Blood mRNA biomarkers distinguish variable systemic and sputum inflammation at treatment initiation of inhaled antibiotics in cystic fibrosis: A prospective non-randomized trial

Inhaled antibiotics control chronic airway infection and maintain respiratory health in cystic fibrosis (CF). Given variation in patient responses to inhaled antibiotics, the ability to identify distinct responder phenotypes would facilitate the delivery of personalized care. Previously, a 10-gene panel was identified, measured directly from blood leukocytes, which predicted host response to intravenous antibiotic treatment during pulmonary exacerbations. In the current study, we tested whether the same panel predicted clinical response in subjects receiving a month of inhaled antibiotic therapy with aztreonam lysine (AZLI; Cayston®). A small cohort of CF subjects infected with Pseudomonas aeruginosa were enrolled at baseline health, prior to initiating one month’s treatment with AZLI using the Altera® nebulizer system. Eighteen CF subjects underwent blood leukocyte gene panel measurements, sputum quantitative microbiology, spirometry, and C-reactive protein (CRP) measurement prior to onset and at completion of 4 weeks of AZLI therapy. Mean absolute improvement in percent predicted Forced Expiratory Volume in one second (ppFEV₁) was 3%. Significant reductions in sputum bacterial colony counts were detected with treatment. CRP increased following treatment. While single genes within the panel did not change significantly following treatment, the analysis of multigene panel data demonstrated that HCA112 gene predicted ppFEV₁ improvement. Hierarchical clustering based on gene expression yielded two distinctive molecular clusters before and after AZLI therapy. In conclusion, peripheral blood leukocyte genes quantifying inflammation are associated with responses to inhaled antibiotic therapy. Molecular quantification of systemic inflammation may indicate subgroups of CF subjects with variations in underlying inflammation and with variable clinical responses to inhaled antibiotics. Given the size limitation of the study, larger studies are needed in order to evaluate whether molecular measures may add precision to the determination of infectious and inflammatory outcomes following courses of inhaled antimicrobial therapies. Clinical Trials.gov Identifier: NCT01736839.

A MexR Mutation Which Confers Aztreonam Resistance to Pseudomonas aeruginosa

Therapy for Pseudomonas aeruginosa infections is hard due to its high natural and acquirable antibiotic resistance. After colonization in the hosts, P. aeruginosa commonly accumulates genomic mutations which confer them antibiotic resistance and better adaptations to the host environment. Deciphering the mechanisms of antibiotic resistance development in the clinical setting may provide critical insights into the design of effective combinatory antibiotic therapies to treat P. aeruginosa infections. In this work, we demonstrate a resistance mechanism to aztreonam of a clinical isolate (ARP36) in comparison with a sensitive one (CSP18). RNAseq and genomic DNA resequencing were carried out to compare the global transcriptional profiles and in the clinical setting genomic profiles between these two isolates. The results demonstrated that hyperexpression of an efflux pump MexAB-OprM caused by a R70Q substitution in MexR, contributed to the increased resistance to aztreonam in the isolate ARP36. Simulation of mexR of ARP36 by gene editing in CSP18 conferred CSP18 an ARP36-like susceptibility to the aztreonam. The R70Q substitution prevented MexR from binding to the intergenic region between mexR and mexAB-oprM operon, with no impact on its dimerization. The presented experimental results explain for the first time why the clinically relevant R70Q substitution in the MexR derepresses the expression of mexAB-oprM in P. aeruginosa.

