Respiratory Infections In Cystic Fibrosis Research Articles

Exploring the Effect of the Composition of Three Different Oregano Essential Oils on the Growth of Multidrug-Resistant Cystic Fibrosis Pseudomonas aeruginosa Strains

Oregano essential oils (EOs) could represent interesting therapeutic strategies to treat multidrug-resistant (MDR) pathogens as Pseudomonas aeruginosa, responsible for respiratory infections in cystic fibrosis (CF) patients. There could be a great variability in EOs composition when extracted from different plant species. The aim of this study was to chemically characterize and to test EOs, extracted from Origanum compactum, Origanum vulgare and Origanum vulgare var. hirtum, for in vitro antimicrobial activity against a panel of twenty MDR P. aeruginosa strains isolated from CF patients. EOs main components were carvacrol (71.8-73.8-47.1%), thymol (1.6-2.3-21.5%), p-cymene (11.6-7.4-10.8%) and γ-terpinene (1.7-3.1-8.4%). In general, the EOs showed inhibitory activity even at low concentration: 0.5% (v/v) OvEO and OhEO were able to inhibit the 80% of P. aeruginosa strains. Furthermore, the three EOs killed at least 75% of the strains at concentrations lower than 1% (v/v). Average MIC and MBC values were not significantly different. Similar levels of OEOs antimicrobial activities might be related to the fact that the main chemical class (i.e. carvacrol/thymol) is represented in quite similar percentages. Hence, the results of the present study shed light on a carvacrol/thymol-rich EO with a well-represented monoterpene hydrocarbons class as promising standardized antimicrobial herbal product.

Cystic fibrosis respiratory tract salt concentration: An Exploratory Cohort Study.

In cystic fibrosis patients, electrolytic and osmolality imbalance secondary to cystic fibrosis transmembrane conductance regulator mutations may impact on mucoid secretion accumulation and secondary colonization by opportunistic pathogens such as nontuberculous mycobacteria.We performed a noninvasive exploratory prospective controlled clinical study comparing sputum salinity and acid-base characteristics of cystic fibrosis and noncystic fibrosis control patients. A total of 57 patients and 62 controls were included.Sputum salt concentrations were 10.5 g/L (95% CI: 7.7–13.3) in patients and 7.4 g/L (95% CI: 5.9–8.9) in aged-matched controls, a difference that was found to be statistically significant (P < .05). No difference in pH was observed between patients and controls.These differences in respiratory secretions salt concentrations could influence host-pathogen interactions in the context of cystic fibrosis respiratory infections. We propose to include respiratory secretion salt measurement as a routine analysis on cystic fibrosis patients’ sputum submitted for bacterial culture.

Aminoglycoside-Induced Cochleotoxicity: A Review.

Aminoglycoside antibiotics are used as prophylaxis, or urgent treatment, for many life-threatening bacterial infections, including tuberculosis, sepsis, respiratory infections in cystic fibrosis, complex urinary tract infections and endocarditis. Although aminoglycosides are clinically-essential antibiotics, the mechanisms underlying their selective toxicity to the kidney and inner ear continue to be unraveled despite more than 70 years of investigation. The following mechanisms each contribute to aminoglycoside-induced toxicity after systemic administration: (1) drug trafficking across endothelial and epithelial barrier layers; (2) sensory cell uptake of these drugs; and (3) disruption of intracellular physiological pathways. Specific factors can increase the risk of drug-induced toxicity, including sustained exposure to higher levels of ambient sound, and selected therapeutic agents such as loop diuretics and glycopeptides. Serious bacterial infections (requiring life-saving aminoglycoside treatment) induce systemic inflammatory responses that also potentiate the degree of ototoxicity and permanent hearing loss. We discuss prospective clinical strategies to protect auditory and vestibular function from aminoglycoside ototoxicity, including reduced cochlear or sensory cell uptake of aminoglycosides, and otoprotection by ameliorating intracellular cytotoxicity.

