Tobramycin Systemic Absorption in Lung Transplant Recipients Treated With Inhaled Tobramycin: A Cohort Study

Inhaled tobramycin treatment has been associated with nephrotoxicity in some case reports, but limited data are available about serum levels and its possible systemic absorption in lung transplant recipients (LTR). We conducted a single-center, observational and retrospective study of all adult (>18 years old) LTR treated with inhaled tobramycin for at least 3 days between June 2019 and February 2022. Trough serum levels were collected and >2 μg/mL was considered a high drug level. The primary outcome assessed the presence of detectable trough levels, while the secondary outcome focused on the occurrence of acute kidney injury (AKI) in individuals with detectable trough levels. Thirty-four patients, with a median age of 60 years, were enrolled. The primary indications for treatment were donor bronchial aspirate bacterial isolation (18 patients) and tracheobronchitis (15 patients). In total, 28 patients (82%) exhibited detectable serum levels, with 9 (26%) presenting high levels (>2 μg/mL). Furthermore, 9 patients (26%) developed acute kidney injury during the treatment course. Median trough tobramycin levels were significantly elevated in invasively mechanically ventilated patients compared to non-ventilated individuals (2.5 μg/mL vs. 0.48 μg/mL) (p < 0.001). Inhaled tobramycin administration in LTRs, particularly in those requiring invasive mechanical ventilation, may result in substantial systemic absorption.

The Efficacy and Safety of Intravenous Colistin Plus Aerosolized Colistin Versus Intravenous Colistin Alone in Critically Ill Trauma Patients With Multi-Drug Resistant Gram-Negative Bacilli Infection

BACKGROUND AND AIM

Gram-negative bacteria (GNB) with potential multiple drug resistance (MDR) have emerged as a major group of organisms causing ventilator-associated pneumonia (VAP). Higher concentrations are deposited directly in the lungs when antibiotics are given via inhalation, minimizing systemic side effects. This study aims to compare the efficacy and safety of intravenous plus aerosolized colistin versus intravenous (IV) colistin alone in critically ill trauma patients who reported MDR-GNB infection on endotracheal aspirate culture.

METHODS

A hundred patients were recruited in the Intensive Care Unit, Trauma Centre, Institute of Medical Sciences, Banaras Hindu University, Varanasi, and randomly assigned to the control (n=50) group, which received IV colistin plus aerosolized colistin and the intervention group (n = 50), which received IV colistin alone. Changes in total leucocyte count (TLC), renal function test (RFT), endotracheal aspirate culture, 24-hour urine output, length of ICU stay, and 28-day ICU mortality were investigated.

RESULTS

Patients receiving intravenous plus nebulized colistin therapy had a better outcome compared to IV colistin alone in terms of faster eradication of MDR-GNB infection. A rise in serum urea and creatinine levels was seen in both groups, which were significantly higher, along with a decrease in urine output in the group receiving intravenous colistin alone. No significant difference was observed in serum sodium and potassium levels in the RFT protocol, length of ICU stay, or 28-day ICU mortality.

CONCLUSION

Intravenous nebulized colistin could be considered a better alternative therapy for VAP caused by multi-drug-resistant Gram-negative bacteria in the ICU in terms of faster microbiological cure and lesser nephrotoxicity.

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.

Inhalational Gentamicin Treatment Is Effective Against Pneumonic Plague in a Mouse Model

Pneumonic plague is an infectious disease characterized by rapid and fulminant development of acute pneumonia and septicemia that results in death within days of exposure. The causative agent of pneumonic plague, Yersinia pestis (Y. pestis), is a Tier-1 bio-threat agent. Parenteral antibiotic treatment is effective when given within a narrow therapeutic window after symptom onset. However, the non-specific “flu-like” symptoms often lead to delayed diagnosis and therapy. In this study, we evaluated inhalational gentamicin therapy in an infected mouse model as a means to improve antibiotic treatment efficacy. Inhalation is an attractive route for treating lung infections. The advantages include directly dosing the main infection site, the relative accessibility for administration and the lack of extensive enzymatic drug degradation machinery. In this study, we show that inhalational gentamicin treatment administered 24 h post-infection, prior to the appearance of symptoms, protected against lethal intranasal challenge with the fully virulent Y. pestis Kimberley53 strain (Kim53). Similarly, a high survival rate was demonstrated in mice treated by inhalation with another aminoglycoside, tobramycin, for which an FDA-approved inhaled formulation is clinically available for cystic fibrosis patients. Inhalational treatment with gentamicin 48 h post-infection (to symptomatic mice) was also successful against a Y. pestis challenge dose of 10 i.n.LD₅₀. Whole-body imaging using IVIS technology demonstrated that adding inhalational gentamicin to parenteral therapy accelerated the clearance of Y. pestis from the lungs of infected animals. This may reduce disease severity and the risk of secondary infections. In conclusion, our data suggest that inhalational therapy with aerosolized gentamicin may be an effective prophylactic treatment against pneumonic plague. We also demonstrate the benefit of combining this treatment with a conventional parenteral treatment against this rapidly progressing infectious disease. We suggest the inhalational administration route as a clinically relevant treatment modality against pneumonic plague and other respiratory bacterial pathogens.

