The use of inhaled antibiotic therapy in the treatment of ventilator-associated pneumonia and tracheobronchitis: a systematic review

Efficacy of adjunctive inhaled colistin and tobramycin for ventilator-associated pneumonia: systematic review and meta-analysis

INTRODUCTION

Ventilator-associated pneumonia (VAP) presents a significant challenge in intensive care units (ICUs). Nebulized antibiotics, particularly colistin and tobramycin, are commonly prescribed for VAP patients. However, the appropriateness of using inhaled antibiotics for VAP remains a subject of debate among experts. This study aims to provide updated insights on the efficacy of adjunctive inhaled colistin and tobramycin through a comprehensive systematic review and meta-analysis.

METHODS

A thorough search was conducted in MEDLINE, EMBASE, LILACS, COCHRANE Central, and clinical trials databases ( www.

CLINICALTRIALS

gov ) from inception to June 2023. Randomized controlled trials (RCTs) meeting specific inclusion criteria were selected for analysis. These criteria included mechanically ventilated patients diagnosed with VAP, intervention with inhaled Colistin and Tobramycin compared to intravenous antibiotics, and reported outcomes such as clinical cure, microbiological eradication, mortality, or adverse events.

RESULTS

The initial search yielded 106 records, from which only seven RCTs fulfilled the predefined inclusion criteria. The meta-analysis revealed a higher likelihood of achieving both clinical and microbiological cure in the groups receiving tobramycin or colistin compared to the control group. The relative risk (RR) for clinical cure was 1.23 (95% CI: 1.04, 1.45), and for microbiological cure, it was 1.64 (95% CI: 1.31, 2.06). However, there were no significant differences in mortality or the probability of adverse events between the groups.

CONCLUSION

Adjunctive inhaled tobramycin or colistin may have a positive impact on the clinical and microbiological cure rates of VAP. However, the overall quality of evidence is low, indicating a high level of uncertainty. These findings underscore the need for further rigorous and well-designed studies to enhance the quality of evidence and provide more robust guidance for clinical decision-making in the management of VAP.

WHO's essential medicines and AWaRe: recommendations on first- and second-choice antibiotics for empiric treatment of clinical infections

The WHO Model List of Essential Medicines (EML) prioritizes medicines that have significant global public health value. The EML can also deliver important messages on appropriate medicine use. Since 2017, in response to the growing challenge of antimicrobial resistance, antibiotics on the EML have been reviewed and categorized into three groups: Access, Watch, and Reserve, leading to a new categorization called AWaRe. These categories were developed taking into account the impact of different antibiotics and classes on antimicrobial resistance and the implications for their appropriate use. The 2023 AWaRe classification provides empirical guidance on 41 essential antibiotics for over 30 clinical infections targeting both the primary health care and hospital facility setting. A further 257 antibiotics not included on the EML have been allocated an AWaRe group for stewardship and monitoring purposes. This article describes the development of AWaRe, focussing on the clinical evidence base that guided the selection of Access, Watch, or Reserve antibiotics as first and second choices for each infection. The overarching objective was to offer a tool for optimizing the quality of global antibiotic prescribing and reduce inappropriate use by encouraging the use of Access antibiotics (or no antibiotics) where appropriate. This clinical evidence evaluation and subsequent EML recommendations are the basis for the AWaRe antibiotic book and related smartphone applications. By providing guidance on antibiotic prioritization, AWaRe aims to facilitate the revision of national lists of essential medicines, update national prescribing guidelines, and supervise antibiotic use. Adherence to AWaRe would extend the effectiveness of current antibiotics while helping countries expand access to these life-saving medicines for the benefit of current and future patients, health professionals, and the environment.

Aerosolized Antibiotics to Manage Ventilator-Associated Infections: A Comprehensive Review

BACKGROUND

Ventilator-associated lower respiratory tract infectious complications in critically ill patients cover a wide spectrum of one disease process (respiratory infection), initiating from tracheal tube and/or tracheobronchial colonization, to ventilator associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). VAP occurence has been associated with increased intensive care unit (ICU) morbidity (ventilator days, as well as length of ICU and hospital stay) and ICU mortality. Therefore, treatments that aim at VAP/VAT incidence reduction are a high priority.

AIM

The aim of the present review is to discuss the current literature concerning two major aspects: (a) can aerosolized antibiotics (AA) administered in a pre-emptive way prevent the occurrence of ventilator-associated infections? and (b) can VAT treatment with aerosolized avert the potential evolution to VAP?

