Inhaled colistin as adjunctive therapy to intravenous colistin for the treatment of microbiologically documented ventilator-associated pneumonia: a comparative cohort study

Co-Administration of High-Dose Nebulized Colistin for Acinetobacter baumannii Bacteremic Ventilator-Associated Pneumonia: Impact on Outcomes

Acinetobacter baumannii (A. baumannii) is a difficult-to-treat (DTR) pathogen that causes ventilator-associated pneumonia (VAP) associated with high mortality. To improve the outcome of DTR A. Baumannii VAP, nebulized colistin (NC) was introduced with promising but conflicting results on mortality in earlier studies. Currently, NC is used at a much higher daily dose compared to the past. Nevertheless, there is little evidence on the effect of high-dose NC on the outcomes of A. baumannii VAPs, especially in the current era where the percentage of colistin-resistant A. baumannii strains is rising. We conducted a retrospective study comparing bacteremic A. baumannii VAP patients who were treated with and without NC co-administration and were admitted in the Intensive Care Unit of University Hospital of Ioannina from March 2020 to August 2023. Overall, 59 patients (21 and 38 with and without NC coadministration, respectively) were included. Both 28-day and 7-day mortalities were significantly lower in the patient group treated with NC (52.4% vs. 78.9%, p 0.034 and 9.5% vs. 47.4%, p 0.003, respectively). Patients treated with NC had a higher percentage of sepsis resolution by day 7 (38.1% vs. 13.5%, p 0.023) and were more likely to be off vasopressors by day 7 (28.6% vs. 8.1%, p 0.039). The addition of NC in the treatment regime of A. baumannii VAP decreased mortality.

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.

A prospective phase IIA multicenter double-blinded randomized placebo-controlled clinical trial evaluating the efficacy and safety of inhaled Tobramycin in patients with ventilator-associated pneumonia (iToVAP)

OBJECTIVE

Treatment of ventilated pneumonia is often unsuccessful, even when patients are treated according to current guidelines. Therefore, we aimed to investigate the efficacy of the adjunctive inhaled Tobramycin in patients with pneumonia caused by Gram-negative pathogens in addition to the standard systemic treatment.

DESIGN

Prospective, multicenter, double-blinded, randomized, placebo-controlled clinical trial.

SETTING

26 patients in medical and surgical ICUs.

PATIENTS

Patients with ventilator-associated pneumonia caused by Gram-negative pathogens.

MEASUREMENT AND MAIN RESULTS

Fourteen patients were assigned to the Tobramycin Inhal group and 12 patients to the control group. The microbiological eradication of the Gram-negative pathogens was significantly higher in the intervention group than in the control group (p < 0.001). The probability of eradication was 100% in the intervention group [95% Confidence Interval: 0.78-1.0] and 25% in the control group [95% CI: 0.09-0.53]. The increased eradication frequency was not associated with increased patient survival.

CONCLUSION

Inhaled aerosolized Tobramycin demonstrated clinically meaningful efficacy in patients with Gram-negative ventilator-associated pneumonia. The probability of eradication in the intervention group was 100%. However, the successful eradication was not associated with a reduction in systemic anti-infective therapy, a shorter ICU stay, or even a survival benefit. In the presence of multidrug-resistant Gram-negative pathogens that are sensitive only to colistin and/or aminoglycosides, supplemental inhaled therapy with nebulizers suitable for this purpose should be considered in addition to systemic antibiotic therapy.

Nebulized colistin as the adjunctive treatment for ventilator-associated pneumonia: A systematic review and meta-analysis

PURPOSE

Nebulized colistin (NC) is a potential therapy for ventilator-associated pneumonia (VAP); however, the clinical efficacy and safety of NC remain unclear. This study investigated whether NC is an effective therapy for patients with VAP.

MATERIALS AND METHODS

We performed a search in Web of Science, PubMed, Embase, and the Cochrane Library to retrieve randomized controlled trials (RCTs) and observational studies published at any time until February 6, 2023. The primary outcome was clinical response. Secondary outcomes included microbiological eradication, overall mortality, length of mechanical ventilation (MV), length of intensive care unit stay (ICU-LOS), nephrotoxicity, neurotoxicity, and bronchospasm.

RESULTS

Seven observational studies and three RCTs were included. Despite exhibiting a higher microbiological eradication rate (OR,2.21; 95%CI, 1.25-3.92) and the same nephrotoxicity risk (OR,0.86; 95%CI, 0.60-1.23), NC was not significantly different in clinical response (OR,1.39; 95%CI, 0.87-2.20), overall mortality (OR,0.74; 95%CI, 0.50-1.12), MV length (mean difference (MD),-2.5; 95%CI, -5.20-0.19), and the ICU-LOS (MD,-1.91; 95%CI, -6.66-2.84) than by the intravenous antibiotic. Besides, the risk of bronchospasm raised significantly (OR, 5.19; 95%CI, 1.05-25.52) among NC.

CONCLUSION

NC was associated with better microbiological outcomes but did not result in any remarkable changes in the prognosis of patients with VAP.