Pseudomonas aeruginosa Susceptibility Patterns and Associated Clinical Outcomes in People with Cystic Fibrosis following Approval of Aztreonam Lysine for Inhalation

The approval of aztreonam lysine for inhalation solution (AZLI) raised concerns that additional antibiotic exposure would potentially affect the susceptibility profiles of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients. This 5-year, prospective, observational study tracked susceptibility changes and clinical outcomes in CF patients in the United States with chronic P. aeruginosa infection. Sputum cultures were collected annually (2011 to 2016). The primary study endpoint was the proportion of subjects whose least susceptible P. aeruginosa isolate had an aztreonam MIC that was >8 μg/ml (parenteral breakpoint) and increased ≥4-fold compared with the least susceptible isolate from the previous year. Annualized data for pulmonary exacerbations, hospitalizations, and percent of predicted forced expiratory volume in 1 s (FEV₁% predicted) were obtained from the CF Foundation Patient Registry and compared between subjects meeting and those not meeting the primary endpoint. A total of 510 subjects were enrolled; 334 (65%) completed the study. A consistent proportion of evaluable subjects (13 to 22%) met the primary endpoint each year, and AZLI use during the previous 12 months was not associated with meeting the primary endpoint. While the annual declines in lung function were comparable for subjects meeting and those not meeting the primary endpoint, more pulmonary exacerbations and hospitalizations were experienced by those who met it. The aztreonam susceptibility of P. aeruginosa remained consistent during the 5-year study. The relationship between P. aeruginosa isolate susceptibilities and clinical outcomes is complex; reduced susceptibility was not associated with an accelerated decline in lung function but was associated with more exacerbations and hospitalizations, likely reflecting increased overall antibiotic exposure. (This study has been registered at ClinicalTrials.gov under identifier NCT01375036.).

Pharmacokinetic and Pharmacodynamic Optimization of Antibiotic Therapy in Cystic Fibrosis Patients: Current Evidences, Gaps in Knowledge and Future Directions

Antibiotic therapy is one of the main treatments for cystic fibrosis (CF). It aims to eradicate bacteria during early infection, calms down the inflammatory process, and leads to symptom resolution of pulmonary exacerbations. CF can modify both the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of antibiotics, therefore specific PK/PD endpoints should be determined in the context of CF. Currently available data suggest that optimal PK/PD targets cannot be attained in sputum with intravenous aminoglycosides. Continuous infusion appears preferable for β-lactam antibiotics, but optimal concentrations in sputum are unlikely to be reached, with some possible exceptions such as meropenem and ceftolozane. Usual doses are likely suboptimal for fluoroquinolones and linezolid, whereas daily doses of 45-60 mg/kg and 200 mg could be convenient for vancomycin and doxycycline, respectively. Weekly azithromycin doses of 22-30 mg/kg could also be appropriate for its anti-inflammatory effect. The difficulty with achieving optimal concentrations supports the use of combined treatments and the inhaled administration route, as very high local concentrations, concomitantly with low systemic exposure, can be obtained with the inhaled route for aminoglycosides, colistin, and fluoroquinolones, thus minimizing the risk of toxicity.

Synergistic antibacterial effect of inhaled aztreonam and tobramycin fixed dose combination to combat multidrug-resistant Gram-negative bacteria

The limited therapeutic option for respiratory infections caused by multi-drug resistant microbial pathogens is a major global health threat. Topical delivery of antibacterial combinations to the lung could dramatically enhance antibacterial activities and provide a means to overcome bacterial resistance development. The aim of the study was to investigate the potential of new inhalable dry powder combinations consisting of a fixed dose of aztreonam (Azt) and tobramycin (Tob) using a spray drying process, against antibiotic resistant Gram-negative respiratory pathogens. The interactions of Azt with Tob on resistant Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii were determined by calculating factional inhibitory concentration indices (FICI). A fixed concentration ratio of Azt and Tob that exhibited a synergistic antimicrobial effect was selected and formulated into inhalable dry powders by co-spray drying with and without L-leucine. The obtained dry powders were characterized with respect to the morphology, particle size distribution, solid state, moisture sorption behaviour, and in vitro dissolution. Storage stability, aerosol performance, and in vitro antibacterial activity were also evaluated. Inhalable dry powders consisting of Azt, Tob and L-leucine could be readily obtained via the spray drying process with a fine particle fraction of above 40% as determined using a next generation impactor. The co-spray drying process resulted in amorphous Azt/Tob dry powders with or without the addition of L-leucine as indicated by X-ray powder diffraction. The dissolution rates of the co-spray dried Azt/Tob dry powders were decreased, and the storage stability was improved with an increase in the proportion of L-leucine in the formulations. The inclusion of L-leucine did not affect the minimum inhibitory concentration and the co-spray dried powders reserved the synergistic antibacterial effects and exhibited enhanced antibacterial activities as compared to the individual antibiotic used alone on multidrug-resistant (Azt and Tob resistant) P. aeruginosa 25756 and A. baumannii K31. This study demonstrates that inhalable Azt/Tob dry powders using L-leucine as a moisture protector as well as a dispersing agent can be readily prepared by the spray drying process. This new inhalable fixed dose combinational dry powders may represent an alternative treatment against multidrug-resistant Gram-negative respiratory pathogens.