RESULTS

There were identified eight studies that provided data on the use of aerosolized antibiotics for the prevention of VAT/VAP. Most of them report favorable data on reducing the colonisation rate and the progression to VAP/VAT. Another four studies dealt with the treatment of VAT/VAP. The results support the decrease in the incidence to VAP transition and/or the improvement in signs and symptoms of VAP. Moreover, there are concise reports on higher cure rates and microbiological eradication in patients treated with aerosolized antibiotics. Yet, differences in the delivery modality adopted and resistance emergence issues preclude the generalisability of the results.

CONCLUSION

Aerosolized antibiotic therapy can be used to manage ventilator-associated infections, especially those with difficult to treat resistance. The limited clinical data raise the need for large randomized controlled trials to confirm the benefits of AA and to evaluate the impact on antibiotic selection pressure.

The Unfulfilled Promise of Inhaled Therapy in Ventilator-Associated Infections: Where Do We Go from Here?

Respiratory infection is common in intubated/tracheotomized patients and systemic antibiotic therapy is often unrewarding. In 1967, the difficulty in treating Gram-negative respiratory infections led to the use of inhaled gentamicin, targeting therapy directly to the lungs. Fifty-three years later, the effects of topical therapy in the intubated patient remain undefined. Clinical failures with intravenous antibiotics persist and instrumented patients are now infected by many more multidrug-resistant Gram-negative species as well as methicillin-resistant Staphylococcus aureus. Multiple systematic reviews and meta-analyses suggest that there may be a role for inhaled delivery but “more research is needed.” Yet there is still no Food and Drug Administration (FDA) approved inhaled antibiotic for the treatment of ventilator-associated infection, the hallmark of which is the foreign body in the upper airway. Current pulmonary and infectious disease guidelines suggest using aerosols only in the setting of Gram-negative infections that are resistant to all systemic antibiotics or not to use them at all. Recently two seemingly well-designed large randomized placebo-controlled Phase 2 and Phase 3 clinical trials of adjunctive inhaled therapy for the treatment of ventilator-associated pneumonia failed to show more rapid resolution of pneumonia symptoms or effect on mortality. Despite evolving technology of delivery devices and more detailed understanding of the factors affecting delivery, treatment effects were no better than placebo. What is wrong with our approach to ventilator- associated infection? Is there a message from the large meta-analyses and these two large recent multisite trials? This review will suggest why current therapies are unpredictable and have not fulfilled the promise of better outcomes. Data suggest that future studies of inhaled therapy, in the milieu of worsening bacterial resistance, require new approaches with completely different indications and endpoints to determine whether inhaled therapy indeed has an important role in the treatment of ventilated patients.

The clinical path to deliver encapsulated phages and lysins

The global emergence of multidrug-resistant pathogens is shaping the current dogma regarding the use of antibiotherapy. Many bacteria have evolved to become resistant to conventional antibiotherapy, representing a health and economic burden for those afflicted. The search for alternative and complementary therapeutic approaches has intensified and revived phage therapy. In recent decades, the exogenous use of lysins, encoded in phage genomes, has shown encouraging effectiveness. These two antimicrobial agents reduce bacterial populations; however, many barriers challenge their prompt delivery at the infection site. Encapsulation in delivery vehicles provides targeted therapy with a controlled compound delivery, surpassing chemical, physical and immunological barriers that can inactivate and eliminate them. This review explores phages and lysins' current use to resolve bacterial infections in the respiratory, digestive, and integumentary systems. We also highlight the different challenges they face in each of the three systems and discuss the advances towards a more expansive use of delivery vehicles.

Pinitol attenuates LPS-induced pneumonia in experimental animals: Possible role via inhibition of the TLR-4 and NF-κB/IκBα signaling cascade pathway

Pneumonia is a chronic disorder of the respiratory system associated with worsening quality of life and a significant economic burden. Pinitol, a plant cyclic polyol, has been documented for immune-inflammatory potential. The aim of present investigation was to evaluate the potential and possible mechanism of action of pinitol against lipopolysaccharide (LPS)-induced pneumonia in the experimental animal model. Pneumonia was induced in Sprague-Dawley rats by intratracheal administration of LPS (2 mg/kg). Animals were treated with either vehicle or dexamethasone or pinitol (5 or 10 or 20 mg/kg). Potential of pinitol against LPS-induced pulmonary insult was assessed based on behavioral, biochemical, molecular, and ultrastructural studies. Intratracheal instillation of LPS induced significant (P < .05) inflammatory infiltration in bronchoalveolar lavage fluid (BALF) and lung tissue reflected by elevated pleural effusion volume, lung edema, BALF polymorphonuclear leukocytes count and lung myeloperoxidase levels, which was attenuated by pinitol (10 and 20 mg/kg) administration. Pinitol also markedly (P < .05) inhibited LPS-induced alterations in electrocardiographic, hemodynamic changes, right ventricular, and lung function tests. The LPS-induced downregulated nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase-1 (HO-1), whereas upregulated transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), and inducible nitric oxide synthase (iNOs) lung messenger RNA expressions were significantly (P < .05) inhibited by pinitol. Western blot analysis suggested pinitol markedly (P < .05) decreased nuclear factor-κB (NF-κB), inhibitor of nuclear factor κB (IkBα), toll-like receptor 4 (TLR-4), and cyclooxygenase-II (COX-II) protein expressions in the lung. These findings were further supported by histological and ultrastructural analyses of lung tissue that show pinitol significantly (P < .05) ameliorates LPS-induced aberrations in lung tissue. In conclusion, pinitol attenuated LPS-induced pneumonia via inhibition of TLR-4 to downregulate the NF-κB/IκBα signaling cascade and thus ameliorated the production of proinflammatory cytokines (TNF-α, ILs, NLRP3, and TGF-β), inflammatory mediators (COX-II and iNOs) and elevated oxidative stress (Nrf-2 and HO-1).

