Aztreonam inhalation solution for suppressive treatment of chronic Pseudomonas aeruginosa lung infection in cystic fibrosis

An aerosol form of aztreonam lysinate has recently been developed as a treatment for cystic fibrosis patients suffering from chronic Pseudomonas aeruginosa lung colonization. Local administration means the drug can reach mucus concentrations in the order of hundreds of times the MIC₅₀ of Pseudomonas associated with severe lung disease in cystic fibrosis, resulting in a significant reduction in airway bacterial density and a parallel improvement in lung function. These advantages are maintained over prolonged periods of treatments. Administration of the drug is optimized by the use of a specific eFlow^® system, resulting in considerable reductions in treatment times when compared with conventional nebulizers. The drug has been proven safe and no concomitant induction of resistance to Pseudomonas was found during the clinical trial period of 18 months. Aztreonam lysinate has been shown to ameliorate pulmonary function in cystic fibrosis patients with chronic airway Pseudomonas infection and this is paralleled by a reduction in bacterial density in the lungs. The increased availability of new aerosolized antibiotics for cystic fibrosis will lead to new scenarios in the treatment of the disease.     

Aztreonam inhalation solution for suppressive treatment of chronic Pseudomonas aeruginosa lung infection in cystic fibrosis

An aerosol form of aztreonam lysinate has recently been developed as a treatment for cystic fibrosis patients suffering from chronic Pseudomonas aeruginosa lung colonization. Local administration means the drug can reach mucus concentrations in the order of hundreds of times the MIC(50) of Pseudomonas associated with severe lung disease in cystic fibrosis, resulting in a significant reduction in airway bacterial density and a parallel improvement in lung function. These advantages are maintained over prolonged periods of treatments. Administration of the drug is optimized by the use of a specific eFlow(?) system, resulting in considerable reductions in treatment times when compared with conventional nebulizers. The drug has been proven safe and no concomitant induction of resistance to Pseudomonas was found during the clinical trial period of 18 months. Aztreonam lysinate has been shown to ameliorate pulmonary function in cystic fibrosis patients with chronic airway Pseudomonas infection and this is paralleled by a reduction in bacterial density in the lungs. The increased availability of new aerosolized antibiotics for cystic fibrosis will lead to new scenarios in the treatment of the disease.     

The efficacy and safety of ciprofloxacin and ofloxacin in chronic Pseudomonas aeruginosa infection in cystic fibrosis

The clinical efficacy and safety of ciprofloxacin and ofloxacin were compared in a prospective, randomized double blind, placebo combined cross-over study in 26 adult cystic fibrosis patients with chronic broncho-pulmonary Pseudomonas aeruginosa infection. Active treatment consisted of ciprofloxacin 750 mg orally twice daily or ofloxacin 400 mg orally twice daily; both treatments were given for 14 days, with three months between treatment periods; 21 patients completed both treatment periods. Treatment with both ciprofloxacin and ofloxacin was associated with a good clinical response as judged by clinical score, lung function tests and inflammatory parameters; no difference between ciprofloxacin and ofloxacin was found. Adverse reactions were seen in nine of 24 patients who received ciprofloxacin and in six of 23 who received ofloxacin. The majority were dyspeptic reactions or photosensitivity. No serious adverse reactions occurred. Three cases of treatment failure were found, one of which was associated with development of resistant P. aeruginosa during ofloxacin treatment. The mean MIC of both drugs increased during treatment but returned to pretreatment values within three months. Ciprofloxacin and ofloxacin seem to be valuable agents for intermittent treatment of chronic P. aeruginosa lung infection in adult cystic fibrosis patients.     

