spa, clfB, sdrC, and sdrD) were upregulated. The expression of genes involved in pyrimidine and purine metabolism and nucleotide interconversion changed significantly. NupC was identified as a major nucleoside transporter, which supported growth of the mutant during TMP-SMX exposure by uptake of extracellular thymidine. The ΔthyA mutant was strongly attenuated in virulence models, including a Caenorhabditis elegans killing model and an acute pneumonia mouse model. This study identified inactivation of TS as the molecular basis of clinical TD-SCV and showed that thyA activity has a major role for S. aureus virulence and physiology.Thymidine-dependent small-colony variants (TD-SCVs) of Staphylococcus aureus carry mutations in the thymidylate synthase (TS) gene (thyA) responsible for de novo synthesis of thymidylate, which is essential for DNA synthesis. TD-SCVs have been isolated from patients treated for long periods with trimethoprim-sulfamethoxazole (TMP-SMX) and are associated with chronic and recurrent infections. In the era of community-associated methicillin-resistant S. aureus, the therapeutic use of TMP-SMX is increasing. Today, the emergence of TD-SCVs is still underestimated due to misidentification in the diagnostic laboratory. This study showed for the first time that mutational inactivation of TS is the molecular basis for the TD-SCV phenotype and that TS inactivation has a strong impact on S. aureus virulence and physiology. Our study helps to understand the clinical nature of TD-SCVs, which emerge frequently once patients are treated with TMP-SMX.
- Directly Sampling the Lung of a Young Child with Cystic Fibrosis Reveals Diverse Microbiota. [JOURNAL ARTICLE]
- Ann Am Thorac Soc 2014 Jul 29.
Rationale: The airways of people with cystic fibrosis (CF) are chronically infected by a variety of bacterial species. While routine culture methods are usually used to diagnose these infections, culture-independent, DNA-based methods have recently identified many bacterial species in CF respiratory secretions that are not routinely cultured. Many prior culture-independent studies focused either on microbiota in explanted CF lungs, reflecting end-stage disease, or those in oropharyngeal (OP) swabs, which likely sample areas in addition to the lower airways. Therefore, it was unknown whether the lower airways of children with CF, well before end-stage but with symptomatic lung disease, truly contained diverse microbiota. Objectives: To define the microbiota in the diseased lung tissue of a child who underwent lobectomy for severe, localized CF lung disease. Methods: After pathologic examination verified that this child's lung tissue reflected CF lung disease, we used bacterial rRNA gene pyrosequencing and computational phylogenetic analysis to identify the microbiota in serial sections of the tissue. Measurements and Main Results: This analysis identified diverse, and anatomically heterogeneous, bacterial populations in the lung tissue that contained both culturable and nonculturable species, including abundant Haemophilus, Ralstonia, and Propionibacterium species. Routine clinical cultures identified only Staphylococcus aureus, which represented only a small fraction of the microbiota found by sequencing. Microbiota analysis of an intraoperative OP swab identified predominantly Streptococcus species. The OP findings therefore represented the lung tissue microbiota poorly, in agreement with findings from earlier studies of OP swabs in end-stage disease. Conclusions: These results support the concept that diverse and spatially heterogeneous microbiota, not necessarily dominated by "traditional CF pathogens", are present in the airways of young, symptomatic children with early CF lung disease.
- Development of allele-specific multiplex PCR to determine the length of poly-T in intron 8 of CFTR. [Journal Article]
- PeerJ 2014.:e468.
Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation analysis has been implemented for Cystic Fibrosis (CF) carrier screening, and molecular diagnosis of CF and congenital bilateral absence of the vas deferens (CBAVD). Although poly-T allele analysis in intron 8 of CFTR is required when a patient is positive for R117H, it is not recommended for routine carrier screening. Therefore, commercial kits for CFTR mutation analysis were designed either to mask the poly-T allele results, unless a patient is R117H positive, or to have the poly-T analysis as a standalone reflex test using the same commercial platform. There are other standalone assays developed to detect poly-T alleles, such as heteroduplex analysis, High Resolution Melting (HRM) curve analysis, allele-specific PCR (AS-PCR) and Sanger sequencing. In this report, we developed a simple and easy-to-implement multiplex AS-PCR assay using unlabeled standard length primers, which can be used as a reflex or standalone test for CFTR poly-T track analysis. Out of 115 human gDNA samples tested, results from our new AS-PCR matched to the previous known poly-T results or results from Sanger sequencing.
