Assessing effects of inhaled antibiotics in adults with non-cystic fibrosis bronchiectasis--experiences from recent clinical trials

Nebulized Antibiotics for Preventing and Treating Gram-Negative Respiratory Infections in Critically Ill Patients: An Overview of Reviews

BACKGROUND

Ventilator-associated tracheobronchitis (VAT) and pneumonia (VAP) are the most frequent nosocomial infections in the critical care setting and are associated with increased morbidity. At the same time, VAP is also associated with attributable mortality, especially when caused by difficult-to-treat (DTR) Gram-negative bacteria (GNB) that have limited treatment options. Studies have assessed the impact of nebulized aminoglycosides or colistin to improve VAT and VAP outcomes or as an adjunct to intravenous antimicrobial treatment or as a preventive approach.

OBJECTIVE

This overview aimed to assess systematic reviews that examine the efficacy and safety of antimicrobial nebulization for preventing and treating ventilator-associated infections in the critically ill.

METHODS

Systematic reviews, meta-analyses, and original randomized controlled trials and prospective observational studies were included. Searches were conducted in MEDLINE (via PubMed), the Cochrane, Epistemonikos, and PROSPERO. The methodological quality assessment was performed using standardized tools.

RESULTS

Regarding VAP treatment, the included systematic reviews presented critically low quality. The clinical response effect size to amikacin and colistin nebulization were RR 1.23 (95% CI 1.13-1.34), I2 = 47% and OR 1.39 (0.87-2.20), I2 = 56%. The main safety concern was bronchospasm with RR 2.55 (1.40-4.66), I2 = 0% and OR 5.19 (1.05-25.52), I2 = 0%. The certainty of evidence was usually very low. For VAT treatment, limited evidence showed a better clinical response and less emergence of resistant bacteria. Regarding VAP prevention, data are limited to two trials; however, only the larger one presented a low risk of bias and resulted in a reduced VAP rate.

CONCLUSIONS

Delivery via nebulization might be considered in addition to IV antimicrobial treatment of GNB ventilator-associated infections. The available evidence is weak, and more studies focused on infections due to DTR-GNBs should be prioritized.

The Efficacy and Safety of Inhaled Antibiotics for the Treatment of Bronchiectasis in Adults: Updated Systematic Review and Meta-Analysis

BACKGROUND

Inhaled antibiotics are recommended conditionally by international bronchiectasis guidelines for the treatment of patients with bronchiectasis, but results of individual studies are inconsistent. A previous meta-analysis demonstrated promising results regarding the efficacy and safety of inhaled antibiotics in bronchiectasis. Subsequent publications have supplemented the existing body of evidence further in this area.

RESEARCH QUESTION

To what extent do inhaled antibiotics demonstrate both efficacy and safety as a treatment option for adults with bronchiectasis?

STUDY DESIGN AND METHODS

Systematic review and meta-analysis of randomized controlled trials of inhaled antibiotics in adult patients with bronchiectasis. We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and ClinicalTrials.gov for eligible studies. Studies were included if they enrolled adults with bronchiectasis diagnosed by CT imaging and had a treatment duration of at least 4 weeks. The primary end point was exacerbation frequency, with additional key efficacy end points including severe exacerbations, bacterial load, symptoms, quality of life, and FEV1. Data were pooled through random-effects meta-analysis.

RESULTS

Twenty studies involving 3,468 patients were included. Inhaled antibiotics were associated with reduced number of patients with exacerbations (risk ratio, 0.85; 95% CI, 0.75-0.96), a slight reduction in exacerbation frequency (rate ratio [RR], 0.78; 95% CI, 0.68-0.91), a probable reduction in the frequency of severe exacerbations (RR, 0.48; 95% CI, 0.31-0.74), and a likely slight increase in time to first exacerbation (hazard ratio, 0.80; 95% CI, 0.68-0.94). Inhaled antibiotics likely lead to a slight increase in the Quality of Life Questionnaire-Bronchiectasis respiratory symptom score (mean difference, 2.51; 95% CI, 0.44-4.31) and may reduce scores on the St. George Respiratory Questionnaire (mean difference, -3.13; 95% CI, -5.93 to -0.32). Bacterial load consistently was reduced, but FEV1 was not changed with treatment. Evidence suggests little to no difference in adverse effects between groups (OR, 0.99; 95% CI, 0.75-1.30). Antibiotic-resistant organisms likely were increased by treatment.

INTERPRETATION

In this systematic review and meta-analysis, inhaled antibiotics resulted in a slight reduction in exacerbations, a probable reduction in severe exacerbations, and a likely slight improvement in symptoms and quality of life in adults with bronchiectasis.