Imipenem/cilastatin treatment of multiresistant Pseudomonas aeruginosa lung infection in cystic fibrosis

Ten patients with cystic fibrosis and chronic broncho-pulmonary Pseudomonas aeruginosa infection received 45 mg imipenem/cilastatin per kg body weight/day, intravenously for two weeks. The treatment was safe with only minor side effects and clinical parameters improved considerably during therapy. In all patients resistance of Ps. aeruginosa to imipenem developed in the second week of treatment; in seven patients the therapy selected for a resistant strain and in three resistance developed in the original strain. The resistance persisted after cessation of treatment and thus the clinical usefulness of imipenem/cilastatin as monotherapy in CF-patients with Ps. aeruginosa seems to be limited.     

Priming of neutrophils for enhanced oxidative burst by sputum from cystic fibrosis patients with Pseudomonas aeruginosa infection

Neutrophils accumulate in the lungs of cystic fibrosis (CF) patients and inflict tissue damage by release of oxygen radicals and proteases. Here we report on the ability of sputum to prime neutrophils for enhanced release of oxygen radicals. Sol phase was prepared by ultracentrifugation of sputum obtained from CF patients attending the CF Clinic, Rigshospitalet, Copenhagen. The oxidative burst response of neutrophils from healthy individuals was measured by oxygen consumption, superoxide production and chemiluminescence. Neutrophils were preincubated with sputum or buffer and then stimulated with f-Met-Leu-Phe or zymosan. Appropriate controls were included in the experiments. It was shown that neutrophils preincubated with CF sol phase and stimulated with f-Met-Leu-Phe generated a three- to five-fold higher chemiluminescence response than those preincubated with buffer. There was no enhancement of the response when zymosan was used for stimulation of the cells. Neutrophils incubated with sol phase alone exhibited no response. Attempts were made to identify and partially characterize the priming factor(s). It was found that the sputum samples contained bacterial endotoxins. The priming activity was resistant to heating at 100 degrees C for 15 min, and was present only in fractions with molecules larger than 100 KD. It is suggested that the priming factor(s) consist of bacterial endotoxins and/or immune complexes. Activation and enhanced release of oxygen radicals from neutrophils may play an important role in the host defence as well as pathogenesis of tissue damage in the lungs of these patients.     

Pseudomonas aeruginosa flagellar antibodies in serum,saliva and sputum from patients with cystic fibrosis

Flagellar preparations from Pseudomonas aeruginosa strains were characterized and used in ELISA and immunoblot studies to detect anti-P. aeruginosa flagellar antibodies in sera, saliva and sputum from patients with cystic fibrosis (CF). Serum antiflagellar IgG antibodies were detected, particularly in those CF patients intermittently or chronically colonized by P. aeruginosa. Antibodies to both type-a and -b flagella were detected; however, in some patients a pronounced antibody response to only one of the flagellar types was evident. Raised levels of anti-flagellar antibodies in intermittently and non-P. aeruginosa colonized patients may represent an early antibody response to P. aeruginosa colonization of the CF respiratory tract and implicate instigation of early anti-pseudomonal antibiotic therapy.     

Circulating immune complexes, antibodies to Pseudomonas aeruginosa, and pulmonary status in cystic fibrosis

Serum samples from 37 patients with cystic fibrosis (CF), whose lungs were colonized by Pseudomonas aeruginosa, were tested in a 1 yr prospective study to examine a possible relationship between levels of circulating immune complexes (CIC) and the following parameters: level of specific antibodies to P. aeruginosa; relative importance of P. aeruginosa mucoid and non-mucoid strains isolated from sputum; the forced expiratory volume (FEV1; percentage predicted); the chest X-Ray score (Brasfield system) and the clinical score (Shwachman system). Reactivity of CIC against P. aeruginosa, Staphylococcus aureus, Haemophilus influenzae and Escherichia coli antigens were also assayed. We found that the FEV1, the chest X-Ray and the clinical scores were significantly lower in patients with high levels of CIC than in those with normal levels of CIC (p less than 0.001 for each). We also found that the level of IgG antibodies against P. aeruginosa was significantly higher (p less than 0.001) in patients with high levels of CIC than in those with normal levels of CIC. 78% of patients with high levels of CIC had predominantly mucoid P. aeruginosa isolates whereas only 21% of patients with normal levels of CIC had also predominantly mucoid P. aeruginosa isolates. Specific antibodies to P. aeruginosa were detected in all CIC isolated by polyethylene glycol precipitations from CF patients exhibiting both high levels of CIC and inferior pulmonary status. Our findings support the hypothesis that a high level of CIC in association with an aggressive humoral response to P. aeruginosa correlates with defective pulmonary status in cystic fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical impact of reducing routine susceptibility testing in chronic Pseudomonas aeruginosa infections in cystic fibrosis