- The microbiome in pediatric cystic fibrosis patients: the role of shared environment suggests a window of intervention. [Journal Article]
- Microbiome 2014.:14.
Cystic fibrosis (CF) is caused by mutations in the CFTR gene that predispose the airway to infection. Chronic infection by pathogens such as Pseudomonas aeruginosa leads to inflammation that gradually degrades lung function, resulting in morbidity and early mortality. In a previous study of CF monozygotic twins, we demonstrate that genetic modifiers significantly affect the establishment of persistent P. aeruginosa colonization in CF. Recognizing that bacteria other than P. aeruginosa contribute to the CF microbiome and associated pathology, we used deep sequencing of sputum from pediatric monozygotic twins and nontwin siblings with CF to characterize pediatric bacterial communities and the role that genetics plays in their evolution.We found that the microbial communities in sputum from pediatric patients living together were much more alike than those from pediatric individuals living apart, regardless of whether samples were taken from monozygous twins or from nontwin CF siblings living together, which we used as a proxy for dizygous twins. In contrast, adult communities were comparatively monolithic and much less diverse than the microbiome of pediatric patients.Taken together, these data and other recent studies suggest that as patients age, the CF microbiome becomes less diverse, more refractory to treatment and dominated by mucoid P. aeruginosa, as well as being associated with accelerated pulmonary decline. Our studies show that the microbiome of pediatric patients is susceptible to environmental influences, suggesting that interventions to preserve the community structure found in young CF patients might be possible, perhaps slowing disease progression.
- A staged approach for a lung-liver transplant patient using ex vivo reconditioned lungs first followed by an urgent liver transplantation. [JOURNAL ARTICLE]
- Transpl Int 2014 Jul 29.
Combined lung-liver transplantation is a logistically challenging procedure hampered by shortage of organ donors. We describe the case of a young patient with end-stage lung disease due to cystic fibrosis and liver cirrhosis who needed combined lung- liver transplantation. The long waiting for this caused an interesting clinical dilemma. We decided to change our policy in this situation by listing him only for the lung transplantation and to apply for a high urgent liver transplantation if the liver failed after the lung transplantation. This strategy enabled us to use lungs treated with ex-vivo lung perfusion (EVLP) from an unsuitable donor after circulatory death. After conditioning for 4 hours via EVLP the pO2 was 59.7 kPa. The lungs were transplanted successfully. He developed an acute-on-chronic liver failure for which he received a successful liver transplantation 19 days after the lung transplantation. This article is protected by copyright. All rights reserved.
- Aquagenic palmoplantar keratoderma: a sign of cystic fibrosis early in life. [LETTER]
- Int J Dermatol 2014 Jul 29.
- Progress towards next-generation therapeutics for cystic fibrosis. [Journal Article]
- Future Med Chem 2014 Jun; 6(9):1067-79.
Cystic fibrosis (CF) is the most common inherited genetic condition amongst Caucasian ethnicities, affecting 1 in 2500 live births. There remains a significant unmet medical need for more and better therapies for this chronic, degenerative condition, in particular those that address the respiratory dysfunction and respiratory infections that characterise CF. CF is caused by mutations in the cystic transmembrane conductance regulator gene (CFTR). The key pathology driver of CF is dysregulated ion transport across the epithelial cell barriers that line the respiratory tract, gastrointestinal tract and other organ systems. This review focuses on the state-of-the-art advances and future directions in therapeutic strategies to combat and manage the symptoms of CF and/or restore functionality of the defective CFTR.
- Environmental risks for nontuberculous mycobacteria: individual exposures and climatic factors in the Cystic Fibrosis population. [JOURNAL ARTICLE]
- Ann Am Thorac Soc 2014 Jul 28.