Inhaled antibiotics for the treatment of pneumonia

PURPOSE OF REVIEW

To describe recent developments in trials exploring inhaled antibiotics for treating severe pneumonia.

RECENT FINDINGS

Three recent randomized studies investigated the potential role for aerosolized antibiotics for gram-negative pneumonia in ventilated patients. One single center, nonblinded investigation suggested a benefit with inhaled amikacin for resistant gram-negative infections. However, two multicenter, blinded trials found no benefit to adjunctive nebulized amikacin for severe gram-negative pneumonia.

SUMMARY

Well done clinical trials do not support the routine use of inhaled amikacin for pneumonia in ventilated patients. There may be a potential role for aerosolized antibiotics when other options are limited.

Ventilator-Associated Tracheobronchitis: To Treat or Not to Treat?

Ventilator-associated tracheobronchitis (VAT) is an infection commonly affecting mechanically ventilated intubated patients. Several studies suggest that VAT is associated with increased duration of mechanical ventilation (MV) and length of intensive care unit (ICU) stay, and a presumptive increase in healthcare costs. Uncertainties remain, however, regarding the cost/benefit balance of VAT treatment. The aim of this narrative review is to discuss the two fundamental and inter-related dilemmas regarding VAT, i.e., (i) how to diagnose VAT? and (ii) should we treat VAT? If yes, should we treat all cases or only selected ones? How should we treat in terms of antibiotic choice, route, treatment duration?

Inhaled amikacin adjunctive to intravenous standard-of-care antibiotics in mechanically ventilated patients with Gram-negative pneumonia (INHALE): a double-blind, randomised, placebo-controlled, phase 3, superiority trial

BACKGROUND

Treatment of ventilated pneumonia is often unsuccessful, even when patients are treated according to established guidelines. Therefore, we aimed to investigate the efficacy of the combination drug device Amikacin Inhale as an adjunctive therapy to intravenous standard-of-care antibiotics for pneumonia caused by Gram-negative pathogens in intubated and mechanically ventilated patients.

METHODS

INHALE was a prospective, double-blind, randomised, placebo-controlled, phase 3 study comprising two trials (INHALE 1 and INHALE 2) done in 153 hospital intensive-care units in 25 countries. Eligible patients were aged 18 years or older; had pneumonia that had been diagnosed by chest radiography and that was documented as being caused by or showing two risk factors for a Gram-negative, multidrug-resistant pathogen; were intubated and mechanically ventilated; had impaired oxygenation within 48 h before screening; and had a modified Clinical Pulmonary Infection Score of at least 6. Patients were stratified by region and disease severity (according to their Acute Physiology and Chronic Health Evaluation [APACHE] II score) and randomly assigned (1:1) via an interactive voice-recognition system to receive 400 mg amikacin (Amikacin Inhale) or saline placebo, both of which were aerosolised, administered every 12 h for 10 days via the same synchronised inhalation system, and given alongside standard-of-care intravenous antibiotics. All patients and all staff involved in administering devices and monitoring outcomes were masked to treatment assignment. The primary endpoint, survival at days 28-32, was analysed in all patients who received at least one dose of study drug, were infected with a Gram-negative pathogen, and had an APACHE II score of at least 10 at diagnosis. Safety analyses were done in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, numbers NCT01799993 and NCT00805168.

