Tacjana Pressler

Pseudomonas aeruginosa biofilms in the respiratory tract of cystic fibrosis patients

The present study was undertaken to investigate the appearance and location of Pseudomonas aeruginosa in the cystic fibrosis (CF) lung and in sputum. Samples include preserved tissues of CF patients who died due to chronic P. aeruginosa lung infection prior to the advent of intensive antibiotic therapy, explanted lungs from 3 intensively treated chronically P. aeruginosa infected CF patients and routine sputum from 77 chronically P. aeruginosa infected CF patients. All samples were investigated microscopically using hematoxylin–eosin (HE), Gram and alcian‐blue stain, PNA FISH and immunofluorescence for alginate.

Association of mannose-binding lectin gene heterogeneity with severity of lung disease and survival in cystic fibrosis

Mannose-binding lectin (MBL) is a key factor in innate immunity, and lung infections are the leading cause of morbidity and mortality in cystic fibrosis (CF). Accordingly, we investigated whether MBL variant alleles, which are associated with recurrent infections, might be risk factors for CF patients. In 149 CF patients, different MBL genotypes were compared with respect to lung function, microbiology, and survival to end-stage CF (death or lung transplantation). The lung function was significantly reduced in carriers of MBL variant alleles when compared with normal homozygotes. The negative impact of variant alleles on lung function was especially confined to patients with chronic Pseudomonas aeruginosa infection. Burkholderia cepacia infection was significantly more frequent in carriers of variant alleles than in homozygotes. The risk of end-stage CF among carriers of variant alleles increased 3-fold, and the survival time decreased over a 10-year follow-up period. Moreover, by using a modified life table analysis, we estimated that the predicted age of survival was reduced by 8 years in variant allele carriers when compared with normal homozygotes. Presence of MBL variant alleles is therefore associated with poor prognosis and early death in patients with CF.

Occurrence of Hypermutable Pseudomonas aeruginosa in Cystic Fibrosis Patients Is Associated with the Oxidative Stress Caused by Chronic Lung Inflammation

ABSTRACT Oxidative stress caused by chronic lung inflammation in patients with cystic fibrosis (CF) and chronic lung infection with Pseudomonas aeruginosa is characterized by the reactive oxygen species (ROS) liberated by polymorphonuclear leukocytes (PMNs). We formulated the hypothesis that oxidation of the bacterial DNA by ROS presents an increased risk for the occurrence of hypermutable P. aeruginosa. The occurrence of hypermutable P. aeruginosa isolates was investigated directly in the sputum of 79 CF patients and among 141 isolates collected from 11 CF patients (10 to 15 isolates/patient) collected from the 1st and up to the 25th year of their chronic lung infection. The level of oxidized guanine moiety 8-oxo-2′-deoxyguanosine (8-oxodG), which is a frequently investigated DNA oxidative lesion, was measured. Hypermutable P. aeruginosa isolates were found in the sputum bacterial population of 54.4% of the CF patients. The earliest mutator P. aeruginosa isolates were found after 5 years from the onset of the chronic lung infection, and once they were present in the CF lung, the prevalence increased with time. The hypermutable isolates were significantly more resistant to antipseudomonal antibiotics than nonhypermutable isolates (P ≤ 0.001). The level of 8-oxodG/106 deoxyguanosine (dG) was significantly higher in hypermutable P. aeruginosa isolates (87 ± 38) than in nonhypermutable P. aeruginosa isolates (59.4 ± 17) (P = 0.02), and an increase to 86.84 from 21.65 8-oxodG/106 dG was found after exposure of the reference strain PAO1 to activated PMNs. Our results suggest that the chronic PMN inflammation in the CF lung promotes oxidative stress and is associated with the occurrence of hypermutable bacteria in the lung. The hypermutable phenotype can associate with mutations that confer adaptation of the bacteria in the lung and persistence of the infection.

The immune response to chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is predominantly of the Th2 type

Most cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa lung infection have a persistent acute type lung inflammation dominated by polymorphonuclear neutrophils (PMN) and a pronounced antibody response against P. aeruginosa. We speculated whether this immune response in CF is of the Th2 type and whether a change to a Th1 type immune response could improve the prognosis. Therefore, we studied 14 CF patients with (CF +P) and 14 CF patients without (CF –P) chronic P. aeruginosa lung infection. The specific production of interferon‐gamma (IFN‐γ) and interleukin‐4 (IL‐4) by peripheral blood mononuclear cells was determined. Cells from CF +P patients had lower IFN‐γ (p<0.05) and higher IL‐4 (p<0.005) production as compared to cells from CF ‐P patients. Furthermore, a positive correlation between IFN‐γ production and lung function was found (FVC: Rho=0.637; p<0.03; FEV1: Rho=0.524; p<0.07). We conclude that a Th2 type immune response is most frequent in CF patients with chronic P. aeruginosa lung infection, and the patients with a Th1‐dominated immune response had the best lung function. The clinical implication is that a change to a Th1 type immune response might improve the prognosis in these patients.