Regulator LdhR and d-Lactate Dehydrogenase LdhA of Burkholderia multivorans Play Roles in Carbon Overflow and in Planktonic Cellular Aggregate Formation.

LysR-type transcriptional regulators (LTTRs) are the most commonly found regulators in Burkholderia cepacia complex, comprising opportunistic pathogens causing chronic respiratory infections in cystic fibrosis (CF) patients. Despite LTTRs being global regulators of pathogenicity in several types of bacteria, few have been characterized in Burkholderia Here, we show that gene ldhR of B. multivorans encoding an LTTR is cotranscribed with ldhA encoding a d-lactate dehydrogenase and evaluate their implication in virulence traits such as exopolysaccharide (EPS) synthesis and biofilm formation. A comparison of the wild type (WT) and its isogenic ΔldhR mutant grown in medium with 2% d-glucose revealed a negative impact on EPS biosynthesis and on cell viability in the presence of LdhR. The loss of viability in WT cells was caused by intracellular acidification as a consequence of the cumulative secretion of organic acids, including d-lactate, which was absent from the ΔldhR mutant supernatant. Furthermore, LdhR is implicated in the formation of planktonic cellular aggregates. WT cell aggregates reached 1,000 μm in size after 24 h in liquid cultures, in contrast to ΔldhR mutant aggregates that never grew more than 60 μm. The overexpression of d-lactate dehydrogenase LdhA in the ΔldhR mutant partially restored the formed aggregate size, suggesting a role for fermentation inside aggregates. Similar results were obtained for surface-attached biofilms, with WT cells producing more biofilm. A systematic evaluation of planktonic aggregates in Burkholderia CF clinical isolates showed aggregates in 40 of 74. As CF patients' lung environments are microaerophilic and bacteria are found as free aggregates/biofilms, LdhR and LdhA might have central roles in adapting to this environment.IMPORTANCE Cystic fibrosis patients often suffer from chronic respiratory infections caused by several types of microorganisms. Among them are the Burkholderia cepacia complex bacteria, which cause progressive deterioration of lung function that, in some patients, might develop into fatal necrotizing pneumoniae with bacteremia, known as "cepacia syndrome." Burkholderia pathogenesis is multifactorial as they express several virulence factors, form biofilms, and are highly resistant to antimicrobial compounds, making their eradication from the CF patients' airways very difficult. As Burkholderia is commonly found in CF lungs in the form of cell aggregates and biofilms, the need to investigate the mechanisms of cellular aggregation is obvious. In this study, we demonstrate the importance of a d-lactate dehydrogenase and a regulator in regulating carbon overflow, cellular aggregates, and surface-attached biofilm formation. This not only enhances our understanding of Burkholderia pathogenesis but can also lead to the development of drugs against these proteins to circumvent biofilm formation.

Pseudomonas aeruginosa Alginate Overproduction Promotes Coexistence with Staphylococcus aureus in a Model of Cystic Fibrosis Respiratory Infection.

ABSTRACTWhile complex intra- and interspecies microbial community dynamics are apparent during chronic infections and likely alter patient health outcomes, our understanding of these interactions is currently limited. For example, Pseudomonas aeruginosa and Staphylococcus aureus are often found to coinfect the lungs of patients with cystic fibrosis (CF), yet these organisms compete under laboratory conditions. Recent observations that coinfection correlates with decreased health outcomes necessitate we develop a greater understanding of these interbacterial interactions. In this study, we tested the hypothesis that P. aeruginosa and/or S. aureus adopts phenotypes that allow coexistence during infection. We compared competitive interactions of P. aeruginosa and S. aureus isolates from mono- or coinfected CF patients employing in vitro coculture models. P. aeruginosa isolates from monoinfected patients were more competitive toward S. aureus than P. aeruginosa isolates from coinfected patients. We also observed that the least competitive P. aeruginosa isolates possessed a mucoid phenotype. Mucoidy occurs upon constitutive activation of the sigma factor AlgT/U, which regulates synthesis of the polysaccharide alginate and dozens of other secreted factors, including some previously described to kill S. aureus. Here, we show that production of alginate in mucoid strains is sufficient to inhibit anti-S. aureus activity independent of activation of the AlgT regulon. Alginate reduces production of siderophores, 2-heptyl-4-hydroxyquinolone-N-oxide (HQNO), and rhamnolipids—each required for efficient killing of S. aureus. These studies demonstrate alginate overproduction may be an important factor driving P. aeruginosa coinfection with S. aureus.