BACKGROUND Susceptibility testing results are not predictive of clinical response to antibiotic therapy in chronic Pseudomonas aeruginosa infections in cystic fibrosis (CF). We assessed the impact of reducing the number of routine susceptibility tests performed on clinical outcome in these cases. METHODS In June 2006, we introduced a protocol whereby susceptibility tests of P. aeruginosa isolates obtained from respiratory samples of people with CF were limited to those taken at the commencement of antibiotic therapy, when there was evidence of clinical failure or routinely if not tested in the previous 3 months. At all other times, isolates were identified and reported as normal but P. aeruginosa isolates were not subjected to susceptibility testing. RESULTS Over a 6 month period, P. aeruginosa was isolated on at least one occasion from 193 patients attending the Adult Cystic Fibrosis Unit. In this period, we reduced the number of routine susceptibility tests by 56% (from a projected 2231 tests on 872 samples to an actual 972 tests on 427 samples). We assessed the response to courses of intravenous antibiotic treatment administered during the 6 month study period in 2006 and for courses administered in the same patients during the same calendar months in 2005. No significant differences in median change of FEV1, FVC, C-reactive protein (CRP), white cell count, weight or duration of intravenous antibiotics were observed. The projected savings of this intervention were 3500 euros in consumables and 170 h (costed at 6500 euros) of laboratory staff time per annum, a total annual saving of 10,000 euros (6500 pounds sterling). CONCLUSIONS For CF units sending regular, routine sputum samples, a reduction in the number of susceptibility tests performed in cases of chronic P. aeruginosa infection can be carried out without impacting on short-term clinical outcomes.     

Excessive inflammatory response of cystic fibrosis mice to bronchopulmonary infection with Pseudomonas aeruginosa.

In cystic fibrosis (CF), defective function of the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells and submucosal glands results in chronic pulmonary infection with Pseudomonas aeruginosa. The pulmonary infection incites an intense host inflammatory response, causing progressive suppurative pulmonary disease. Mouse models of CF, however, fail to develop pulmonary disease spontaneously. We examined the effects of bronchopulmonary infection on mice homozygous for the S489X mutation of the CFTR gene using an animal model of chronic Pseudomonas endobronchial infection. Slurries of sterile agarose beads or beads containing a clinical isolate of mucoid P. aeruginosa were instilled in the right lung of normal or CF mice. The mortality of CF mice inoculated with Pseudomonas-laden beads was significantly higher than that of normal animals: 82% of infected CF mice, but only 23% of normal mice, died within 10 d of infection (P = 0.023). The concentration of inflammatory mediators, including TNF-alpha, murine macrophage inflammatory protein-2, and KC/N51, in bronchoalveolar lavage fluid in CF mice 3 d after infection and before any mortality, was markedly elevated compared with normal mice. This inflammatory response also correlated with weight loss observed in both CF and normal littermates after inoculation. Thus, this model may permit examination of the relationship of bacterial infections, inflammation, and the cellular and genetic defects in CF.     