Nebulized Versus IV Amikacin as Adjunctive Antibiotic for Hospital and Ventilator-Acquired Pneumonia Postcardiac Surgeries: A Randomized Controlled Trial

OBJECTIVE

Nebulized antibiotics offer high efficacy due to significant local concentrations and safety with minimal blood levels. This study evaluates the efficacy and nephrotoxicity of nebulized versus IV amikacin in postcardiothoracic surgical patients with nosocomial pneumonia caused by multidrug-resistant Gram- negative bacilli.

DESIGN

Prospective, randomized, controlled study on surgical patients divided into two groups.

SETTING

Postcardiac surgery ICU.

INTERVENTIONS

The first gtroup was administered IV amikacin 20 mg/kg once daily. The second group was prescribed amikacin nebulizer 400 mg twice daily. Both groups were co-administered IV piperacillin/tazobactam empirically.

PATIENTS

Recruited patients were diagnosed by either hospital-acquired pneumonia or ventilator-associated pneumonia where 56 (42.1%) patients were diagnosed with hospital-acquired pneumonia, 51 (38.34%) patients were diagnosed with early ventilator-associated pneumonia, and 26 (19.54%) patients with late ventilator-associated pneumonia.

MEASUREMENTS AND MAIN RESULTS

Clinical cure in both groups assessed on day 7 of treatment was the primary outcome. Efficacy was additionally evaluated through assessing the length of hospital stay, ICU stay, days on amikacin, days on mechanical ventilator, mechanical ventilator-free days, days to reach clinical cure, and mortality rate. Lower nephrotoxicity in the nebulized group was observed through significant preservation of kidney function (p < 0.001). Although both groups were comparable regarding length of hospital stay, nebulizer group showed shorter ICU stay (p = 0.010), lower number of days to reach complete clinical cure (p = 0.001), fewer days on mechanical ventilator (p = 0.035), and fewer days on amikacin treatment (p = 0.022).

CONCLUSION

Nebulized amikacin showed better clinical cure rates, less ICU stay, and fewer days to reach complete recovery compared to IV amikacin for surgical patients with nosocomial pneumonia. It is also a less nephrotoxic option associated with less deterioration in kidney function.

An Update on Aerosolized Antibiotics for Treating Hospital-Acquired and Ventilator-Associated Pneumonia in Adults

OBJECTIVE

A significant percentage of patients with hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) have poor outcomes with intravenous antibiotics. It is not clear if adding aerosolized antibiotics improves treatment. This review is an update on using aerosolized antibiotics for treating HAP/VAP in adults.

DATA SOURCES

PubMed search using the terms "aerosolized antibiotics pneumonia," "nebulized antibiotics pneumonia," and "inhaled antibiotics pneumonia." Reference lists from identified articles were also searched.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies of aerosolized antibiotics for treating HAP/VAP in adults from July 2010 to March 2017. This article updates a previous review on this topic written in mid-2010.

DATA SYNTHESIS

The size and quality of studies have improved dramatically in the recent time period compared to previous studies. However, there still are not large randomized controlled trials available. Colistin and aminoglycosides were the most commonly studied agents, and the most common pathogens were Pseudomonas and Acinetobacter. The clinical efficacy of adding aerosolized antibiotics was mixed. Approximately half of the studies showed better outcomes, and none showed worse outcomes. Aerosolized antibiotics appear to be relatively safe, though pulmonary adverse events can occur. Attention to proper administration technique in mechanically ventilated patients is required, including the use of vibrating plate nebulizers.

