Vitamin-D deficiency is associated with chronic bacterial colonisation and disease severity in bronchiectasis.

INTRODUCTION: Vitamin-D deficiency has been linked to an increased risk of respiratory infections. The objective of this study was to determine the frequency and clinical importance of vitamin-D deficiency in patients with bronchiectasis. METHODS: 25-hydroxyvitamin-D was measured by immunoassay in 402 stable patients with bronchiectasis. Patients were classified as vitamin-D deficient (serum 25-hydroxyvitamin-D <25 nmol/l), insufficient (25 nmol/l-74 nmol/l) or sufficient (≥ 75 nmol/l). Disease severity was assessed, including exacerbation frequency, measurement of airway inflammatory markers, sputum bacteriology and lung function over 3 years follow-up. RESULTS: 50% of bronchiectasis patients were vitamin-D deficient, 43% insufficient and only 7% sufficient. This compared to only 12% of age and sex matched controls with vitamin-D deficiency (p<0.0001). Vitamin-D deficient patients were more frequently chronically colonised with bacteria (p<0.0001), 21.4% of vitamin-D deficient subjects were colonised with Pseudomonas aeruginosa compared to 10.4% of insufficient patients and 3.6% of sufficient patients, p=0.003. Vitamin-D deficient patients had lower FEV(1)% predicted (p=0.002), and more frequent pulmonary exacerbations (p=0.04). Vitamin-D deficient patients had higher sputum levels of inflammatory markers and demonstrated a more rapid decline in lung function over 3 years follow-up. Defects in neutrophil function and assessment of airway LL-37 levels did not provide a mechanistic explanation for these findings. Vitamin-D deficient patients had, however, higher levels of Vitamin-D Binding Protein in sputum sol. CONCLUSIONS: Vitamin-D deficiency is common in bronchiectasis and correlates with markers of disease severity. The mechanism of this association is unclear.

Short- and long-term antibiotic treatment reduces airway and systemic inflammation in non-cystic fibrosis bronchiectasis.

RATIONALE: The vicious cycle hypothesis of bronchiectasis argues that bacterial colonization leads to airway inflammation and progressive lung damage. The logical extension of this hypothesis is that acute or chronic antibiotic therapy should improve airway inflammation and clinical outcome. There are little data to support this hypothesis in patients with non-cystic fibrosis (CF) bronchiectasis. OBJECTIVES: To determine whether acute or chronic antibiotic therapy improves airway inflammation and clinical outcome in non-CF bronchiectasis. METHODS: The relationship between bacterial load and airway and systemic inflammation was investigated in 385 stable patients, 15 stable patients treated with intravenous antibiotics, and 34 patients with an exacerbation of bronchiectasis treated with intravenous antibiotics. Long-term antibiotic therapy was investigated using samples from a 12-month controlled trial of nebulized gentamicin. MEASUREMENTS AND MAIN RESULTS: In stable patients, there was a direct relationship between airway bacterial load and markers of airway inflammation (P < 0.0001 for all analyses). High bacterial loads were associated with higher serum intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 (P < 0.05 above bacterial load ≥1 × 10(7) cfu/ml). In stable patients, there was a direct relationship between bacterial load and the risk of subsequent exacerbations (odds ratio, 1.20; 95% confidence interval, 1.11-1.29; P < 0.0001) and severe exacerbations (odds ratio, 1.11; 95% confidence interval, 1.01-1.21; P = 0.02). Short- and long-term antibiotic treatments were associated with reductions in bacterial load, airways, and systemic inflammation. CONCLUSIONS: High airway bacterial loads in non-CF bronchiectasis are associated with airway and systemic inflammation and a greater risk of exacerbations. Short- and long-term antibiotic therapy reduce markers of airways and systemic inflammation.

A randomized controlled trial of nebulized gentamicin in non-cystic fibrosis bronchiectasis.