TRIAL REGISTRY

International Prospective Register of Systematic Reviews; No.: CRD42023384694; URL: https://www.crd.york.ac.uk/prospero/.

Inhaled antibiotics: A promising drug delivery strategies for efficient treatment of lower respiratory tract infections (LRTIs) associated with antibiotic resistant biofilm-dwelling and intracellular bacterial pathogens

Antibiotic-resistant bacteria associated with LRTIs are frequently associated with inefficient treatment outcomes. Antibiotic-resistant Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, and Staphylococcus aureus, infections are strongly associated with pulmonary exacerbations and require frequent hospital admissions, usually following failed management in the community. These bacteria are difficult to treat as they demonstrate multiple adaptational mechanisms including biofilm formation to resist antibiotic threats. Currently, many patients with the genetic disease cystic fibrosis (CF), non-CF bronchiectasis (NCFB) and chronic obstructive pulmonary disease (COPD) experience exacerbations of their lung disease and require high doses of systemically administered antibiotics to achieve meaningful clinical effects, but even with high systemic doses penetration of antibiotic into the site of infection within the lung is suboptimal. Pulmonary drug delivery technology that reliably deliver antibacterials directly into the infected cells of the lungs and penetrate bacterial biofilms to provide therapeutic doses with a greatly reduced risk of systemic adverse effects. Inhaled liposomal-packaged antibiotic with biofilm-dissolving drugs offer the opportunity for targeted, and highly effective antibacterial therapeutics in the lungs. Although the challenges with development of some inhaled antibiotics and their clinicals trials have been studied; however, only few inhaled products are available on market. This review addresses the current treatment challenges of antibiotic-resistant bacteria in the lung with some clinical outcomes and provides future directions with innovative ideas on new inhaled formulations and delivery technology that promise enhanced killing of antibiotic-resistant biofilm-dwelling bacteria.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Physiology and pathophysiology of human airway mucus

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Safety and tolerability of inhaled antibiotics in patients with bronchiectasis

INTRODUCTION

Bronchiectasis is typically treated with inhaled antibiotics in clinical practice. However, there is a striking lack of standardised procedures for the preparation of noncommercial solutions. We used biochemical parameters to analyse the safety and tolerability of inhaled antibiotics in patients with bronchiectasis, and determined potential associations between the inhaled antibiotics used and adherence to the medications and quality of life.

METHODS

We conducted a literature review, biochemical testing, and a pilot study of patients admitted to our hospital with noncystic fibrosis bronchiectasis. The MEDLINE database was searched for studies involving inhaled antibiotics to treat bronchiectasis. We analysed the pH, osmolality, and sodium and chloride ion concentrations of the antibiotics used. The pilot study included patients receiving inhaled antibiotic treatment. Demographic data, adherence, and quality of life were recorded and assessed. We determined potential associations between the study variables.

RESULTS

The literature review identified 429 articles: 106 included precise instructions for diluting antibiotics, and 18 reported data on the biochemical parameters analysed. Laboratory results showed that some antibiotic dilutions were outside the range of tolerability, especially those involving dry powders for intravenous infusion, which must be diluted for their inhalation. Adherence was good in more than 80% of the patients, and higher in men and older patients. Men reported better quality of life. No associations were found between the antibiotics used and the other variables.

CONCLUSION

Regarding the biochemical parameters analysed, there is a lack of information on the tolerability and biochemical safety of noncommercial dilutions of inhaled antibiotics used to treat bronchiectasis.

Effects of long-term tobramycin inhalation solution (TIS) once daily on exacerbation rate in patients with non-cystic fibrosis bronchiectasis

BACKGROUND

Use of long-term tobramycin inhalation solution (TIS) has been shown beneficial in cystic fibrosis (CF) and earlier findings also suggest a benefit in non-CF bronchiectasis. We investigated the efficacy and safety of maintenance TIS once daily (OD) in frequent exacerbating bronchiectasis patients chronically infected by different pathogens sensitive for tobramycin.

OBJECTIVE

The primary outcome was the frequency of exacerbations during the 12-month study period. Secondary outcomes were time to first exacerbation, change in lung function and quality of life (QoL), bacterial analysis and safety.