Aspergillus Species and Other Molds in Respiratory Samples from Patients with Cystic Fibrosis: a Laboratory-Based Study with Focus on Aspergillus fumigatus Azole Resistance

ABSTRACT Respiratory tract colonization by molds in patients with cystic fibrosis (CF) were analyzed, with particular focus on the frequency, genotype, and underlying mechanism of azole resistance among Aspergillus fumigatus isolates. Clinical and demographic data were also analyzed. A total of 3,336 respiratory samples from 287 CF patients were collected during two 6-month periods in 2007 and 2009. Azole resistance was detected using an itraconazole screening agar (4 mg/liter) and the EUCAST method. cyp51A gene sequencing and microsatellite genotyping were performed for isolates from patients harboring azole-resistant A. fumigatus. Aspergillus spp. were present in 145 patients (51%), of whom 63 (22%) were persistently colonized. Twelve patients (4%) harbored other molds. Persistently colonized patients were older, provided more samples, and more often had a chronic bacterial infection. Six of 133 patients (4.5%) harbored azole-nonsusceptible or -resistant A. fumigatus isolates, and five of those six patients had isolates with Cyp51A alterations (M220K, tandem repeat [TR]/L98H, TR/L98H-S297T-F495I, M220I-V101F, and Y431C). All six patients were previously exposed to azoles. Genotyping revealed (i) microevolution for A. fumigatus isolates received consecutively over the 2-year period, (ii) susceptible and resistant isolates (not involving TR/L98H isolates) with identical or very closely related genotypes (two patients), and (iii) two related susceptible isolates and a third unrelated resistant isolate with a unique genotype and the TR/L98H resistance combination (one patient). Aspergilli were frequently found in Danish CF patients, with 4.5% of the A. fumigatus isolates being azole nonsusceptible or resistant. Genotyping suggested selection of resistance in the patient as well as resistance being achieved in the environment.

Spread of colistin resistant non-mucoid Pseudomonas aeruginosa among chronically infected Danish cystic fibrosis patients

BACKGROUND Colistin resistant Pseudomonas aeruginosa have rarely been reported in cystic fibrosis (CF) patients. METHODS We performed a 17-year prospective study on colistin susceptibility and compared our findings with clinical variables. RESULTS The first outbreak started in 1995 and lasted 5 years. It involved 27 CF patients who had inhaled colistin twice daily for a median of 10 years. Colistin resistant isolates persisted in individual patients for a median of 75 days after colistin was withdrawn. A second outbreak started in 2004. It involved 40 patients, 17 of whom were the same as in the first outbreak. Most resistant isolates belonged to two major clones that had similar genotypes in the two outbreaks. The P. aeruginosa isolates were all non-mucoid and they appeared in a group of chronically infected patients that had been admitted to the same ward for antibiotic treatment and had been followed at the same week-days in the outpatient clinic. Patients were individually isolated to avoid cross-infection and colistin inhalation was avoided in the CF outpatient clinic and in the ward after both outbreaks. Since 2004, no further spread has been observed. CONCLUSION It is important that the colistin resistant clones do not spread to non-infected patients since colistin is an important antibiotic for eradication of initial and intermittent P. aeruginosa colonisation.

Inhaled aztreonam lysine vs. inhaled tobramycin in cystic fibrosis: A comparative efficacy trial

BACKGROUND Open-label, parallel-group, international trial comparing aztreonam for inhalation solution (AZLI) and tobramycin nebulizer solution (TNS) for cystic fibrosis patients with airway Pseudomonas aeruginosa. METHODS 273 patients (≥ 6 years); randomized to three 28-day courses (AZLI 75 mg [three-times/day] or TNS 300 mg [twice/day]); 28 off-days separated each course. RESULTS 268 patients were treated (AZLI/TNS: 136/132). Mean baseline FEV1 was 52% predicted. Mean relative changes after 1 course (AZLI: 8.35%; TNS: 0.55%; p<0.001) and mean actual changes across 3 courses (AZLI: 2.05%; TNS: -0.66%; p=0.002) indicated AZLI statistical superiority vs. TNS. AZLI-treated patients had fewer respiratory hospitalizations (p=0.044) and respiratory events requiring additional antipseudomonal antibiotics (p=0.004); both treatments were well tolerated. 133 patients received 1 to 3 courses of AZLI treatment in the open-label extension-period (28-day courses separated by 28 days off-treatment); lung function improvements were comparable regardless of whether patients had received TNS or AZLI in the preceding comparative period. CONCLUSIONS AZLI demonstrated statistical superiority in lung function and a reduction in acute pulmonary exacerbations compared to TNS over 3 treatment courses (ClinicalTrials.gov: NCT00757237).