FINDINGS

Between April 13, 2013, and April 7, 2017, 807 patients were assessed for eligibility and 725 were randomly assigned to Amikacin Inhale (362 patients) or aerosolised placebo (363 patients). 712 patients received at least one dose of study drug (354 in the Amikacin Inhale group and 358 in the placebo group), although one patient assigned to Amikacin Inhale received placebo in error and was included in the placebo group for safety analyses. 508 patients (255 in the Amikacin Inhale group and 253 in the placebo group) were assessed for the primary endpoint. We found no between-group difference in survival: 191 (75%) patients in the Amikacin Inhale group versus 196 (77%) patients in the placebo group survived until days 28-32 (odds ratio 0·841, 95% CI 0·554-1·277; p=0·43). Similar proportions of patients in the two treatment groups had a treatment-emergent adverse event (295 [84%] of 353 patients in the Amikacin Inhale group vs 303 [84%] of 359 patients in the placebo group) or a serious treatment-emergent adverse event (101 [29%] patients vs 97 [27%] patients).

INTERPRETATION

Our findings do not support use of inhaled amikacin adjunctive to standard-of-care intravenous therapy in mechanically ventilated patients with Gram-negative pneumonia.

FUNDING

Bayer AG.

Aerosol Therapy for Pneumonia in the Intensive Care Unit

Antibiotic aerosolization in patients with ventilator-associated pneumonia (VAP) allows very high concentrations of antimicrobial agents in the respiratory secretions, far more than those achievable using the intravenous route. However, data in critically ill patients with pneumonia are limited. Administration of aerosolized antibiotics might increase the likelihood of clinical resolution, but no significant improvements in important outcomes have been consistently documented. Thus, aerosolized antibiotics should be restricted to the treatment of extensively resistant gram-negative pneumonia. In these cases, the use of a vibrating-mesh nebulizer seems to be more efficient, but specific settings and conditions are required to improve lung delivery.

RETRACTED: Quercetin ameliorates lipopolysaccharide-caused inflammatory damage via down-regulation of miR-221 in WI-38 cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Given the comments of Dr Elisabeth Bik regarding this article “… the Western blot bands in all 400+ papers are all very regularly spaced and have a smooth appearance in the shape of a dumbbell or tadpole, without any of the usual smudges or stains. All bands are placed on similar looking backgrounds, suggesting they were copy/pasted from other sources, or computer generated”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Adjunctive Nebulized Antibiotics: What Is Their Place in ICU Infections?

Inhaled antibiotics have been used as adjunctive therapy for patients with pneumonia, primarily caused by multidrug resistant (MDR) pathogens. Most studies have been in ventilated patients, although non-ventilated patients have also been included (but not discussed in this review), and most patients have had nosocomial pneumonia. Aerosolized antibiotics are generally added to systemic therapy, and have shown efficacy, primarily as salvage therapy for failing patients and as adjunctive therapy after an MDR gram-negative has been identified. An advantage to aerosolized antibiotics is that they can achieve high intra-pulmonary concentrations that are potentially effective, even for highly resistant pathogens, and because they are generally not well-absorbed systemically, it is possible to avoid some of the toxicities of systemic therapy. When using inhaled antibiotics, it is essential to choose the appropriate agent and the optimal delivery method. Animal and human studies have shown that aerosolized antibiotics reach higher concentrations in the lung than systemic antibiotics, but that areas of dense pneumonia may not receive as much antibiotic as less affected areas of lung. Optimal delivery in ventilated patients depends on device selection, generally with a preference for vibrating mesh nebulizers and with careful attention to where the device is placed in the ventilator circuit and how the delivery is coordinated with the ventilator cycle. Although some studies have shown a benefit for clinical cure, adjunctive therapy has not led to reduced mortality. In some studies, adjunctive aerosol therapy has reduced the duration of systemic antibiotic therapy, thus serving to promote antimicrobial stewardship. Two recent multicenter, randomized, double-blinded, placebo-controlled trials of adjunctive nebulized antibiotics for VAP patients with suspected MDR gram-negative pneumonia were negative for their primary endpoints. This may have been related to trial design and execution and the lessons learned from these studies need to be incorporated in any future trials. Currently, routine use of adjunctive aerosolized therapy cannot be supported by available data, and this therapy is only recommended to assist in the eradication of highly resistant pathogens and to be used as salvage therapy for patients failing systemic therapy.

Drug Prevention and Control of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is one of the most prevalent and serious complications of mechanical ventilation, which is considered a common nosocomial infection in critically ill patients. There are some great options for the prevention of VAP: (i) minimize ventilator exposure; (ii) intensive oral care; (iii) aspiration of subglottic secretions; (iv) maintain optimal positioning and encourage mobility; and (v) prophylactic probiotics. Furthermore, clinical management of VAP depends on appropriate antimicrobial therapy, which needs to be selected based on individual patient factors, such as previous antibacterial therapy, history of hospitalization or mechanical ventilation, and bacterial pathogens and antibiotic resistance patterns. In fact, antibiotic resistance has exponentially increased over the last decade, and the isolation of a multidrug-resistant (MDR) pathogen has been identified as an independent predictor of inadequate initial antibiotic therapy and which is significantly associated with increased mortality. Multiple attempts were used in the treatment of VAP, such as novel antibacterial agents, inhaled antibiotics and monoclonal antibodies. In this review, we summarize the current therapeutic options for the prevention and treatment of VAP, aiming to better management of VAP in clinical practice.