Rationale: Persons with cystic fibrosis are at high risk of pulmonary nontuberculous mycobacterial infection with a national prevalence estimated at 13%. The risk of nontuberculous mycobacteria associated with specific environmental exposures and the correlation with climatic conditions in this population have not been described. Objectives: To describe the association of pulmonary nontuberculous mycobacteria with individual exposures to water and soil aerosols, and the population associations of these infections with climatic factors. Methods: A nested case-control study was conducted within a cohort study of pulmonary nontuberulous mycobacteria prevalence at 21 geographically diverse National Cystic Fibrosis Centers. Incident nontuberculous mycobacterial cases (at least one prior negative culture following by one positive culture) were age- and sex- matched to culture negative controls; exposures to water and soil were assessed by a standardized questionnaire. Cohort prevalence at each of 21 centers was correlated with climatic conditions in the same area through linear regression modeling. Measurements and Main Results: Overall, 48 cases and 85 controls were enrolled. Indoor swimming was associated with incident infection (ORadj= 5.9, C.L, 1.3, 26.1), although only nine (19%) cases and five (6%) controls reported indoor swimming in the four months prior to infection. Exposure to showering and municipal water supply was common among both cases and controls: 77% of cases and 76% of controls reported showering at least daily. In linear regression, average annual atmospheric water vapor content was significantly predictive of center prevalence (p=0.0019), with R2=0.40. Conclusions: Atmospheric conditions explain more of the variation in disease prevalence than individual behaviors. The risk of specific exposures may vary by geographic region due to differences in conditions favoring mycobacterial growth and survival. However, because exposure to these organisms is ubiquitous and behaviors are similar among persons with and without pulmonary nontuberculous mycobacteria , genetic susceptibility beyond cystic fibrosis is likely to be important for disease development. Common individual risk factors in high risk populations remain to be identified.
- Blocking Phosphatidylcholine Utilization in Pseudomonas aeruginosa, via Mutagenesis of Fatty Acid, Glycerol and Choline Degradation Pathways, Confirms the Importance of This Nutrient Source In Vivo. [Journal Article]
- PLoS One 2014; 9(7):e103778.
Pseudomonas aeruginosa can grow to very high-cell-density (HCD) during infection of the cystic fibrosis (CF) lung. Phosphatidylcholine (PC), the major component of lung surfactant, has been hypothesized to support HCD growth of P. aeruginosa in vivo. The phosphorylcholine headgroup, a glycerol molecule, and two long-chain fatty acids (FAs) are released by enzymatic cleavage of PC by bacterial phospholipase C and lipases. Three different bacterial pathways, the choline, glycerol, and fatty acid degradation pathways, are then involved in the degradation of these PC components. Here, we identified five potential FA degradation (Fad) related fadBA-operons (fadBA1-5, each encoding 3-hydroxyacyl-CoA dehydrogenase and acyl-CoA thiolase). Through mutagenesis and growth analyses, we showed that three (fadBA145) of the five fadBA-operons are dominant in medium-chain and long-chain Fad. The triple fadBA145 mutant also showed reduced ability to degrade PC in vitro. We have previously shown that by partially blocking Fad, via mutagenesis of fadBA5 and fadDs, we could significantly reduce the ability of P. aeruginosa to replicate on FA and PC in vitro, as well as in the mouse lung. However, no studies have assessed the ability of mutants, defective in choline and/or glycerol degradation in conjunction with Fad, to grow on PC or in vivo. Hence, we constructed additional mutants (ΔfadBA145ΔglpD, ΔfadBA145ΔbetAB, and ΔfadBA145ΔbetABΔglpD) significantly defective in the ability to degrade FA, choline, and glycerol and, therefore, PC. The analysis of these mutants in the BALB/c mouse lung infection model showed significant inability to utilize PC in vitro, resulted in decreased replication fitness and competitiveness in vivo compared to the complement strain, although there was little to no variation in typical virulence factor production (e.g., hemolysin, lipase, and protease levels). This further supports the hypothesis that lung surfactant PC serves as an important nutrient for P. aeruginosa during CF lung infection.