Genomic Analysis Identifies Novel Pseudomonas aeruginosa Resistance Genes under Selection during Inhaled Aztreonam Therapy In Vivo

Inhaled aztreonam is increasingly used for chronic Pseudomonas aeruginosa suppression in patients with cystic fibrosis (CF), but the potential for that organism to evolve aztreonam resistance remains incompletely explored. Here, we performed genomic analysis of clonally related pre- and posttreatment CF clinical isolate pairs to identify genes that are under positive selection during aztreonam therapy in vivo We identified 16 frequently mutated genes associated with aztreonam resistance, the most prevalent being ftsI and ampC, and 13 of which increased aztreonam resistance when introduced as single gene transposon mutants. Several previously implicated aztreonam resistance genes were found to be under positive selection in clinical isolates even in the absence of inhaled aztreonam exposure, indicating that other selective pressures in the cystic fibrosis airway can promote aztreonam resistance. Given its potential to confer plasmid-mediated resistance, we further characterized mutant ampC alleles and performed artificial evolution of ampC for maximal activity against aztreonam. We found that naturally occurring ampC mutants conferred variably increased resistance to aztreonam (2- to 64-fold) and other β-lactam agents but that its maximal evolutionary capacity for hydrolyzing aztreonam was considerably higher (512- to 1,024-fold increases) and was achieved while maintaining or increasing resistance to other drugs. These studies implicate novel chromosomal aztreonam resistance determinants while highlighting that different mutations are favored during selection in vivo and in vitro, show that ampC has a high maximal potential to hydrolyze aztreonam, and provide an approach to disambiguate mutations promoting specific resistance phenotypes from those more generally increasing bacterial fitness in vivo.

Defining antimicrobial resistance in cystic fibrosis

Antimicrobial resistance (AMR) can present significant challenges in the treatment of cystic fibrosis (CF) lung infections. In CF and other chronic diseases, AMR has a different profile and clinical consequences compared to acute infections and this requires different diagnostic and treatment approaches. This review defines AMR, explains how it occurs, describes the methods used to measure AMR as well as their limitations, and concludes with future directions for research and development in the area of AMR in CF.

Evolved Aztreonam Resistance Is Multifactorial and Can Produce Hypervirulence in Pseudomonas aeruginosa

While much attention has been focused on acquired antibiotic resistance genes, chromosomal mutations may be most important in chronic infections where isolated, persistently infecting lineages experience repeated antibiotic exposure. Here, we used experimental evolution and whole-genome sequencing to investigate chromosomally encoded mutations causing aztreonam resistance in Pseudomonas aeruginosa and characterized the secondary consequences of resistance development. We identified 19 recurrently mutated genes associated with aztreonam resistance. The most frequently observed mutations affected negative transcriptional regulators of the mexAB-oprM efflux system and the target of aztreonam, ftsI. While individual mutations conferred modest resistance gains, high-level resistance (1,024 µg/ml) was achieved through the accumulation of multiple variants. Despite being largely stable when strains were passaged in the absence of antibiotics, aztreonam resistance was associated with decreased in vitro growth rates, indicating an associated fitness cost. In some instances, evolved aztreonam-resistant strains exhibited increased resistance to structurally unrelated antipseudomonal antibiotics. Surprisingly, strains carrying evolved mutations which affected negative regulators of mexAB-oprM (mexR and nalD) demonstrated enhanced virulence in a murine pneumonia infection model. Mutations in these genes, and other genes that we associated with aztreonam resistance, were common in P. aeruginosa isolates from chronically infected patients with cystic fibrosis. These findings illuminate mechanisms of P. aeruginosa aztreonam resistance and raise the possibility that antibiotic treatment could inadvertently select for hypervirulence phenotypes.