Demonstration of neutrophil chemotactic activity in the sputum of cystic fibrosis patients with Pseudomonas aeruginosa infection

The pathogenesis of tissue damage in the lungs of cystic fibrosis patients with chronic P. aeruginosa infection is quite complex and not well understood. Inflammatory cells, particularly neutrophils, are accumulated in the damaged tissues and in the sputum. This study demonstrates the presence of a heat-stable neutrophil chemotactic factor(s) in the sputum of CF patients. The chemotactic activity seems to be associated with the endotoxin present in the sputum. Chemotaxis of sol phase sputum was determined in a modified Boyden chamber assay. It was found that the sputum obtained from the patients showed strong chemotactic activity for peripheral blood neutrophils of normal individuals. The activity was greater than twice that of casein, a strong neutrophil chemo-attractant. Sputum at about dilution of 1:50 exhibited chemotactic activity equal to that of casein. Heat treatment of the sputum at 56 degrees C for 30 min, to inactivate complement, and at 100 degrees C for 15 min, to denature other proteins, somewhat reduced the chemotactic activity, but there was still strong chemotactic activity. The presence of endotoxin was demonstrated in both the non-heated and the heated samples by LAL and rocket immunoelectrophoresis. It is concluded that the sputum of CF patients contain chemotactic activity of heat-stable nature and most likely of bacterial origin endotoxin. These factors are involved in attraction of neutrophils to the lungs and sputum of these patients and contribute to the tissue damage of cystic fibrosis.     

Emergence of ceftriaxone-resistant strains of Pseudomonas aeruginosa in cystic fibrosis patients

Cystic fibrosis patients with Pseudomonas aeruginosa chest infections were treated with ceftriaxone alone or ceftriaxone plus tobramycin. P. aeruginosa strains isolated before and after treatment were studied for changes in sensitivity to ceftriaxone. After therapy with either the single agent or the combination six strains from five patients were found to be resistant to ceftriaxone. No resistant strains were isolated before therapy. Resistance was mediated by excess production of Id beta-lactamase which in five of six strains was permanently derepressed. Bacterial resistance appearing during therapy reduces the value of this antibiotic in cystic fibrosis chest infections.     

Functional importance of cystic fibrosis immunoglobulin G fragments generated by Pseudomonas aeruginosa elastase

We examined the functional importance of immunoglobulin polypeptide fragments generated by Pseudomonas aeruginosa elastase (Pseudomonas elastase). The purpose of this study was to determine whether the elastase produced by Pseudomonas aeruginosa cleaves human IgG into immune fragments that functionally inhibit opsonophagocytosis. Our results confirm that IgG isolated from patients with cystic fibrosis (CF) incubated with purified pseudomonas elastase results in the generation of two major polypeptide fragments and that, furthermore, these fragments significantly inhibit bacterial uptake by human neutrophils. After 75 minutes bacterial uptake was six times greater when intact IgG was used as an opsonin (uptake 90.2% +/- 18.6% SEM) compared with a IgG was used as an opsonin (uptake 90.2% +/- 18.6% SEM) compared with a mixture of pseudomonas-lipopolysaccharide-reactive Fab and F(ab')2 fragments generated by pseudomonas elastase (uptake 15.4% +/- 0.8% SEM, p less than 0.001). Hydrolyzed CF IgG antibodies consistently resulted in a level of bacterial uptake less than that of normal saline negative controls (NS): (at 10 minutes, NS 26.6% vs CF 16.8%, p less than 0.05; at 75 minutes, NS 28.2% vs CF 15.4%, p less than 0.01. This suggests that the immune polypeptides are active inhibitors of the essential neutrophil phagocyte-bacterial cell interaction. Intact immune IgG reversed the defect in opsonophagocytosis. When intact IgG was mixed with IgG fragments the phagocytic rates increased directly with increasing amounts of intact IgG. We conclude that the elastase exoproduct secreted by Pseudomonas aeruginosa is capable of cleaving IgG into functionally important fragments that inhibit bacterial uptake. Furthermore, this inhibition can be overcome by increasing amounts of a commercially available preparation of intact immune IgG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of ciprofloxacin in an in-vitro pharmacokinetic model against Pseudomonas aeruginosa isolated during cystic fibrosis lung infection