CONCLUSIONS

Adding aerosolized antibiotics to intravenous antibiotics may improve the outcomes of adult patients with HAP/VAP in some settings. It seems reasonable to add aerosolized antibiotics in patients with multidrug-resistant organisms or who appear to be failing therapy. Clinicians should pay attention to potential adverse events and proper administration technique.

Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate's phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.

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.

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.

Characteristics of an ideal nebulized antibiotic for the treatment of pneumonia in the intubated patient

Gram-negative pneumonia in patients who are intubated and mechanically ventilated is associated with increased morbidity and mortality as well as higher healthcare costs compared with those who do not have the disease. Intravenous antibiotics are currently the standard of care for pneumonia; however, increasing rates of multidrug resistance and limited penetration of some classes of antimicrobials into the lungs reduce the effectiveness of this treatment option, and current clinical cure rates are variable, while recurrence rates remain high. Inhaled antibiotics may have the potential to improve outcomes in this patient population, but their use is currently restricted by a lack of specifically formulated solutions for inhalation and a limited number of devices designed for the nebulization of antibiotics. In this article, we review the challenges clinicians face in the treatment of pneumonia and discuss the characteristics that would constitute an ideal inhaled drug/device combination. We also review inhaled antibiotic options currently in development for the treatment of pneumonia in patients who are intubated and mechanically ventilated.

Treatment of Gram-negative pneumonia in the critical care setting: is the beta-lactam antibiotic backbone broken beyond repair?

Beta-lactam antibiotics form the backbone of treatment for Gram-negative pneumonia in mechanically ventilated patients in the intensive care unit. However, this beta-lactam antibiotic backbone is increasingly under pressure from emerging resistance across all geographical regions, and health-care professionals in many countries are rapidly running out of effective treatment options. Even in regions that currently have only low levels of resistance, the effects of globalization are likely to increase local pressures on the beta-lactam antibiotic backbone in the near future. Therefore, clinicians are increasingly faced with a difficult balancing act: the need to prescribe adequate and appropriate antibiotic therapy while reducing the emergence of resistance and the overuse of antibiotics. In this review, we explore the burden of Gram-negative pneumonia in the critical care setting and the pressure that antibiotic resistance places on current empiric therapy regimens (and the beta-lactam antibiotic backbone) in this patient population. New treatment approaches, such as systemic and inhaled antibiotic alternatives, are on the horizon and are likely to help tackle the rising levels of beta-lactam antibiotic resistance. In the meantime, it is imperative that the beta-lactam antibiotic backbone of currently available antibiotics be supported through stringent antibiotic stewardship programs.

Intravenous combined with aerosolised polymyxin versus intravenous polymyxin alone in the treatment of pneumonia caused by multidrug-resistant pathogens: a systematic review and meta-analysis

Colistin has been used to treat nosocomial pneumonia (NP) caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) via different administration routes. Whether patients may benefit from aerosolised colistin as adjunctive treatment was contradictory. We aimed to clarify the safety and efficacy of administering aerosolised and intravenous (IV-AS) colistin versus intravenous (IV) colistin alone in patients with NP caused by MDR-GNB. Two reviewers independently evaluated and extracted data from PubMed, EMBASE and Cochrane databases. Primary outcomes were clinical response rate, all-cause mortality (ICU or hospital), microbiological eradication and nephrotoxicity. Pooled odds ratios (ORs) were calculated and significance was determined by the Z test. Nine eligible studies involving 672 participants were included. The overall clinical response rate (improvement and cure) was significantly higher in the IV-AS group than that in the IV group [OR=1.81, 95% confidence interval (CI) 1.30-2.53; P=0.0005]. Patients treated with IV-AS colistin showed a higher rate of pathogen eradication (OR=1.66, 95% CI 1.11-2.49; P=0.01) and lower all-cause mortality compared with IV colistin (OR=0.69, 95% CI 0.50-0.95; P=0.02). Nephrotoxicity did not differ significantly between IV-AS and IV groups (five studies; 383 patients) (OR=1.11, 95% CI 0.69-1.80; P=0.67). These data indicate that IV-AS colistin has additional benefits compared with IV colistin alone. Clinicians should be encouraged to give combined administration routes in critically ill patients with NP caused by MDR-GNB.

A randomized double-blind placebo-controlled dose-escalation phase 1 study of aerosolized amikacin and fosfomycin delivered via the PARI investigational eFlow® inline nebulizer system in mechanically ventilated patients

BACKGROUND

This clinical trial evaluated the pharmacokinetics and safety/tolerability of amikacin/fosfomycin solution using a vibrating plate nebulizer, in mechanically ventilated patients with ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP).