Lower respiratory infection in patients with cystic fibrosis in Russian Federation according to the National Register, 2014

The aim of this study was to characterize chronic respiratory infection in cystic fibrosis (CF) patients in Russia according to the National Russian CF Register. Methods. The National Russian CF Register included 2,131 patients from 74 Russian regions (2,092 alive patients and 39 died patients) in 2014 (the median age, 10.2 (15.2) years; 29.2% were adults ≥ 18 лет). Microbiological findings of CF patients (chronic infection caused by Staphylococcus aureus, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia соmplex, non-tuberculous mycobacteria (NTM), non-Pseudomonas Gram negative pathogens including Achromobacter spp., and frequency of intermittent P. aeruginosa infection) have been analyzed in this article. Results. The tested pathogens were not found in 18.0% of patients. The prevalence of pathogens in descending order was as follows: S. aureus, 54,5%; P. aeruginosa, (chronic infection), 32,1%; P. aeruginosa (intermittent infection), 14,1%; B. cepacia complex, 7,3%; Achromobacter spp., 3,5%; Stenotrophomonas maltophilia, 3,3%; NTM, 0,8%. Other non-Pseudomonas Gram negative pathogens including Achromobacter spp., Escherichia coli, Acinetobacter spp., Klebsiella spp., Citrobacter spp. caused chronic airway infection in 11.8% of patients. Children were infected more frequently by S. aureus and adult patients infected were frequently by P. aeruginosa, В.сepacia complex, Achromobacter spp., and NTM. No geographic prevalence of pathogen distribution was found. Russian CF patients were more often infected by S. aureus and B. cepacia complex compared to European CF patients. P. aeruginosa was yielded with equal rate in Russia and in Europe. S. maltophilia and NTM were found less frequently in Russia compared to Europe. Conclusion. According to the National Russian CF Register, the airways of 18.0% of CF patients in Russia are not colonized by respiratory pathogens. As the patient's age increases, the rate of Gram negative respiratory infection is growing. The most harmful infections are thought to be B. cepacia complex and Achromobacter spp.

Consensus “Cystic Fibrosis: definition, diagnostic criteria, treatment” Section “Microbiology and Epidemiology of chronic respiratory infections in cystic fibrosis”

The main causative agents of lung infection in patients with cystic fibrosis (CF) are P. aeruginosa, S. aureus and H. influenzae. In the last decade, gram-negative nonfermentative microorganisms (NFMO) - Вurkholderia cepacia complex (Bcc), Stenotrophomonas maltophilia, Achromobacter xylosoxidans and non-tuberculous mycobacteria, fungi of the genus Aspergillus have acquired the clinical significance. It is found that the chronic lung infection in 2/3 of the cases caused by association of microorganisms. Among hospitalized patients, in contrast to outpatients, these associations are represented by two, three or more species of microorganisms. The associations of P. aeruginosa + S. aureus (18,2 %) and P. aeruginosa + Bcc (9,1 %) are the most common. Other representatives - A. xylosoxidans, S. maltophilia and A. baumanii - is often identified in the associations of microorganisms. The focuses of chronic lung infections are formed in patients with increasing age. The dominant pathogens are P. aeruginosa and S. aureus. The methicillinresistant staphylococci and P. aeruginosa strains with a mucoid phenotype are of particular importance for cystic fibrosis patients. Bcc isolates from cystic fibrosis patients in Russia often belong to genomovar III A-B. cenocepacia. The Bcc strains colonize the lower airways of patients with CF and are able for long-term persistence and transmission from patient to patient. The resistance to many antibiotics is the main feature of the P. aeruginosa, S. aureus and Bcc strains. The strains of microorganisms with atypical phenotype (small colony variants) are formed under the action of the antibiotic. Infections caused by Bcc and other NFMO are difficult to identify and we need to use a wide range of bacteriological, biochemical, molecular biological techniques and mass spectrometry.