Notoginsenoside R1 up-regulates microRNA-132 to protect human lung fibroblast MRC-5 cells from lipopolysaccharide-caused injury

BACKGROUND

Pneumonia is a common lung disease in children with high fatality rate. Notoginsenoside R1 (NGR1) is the main active component extracted from the roots of Panax notoginseng (Burk.) F.H. Chen (Araliaceae). Here, we carefully explored the potential anti-inflammatory and protective effects of NGR1 on lipopolysaccharide (LPS)-induced lung fibroblast MRC-5 cell injury.

METHODS

Viability and apoptosis of MRC-5 cells after different treatment or transfection were respectively assessed using CCK-8 assay and Annexin V-FITC/PI staining. The expression levels of microRNA-132 (miR-132), IL-1β, IL-6 and TNF-α in MRC-5 cells were measured using qRT-PCR. MicroRNA transfection was conducted to reduce the expression level of miR-132. Western blotting was used to analyze the protein expression levels of key factors involving in cell proliferation, apoptosis, NF-κB pathway and JNK pathway.

RESULTS

LPS treatment caused MRC-5 cell proliferation inhibition, apoptosis and over-production of inflammatory cytokines. NGR1 treatment had no significant effects on MRC-5 cell proliferation, apoptosis and production of inflammatory cytokines, but protected MRC-5 cells from LPS-caused cell proliferation inhibition, apoptosis and over-production of inflammatory cytokines. In addition, NGR1 increased the expression level of miR-132 in MRC-5 cells. Knockdown of miR-132 reversed the protective effects of NGR1 on LPS-treated MRC-5 cells. Furthermore, NGR1 attenuated LPS-activated NF-κB and JNK pathways in MRC-5 cells via up-regulation of miR-132.

CONCLUSION

This research confirmed the protective roles of NGR1 in lung fibroblast cell inflammatory injury. NGR1 protected MRC-5 cells from LPS-caused inflammatory injury through up-regulating miR-132 and then inactivating NF-κB and JNK pathways.

Antibiotic therapy in ventilator-associated tracheobronchitis: a literature review

The concept of ventilator-associated tracheobronchitis is controversial; its definition is not unanimously accepted and often overlaps with ventilator-associated pneumonia. Ventilator-associated tracheobronchitis has an incidence similar to that of ventilator-associated pneumonia, with a high prevalence of isolated multiresistant agents, resulting in an increase in the time of mechanical ventilation and hospitalization but without an impact on mortality. The performance of quantitative cultures may allow better diagnostic definition of tracheobronchitis associated with mechanical ventilation, possibly avoiding the overdiagnosis of this condition. One of the major difficulties in differentiating between ventilator-associated tracheobronchitis and ventilator-associated pneumonia is the exclusion of a pulmonary infiltrate by chest radiography; thoracic computed tomography, thoracic ultrasonography, or invasive specimen collection may also be required. The institution of systemic antibiotic therapy does not improve the clinical impact of ventilator-associated tracheobronchitis, particularly in reducing time of mechanical ventilation, hospitalization or mortality, despite the possible reduced progression to ventilator-associated pneumonia. However, there are doubts regarding the methodology used. Thus, considering the high prevalence of tracheobronchitis associated with mechanical ventilation, routine treatment of this condition would result in high antibiotic usage without clear benefits. However, we suggest the institution of antibiotic therapy in patients with tracheobronchitis associated with mechanical ventilation and septic shock and/or worsening of oxygenation, and other auxiliary diagnostic tests should be simultaneously performed to exclude ventilator-associated pneumonia. This review provides a better understanding of the differentiation between tracheobronchitis associated with mechanical ventilation and pneumonia associated with mechanical ventilation, which can significantly decrease the use of antibiotics in critically ventilated patients.

Inhaled Antimicrobials for Ventilator-Associated Pneumonia: Practical Aspects

Positive experience with inhaled antibiotics in pulmonary infections of patients with cystic fibrosis has paved the way for their utilization in mechanically ventilated, critically ill patients with lower respiratory tract infections. A successful antibiotic delivery depends upon the size of the generated particle and the elimination of drug impaction in the large airways and the ventilator circuit. Generated droplet size is mainly affected by the type of the nebulizer employed. Currently, jet, ultrasonic, and vibrating mesh nebulizers are marketed; the latter can deliver optimal antibiotic particle size. Promising novel drug-device combinations are able to release drug concentrations of 25- to 300-fold the minimum inhibitory concentration of the targeted pathogens into the pulmonary alveoli. The most important practical steps of nebulization include pre-assessment and preparation of the patient (suctioning, sedation, possible bronchodilation, adjustment of necessary ventilator settings); adherence to the procedure (drug preparation, avoidance of unnecessary tubing connections, interruption of heated humidification, removal of heat-moisture exchanger); inspection of the procedure (check for residual in drug chamber, change of expiratory filter, return sedation, and ventilator settings to previous status); and surveillance of the patient for adverse events (close monitoring of the patient and particularly of peak airway pressure and bronchoconstriction). Practical aspects of nebulization are very important to ensure optimal drug delivery and safe procedure for the patient. Therefore, the development of an operational checklist is a priority for every department adopting this modality.