METHODS

Nine adult patients were consented to receive three escalating doses of a combination of 50 mg/mL amikacin and 20 mg/mL fosfomycin; doses were separated by 24±2 hr. On day 3, patients received two blinded, randomized treatments (amikacin/fosfomycin and volume-matched placebo), separated by 2 hr. All treatments were administered with a single-patient, multitreatment nebulizer (Investigational eFlow(®) Inline Nebulizer System; PARI Pharma GmbH, positioned in the inspiratory limb tubing between the ventilator and the patient. The nebulizer remained in-line until all treatments had been delivered. Concentrations of amikacin and fosfomycin were measured in tracheal aspirate and plasma samples obtained during the 24 hr after each dose.

RESULTS

Fifteen minutes after dosing with the 300/120 mg amikacin/fosfomycin combination, tracheal aspirate amikacin concentrations±SD were 12,390±3,986 μg/g, and fosfomycin concentrations were 6,174±2,548 μg/g (n=6). Airway clearance was rapid. Plasma concentrations were subtherapeutic; the highest observed amikacin plasma concentration was 1.4 μg/mL, and the highest observed fosfomycin plasma concentration was 0.8 μg/mL. Administration time was approximately 2 min/mL. No adverse effects on respiratory rate, peak airway pressures, or oxygenation were observed during or following drug or placebo administration.

CONCLUSIONS

High tracheal aspirate concentrations of amikacin and fosfomycin were achieved in mechanically ventilated patients with VAT or VAP after aerosolized administration with an inline nebulizer system. Airway clearance was rapid. No adverse respiratory effects were noted during or following drug administration.

Nebulizers for drug delivery to the lungs

INTRODUCTION

Nebulizers are the oldest modern method of delivering aerosols to the lungs for the purpose of respiratory drug delivery. While use of nebulizers remains widespread in the hospital and home setting, certain newer nebulization technologies have enabled more portable use. Varied fundamental processes of droplet formation and breakup are used in modern nebulizers, and these processes impact device performance and suitability for nebulization of various formulations.

AREAS COVERED

This review first describes basic aspects of nebulization technologies, including jet nebulizers, various high-frequency vibration techniques, and the use of colliding liquid jets. Nebulizer use in hospital and home settings is discussed next. Complications in aerosol droplet size measurement owing to the changes in nebulized droplet diameters due to evaporation or condensation are discussed, as is nebulization during mechanical ventilation.

EXPERT OPINION

While the limelight may often appear to be focused on other delivery devices, such as pressurized metered dose and dry powder inhalers, the ease of formulating many drugs in water and delivering them as aqueous aerosols ensures that nebulizers will remain as a viable and relevant method of respiratory drug delivery. This is particularly true given recent improvements in nebulizer droplet production technology.

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.

Colistin for the treatment of ventilator-associated pneumonia caused by multidrug-resistant Gram-negative bacteria: a systematic review and meta-analysis

Ventilator-associated pneumonia (VAP) caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) has emerged as an important and intractable clinical problem. This review assessed the efficacy and safety of colistin for treatment of MDR GNB VAP. PubMed and Embase were searched for controlled studies of colistin for treatment of MDR GNB VAP. The Mantel-Haenszel random-effects model was used to pool odds ratios (ORs) with 95% confidence intervals (CIs). The primary outcome was clinical cure; secondary outcomes were microbiological eradication, ICU mortality, hospital mortality, length of ICU stay and nephrotoxicity. Fourteen controlled studies involving 1167 patients were identified, including six reporting colistin versus β-lactam antibiotics, three reporting aerosolised (AS) plus intravenous (IV) colistin versus IV colistin alone and five reporting colistin combined therapy versus colistin monotherapy. The clinical cure rate of colistin was comparable with that of β-lactam antibiotics (OR=1.00, 95% CI 0.68-1.47). Compared with IV colistin alone, AS plus IV colistin exhibited a better clinical cure (OR=2.12, 95% CI 1.40-3.20). Compared with colistin monotherapy, colistin combined therapy did not appear to provide a better clinical cure (OR=1.38, 95% CI 0.81-2.33). There was no significant difference in nephrotoxicity and other secondary outcomes between the treatment groups. Colistin appears as effective and safe as β-lactam antibiotics for the treatment of MDR GNB VAP. AS colistin may be a beneficial adjunct to IV colistin in the management of MDR GNB VAP. Colistin combined therapy does not appear to provide better outcomes compared with colistin monotherapy.