RATIONALE: Bronchiectasis is a chronic debilitating disease with few evidence-based long-term treatments. OBJECTIVES: A randomized controlled trial assessing the efficacy of nebulized gentamicin therapy over 1 year in patients with non-cystic fibrosis bronchiectasis. METHODS: Sixty-five patients were randomized to either twice-daily nebulized gentamicin, 80 mg, or nebulized 0.9% saline, for 12 months. All were reviewed at three-monthly intervals during treatment and at 3 months' follow-up. MEASUREMENTS AND MAIN RESULTS: At each review the following were assessed: quantitative and qualitative sputum bacteriology; sputum purulence and 24-hour volume; FEV(1), FVC, and forced expiratory flow, midexpiratory phase; exercise capacity; Leicester Cough Questionnaire and St. George's Respiratory Questionnaire; and exacerbation frequency. Fifty-seven patients completed the study. At the end of 12 months' treatment, compared with the saline group, in the gentamicin group there was reduced sputum bacterial density with 30.8% eradication in those infected with Pseudomonas aeruginosa and 92.8% eradication in those infected with other pathogens; less sputum purulence (8.7% vs. 38.5%; P < 0.0001); greater exercise capacity (510 [350-690] m vs. 415 [267.5-530] m; P = 0.03); and fewer exacerbations (0 [0-1] vs. 1.5 [1-2]; P < 0.0001) with increased time to first exacerbation (120 [87-161.5] d vs. 61.5 [20.7-122.7] d; P = 0.02). The gentamicin group had greater improvements in Leicester Cough Questionnaire (81.4% vs. 20%; P < 0.01) and St. George's Respiratory Questionnaire (87.5% vs. 19.2%; P < 0.004) score. No differences were seen in 24-hour sputum volume, FEV(1), FVC, or forced expiratory flow, midexpiratory phase. No P. aeruginosa isolates developed resistance to gentamicin. At follow-up, all outcome measures were similar to baseline. CONCLUSIONS: Regular, long-term nebulized gentamicin is of significant benefit in non-cystic fibrosis bronchiectasis but treatment needs to be continuous for its ongoing efficacy. Clinical trial registered with www.clinicaltrials.gov (NCT 00749866).

The human cathelicidin LL-37 preferentially promotes apoptosis of infected airway epithelium.

Cationic host defense peptides are key, evolutionarily conserved components of the innate immune system. The human cathelicidin LL-37 is an important cationic host defense peptide up-regulated in infection and inflammation, specifically in the human lung, and was shown to enhance the pulmonary clearance of the opportunistic pathogen Pseudomonas aeruginosa in vivo by as yet undefined mechanisms. In addition to its direct microbicidal potential, LL-37 can modulate inflammation and immune mechanisms in host defense against infection, including the capacity to modulate cell death pathways. We demonstrate that at physiologically relevant concentrations of LL-37, this peptide preferentially promoted the apoptosis of infected airway epithelium, via enhanced LL-37-induced mitochondrial membrane depolarization and release of cytochrome c, with activation of caspase-9 and caspase-3 and induction of apoptosis, which only occurred in the presence of both peptide and bacteria, but not with either stimulus alone. This synergistic induction of apoptosis in infected cells was caspase-dependent, contrasting with the caspase-independent cell death induced by supraphysiologic levels of peptide alone. We demonstrate that the synergistic induction of apoptosis by LL-37 and Pseudomonas aeruginosa required specific bacteria-epithelial cell interactions with whole, live bacteria, and bacterial invasion of the epithelial cell. We propose that the LL-37-mediated apoptosis of infected, compromised airway epithelial cells may represent a novel inflammomodulatory role for this peptide in innate host defense, promoting the clearance of respiratory pathogens.

Subdivision of the bacterioferritin comigratory protein family of bacterial peroxiredoxins based on catalytic activity.

Peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, thus conferring resistance to oxidative stress. Using high-resolution mass spectrometry, we recently reclassified one such peroxiredoxin, bacterioferritin comigratory protein (BCP) of Escherichia coli, as an atypical 2-Cys peroxiredoxin that functions through the formation of an intramolecular disulfide bond between the active and resolving cysteine. An engineered E. coli BCP, which lacked the resolving cysteine, retained enzyme activity through a novel catalytic pathway. Unlike the active cysteine, the resolving cysteine of BCP peroxiredoxins is not conserved across all members of the family. To clarify the catalytic mechanism of native BCP enzymes that lack the resolving cysteine, we have investigated the BCP homologue of Burkholderia cenocepacia. We demonstrate that the B. cenocepacia BCP (BcBCP) homologue functions through a 1-Cys catalytic pathway. During catalysis, BcBCP can utilize thioredoxin as a reductant for the sulfenic acid intermediate. However, significantly higher peroxidase activity is observed utilizing glutathione as a resolving cysteine and glutaredoxin as a redox partner. Introduction of a resolving cysteine into BcBCP changes the activity from a 1-Cys pathway to an atypical 2-Cys pathway, analogous to the E. coli enzyme. In contrast to the native B. cenocepacia enzyme, thioredoxin is the preferred redox partner for this atypical 2-Cys variant. BCP-deficient B. cenocepacia exhibit a growth-phase-dependent hypersensitivity to oxidative killing. On the basis of sequence alignments, we believe that BcBCP described herein is representative of the major class of bacterial BCP peroxiredoxins. To our knowledge, this is the first detailed characterization of their catalytic activity. These studies support the subdivision of the BCP family of peroxiredoxins into two classes based on their catalytic activity.

Diagnostic importance of pulmonary interleukin-1beta and interleukin-8 in ventilator-associated pneumonia.

BACKGROUND: Ventilator-associated pneumonia (VAP) is the most commonly fatal nosocomial infection. Clinical diagnosis of VAP remains notoriously inaccurate. The hypothesis was tested that significantly augmented inflammatory markers distinguish VAP from conditions closely mimicking VAP. METHODS: A prospective, observational cohort study was carried out in two university hospital intensive care units recruiting 73 patients with clinically suspected VAP, and a semi-urban primary care practice recruiting a reference group of 21 age- and sex-matched volunteers. Growth of pathogens at >10(4) colony-forming units (cfu)/ml of bronchoalveolar lavage fluid (BALF) distinguished VAP from "non-VAP". Inflammatory mediators were quantified in BALF and serum. Mediators showing significant differences between patients with and without VAP were analysed for diagnostic utility by receiver operator characteristic (ROC) curves. RESULTS: Seventy-two patients had recoverable lavage-24% had VAP. BALF interleukin-1beta (IL-1beta), IL-8, granulocyte colony-stimulating factor and macrophage inflammatory protein-1alpha were significantly higher in the VAP group (all p<0.005). Using a cut-off of 10 pg/ml, BALF IL-1beta generated negative likelihood ratios for VAP of 0.09. In patients with BALF IL-1beta <10 pg/ml the post-test probability of VAP was 2.8%. Using a cut-off value for IL-8 of 2 ng/ml, the positive likelihood ratio was 5.03. There was no difference in cytokine levels between patients with sterile BALF and those with growth of <10(4) cfu/ml. CONCLUSIONS: BALF IL-1beta and IL-8 are amongst the strongest markers yet identified for accurately demarcating VAP within the larger population of patients with suspected VAP. These findings have potential implications for reduction in unnecessary antibiotic use but require further validation in larger populations.

Trappin-2 promotes early clearance of Pseudomonas aeruginosa through CD14-dependent macrophage activation and neutrophil recruitment.

Microaspiration of Pseudomonas aeruginosa contributes to the pathogenesis of nosocomial pneumonia. Trappin-2 is a host defense peptide that assists with the clearance of P. aeruginosa through undefined mechanisms. A model of macrophage interactions with replicating P. aeruginosa (strain PA01) in serum-free conditions was developed, and the influence of subantimicrobial concentrations of trappin-2 was subsequently studied. PA01 that was pre-incubated with trappin-2 (at concentrations that have no direct antimicrobial effects), but not control PA01, was cleared by alveolar and bone marrow-derived macrophages. However, trappin-2-enhanced clearance of PA01 was completely abrogated by CD14- null macrophages. Fluorescence microscopy demonstrated the presence of trappin-2 on the bacterial cell surface of trappin-2-treated PA01. In a murine model of early lung infection, trappin-2-treated PA01 was cleared more efficiently than control PA01 2 hours of intratracheal instillation. Furthermore, trappin-2-treated PA01 up-regulated the murine chemokine CXCL1/KC after 2 hours with a corresponding increase in neutrophil recruitment 1 hour later. These in vivo trappin-2-treated PA01 effects were absent in CD14-deficient mice. Trappin-2 appears to opsonize P. aeruginosa for more efficient, CD14-dependent clearance by macrophages and contributes to the induction of chemokines that promote neutrophil recruitment. Trappin-2 may therefore play an important role in innate recognition and clearance of pathogens during the very earliest stages of pulmonary infection.