Destruction of Opportunistic Pathogens via Polymer Nanoparticle-Mediated Release of Plant-Based Antimicrobial Payloads.

The synthesis of antimicrobial thymol/carvacrol-loaded polythioether nanoparticles (NPs) via a one-pot, solvent-free miniemulsion thiol-ene photopolymerization process is reported. The active antimicrobial agents, thymol and carvacrol, are employed as "solvents" for the thiol-ene monomer phase in the miniemulsion to enable facile high capacity loading (≈50% w/w), excellent encapsulation efficiencies (>95%), and elimination of all postpolymerization purification processes. The NPs serve as high capacity reservoirs for slow-release and delivery of thymol/carvacrol-combination payloads that exhibit inhibitory and bactericidal activity (>99.9% kill efficiency at 24 h) against gram-positive and gram-negative bacteria, including both saprophytic (Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 25922) and pathogenic species (E. coli ATCC 43895, Staphylococcus aureus RN6390, and Burkholderia cenocepacia K56-2). This report is among the first to demonstrate antimicrobial efficacy of essential oil-loaded nanoparticles against B. cenocepacia - an innately resistant opportunistic pathogen commonly associated with debilitating respiratory infections in cystic fibrosis. Although a model platform, these results point to promising pathways to particle-based delivery of plant-derived extracts for a range of antimicrobial applications, including active packaging materials, topical antiseptics, and innovative therapeutics.

Managing Pseudomonas aeruginosa respiratory infections in cystic fibrosis.

The current guidelines and recent clinical research in the management of Pseudomonas aeruginosa respiratory infections in cystic fibrosis (CF) are reviewed. Areas where further research is required will also be highlighted. P. aeruginosa is a key respiratory pathogen in CF. Inhaled tobramycin or colistin is recommended for early eradication to prevent establishment of chronic infection. Other antibiotic options are currently being investigated. The long-term success of eradication strategies is also now being assessed. The use of inhaled antibiotics in the management of chronic P. aeruginosa infection is an area of active investigation. Acute pulmonary exacerbations are still a major cause of morbidity and mortality. Guidelines continue to recommend combination intravenous therapy but further research is required to clarify the advantage of this approach. Multidrug resistance is common and potentially more effective antipseudomonal antibiotics may soon become available. The management of P. aeruginosa respiratory infection in CF remains a challenging area, especially in the setting of multidrug resistance. The role of inhaled antibiotics continues to be expanded. Further research is required in the key areas of eradication and management of chronic infection and acute pulmonary exacerbations to identify those treatments that optimize long-term, clinical benefits.

Genotypic and phenotypic analyses of a Pseudomonas aeruginosa chronic bronchiectasis isolate reveal differences from cystic fibrosis and laboratory strains.