Aerosolized antibiotics: do they add to the treatment of pneumonia?

Purpose of review

The increasing rate of ventilator-associated pneumonia (VAP) caused by multidrug-resistant pathogens warrants the development of new treatment strategies. Carefully engineered delivery systems are undergoing evaluation to test the hypothesis that aerosolized administration of antibiotics will provide high local concentrations and fast clearance, which in turn may improve efficacy and decrease the risk of microbial resistance.

Recent findings

Recent studies indicate that aerosolized delivery systems for specially formulated antibiotics yield high local concentrations with rapid clearance and low systemic exposure. Preliminary clinical studies reveal that aerosolized delivery of antibiotics is well tolerated and active, when combined with intravenous antibiotics. No single aerosolized antibiotic is likely to provide broad-spectrum activity against both Gram-negative and Gram-positive bacteria.

Summary

Large multicenter trials are needed to determine whether preliminary findings will translate to improved clinical activity and decreased microbial resistance in VAP patients, and to optimize the use of aerosolized antibiotics.

Effect of aerosolized colistin as adjunctive treatment on the outcomes of microbiologically documented ventilator-associated pneumonia caused by colistin-only susceptible gram-negative bacteria

BACKGROUND

The increasing frequency of ventilator-associated pneumonia (VAP) caused by colistin-only susceptible (COS) gram-negative bacteria (GNB) is of great concern. Adjunctive aerosolized (AS) colistin can reportedly increase alveolar levels of the drug without increasing systemic toxicity. Good clinical results have been obtained in patients with cystic fibrosis, but conflicting data have been reported in patients with VAP.

METHODS

We conducted a retrospective, 1:1 matched case-control study to evaluate the efficacy and safety of AS plus IV colistin vs IV colistin alone in 208 patients in the ICU with VAP caused by COS Acinetobacter baumannii, Pseudomonas aeruginosa, or Klebsiella pneumoniae.

RESULTS

Compared with the IV colistin cohort, the AS-IV colistin cohort had a higher clinical cure rate (69.2% vs 54.8%, P = .03) and required fewer days of mechanical ventilation after VAP onset (8 days vs 12 days, P = .001). In the 166 patients with posttreatment cultures, eradication of the causative organism was also more common in the AS-IV colistin group (63.4% vs 50%, P = .08). No between-cohort differences were observed in all-cause ICU mortality, length of ICU stay after VAP onset, or rates of acute kidney injury (AKI) during colistin therapy. Independent predictors of clinical cure were trauma-related ICU admission (P = .01) and combined AS-IV colistin therapy (P = .009). Higher mean Simplified Acute Physiology Score II (P = .002) and Sequential Organ Failure Assessment (P = .05) scores, septic shock (P &lt; .001), and AKI onset during colistin treatment (P = .04) were independently associated with clinical failure.

CONCLUSIONS

Our results suggest that AS colistin might be a beneficial adjunct to IV colistin in the management of VAP caused by COS GNB.

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.

New insights in the production of aerosol antibiotics. Evaluation of the optimal aerosol production system for ampicillin-sulbactam, meropenem, ceftazidime, cefepime and piperacillin-tazobactam

BACKGROUND

Several aerosol antibiotics are on the market and several others are currently being evaluated. Aim of the study was to evaluate the aerosol droplet size of five different antibiotics for future evaluation as an aerosol administration.

MATERIALS AND METHODS

The nebulizers Sunmist(®), Maxineb(®) and Invacare(®) were used in combination with four different "small <6 ml" residual cups and two "large <10 ml" with different loadings 2-4-6-8 ml (8 ml only for large residual cups) with five different antibiotic drugs (ampicilln-sulbactam, meropenem, ceftazidime, cefepime and piperacillin-tazobactam). The Mastersizer 2000 (Malvern) was used to evaluate the produced droplet size from each combination

RESULTS

Significant effect on the droplet size produced the different antibiotic (F=96.657, p<0.001) and the residual cup design (F=68.535, p<0.001) but not the different loading amount (p=0.127) and the nebulizer (p=0.715). Interactions effects were found significant only between antibiotic and residual cup (F=16.736, p<0.001). No second order interactions were found statistically significant.

CONCLUSION

Our results firstly indicate us indirectly that the chemical formulation of the drug is the main factor affecting the produced droplet size and secondly but closely the residual cup design.