An in-vitro pharmacokinetic model was used to simulate ciprofloxacin concentrations in serum observed in vivo following oral doses of 250, 500 and 750 mg, in a culture of Pseudomonas aeruginosa isolated from the sputum of a cystic fibrosis patient. In the 12 h interval following each dose, a period of bactericidal activity was observed, succeeded by bacteriostasis and subsequent bacterial regrowth. In all cases bacterial regrowth was first observed when the ciprofloxacin concentration in the culture flask of the dynamic model fell below the MIC. For the three doses investigated, the surviving bacteria at the end of each 12-h dosing interval showed an increase in MIC compared with that of the culture before ciprofloxacin exposure. The post-antibiotic effect of ciprofloxacin against P. aeruginosa was observed for 1-5 h, and was dose related.     

Antibiotic tolerance induced by lactoferrin in clinical Pseudomonas aeruginosa isolates from cystic fibrosis patients

Lactoferrin-induced cell depolarization and a delayed tobramycin-killing effect on Pseudomonas aeruginosa cells were correlated. This antibiotic tolerance effect (ATE) reflects the ability of a defense protein to modify the activity of an antibiotic as a result of its modulatory effect on bacterial physiology. P. aeruginosa isolates from cystic fibrosis patients showed higher ATE values (< or = 6-fold) than other clinical strains.     

Characterization of non-typable strains of Pseudomonas aeruginosa from cystic fibrosis patients by means of monoclonal antibodies and SDS-polyacrylamide gel electrophoresis

Fifty-three non-typable strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients were examined to determine if these bacteria could be classified by means of their interactions with a recently completed panel of serotype specific monoclonal antibodies and by analysis of their lipopolysaccharide (LPS) separation (or banding) patterns in SDS-polyacrylamide gels. Based on agglutination reactions and interaction of LPS of these strains in Western immunoblots with monoclonal antibodies, 24 (45%) of all the strains tested were found to be typable. These include 13 that typed 06, five that typed 05, three that typed 04, two that typed 01, one that typed 03, and one that typed 016. LPS from these “newly” typable strains were isolated and characterized and a correlation was found between the LPS banding pattern of each strain and its O-specificity. Among the group of isolates that agglutinated with the 05-specific monoclonal antibody MF15-2, strain C418M had a different LPS banding pattern when compared to that of the standard serotype 05 strain and the other type 05 clinical isolates. The LPS of this strain was subsequently found to be non-reactive with monoclonal antibody MF15-2 in immunoblots thus confirming that this bacterium did not belong to the 05 serogroup. While there are still some clinical strains that could not be typed, we found that the occurrence of polytypability characteristics among clinical isolates was substantially reduced by the use of monoclonal antibodies.     

An epidemic spread of multiresistant Pseudomonas aeruginosa in a cystic fibrosis centre

Early in 1983 an epidemic of a Pseudomonas aeruginosa resistant to aminoglycosides, carbenicillin, ureidopenicillins, ceftazidime, cefsulodin and imipenem occurred in a cystic fibrosis centre. Most of the epidemic could be attributed to a specific nosocomial strain by means of O-grouping and phage-typing. This strain was present in the centre at a low frequency in 1973 and developed resistance during courses of chemotherapy. The epidemic was stopped by isolating patients with the resistant strains. Restrictive and selective use of antibiotics have not been sufficient to eradicate the resistant strains, which persist in 42% of the patients. The extensive use of the third generation cephalosporins in the clinic is probably responsible for inducing and selecting for the resistant strains. Clustering of patients in the centre has facilitated the spread. First-line use of older beta-lactam antibiotics, close bacteriological monitoring and prompt isolation of patients with resistant strains are recommended.     

Occurrence of hypermutable Pseudomonas aeruginosa in cystic fibrosis patients is associated with the oxidative stress caused by chronic lung inflammation

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相似文献