Inhaled aztreonam is a relatively new antibiotic which is being increasingly used to treat cystic fibrosis patients with Pseudomonas aeruginosa airway infections. As for all antimicrobial agents, bacteria can evolve resistance that decreases the effectiveness of the drug; however, the mechanisms and consequences of aztreonam resistance are incompletely understood. Here, using experimental evolution, we have cataloged spontaneous mutations conferring aztreonam resistance and have explored their effects. We found that a diverse collection of genes contributes to aztreonam resistance, each with a small but cumulative effect. Surprisingly, we found that selection for aztreonam resistance mutations could confer increased resistance to other antibiotics and promote hypervirulence in a mouse infection model. Our study reveals inherent mechanisms of aztreonam resistance and indicates that aztreonam exposure can have unintended secondary effects.

Relevance of multidrug-resistant Pseudomonas aeruginosa infections in cystic fibrosis

Multidrug-resistant (MDR) Pseudomonas aeruginosa is an important issue for physicians who take care of patients with cystic fibrosis (CF). Here, we review the latest research on how P. aeruginosa infection causes lung function to decline and how several factors contribute to the emergence of antibiotic resistance in P. aeruginosa strains and influence the course of the infection course. However, many aspects of the practical management of patients with CF infected with MDR P. aeruginosa are still to be established. Less is known about the exact role of susceptibility testing in clinical strategies for dealing with resistant infections, and there is an urgent need to find a tool to assist in choosing the best therapeutic strategy for MDR P. aeruginosa infection. One current perception is that the selection of antibiotic therapy according to antibiogram results is an important component of the decision-making process, but other patient factors, such as previous infection history and antibiotic courses, also need to be evaluated. On the basis of the known issues and the best current data on respiratory infections caused by MDR P. aeruginosa, this review provides practical suggestions to optimize the diagnostic and therapeutic management of patients with CF who are infected with these pathogens.

Inhaled Antibiotic Therapy in Chronic Respiratory Diseases

The management of patients with chronic respiratory diseases affected by difficult to treat infections has become a challenge in clinical practice. Conditions such as cystic fibrosis (CF) and non-CF bronchiectasis require extensive treatment strategies to deal with multidrug resistant pathogens that include Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus, Burkholderia species and non-tuberculous Mycobacteria (NTM). These challenges prompted scientists to deliver antimicrobial agents through the pulmonary system by using inhaled, aerosolized or nebulized antibiotics. Subsequent research advances focused on the development of antibiotic agents able to achieve high tissue concentrations capable of reducing the bacterial load of difficult-to-treat organisms in hosts with chronic respiratory conditions. In this review, we focus on the evidence regarding the use of antibiotic therapies administered through the respiratory system via inhalation, nebulization or aerosolization, specifically in patients with chronic respiratory diseases that include CF, non-CF bronchiectasis and NTM. However, further research is required to address the potential benefits, mechanisms of action and applications of inhaled antibiotics for the management of difficult-to-treat infections in patients with chronic respiratory diseases.

Inhaled Antibiotics for Gram-Negative Respiratory Infections

Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena.