BackgroundPseudomonas aeruginosa is an environmentally ubiquitous Gram-negative bacterium and important opportunistic human pathogen, causing severe chronic respiratory infections in patients with underlying conditions such as cystic fibrosis (CF) or bronchiectasis. In order to identify mechanisms responsible for adaptation during bronchiectasis infections, a bronchiectasis isolate, PAHM4, was phenotypically and genotypically characterized.ResultsThis strain displays phenotypes that have been associated with chronic respiratory infections in CF including alginate over-production, rough lipopolysaccharide, quorum-sensing deficiency, loss of motility, decreased protease secretion, and hypermutation. Hypermutation is a key adaptation of this bacterium during the course of chronic respiratory infections and analysis indicates that PAHM4 encodes a mutated mutS gene responsible for a ~1,000-fold increase in mutation rate compared to wild-type laboratory strain P. aeruginosa PAO1. Antibiotic resistance profiles and sequence data indicate that this strain acquired numerous mutations associated with increased resistance levels to β-lactams, aminoglycosides, and fluoroquinolones when compared to PAO1. Sequencing of PAHM4 revealed a 6.38 Mbp genome, 5.9 % of which were unrecognized in previously reported P. aeruginosa genome sequences. Transcriptome analysis suggests a general down-regulation of virulence factors, while metabolism of amino acids and lipids is up-regulated when compared to PAO1 and metabolic modeling identified further potential differences between PAO1 and PAHM4.ConclusionsThis work provides insights into the potential differential adaptation of this bacterium to the lung of patients with bronchiectasis compared to other clinical settings such as cystic fibrosis, findings that should aid the development of disease-appropriate treatment strategies for P. aeruginosa infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2069-0) contains supplementary material, which is available to authorized users.

Semi-automated repetitive sequence-based PCR amplification for species of the Scedosporium apiospermum complex.

The Scedosporium apiospermum species complex usually ranks second among the filamentous fungi colonizing the airways of patients with cystic fibrosis (CF), but little is known about the molecular epidemiology of the airway colonization. Polymerase chain reaction (PCR) amplification of repetitive sequences (rep-PCR) was applied to the retrospective analysis of a panel of isolates already studied by random amplification of polymorphic DNA (RAPD) and comprising 63 isolates recovered from sputa from 9 CF patients. Results were compared to those obtained previously by RAPD, and herein by beta-tubulin (TUB) gene sequencing and Multilocus Sequence Typing (MLST). Within the panel of isolates studied,S. apiospermum sensu stricto and Scedosporium boydii, as expected, were the predominant species with 21 and 36 isolates, respectively. Four isolates from one patient were identified as Scedosporium aurantiacum, whereas two isolates belonged to the Pseudallescheria ellipsoidea subgroup of S. boydii rep-PCR analysis of these isolates clearly differentiated the three species and P. ellipsoidea isolates, whatever the rep-PCR kit used, and also permitted strain differentiation. When using the mold primer kit, results from rep-PCR were in close agreement with those obtained by MLST. For both S. apiospermum and S. boydii, 8 genotypes were differentiated by rep-PCR and MLST compared to 10 by RAPD. All S. aurantiacum isolates shared the same RAPD genotype and exhibited the same rep-PCR profile and sequence type. These results illustrate the efficacy of rep-PCR for both species identification within the S. apiospermum complex and genotyping for the two major species of this complex.Abstract presentation: Part of this work was presented during the 18th Congress of the International Society for Human and Animal Mycology, Berlin (Germany), June 2012.S. Giraud, C. Godon, A. Rougeron, J.P. Bouchara and L. Favennec are members of the ECMM/ISHAM working group on Fungal respiratory infections in Cystic Fibrosis(Fri-CF).

Quantitative analysis of volatile metabolites released in vitro by bacteria of the genus Stenotrophomonas for identification of breath biomarkers of respiratory infection in cystic fibrosis.

The aim of the present study was to characterize the volatile metabolites produced by genotypically diverse strains of the Stenotrophomonas genus in order to evaluate their potential as biomarkers of lung infection by non-invasive breath analysis. Volatile organic compounds (VOCs) emitted from 15 clinical and five environmental strains belonging to different genogroups of Stenotrophomonas maltophilia (n = 18) and Stenotrophomonas rhizophila (n = 2) cultured in Mueller-Hinton Broth (MHB) liquid media were analysed by gas chromatography mass spectrometry (GC–MS) and selected ion flow tube mass spectrometry (SIFT–MS). Several VOCs were detected in high concentration, including ammonia, propanol, dimethyl disulphide propanol and dimethyl disulphide. The GC–MS measurements showed that all 15 clinical strains produced similar headspace VOCs compositions, and SIFT–MS quantification showed that the rates of production of the VOCs by the genotypically distinct strains were very similar. All in vitro cultures of both the Stenotrophomonas species were characterised by efficient production of two isomers of methyl butanol, which can be described by known biochemical pathways and which is absent in other pathogens, including Pseudomonas aeruginosa. These in-vitro data indicate that methyl butanol isomers may be exhaled breath biomarkers of S. maltophilia lung infection in patients with cystic fibrosis.