The genome of Burkholderia cenocepacia J2315, an epidemic pathogen of cystic fibrosis patients.

Bacterial infections of the lungs of cystic fibrosis (CF) patients cause major complications in the treatment of this common genetic disease. Burkholderia cenocepacia infection is particularly problematic since this organism has high levels of antibiotic resistance, making it difficult to eradicate; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates. B. cenocepacia strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although B. cenocepacia strains can be isolated from soil and can be pathogenic to both plants and man, J2315 is representative of a lineage of B. cenocepacia rarely isolated from the environment and which spreads between CF patients. Comparative analysis revealed that ca. 21% of the genome is unique in comparison to other strains of B. cenocepacia, highlighting the genomic plasticity of this species. Pseudogenes in virulence determinants suggest that the pathogenic response of J2315 may have been recently selected to promote persistence in the CF lung. The J2315 genome contains evidence that its unique and highly adapted genetic content has played a significant role in its success as an epidemic CF pathogen.

The changing epidemiology of Burkholderia species infection at an adult cystic fibrosis centre.

BACKGROUND: This study reviews the impact of changing infection control practices at the Manchester Adult Cystic Fibrosis Centre (MACFC) upon the epidemiology of Burkholderia species infections. METHODS: We reviewed strain and genomovar typing of all available Burkholderia isolates at our centre between 1983-2006. RESULTS: The incidence/prevalence of infection with Burkholderia species between 1983-1990 was below 5%/9% each year. There was a rise in incidence/prevalence of Burkholderia species between 1991 and 1994 with a peak of 16.3%/31.2% in 1992. Following complete cohort segregation, the incidence has fallen to below 3% for all but one year and the prevalence has gradually reduced to 9.3% in 2005. Currently, there is an increase in the prevalence to 10.6% for the first time since 1994, predominantly due to patients with unique infections transferring into the unit from referring centres. The presence of unique strains now exceeds transmissible strains for the first time since 1991. CONCLUSIONS: Infection control measures including patient segregation have controlled spread of transmissible B. cenocepacia strains, but not the acquisition of unique strains. Unique strains of Burkholderia species now account for the majority of new infections at the Manchester Adult Cystic Fibrosis Centre.

In situ identification of Gram-negative bacteria in human lungs using a topical fluorescent peptide targeting lipid A.

Respiratory infections in mechanically ventilated patients caused by Gram-negative bacteria are a major cause of morbidity. Rapid and unequivocal determination of the presence, localization, and abundance of bacteria is critical for positive resolution of the infections and could be used for patient stratification and for monitoring treatment efficacy. Here, we developed an in situ approach to visualize Gram-negative bacterial species and cellular infiltrates in distal human lungs in real time. We used optical endomicroscopy to visualize a water-soluble optical imaging probe based on the antimicrobial peptide polymyxin conjugated to an environmentally sensitive fluorophore. The probe was chemically stable and nontoxic and, after in-human intrapulmonary microdosing, enabled the specific detection of Gram-negative bacteria in distal human airways and alveoli within minutes. The results suggest that pulmonary molecular imaging using a topically administered fluorescent probe targeting bacterial lipid A is safe and practical, enabling rapid in situ identification of Gram-negative bacteria in humans.

A Randomized Controlled Trial of Atorvastatin in Patients With Bronchiectasis Infected With Pseudomonas Aeruginosa: A Proof of Concept Study.