MATERIALS/PATIENTS

IN THIS MULTICENTER RCT PATIENTS AGED ≥ 18-YEAR-OLD WERE INCLUDED WITH CONFIRMED BRONCHIECTASIS AND ≥ 2 EXACERBATIONS IN THE PRECEDING YEAR. PATIENTS WERE ASSIGNED (1:1) TO RECEIVE TIS OR PLACEBO OD FOR 1-YEAR.: RESULTS: 58 patients were included of which 52 were analyzed in the mITT analysis. TIS reduced exacerbation frequency with a RR of 0.74 (95% CI 0.49-1.14) (p = 0.15). Within the TIS population a decrease in number of exacerbations was found (2; p = 0.00), which was also seen in the placebo-treated patients (1.5; p = 0.00). In the TIS-treated patients the QoL improved (LRTI-VAS p = 0.02 Leicester Cough p = 0.02) without additional safety concerns. No differences were found for the other secondary outcomes.

CONCLUSION

Long-term TIS OD is a safe treatment modality and showed a non-significant reduced exacerbation frequency of 0.74 as compared to placebo in bronchiectasis patients chronically infected by tobramycin sensitive pathogens. TIS OD may be a potential therapeutic strategy in selected patients with bronchiectasis suffering from a high burden of disease.

TRAIL REGISTRATION NUMBER

The BATTLE study was registered at Clinical trials.gov number: NCT02657473 . Date: 13 august 2016.

The Effect of Vanadium Inhalation on the Tumor Progression of Urethane-Induced Lung Adenomas in a Mice Model

Lung cancer has the highest death rates. Aerosol drug delivery has been used for other lung diseases. The use of inhaled vanadium (V) as an option for lung cancer treatment is explored. Four groups of mice were studied: (1) Saline inhalation alone, (2) Single intraperitoneal (i.p.) dose of urethane, (3) V nebulization twice a week (Wk) for 8 Wk, and (4) A single dose of urethane and V nebulization for 8 Wk. Mice were sacrificed at the end of the experiment. Number and size of tumors, PCNA (proliferating cell nuclear antigen) and TUNEL (terminal deoxynucleotidyl tranferase dUTP nick-end labeling) immunohistochemistry were evaluated and compared within groups. Results: The size and number of tumors decreased in mice exposed to V-urethane and the TUNEL increased in this group; differences in the PCNA were not observed. Conclusions: Aerosol V delivery increased apoptosis and possibly the growth arrest of the tumors with no respiratory clinical changes in the mice.

Inhaled antibiotics for treatment of adults with non-cystic fibrosis bronchiectasis: A systematic review and meta-analysis

BACKGROUND

Inhaled antibiotics (IA) in non-cystic fibrosis bronchiectasis (NCFB) are recommended by some clinical practice guidelines for prevention or treatment of NCFB exacerbations.

METHODS

We performed a systematic review and meta-analysis to evaluate the efficacy and safety of IA use for treatment of adults with NCFB and Pseudomonas aeruginosa chronic bronchial infection. The search was performed in the Cochrane Library, PubMed, and Web of Science databases from 2000 to 2019. Studies of IA for treatment of stable or exacerbated NCFB adults (≥18 years) with P. aeruginosa infection were considered eligible. PROSPERO Registration number: CRD42019136154.

RESULTS

Twelve trials (2476 participants) were included. IA therapy increased P. aeruginosa eradication from sputum in patients with exacerbations (OR: 3.19, 95%CI: 1.70-5.99) with similar effects on stable patients (OR: 7.22, 95%CI: 2.81-18.59), and a trend to reduced emergence of new respiratory pathogens (OR: 0.58, 95%CI: 0.28-1.18). IA achieved significant reduced exacerbation rates (RR: 0.90; 95%CI: 0.82-0.98) in stable patients, with a number needed to treat (NNT) of 59, but no significant changes in FEV₁, mortality, hospitalizations or quality of life were identified. In stable patients, IA use increased antimicrobial resistance (RR: 2.10, 95%CI: 1.35-3.27) at the end of therapy, with a number needed to treat of 6.

CONCLUSIONS

IA therapy achieved a statistically significant eradication of P. aeruginosa from sputum, with a 10% reduction of exacerbations in stable patients. This effect has to be balanced with significant increases in antimicrobial resistance. Our meta-analysis failed to show a significant benefit in terms of patient-centered outcomes.