Improving complex medical care while awaiting next-generation CFTR potentiators and correctors: The current pipeline of therapeutics

While a major target in cystic fibrosis (CF) research in recent years has been the development of corrector and potentiator drugs targeting the cystic fibrosis transmembrane conductance regulator (CFTR) protein, these therapies have not yet proven robust enough to replace or eliminate other therapies that have demonstrated improved health outcomes and quality of life in patients with CF. Further, ivacaftor is only indicated for approximately 5% of the US CF population, although the FDA has recently approved lumacaftor/ivacaftor, a combination therapy intended for those homozygous for Phe508del, which should reach a much larger number of patients. This review appraises therapeutics currently available or being studied while we await the next generation of CFTR potentiators and correctors.

Management of pulmonary exacerbations in cystic fibrosis: still an unmet medical need in clinical practice

Pulmonary exacerbation (PEx) is a hallmark of cystic fibrosis. Although several criteria have been proposed for the definition of PEx, no consensus has yet been reached. Very often, many PEx cases go unreported. A standardized and validated definition is needed to reduce variability in clinical practice. The pathophysiology of recurrent episodes remains unclear, and both onset and risk are multifactorial. PEx leads to increased healthcare costs, impaired quality of life and a cycle in which PEx causes loss of lung function, which predisposes to further episodes. The number of episodes affects survival. Although early diagnosis and aggressive treatment are highly recommended, measures to prevent the emergence of new PEx are even more important. In particular, inhaled antibiotics administered under new treatment schedules could play a key role in preventing exacerbations and thus delay decline in lung function and reduce mortality. The primary objective is zero exacerbations.

Evidence for the efficacy of aztreonam for inhalation solution in the management of Pseudomonas aeruginosa in patients with cystic fibrosis

Chronic airway infection in cystic fibrosis (CF) is a main cause of the increased morbidity and mortality found with this disease. The most common cause of Gram-negative infection is Pseudomonas aeruginosa. The introduction of inhaled antibiotics has changed the lives of affected patients and the clinical outcome of this infection; this article focuses on the use of inhaled antibiotics in chronic P. aeruginosa infection in CF, and specifically on studies including the use of inhaled aztreonam lysine in P. aeruginosa infection. Studies were identified using PubMed and ClinicalTrials.gov, searching for ‘inhaled aztreonam’ and ‘cystic fibrosis’. Inhaled aztreonam is an important new treatment option for chronic P. aeruginosa infection in CF. Long-term studies have shown that the drug is safe and superior to inhaled tobramycin in these specific infections.

Pharmacokinetics and pharmacodynamics of aerosolized antibacterial agents in chronically infected cystic fibrosis patients

Bacteria adapt to growth in lungs of patients with cystic fibrosis (CF) by selection of heterogeneously resistant variants that are not detected by conventional susceptibility testing but are selected for rapidly during antibacterial treatment. Therefore, total bacterial counts and antibiotic susceptibilities are misleading indicators of infection and are not helpful as guides for therapy decisions or efficacy endpoints. High drug concentrations delivered by aerosol may maximize efficacy, as decreased drug susceptibilities of the pathogens are compensated for by high target site concentrations. However, reductions of the bacterial load in sputum and improvements in lung function were within the same ranges following aerosolized and conventional therapies. Furthermore, the use of conventional pharmacokinetic/pharmacodynamic (PK/PD) surrogates correlating pharmacokinetics in serum with clinical cure and presumed or proven eradication of the pathogen as a basis for PK/PD investigations in CF patients is irrelevant, as minimization of systemic exposure is one of the main objectives of aerosolized therapy; in addition, bacterial pathogens cannot be eradicated, and chronic infection cannot be cured. Consequently, conventional PK/PD surrogates are not applicable to CF patients. It is nonetheless obvious that systemic exposure of patients, with all its sequelae, is minimized and that the burden of oral treatment for CF patients suffering from chronic infections is reduced.