BACKGROUND: There are no randomized controlled trials of statin therapy in patients with severe bronchiectasis who are chronically infected with Pseudomonas aeruginosa. METHODS: Thirty-two patients chronically infected with P aeruginosa were recruited in this double-blind cross-over randomized controlled trial. Sixteen patients were recruited in each arm, were given atorvastatin 80 mg or placebo for 3 months followed by a washout period for 6 weeks, and then crossed over and administered the alternative therapy for 3 months. RESULTS: Twenty-seven patients completed the study. Atorvastatin did not significantly improve the primary end point of cough as measured by the Leicester Cough Questionnaire (mean difference, 1.92; 95% CI for difference, -0.57-4.41; P = .12). However, atorvastatin treatment resulted in an improved St. Georges Respiratory Questionnaire (-5.62 points; P = .016) and reduced serum levels of CXCL8 (P = .04), tumor necrosis factor (P = .01), and intercellular adhesion molecule 1 (P = .04). There was a trend toward improvement in serum C-reactive protein and serum neutrophil counts (P = .07 and P = .06, respectively). We demonstrated in vitro that atorvastatin 10 µM reduced formyl-methionyl-leucyl phenylalanine-induced upregulation of CD11b expression and changes in calcium flux, reflecting an ability to decrease neutrophil activation. CONCLUSIONS: We demonstrated that atorvastatin reduced systemic inflammation and improved quality of life in patients with bronchiectasis who were infected with P aeruginosa. These effects may be due to an ability of atorvastatin to modulate neutrophil activation. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01299194; URL: www.clinicaltrials.gov.

Distribution and genomic location of active insertion sequences in the Burkholderia cepacia complex.

This study aimed firstly to establish the distribution and copy number within the Burkholderia cepacia complex of three insertion sequences (IS402, IS407 and IS1416) that possess the ability to activate transcription and hence influence gene expression. A second aim was to map the genomic insertion sites of one of the active insertion sequences (IS407) to establish putative links between insertion site and downstream gene activation. The resulting data revealed that all three insertion sequences were present in one-third of the 66 isolates tested. The three insertion sequences were prevalent across the nine B. cepacia complex species, although IS402 was absent from the 16 Burkholderia anthina strains tested and IS407 was absent from all 10 Burkholderia pyrrocinia strains. IS407 copies from six strains (two Burkholderia cenocepacia strains and one strain each of Burkholderia multivorans, Burkholderia stabilis, Burkholderia vietnamiensis and B. anthina) were mapped to the genome using hemi-nested inverse PCR. Insertions were found upstream of genes with wide-ranging functions. This study suggests that the abundance and distribution of these active insertion sequences is likely to affect genomic plasticity, and potentially gene transcription and pathogenicity.

Growth in Stewart's medium is a simple, rapid and inexpensive screening tool for the identification of Burkholderia cepacia complex.

Ninety-one percent of Burkholderia cepacia complex reference strains (66 out of 72) displayed a yellow slope-green butt colour reaction after growth in Stewart's medium indicating the oxidation of glucose and the absence of an arginine dihydrolase system. This same colour reaction was observed for Burkholderia gladioli and several Ralstonia species, but not for Pseudomonas aeruginosa, Stenotrophomonas, Achromobacter, Pandoraea and several other Gram-negative non-fermenting bacilli. We therefore consider growth in Stewart's medium a useful, simple, rapid and inexpensive screening test to reduce the number of false positive isolates from B. cepacia complex selective media.

Burkholderia cenocepacia sp. nov.--a new twist to an old story.

DNA-DNA hybridisation experiments between isolates representing Burkholderia cepacia genomovar III recA lineages IIIA and IIIB reinforced the classification of both phylogenetic subgroups as a single genospecies, distinct from B. cepacia (genomovar I). A formal classification of B. cepacia genomovar III encompassing the recA lineages IIIA and IIIB, and the new recA lineages IIIC and IIID, as B. cenocepacia sp. nov., with LMG 16656 as the type strain, is proposed.

Lipopolysaccharide chemotypes of Burkholderia cepacia.