Investigation of the multifaceted iron acquisition strategies of Burkholderia cenocepacia

Burkholderia cenocepacia is a bacterial pathogen which causes severe respiratory infections in cystic fibrosis (CF). These studies were aimed at gaining an insight into the iron acquisition strategies of B. cenocepacia. In iron restricted conditions, genes associated with the synthesis and utilisation of ornibactin (pvdA, orbA, orb F) were significantly upregulated compared to the expression of pyochelin associated genes (pchD, fptA). In the absence of alternative iron sources, B. cenocepacia J2315 and 715j utilised ferritin and haemin, but not transferrin or lactoferrin for growth. Significantly, mutants unable to produce ornibactin, (715j-orbI) or ornibactin and pyochelin, (715j-pobA), utilised haemin and ferritin more efficiently than the wild-type. Moreover, both mutants were also able to utilise lactoferrin for growth (P ≤ 0.01) and additionally 715j-pobA utilised transferrin (P ≤ 0.01), potentially facilitating adaptation to the host environment. Furthermore, B. cenocepacia increased ornibactin gene expression in response to pyoverdine from Pseudomonas aeruginosa (P ≤ 0.01), demonstrating the capacity to compete for iron in co-colonised niches. Pyoverdine also significantly diminished the growth of B. cenocepacia (P < 0.001) which was related to its iron chelating activity. In a study of three B. cenocepacia sequential clonal isolates obtained from a CF patient over a 3.5 year period, ornibactin upregulation in response to pyoverdine was less pronounced in the last isolate compared to the earlier isolates, as was growth in the presence of haemin and ferritin, indicating alternative iron acquisition mechanism(s) may dominate as chronic infection progresses. These data demonstrate the multifaceted iron acquisition strategies of B. cenocepacia and their capacity to be differentially activated in the presence of P. aeruginosa and during chronic infection.

Eradication strategy for persistent methicillin-resistant Staphylococcus aureus infection in individuals with cystic fibrosis--the PMEP trial: study protocol for a randomized controlled trial.

BackgroundThe prevalence of methicillin-resistant Staphylococcus aureus (MRSA) respiratory infection in cystic fibrosis (CF) has increased dramatically over the last decade, and is now affecting approximately 25% of patients. Epidemiologic evidence suggests that persistent infection with MRSA results in an increased rate of decline in FEV1 and shortened survival. Currently, there are no conclusive studies demonstrating an effective and safe treatment protocol for persistent MRSA respiratory infection in CF.Methods/DesignThe primary objective of this study is to evaluate the safety and efficacy of a 28-day course of vancomycin for inhalation in combination with oral antibiotics in eliminating MRSA from the respiratory tract of individuals with CF and persistent MRSA infection. This is a two-center, randomized, double-blind, comparator-controlled, parallel-group study with 1:1 assignment to either vancomycin for inhalation (250 mg twice a day) or taste-matched placebo for 28 days in individuals with cystic fibrosis. In addition, both groups will receive oral rifampin, a second oral antibiotic – trimethoprim/sulfamethoxazole (TMP/SMX) or doxycycline, protocol determined – mupirocin intranasal cream, and chlorhexidine body washes. Forty patients with persistent respiratory tract MRSA infection will be enrolled: 20 will be randomized to vancomycin for inhalation and 20 to a taste-matched placebo. The primary outcome will be the presence of MRSA in sputum respiratory tract cultures 1 month after the conclusion of treatment. Secondary outcomes include the efficacy of the intervention on: FEV1% predicted, patient reported outcomes, pulmonary exacerbations, and MRSA colony-forming units found in respiratory tract sample culture.DiscussionResults of this study will provide guidance to clinicians regarding the safety and effectiveness of a targeted eradication strategy for persistent MRSA infection in CF.Trial registrationThis trial is registered at ClinicalTrials.gov (NCT01594827, received 05/07/2012) and is funded by the Cystic Fibrosis Foundation (Grants: PMEP10K1 and PMEP11K1).