Effect of aerosolized rhDNase (Pulmozyme®) on pulmonary colonization in patients with cystic fibrosis

Background: Aerosolized recombinant human deoxyribonuclease (rhDNase I (Pulmozyme®)) has previously been shown to increase pulmonary function and reduce exacerbations of respiratory symptoms in cystic fibrosis (CF) patients with moderate to severe reduction in pulmonary function. Aim: To analyse whether aerosolized Pulmozyme® could reduce the number of bacterial infections in the lower respiratory airways of CF patients without chronic pulmonary infection. Methods: Patients were randomized either to aerosolized Pulmozyme® 2½ mg once daily or to no rhDNase treatment. The study period was 1 y, and the study was blinded for the Department of Clinical Microbiology. Results: Overall, the number of positive cultures was significantly higher in the untreated group (82%) compared with the treated group (72%) (p<0.05). The most striking difference was found for Staphylococcus aureus, with a prevalence of 30% in the untreated group compared with 16% in the treated group (χ2 test, p<0.0001). Pulmonary function (FEV1) in the treated group showed a significant increase of 7.3% compared to 0.9% in the untreated group (p<0.05).

Barriers to adherence in adolescents and young adults with cystic fibrosis: a questionnaire study in young patients and their parents

Background Treatment adherence is crucial in patients with cystic fibrosis, but poor adherence is a problem, especially during adolescence. Identification of barriers to treatment adherence and a better understanding of how context shapes barriers is of great importance in the disease. Adolescent reports of barriers to adherence have been studied, but studies of their parents’ experience of such barriers have not yet been carried out. The aim of the present study was to explore barriers to treatment adherence identified by young patients with cystic fibrosis and by their parents. Methods A questionnaire survey of a cohort of young Danish patients with cystic fibrosis aged 14–25 years and their parents was undertaken. Results Barriers to treatment adherence were reported by 60% of the patients and by 62% of their parents. Patients and parents agreed that the three most common barriers encountered were lack of time, forgetfulness, and unwillingness to take medication in public. We found a significant positive correlation between reported number of barriers and perceived treatment burden. We also found a statistically significant relationship between the reported number of barriers and treatment adherence. A significant association was found between the number of barriers and the reactions of adolescents/young adults and those of their mothers and fathers, and between the number of barriers and the way the family communicated about cystic fibrosis. Conclusion The present study showed that the majority of adolescents with cystic fibrosis and their parents experienced barriers to treatment adherence. Agreement between adolescents and their parents regarding the level and types of barriers indicates an opportunity for close cooperation between adolescents, their parents, and health care professionals in overcoming adolescent adherence problems.

Diagnostic significance of measurements of specific IgG antibodies to Pseudomonas aeruginosa by three different serological methods

UNLABELLED The aim of the study was to evaluate three serological methods for their ability to identify CF patients in different infection status especially those at risk of developing chronic Pseudomonas aeruginosa (Pa) infection. METHODS Two ELISA methods: exotoxin A (ExoA) and CF-IgG-ELISA (CF-IgG) and Crossed Immunoelectrophoresis (CIE) were used for measurement of Pa-antibodies in sera from 791 Scandinavian CF patients. RESULTS 381 patients were cultured negative for Pa in the year before study start, 129 patients were intermittently colonized and 281 patients were chronically infected. The sensitivity of the investigated assays was 96%, 93% and 97%, specificity 89%, 89% and 83% for CIE, ExoA and CF-IgG respectively. The negative predictive value was for CIE 97%, for ExoA 95% and for CF-IgG 98% and positive predictive values 87%, 86% and 80%. Out of the 381 patients cultured negative for Pa, 11 changed status to chronically infected. Twenty-four out of the 129 patients intermittently colonized became chronically infected. The antibody levels in this latter group of patients were significantly higher already at the study start and increased significantly during the study period (p<0.05). Elevated levels of specific anti-Pseudomonal antibodies showed to be the risk factor for developing chronic P. aeruginosa infection (OR 4.9 and OR 2.7, p<0.05 for CF-IgG and ExoA). CONCLUSION All three serological assays were equally informative. The very high sensitivity of the assays made it possible to characterize patients with different infection status. Elevated levels of specific anti-Pseudomonas antibodies showed to be the risk factor for developing chronic Pa infection. Due to the specificity of the tests, antibiotic treatment based on serology might be considered in selected cases. There is a window of opportunity for suppression and eradication of initial P. aeruginosa infection making measurement of specific anti-Pseudomonas antibodies helpful.