Characterisation of 40 mg/ml and 100 mg/ml tobramycin formulations for aerosol therapy with adult mechanical ventilation

BACKGROUND

Preservative-free tobramycin is commonly used as aerosolized therapy for ventilator associated pneumonia. The comparative delivery profile of the formulations of two different concentrations (100 mg/ml and 40 mg/ml) is unknown. This study aims to evaluate the aerosol characteristics of these tobramycin formulations in a simulated adult mechanical ventilation model.

METHODS

Simulated adult mechanical ventilation set up and optimal settings were used in the study. Inhaled mass study was performed using bacterial/viral filters at the tip of the tracheal tube and in the expiratory limb of circuit. Laser diffractometer was used for characterising particle size distribution. The physicochemical characteristics of the formulations were described and nebulization characteristics compared using two airways, an endotracheal tube (ET) and a tracheostomy tube (TT). For each type of tube, three internal tube diameters were studied, 7 mm, 8 mm and 9 mm.

RESULTS

The lung dose was significantly higher for 100 mg/ml solution (mean 121.3 mg vs 41.3 mg). Viscosity was different (2.11cp vs 1.58cp) for 100 mg/ml vs 40 mg/ml respectively but surface tension was similar. For tobramycin 100 mg/ml vs 40 mg/ml, the volume median diameter (2.02 vs 1.9 μm) was comparable. The fine particle fraction (98.5 vs 85.4%) was higher and geometric standard deviation (1.36 vs 1.62 μm) was significantly lower for 100 mg/ml concentration. Nebulization duration was longer for 100 mg/ml solution (16.9 vs 10.1 min). The inhaled dose percent was similar (30%) but the exhaled dose was higher for 100 mg/ml solution (18.9 vs 10.4%). The differences in results were non-significant for type of tube or size except for a small but statistically significant reduction in inhaled mass with TT compared to ET (0.06%).

CONCLUSION

Aerosolized tobramycin 100 mg/ml solution delivered higher lung dose compared to tobramycin 40 mg/ml solution. Tracheal tube type or size did not influence the aerosol characteristics and delivery parameters.

Efficacy of a bundle approach in preventing the incidence of ventilator associated pneumonia (VAP)

Ventilator-associated pneumonia (VAP) is a potentially preventable iatrogenic illness that may develop following mechanical ventilation. A bundle for the prevention of VAP consists of different measures which may vary between institutions, and may include: elevation of the head of the bed, oral care with chlorhexidine, subglottic suctioning, daily assessment for extubation and the need for proton-pump inhibitors, use of closed suction systems, and maintaining endotracheal cuff pressure at 25 cmH2O. Our aim was to determine the efficacy of a VAP prevention bundle, consisting of the above-mentioned measures, by evaluating the incidence of VAP before (no-VAP-B group) and after (VAP-B group) the introduction of the bundle. We retrospectively evaluated the data for patients who were mechanically ventilated with an endotracheal tube, in the period between 1 September and 31 December 2014 (no-VAP-B group, n = 55, 54.5% males, mean age 67.8 ± 14.5 years) and between 1 January to 30 April 2015 (VAP-B group, n = 74, 62.1% males, mean age 64.8 ± 13.7 years). There were no statistically significant differences between no-VAP-B and VAP-B groups in demographic data, intensive care unit (ICU) mortality, hospital mortality, duration of ICU treatment, and duration of mechanical ventilation. No significant differences in the rates of VAP and early VAP (onset ≤7 days after intubation) were found between no-VAP-B and VAP-B groups (41.8% versus 25.7%, p = 0.06 and 10.9% versus 12.2%, p > 0.99, respectively). However, a significant decrease in the late VAP (onset >8 days after intubation) was found in VAP-B group compared to no-VAP-B group (13.5% versus 30.9%, p = 0.027). Overall, our results support the use of VAP prevention bundle in clinical practice.

In vitro evaluation of aerosol delivery of aztreonam lysine (AZLI): an adult mechanical ventilation model

BACKGROUND

The delivery profile of Aztreonam lysine (AZLI) during mechanical ventilation (MV) is unknown. We evaluated the amount of AZLI drug delivered using an in vitro model of adult MV.