Time between Collection and Storage Significantly Influences Bacterial Sequence Composition in Sputum Samples from Cystic Fibrosis Respiratory Infections

Spontaneously expectorated sputum is traditionally used as the sampling method for the investigation of lower airway infections. While guidelines exist for the handling of these samples for culture-based diagnostic microbiology, there is no comparable consensus on their handling prior to culture-independent analysis. The increasing incorporation of culture-independent approaches in diagnostic microbiology means that it is of critical importance to assess potential biases. The aim of this study was to assess the impact of delayed freezing on culture-independent microbiological analyses and to identify acceptable parameters for sample handling. Sputum samples from eight adult cystic fibrosis (CF) patients were collected and aliquoted into sterile Bijou bottles. Aliquots were stored at room temperature before being frozen at −80°C for increasing intervals, up to a 72-h period. Samples were treated with propidium monoazide to distinguish live from dead cells prior to DNA extraction, and 16S rRNA gene pyrosequencing was used to characterize their bacterial compositions. Substantial variation was observed in samples with high-diversity bacterial communities over time, whereas little variation was observed in low-diversity communities dominated by recognized CF pathogens, regardless of time to freezing. Partitioning into common and rare species demonstrated that the rare species drove changes in similarity. The percentage abundance of anaerobes over the study significantly decreased after 12 h at room temperature (P = 0.008). Failure to stabilize samples at −80°C within 12 h of collection results in significant changes in the detected community composition.

Single versus combination intravenous antibiotic therapy for people with cystic fibrosis.

Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in CF requires further evaluation. To assess the effectiveness of single compared to combination intravenous antibiotic therapy for treating people with CF. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 22 August 2013. Randomised controlled trials (RCTs) comparing a single intravenous antibiotic with a combination of that antibiotic plus a second antibiotic in people with CF. Two authors independently assessed trial quality and extracted data. We identified 43 trials, of which eight trials (356 participants) comparing a single agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials, leading to difficulties in performing the review and interpreting the results. The meta-analysis did not demonstrate any significant differences between monotherapy and combination therapy, in terms of lung function; symptom scores; adverse effects; and bacteriological outcome measures.These results should be interpreted cautiously. Six of the included trials were published between 1977 and 1988; these were single-centre trials with flaws in the randomisation process and small sample size. Overall, the methodological quality was poor. The results of this review are inconclusive. The review raises important methodological issues. There is a need for an RCT which needs to be well-designed in terms of adequate randomisation allocation, blinding, power and long-term follow up. Results need to be standardised to a consistent method of reporting, in order to validate the pooling of results from multiple trials.

The future of antimicrobial therapy in the era of antibiotic resistance in cystic fibrosis pulmonary infection

Cystic fibrosis (CF) is characterised by chronic polymicrobial airway infection and inflammation, which is the major cause of morbidity and mortality. Aggressive use of antimicrobials has been fundamental in increasing the life expectancy of CF patients in recent years. However, enhanced culture and non-culture based detection methods have identified bacteria in the CF lung not previously isolated from CF patients by routine diagnostic microbiology Coupled with increasing antimicrobial resistance, the future of antimicrobial therapy in CF respiratory infection remains challenging. New strategies are needed to address these problems and ensure improvements in life expectancy are maintained. Potential future strategies include the use of new antimicrobial agents and formulations currently in clinical trials, alternative methods of selecting appropriate therapeutic regimens, determination of the pathogenicity of species newly associated with CF and the development of new antimicrobials and adjuvants for use in clinical practice.