Burkholderia cepacia is an important pathogen in patients with cystic fibrosis (CF) and much is now known of its epidemiology. In contrast, its virulence mechanisms are poorly understood. The lipopolysaccharide (LPS) of B. cepacia, a well-recognised virulence factor of other gram-negative bacteria, is known to be strongly endotoxic in vitro. The aim of this study was to observe if there were any links between the structure of B. cepacia LPS and virulence. This has been investigated by polyacrylamide gel electrophoresis and immunoblotting to define the chemotype and antigenic cross reactivity of B. cepacia LPS. Strains (16) belonging to different genomovars of the B. cepacia complex were selected to represent epidemic and non-epidemic clinical isolates and environmental strains. All strains belonging to genomovars I and II (the latter now renamed B. multivorans) had smooth LPS. However, isolates belonging to genomovar III, the group to which most of the epidemic CF isolates belong - including the highly transmissible strain (ET 12) which has been found in both the UK and North America - were of either rough or smooth LPS chemotype. In this study, B. cepacia J2315 represents the ET 12 lineage, and has a rough chemotype. Rabbit antiserum raised to strain J2315 revealed that the LPS core of this strain was antigenically related to some but not all other genomovar III strains, but it also cross-reacted strongly with all B. multivorans (genomovar II) and most genomovar I strains. Intra-strain phenotypic variation was demonstrated between bacteria grown in broth or on solid agar with a concomitant variation in antigenic cross reactivity. There was no clear evidence to associate any particular LPS phenotype with epidemic or non-epidemic strains, but changes in phenotype in vitro may provide clues to the survival and adaptability of B. cepacia in hostile environments and possibly to its ability to produce an inflammatory response in vivo.

Lysogeny and bacteriophage host range within the Burkholderia cepacia complex.

The Burkholderia cepacia complex comprises a group of nine closely related species that have emerged as life-threatening pulmonary pathogens in immunocompromised patients, particularly individuals with cystic fibrosis or chronic granulomatous disease. Attempts to explain the genomic plasticity, adaptability and virulence of the complex have paid little attention to bacteriophages, particularly the potential contribution of lysogenic conversion and transduction. In this study, lysogeny was observed in 10 of 20 representative strains of the B. cepacia complex. Three temperate phages and five lytic phages isolated from soils, river sediments or the plant rhizosphere were chosen for further study. Six phages exhibited T-even morphology and two were lambda-like. The host range of individual phages, when tested against 66 strains of the B. cepacia complex and a representative panel of other pseudomonads, was not species-specific within the B. cepacia complex and, in some phages, included Burkholderia gladioli and Pseudomonas aeruginosa. These new data indicate a potential role for phages of the B. cepacia complex in the evolution of these soil bacteria as pathogens of plants, humans and animals, and as novel therapeutic agents.

Lack of correlation between O-serotype, bacteriophage susceptibility and genomovar status in the Burkholderia cepacia complex.

The Burkholderia cepacia complex comprises at least nine phylogenetically related genomic species (genomovars) which cause life-threatening infection in immunocompromised humans, particularly individuals with cystic fibrosis or chronic granulomatous disease. Prior to recognition that 'B. cepacia' comprise multiple species, in vitro studies revealed that the lipopolysaccharide (LPS) of these Gram-negative bacteria is strongly endotoxic. In this study, we used 117 B. cepacia complex isolates to determine if there is a correlation between O-antigen serotype and genomovar status. Isolates were also tested for their ability to act as bacterial hosts for the LPS-binding bacteriophages NS1 and NS2. The absence of genomovar II (Burkholderia multivorans) in 'historical B. cepacia' isolates was notable. Neither O-serotype nor phage susceptibility correlated with genomovar status. We conclude that variability in LPS may contribute to the success of these highly adaptable bacteria as human pathogens.

Burkholderia anthina sp. nov. and Burkholderia pyrrocinia, two additional Burkholderia cepacia complex bacteria, may confound results of new molecular diagnostic tools.

Nineteen Burkholderia cepacia-like isolates of human and environmental origin could not be assigned to one of the seven currently established genomovars using recently developed molecular diagnostic tools for B. cepacia complex bacteria. Various genotypic and phenotypic characteristics were examined. The results of this polyphasic study allowed classification of the 19 isolates as an eighth B. cepacia complex genomovar (Burkholderia anthina sp. nov.) and to design tools for its identification in the diagnostic laboratory. In addition, new and published data for Burkholderia pyrrocinia indicated that this soil bacterium is also a member of the B. cepacia complex. This highlights another potential source for diagnostic problems with B. cepacia-like bacteria.