Intravenous and Inhaled Antimicrobials at Home in Cystic Fibrosis Patients

The primary clinical characteristics of cystic fibrosis (CF) are malnutrition caused by malabsorption secondary to pancreatic insufficiency, chronic pulmonary infections, and male infertility. The major cause of morbidity and mortality are bronchiectasis and obstructive pulmonary disease. Lung disease in CF is manifested by this chronic lung disease progression, with intermittent episodes of acute worsening of symptoms called pulmonary exacerbations. Once the patient has stabilized, and if suitable care can be arranged, these interventions are often transitioned to the home. This review summarizes important points pertinent to the use of intravenous and inhaled antimicrobials that may be encountered by prescribers, nurses, technicians, and case managers in the home health setting. Appropriate dosing, indications, adverse drug reactions, monitoring parameters, and practicality of both intravenous and inhaled antimicrobials are discussed.

Amikacin-fosfomycin at a five-to-two ratio: characterization of mutation rates in microbial strains causing ventilator-associated pneumonia and interactions with commonly used antibiotics

The amikacin-fosfomycin inhalation system (AFIS), a combination of antibiotics administered with an in-line nebulizer delivery system, is being developed for adjunctive treatment of ventilator-associated pneumonia (VAP). The in vitro characterization of amikacin-fosfomycin (at a 5:2 ratio) described here included determining resistance selection rates for pathogens that are representative of those commonly associated with VAP (including multidrug-resistant strains) and evaluating interactions with antibiotics commonly used intravenously to treat VAP. Spontaneous resistance to amikacin-fosfomycin (5:2) was not observed for most strains tested (n, 10/14). Four strains had spontaneously resistant colonies (frequencies, 4.25 × 10(-8) to 3.47 × 10(-10)), for which amikacin-fosfomycin (5:2) MICs were 2- to 8-fold higher than those for the original strains. After 7 days of serial passage, resistance (>4-fold increase over the baseline MIC) occurred in fewer strains (n, 4/14) passaged in the presence of amikacin-fosfomycin (5:2) than with either amikacin (n, 7/14) or fosfomycin (n, 12/14) alone. Interactions between amikacin-fosfomycin (5:2) and 10 comparator antibiotics in checkerboard testing against 30 different Gram-positive or Gram-negative bacterial strains were synergistic (fractional inhibitory concentration [FIC] index, ≤ 0.5) for 6.7% (n, 10/150) of combinations tested. No antagonism was observed. Synergy was confirmed by time-kill methodology for amikacin-fosfomycin (5:2) plus cefepime (against Escherichia coli), aztreonam (against Pseudomonas aeruginosa), daptomycin (against Enterococcus faecalis), and azithromycin (against Staphylococcus aureus). Amikacin-fosfomycin (5:2) was bactericidal at 4-fold the MIC for 7 strains tested. The reduced incidence of development of resistance to amikacin-fosfomycin (5:2) compared with that for amikacin or fosfomycin alone, and the lack of negative interactions with commonly used intravenous antibiotics, further supports the development of AFIS for the treatment of VAP.

Inhaled antibiotics for lower airway infections

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post-lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized "off-label" to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated.

High level of resistance to aztreonam and ticarcillin in Pseudomonas aeruginosa isolated from soil of different crops in Brazil

Pseudomonas aeruginosa can be found in water, soil, plants and, human and animal fecal samples. It is an important nosocomial pathogenic agent characterized by an intrinsic resistance to multiple antimicrobial agents and the ability to develop high-level (acquired) multidrug resistance through some mechanisms, among them, by the acquisition of plasmids and integrons, which are mobile genetic elements. In this study, 40 isolates from Brazilian soil were analyzed for antibiotic resistance, presence of integrons and plasmidial profile. The results demonstrated that the vast majority of the isolates have shown resistance for aztreonam (92.5%, n=37) and ticarcillin (85%, n=34), four isolates presented plasmids and eight isolates possess the class 1 integron. These results demonstrated that environmental isolates of P. aeruginosa possess surprising antibiotic resistance profile to aztreonam and ticarcillin, two antimicrobial agents for clinical treatment of cystic fibrosis patients and other infections occurred by P. aeruginosa.