Extensive diversification is a common feature of Pseudomonas aeruginosa populations during respiratory infections in cystic fibrosis

BackgroundPopulations of the Liverpool Epidemic Strain (LES) of Pseudomonas aeruginosa undergo extensive diversification in the cystic fibrosis (CF) lung during long-term chronic infections.MethodsWe analyzed sets of 40 isolates from the sputa of five CF patients, each chronically infected with a different non-LES strain of P. aeruginosa. For each sample (two per patient), diversity was assessed by characterizing nine phenotypic traits.ResultsAll P. aeruginosa populations were highly diverse, with the majority of phenotypic variation being due to within-sample diversity.ConclusionsMaintenance of diverse populations in the CF lung is a common feature of P. aeruginosa infections.

Desulfurization of mucin by Pseudomonas aeruginosa: influence of sulfate in the lungs of cystic fibrosis patients

Pseudomonas aeruginosa is a common cause of chronic respiratory infection in cystic fibrosis (CF) patients. Infection is established within the lung epithelial mucus layer through adhesion to mucins. Terminal residues on mucin oligosaccharide chains are highly sulfated and sialylated, which increases their resistance to degradation by bacterial enzymes. However, a number of microbes, including P. aeruginosa, display mucin sulfatase activity. Using ion chromatography, the levels of sulfation on different respiratory mucins and the availability of inorganic sulfate to pathogens in sputum from CF patients were quantified. The ability of clinical isolates of P. aeruginosa to desulfate mucin was tested by providing mucin as a sole sulfur source for growth. All tested P. aeruginosa strains isolated from the lungs of CF patients were able to use human respiratory mucin as a source of sulfur for growth, whereas other non-clinical species of the genus Pseudomonas were not. However, measured levels of inorganic sulfate in sputum from CF patients suggested that bacteria resident in the lung have sufficient inorganic sulfate for growth and are unlikely to require access to mucin sulfur as a sulfur source during chronic infection. This was confirmed when expression of sulfate-repressed P. aeruginosa genes atsK and msuE was found to be repressed in the sputum of CF patients, which was detected by using quantitative RT-PCR. These results indicate that sulfate starvation is unlikely to occur in pathogens residing in the sputum of CF patients and, therefore, mucin desulfation may have an alternative purpose in the association between P. aeruginosa and the airways of CF patients.

Elective versus symptomatic intravenous antibiotic therapy for cystic fibrosis.

Pseudomonas aeruginosa is the commonest micro-organism associated with respiratory infections in cystic fibrosis. Retrospective studies have suggested that using an aggressive policy of intravenous anti-pseudomonal antibiotics at regular intervals, irrespective of symptoms, increases survival. To determine whether there is evidence that an elective (regular) versus symptomatic intravenous antibiotic regimen is associated with an improvement in clinical status and survival rates in people with cystic fibrosis. To identify any adverse effects associated with the use of elective intravenous antibiotics, including an increase in the development of resistant organisms. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 15 March 2012. All randomised or quasi-randomised controlled trials describing the use of elective compared with symptomatic intravenous antibiotic policies for any duration or dose regimen. Elective versus symptomatic intravenous antibiotic regimens against any organisms were considered. People with cystic fibrosis of any age or disease severity were included. Both authors independently assessed trial eligibility and quality; both extracted the data. Searches identified four studies. Two studies reporting results from a total of 79 participants were included in the review. Differences in study design and objectives meant that data could not be pooled for meta-analysis. Neither study demonstrated significant differences in outcome measures between intervention and comparison groups. Studies are insufficient to identify conclusive evidence favouring a policy of elective intravenous antibiotic administration, despite its widespread use, neither are the potential risks adequately evaluated. The results should be viewed with caution, as participant numbers are small. Clearly there is a need for a well-designed, adequately-powered, multicentred randomised controlled trial to evaluate these issues.