METHODS

An adult lung model designed to mimic current clinical practice was used. Both nebulizers were placed before a Y-piece and 4 settings were tested: A) Aeroneb solo® [AS] with a t-piece; B) AS with the spacer; C) M-Neb® [MN] with a t-piece and D) MN with the spacer. Performance was evaluated in terms of: 1) Mass median aerodynamic diameter (MMAD); 2) Geometric standard deviation (GSD), 3) Fine particle dose (FPD), 4) Fine particle fraction (FPF), 5) Inhalable mass (IM), and 6) Recovery rate (RR).

RESULTS

Both devices showed an adequate delivery of AZLI during MV, with MMAD between 2.4-2.5 µm and 87% of FPF. The FPD (38.8 and 31.7), IM (44.8 and 36.1) and RR (30 and 24) were similar for AS and MN respectively. Nebulizer aerosol delivery increased (50 and 70% respectively) for both nebulizers when using the spacer.

CONCLUSION

Both AS and MN showed a good aerosol delivery profile for AZLI during in vitro mechanical ventilation. Better aerosol delivery performance was obtained using the spacer.

Nebulized antibiotics in mechanically ventilated patients: a challenge for translational research from technology to clinical care

Nebulized antibiotic therapy directly targets airways and lung parenchyma resulting in high local concentrations and potentially lower systemic toxicities. Experimental and clinical studies have provided evidence for elevated lung concentrations and rapid bacterial killing following the administration of nebulized antibiotics during mechanical ventilation. Delivery of high concentrations of antibiotics to infected lung regions is the key to achieving efficient nebulized antibiotic therapy. However, current non-standardized clinical practice, the difficulties with implementing optimal nebulization techniques and the lack of robust clinical data have limited its widespread adoption. The present review summarizes the techniques and clinical constraints for optimal delivery of nebulized antibiotics to lung parenchyma during invasive mechanical ventilation. Pulmonary pharmacokinetics and pharmacodynamics of nebulized antibiotic therapy to treat ventilator-associated pneumonia are discussed and put into perspective. Experimental and clinical pharmacokinetics and pharmacodynamics support the use of nebulized antibiotics. However, its clinical benefits compared to intravenous therapy remain to be proved. Future investigations should focus on continuous improvement of nebulization practices and techniques. Before expanding its clinical use, careful design of large phase III randomized trials implementing adequate therapeutic strategies in targeted populations is required to demonstrate the clinical effectiveness of nebulized antibiotics in terms of patient outcomes and reduction in the emergence of antibiotic resistance.

Nebulization of Antiinfective Agents in Invasively Mechanically Ventilated Adults: A Systematic Review and Meta-analysis

BACKGROUND

Nebulization of antiinfective agents is a common but unstandardized practice in critically ill patients.

METHODS

A systematic review of 1,435 studies was performed in adults receiving invasive mechanical ventilation. Two different administration strategies (adjunctive and substitute) were considered clinically relevant. Inclusion was restricted to studies using jet, ultrasonic, and vibrating-mesh nebulizers. Studies involving children, colonized-but-not-infected adults, and cystic fibrosis patients were excluded.

RESULTS

Five of the 11 studies included had a small sample size (fewer than 50 patients), and only 6 were randomized. Diversity of case-mix, dosage, and devices are sources of bias. Only a few patients had severe hypoxemia. Aminoglycosides and colistin were the most common antibiotics, being safe regarding nephrotoxicity and neurotoxicity, but increased respiratory complications in 9% (95% CI, 0.01 to 0.18; I = 52%), particularly when administered to hypoxemic patients. For tracheobronchitis, a significant decrease in emergence of resistance was evidenced (risk ratio, 0.18; 95% CI, 0.05 to 0.64; I = 0%). Similar findings were observed in pneumonia by susceptible pathogens, without improvement in mortality or ventilation duration. In pneumonia caused by resistant pathogens, higher clinical resolution (odds ratio, 1.96; 95% CI, 1.30 to 2.96; I = 0%) was evidenced. These findings were not consistently evidenced in the assessment of efficacy against pneumonia caused by susceptible pathogens.

CONCLUSIONS

Performance of randomized trials evaluating the impact of nebulized antibiotics with more homogeneous populations, standardized drug delivery, predetermined clinical efficacy, and safety outcomes is urgently required. Infections by resistant pathogens might potentially have higher benefit from nebulized antiinfective agents. Nebulization, without concomitant systemic administration of the drug, may reduce nephrotoxicity but may also be associated with higher risk of respiratory complications.