Clinical experimentation with aerosol antibiotics: current and future methods of administration

Currently almost all antibiotics are administered by the intravenous route. Since several systems and situations require more efficient methods of administration, investigation and experimentation in drug design has produced local treatment modalities. Administration of antibiotics in aerosol form is one of the treatment methods of increasing interest. As the field of drug nanotechnology grows, new molecules have been produced and combined with aerosol production systems. In the current review, we discuss the efficiency of aerosol antibiotic studies along with aerosol production systems. The different parts of the aerosol antibiotic methodology are presented. Additionally, information regarding the drug molecules used is presented and future applications of this method are discussed.

Inhaled aztreonam lysine: an evidence-based review

INTRODUCTION

Chronic airway infection in cystic fibrosis (CF) is linked with progressive loss of pulmonary function and is the primary cause of mortality. Treatment regimens have generally focused on the use of chronic antibiotic therapy to target Pseudomonas aeruginosa (PA), a major pathogen associated with a decline in FEV1%. Specifically, inhaled antibiotic therapy provides high antibiotic sputum concentrations and decreases bacterial burden.

AREAS COVERED

This article describes the pharmacology, pharmacodynamics/pharmacokinetics, clinical efficacy, microbiology and safety of aztreonam lysine (AZLI, Cayston), an inhaled antibiotic indicated for use in CF patients with PA. Articles were identified using MEDLINE (1966 - June 13, 2013) and EMBASE (1947 - June 13, 2013). Abstracts from the annual meeting (2011 - 2012) of the North American Cystic Fibrosis Conference were searched to identify additional publications.

EXPERT OPINION

AZLI is an additional product that can be used in the management of CF and will likely play a major role in the suppression of PA. Clinical trials have demonstrated improvements in pulmonary function and patient reported symptoms. AZLI may therefore be used as an alternative to traditional inhaled antibiotics in patients with moderate-to-severe CF and PA colonization. Further investigation is warranted into use of AZLI in mild lung disease and for PA eradication.

Antibiotics for treatment and prevention of exacerbations of chronic obstructive pulmonary disease

Acute exacerbations (AE) can be recurrent problems for patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) increasing morbidity and mortality. Evidence suggests that ≥50% of acute exacerbations involve bacteria requiring treatment with an antibiotic which should have high activity against the causative pathogens. However, sputum analysis is not a pre-requisite for antibiotic prescription in outpatients as results are delayed and patients are likely to be colonised with bacteria in the stable state. Clinicians rely on the clinical symptoms, sputum appearance and the patient's medical history to decide if an AE-COPD should be treated with antibiotics. This article reviews the available data of antibiotic trials in AE-COPD. Management of frequent exacerbators is particularly challenging for physicians. This may include antibiotic prophylaxis, especially macrolides because of anti-inflammatory properties; though successful in reducing exacerbations, concerns about resistance development remain. Inhalation of antibiotics achieves high local concentrations and minimal systemic exposure; therefore, it may represent an attractive alternative for antibiotic prophylaxis in certain COPD patients. Inhaled antibiotic prophylaxis has been successfully used in other respiratory conditions such as non-cystic fibrosis bronchiectasis which itself might be present in COPD patients who have chronic bacterial infection, particularly with Pseudomonas aeruginosa.

A model for treating avian aspergillosis: serum and lung tissue kinetics for Japanese quail (Coturnix japonica) following single and multiple aerosol exposures of a nanoparticulate itraconazole suspension