Results of Tobramycin Inhalation Therapy in Patients with Noncystic Fibrosis Bronchiectasis with Pseudomonas aeruginosa Colonization: Real Life Management

Background: Inhaled antibiotics for treating bronchiectasis have been investigated in the cystic fibrosis population since 1981 and long-term clinical benefits have been reported. However, studies on noncystic fibrosis bronchiectasis (NCFB) have only been performed more recently. Owing to limited evidence, inhaled antibiotics are not currently approved for treating NCFB by the U.S. Food and Drug Administration and the European Medicines Agency. The aim of this study was to evaluate the efficacy and safety of tobramycin inhalation therapy in patients with bronchiectasis with Pseudomonas aeruginosa (PA) colonization. Methods: In this retrospective cross-sectional study, NCFB patients who were Pseudomonas positive on three consecutive cultures 1 month apart and receiving tobramycin inhalation therapy were evaluated. Evaluation of the following parameters was done in this study: age, gender, smoking history, symptoms, pulmonary function test results, sputum culture results, tobramycin treatment duration, side effects of tobramycin and response evaluation, and hospital admissions before and after treatment. Treatment with 300 mg tobramycin through nebulizer twice daily for 28 days on-off cycles for a total of 6 months was considered to be one treatment period. The approvals for the study were received by the local ethics committee and institutional review board. Results: Of the 27 patients, 21 patients completed the first period, 7 patients completed the second period, 4 patients completed the third period, and 1 patient completed the fourth period. Sputum culture was negative in 10 (47.6%) of the 21 patients who completed the first period. Decreased sputum purulence and quantity, dyspnea, and cough were observed during treatment. The frequency of hospitalizations before treatment was 1.24 ± 1.36, whereas after treatment, it decreased to 0.52 ± 0.91, this difference was statistically significant (p = 0.019). The most common side effect was increased dyspnea after nebulization in five patients. Conclusion: Tobramycin inhalation appears to be a well-tolerated treatment in patients with PA colonization with bronchiectasis. This treatment may decrease the hospitalization rates and improve the symptoms.

Inhaled tobramycin for chronic infection with pseudomonas aeruginosa in non-cystic fibrosis bronchiectasis: A systematic review and meta-analysis

INTRODUCTION

Non-cystic fibrosis bronchiectasis (NCFBE) is a chronic and progressive disease characterized by the permanent destruction of small and mid-sized airways. Many patients are chronically colonized by Pseudomona aueruginosa, for which oral antibiotics are given. Evidence to support the use of inhaled antibiotics is contradictory.

OBJECTIVE

To describe the clinical effects of inhaled Tobramycin in P. aeruginosa density in sputum and eradication, lung function, bacterial resistance, and exacerbations requiring hospital admission, in the context of patients with NCFBE colonized by P. aeruginosa.

METHODS

We included RCTs comparing inhaled tobramycin to other antibiotics and placebo in patients with NCFBE.

MAIN FINDINGS

5 studies with 211 participants were included. 2 studies reported a significant but transitory decrease in P. aeruginosa density in sputum as compared to placebo. There was a small difference in the eradication of P. aeruginosa among groups, although with very wide confidence intervals. Tobramycin reduced the rate of hospital admissions but no frequency of exacerbations. There was no evidence of an increased rate of bacterial resistance but was associated to respiratory adverse effects.

CONCLUSIONS

Evidence is not robust enough to confirm a benefit of inhaled Tobramycin in reducing P. aeruginosa sputum density or eradication. There was a high attrition rate, in part due to respiratory adverse events after drug administration, which affects interpretation of the data and raises concerns about the tolerability of the drug. Further network meta-analysis should be done to compare the efficacy and safety of different inhaled antibiotics.

Inhaled Liposomal Antimicrobial Delivery in Lung Infections

The management of difficult-to-treat acute and chronic respiratory infections (infections in cystic fibrosis, non-cystic fibrosis bronchiectasis, immunocompromised and mechanically ventilated patients) and difficult-to-treat pathogens (including multidrug-resistant strains) has become a challenge in clinical practice. The arsenal of conventional antibiotic drugs can be limited by tissue penetration, toxicities, or increasing antibiotic resistance. Inhaled antimicrobials are an interesting therapeutic approach for optimizing the management of respiratory infections. Due to extensive developments in liposome technology, a number of inhaled liposome-based antibiotic and antifungal formulations are available for human use and many products are undergoing clinical trials. Liposomes are biocompatible, biodegradable, and nontoxic vesicles able to encapsulate and carry antimicrobials, enhancing the therapeutic index of various agents and retention at the desired target within the lung. Liposomes reduce drug toxicity and improve tolerability, leading to better compliance and to decreased respiratory side effects. The aim of this article was to provide an up-to-date overview of nebulized liposomal antimicrobials for lung infections (with a special focus on liposomal amikacin, tobramycin, ciprofloxacin, and amphotericin B for inhalation), discussing the feasibility and therapeutic potential of these new strategies of preventing and treating bacteria, mycobacterial and fungal infections.