In vitro activity of a novel compound, Mul-1867, against clinically significant fungi Candida spp. and Aspergillus spp

There is an urgent need for new antifungal compounds to treat various types of fungal infections, including pulmonary infections. This study was designed to investigate the potency of a novel compound (Mul-1867) against Candida spp. and Aspergillus spp. isolated from patients with fungal pneumonia, cystic fibrosis and chronic obstructive pulmonary disease. Mul-1867 was highly effective against susceptible control strains as well as resistant clinical isolates, with minimum fungicidal concentrations (MFCs) varying from 0.06 µg/mL to 0.5 µg/mL. It was also highly effective against pre-formed 48-h-old biofilms formed by yeasts and moulds. The half-minimal biofilm eradication concentration (MBEC₅₀) was equal to the MFC. The minimum biofilm eradication concentration to eliminate 90% of biofilms (MBEC₉₀) varied from 1 × to 4 × MFC. Scanning electron microscopy revealed morphological changes accompanied by the release of intracellular material from the fungal cells following exposure to Mul-1867. Furthermore, an increased concentration of nucleic acids was found in the medium after 5 min and 20 min of Mul-1867 treatment, indicating leakage of cytoplasmic contents. Overall, these data indicate that Mul-1867 may be a promising inhaled antifungal agent for the treatment and prevention of fungal respiratory infections.

New horizons in hospital acquired pneumonia in older people

Approximately 1.5% of hospital patients develop hospital acquired pneumonia. Aspiration is the major risk factor for pneumonia and is associated with reduced ability to mechanically clear respiratory pathogens into the stomach. Currently non-invasive methods of diagnosing hospital acquired pneumonia are less robust than invasive methods, and lead to over-diagnosis. Accurate diagnosis is key to surveillance, prevention and treatment of HAP, and also to improving outcomes; newer imaging modalities such as phase contrast X-ray imaging and nanoparticle enhanced magnetic resonance imaging may help. Potential preventative strategies such as systematic swallowing assessment in non-stroke patients, and interventions such as improving oral hygiene need further, robust randomised controlled trials. Antibiotics are likely to continue to be the mainstay of treatment, and new antibiotics such as ceftobiprole are likely to have a role in treating hospital acquired pneumonia. Given the spread of antimicrobial resistance, alternative treatment strategies including bacteriophages, peptides and antibodies are under investigation. Reducing the incidence of hospital acquired pneumonia could decrease length of hospital stay, reduce inappropriate antibiotic use, and both improve functional outcomes and mortality in our increasingly aged population.

Antibiotic treatment of biofilm infections

Bacterial biofilms are associated with a wide range of infections, from those related to exogenous devices, such as catheters or prosthetic joints, to chronic tissue infections such as those occurring in the lungs of cystic fibrosis patients. Biofilms are recalcitrant to antibiotic treatment due to multiple tolerance mechanisms (phenotypic resistance). This causes persistence of biofilm infections in spite of antibiotic exposure which predisposes to antibiotic resistance development (genetic resistance). Understanding the interplay between phenotypic and genetic resistance mechanisms acting on biofilms, as well as appreciating the diversity of environmental conditions of biofilm infections which influence the effect of antibiotics are required in order to optimize the antibiotic treatment of biofilm infections. Here, we review the current knowledge on phenotypic and genetic resistance in biofilms and describe the potential strategies for the antibiotic treatment of biofilm infections. Of note is the optimization of PK/PD parameters in biofilms, high-dose topical treatments, combined and sequential/alternate therapies or the use antibiotic adjuvants.

Can we improve clinical outcomes in patients with pneumonia treated with antibiotics in the intensive care unit?

INTRODUCTION

Pneumonia in the intensive care unit (ICU) is associated with high morbidity, mortality and healthcare costs. However, treatment outcomes with conventional intravenous (IV) antibiotics remain suboptimal, and there is an urgent need for improved therapy options.

AREAS COVERED

We review how clinical outcomes in patients with pneumonia treated in the ICU could be improved; we discuss the importance of choosing appropriate outcome measures in clinical trials, highlight the current suboptimal outcomes in patients with pneumonia, and outline potential solutions. We have included key studies and papers based on our clinical expertise, therefore a systematic literature review was not conducted. Expert commentary: Reasons for poor outcomes in patients with nosocomial pneumonia in the ICU include inappropriate initial therapy, increasing bacterial resistance and the complexities of IV dosing in critically ill patients. Robust clinical trial endpoints are needed to enable an accurate assessment of the success of new treatment approaches, but progress in this field has been slow. In addition, only very few new antimicrobials are currently in development for nosocomial pneumonia; two potential alternative solutions to improve outcomes could therefore include the optimization of pharmacokinetic/pharmacodynamics (PK/PD) and dosing of existing therapies, and the refinement of antimicrobial delivery by inhalation.