Aspergillosis is frequently reported in parrots, falcons and other birds held in captivity. Inhalation is the main route of infection for Aspergillus fumigatus, resulting in both acute and chronic disease conditions. Itraconazole (ITRA) is an antifungal commonly used in birds, but administration requires repeated oral dosing and the safety margin is narrow. We describe lung tissue and serum pharmacokinetics of a nanoparticulate ITRA suspension administered to Japanese quail by aerosol exposure. Aerosolized ITRA (1 and 10% suspension) administered over 30 min did not induce adverse clinical reactions in quail upon single or 5-day repeated doses. High lung concentrations, well above the inhibitory levels for A. fumigatus, of 4.14 ± 0.19 μg/g and 27.5 ± 4.58 μg/g (mean ± SEM, n = 3), were achieved following single-dose inhalation of 1% and 10% suspension, respectively. Upon multiple dose administration of 10% suspension, mean lung concentrations reached 104.9 ± 10.1 μg/g. Drug clearance from the lungs was slow with terminal half-lives of 19.7 h and 35.8 h following inhalation of 1% and 10% suspension, respectively. Data suggest that lung clearance is solubility driven. Lung concentrations of hydroxy-itraconazole reached 1-2% of the ITRA lung tissue concentration indicating metabolism in lung tissue. Steady, but low, serum concentrations of ITRA could be measured after multiple dose administration, reaching less than 0.1% of the lung tissue concentration. This formulation may represent a novel, easy to administer treatment modality for fungal lung infection, preventing high systemic exposure. It may also be useful as metaphylaxis to prevent the outbreak of aspergillosis in colonized animals.

Inhaled aztreonam lysine for cystic fibrosis pulmonary disease-related outcomes

OBJECTIVE

To evaluate the pharmacology, clinical efficacy, and safety of aztreonam lysine for inhalation (AZLI) for cystic fibrosis (CF)-related signs and symptoms of pulmonary disease.

DATA SOURCES

Literature was searched in MEDLINE through PubMed and cross-referenced with EMBASE (1980-June 2012). The key search terms used were aztreonam lysine, nebulized, inhaled, and cystic fibrosis. Bibliographies of selected articles were used to identify additional references. Ongoing trials were identified through a review of Web site trial registries.

STUDY SELECTION AND DATA EXTRACTION

Articles were limited to those written in English about studies conducted in humans. Studies included in this review examined both adult and pediatric patients with CF.

DATA SYNTHESIS

Aztreonam lysine is an inhaled monocyclic β-lactam antibiotic approved for use in the CF population. Four completed clinical trials with peer-reviewed published data were reviewed to assess the efficacy and safety of single-course AZLI; a fifth trial assessed the safety and efficacy of repeat courses of AZLI. None of these trials compared AZLI in a head-to-head manner with tobramycin for inhalation. In patients with moderate to severe pulmonary disease, AZLI administration improved forced expiratory volume in 1 second measurements, decreased sputum bacterial Pseudomonas aeruginosa density, and improved symptoms. Adverse effects in clinical trials were generally mild and similar to those with placebo.

CONCLUSIONS

AZLI is safe and effective for management of pulmonary-related symptoms in patients with CF who are colonized with P. aeruginosa and have moderate to severe pulmonary disease. Additional trial data comparing AZLI with tobramycin are warranted to further establish the place of AZLI in therapy.

Therapeutic approaches to chronic cystic fibrosis respiratory infections with available, emerging aerosolized antibiotics

Chronic airway infection and inflammation are key events in the clinical course of cystic fibrosis (CF). The most relevant, best investigated strain of bacteria in these circumstances is Pseudomonas aeruginosa. Since pulmonary infection with P. aeruginosa is localized in the lower conducting airways, treatment is accessible with the use of inhaled aerosolized antibiotics. Tobramycin inhalation solution was the first antibiotic to be developed and approved (in 1998) for use as an aerosolized antibiotic in patients with CF. The only other aerosolized antibiotic indicated for this use is aztreonam lysine solution for inhalation, which has been approved by both European and US authorities. In prospective, randomized, controlled trails, both agents exhibited a very acceptable safety profile, along with an increase in forced expiratory volume in 1 second and other clinically relevant endpoints. New developments focus on such components as reducing the treatment burden by using dry power inhalers, decreasing inhalation frequency to once daily, penetrating P. aeruginosa biofilms, and combining two antibiotics in one solution for inhalation. However, the ideal aerosolized antibiotic regimen for the treatment of chronic P. aeruginosa infection has yet not been selected.