Efficacy and safety of intravenous combined with aerosolised polymyxin versus intravenous polymyxin alone in the treatment of multidrug-resistant gram-negative bacterial pneumonia: A systematic review and meta-analysis

Background

Previous studies have questioned the efficacy and safety of intravenous combined with aerosolised (IV + AS) polymyxin versus intravenous (IV) polymyxin alone in the treatment of patients with multidrug-resistant gram-negative bacterial (MDR-GNB) pneumonia. Therefore, we conducted a meta-analysis to evaluate the efficacy and safety of IV + AS polymyxin in the treatment of MDR-GNB pneumonia.

Methods

We identified all relevant studies by searching the PubMed, EMBASE and Cochrane library databases from their inception to May 31, 2022. All included studies were evaluated using the Newcastle Ottawa scale (NOS) checklist. The summary relative risk (RR) and 95% confidence interval (CI) were used to determine the outcome differences between the IV + AS and the IV groups. Subgroup analysis was performed based on population, polymyxin dose and kinds of polymyxin.

Results

A total of 16 studies were included in the meta-analysis. The IV + AS group had lower mortality (RR = 0.86, 95% CI: 0.77-0.97, P = 0.01) than the IV group. Subgroup analysis revealed that IV + AS polymyxin could reduce mortality only when used in low doses. Simultaneously, the IV + AS group outperformed the IV group in terms of clinical response rate, clinical cure rate, microbiological eradication and duration of mechanical ventilation. The duration of hospitalisation and the incidence of nephrotoxicity did not differ significantly between the two groups.

Conclusions

IV + AS polymyxin is beneficial in the treatment of MDR-GNB pneumonia. It could lower patient mortality and improve clinical and microbial outcomes without increasing the risk of nephrotoxicity. However, retrospective analysis in the majority of studies and heterogeneity between studies implies that our findings must be interpreted carefully.

How to Use Nebulized Antibiotics in Severe Respiratory Infections

Difficult-to-treat pulmonary infections caused by multidrug-resistant (MDR) pathogens are of great concern because their incidence continues to increase worldwide and they are associated with high morbidity and mortality. Nebulized antibiotics are increasingly being used in this context. The advantages of the administration of a nebulized antibiotic in respiratory tract infections due to MDR include the potential to deliver higher drug concentrations to the site of infection, thus minimizing the systemic adverse effects observed with the use of parenteral or oral antibiotic agents. However, there is an inconsistency between the large amount of experimental evidence supporting the administration of nebulized antibiotics and the paucity of clinical studies confirming the efficacy and safety of these drugs. In this narrative review, we describe the current evidence on the use of nebulized antibiotics for the treatment of severe respiratory infections.

Ventilator-Associated Pneumonia Caused by Multidrug-Resistant Gram-Negative Bacteria in Vietnam: Antibiotic Resistance, Treatment Outcomes, and Colistin-Associated Adverse Effects

Background: Ventilator-associated pneumonia (VAP) caused by multidrug-resistant (MDR) gram-negative bacteria (GNB) presents a serious clinical scenario, and there is disagreement regarding the role of colistin in treatment. This study aimed to characterize the antibiotic resistance of MDR GNB and evaluate the treatment outcomes and side effects of colistin in VAP patients caused by MDR GNB, particularly in Vietnam. Methods: A prospective cohort research was undertaken. We enrolled 136 intubated patients diagnosed with VAP according to the Centers for Disease Control and Prevention (CDC) 2019. Sixty-six individuals with an isolated gram-negative bacterium (Acinetobacter baumannii, Klebsiella pneumoniae, or Pseudomonas aeruginosa) satisfied the European Centre for Disease Prevention and Control (ECDC)’s criteria for multi-antibiotic resistance. Results: GNB resistance was categorized as 10.6% MDR, 63.6% XDR, and 25.8% PDR. GNB were resistant to β-lactams 80–100%, aminoglycosides 50–86.7%, fluoroquinolones 100% and colistin 2.8–20%. The 28-day mortality rate was 54.5%, and acute kidney injury occurred at 12.1%. There was no statistically significant difference in mortality rate between groups receiving regimens with or without colistin (58.3% and 73.3%, respectively; OR = 1.964; 95%CI 0.483–7.989). Neither was there a statistically significant difference in acute renal damage rate between groups receiving regimens with or without colistin (14.3% and 9.7%, respectively; OR = 1.556; 95%CI 0.34–7.121). Conclusions: GNB had a high rate of antibiotic resistance to most antibiotics. The addition of colistin to the medication did not show significant differences in renal toxicity or mortality, while colistin resistance was relatively low; larger studies need to be conducted.

Recommendations and guidelines for the treatment of infections due to multidrug resistant organisms

Antimicrobial drug resistance is one of the major threats to global health. It has made common infections increasingly difficult or impossible to treat, and leads to higher medical costs, prolonged hospital stays and increased mortality. Infection rates due to multidrug-resistant organisms (MDRO) are increasing globally. Active agents against MDRO are limited despite an increased in the availability of novel antibiotics in recent years. This guideline aims to assist clinicians in the management of infections due to MDRO. The 2019 Guidelines Recommendations for Evidence-based Antimicrobial agents use in Taiwan (GREAT) working group, comprising of infectious disease specialists from 14 medical centers in Taiwan, reviewed current evidences and drafted recommendations for the treatment of infections due to MDRO. A nationwide expert panel reviewed the recommendations during a consensus meeting in Aug 2020, and the guideline was endorsed by the Infectious Diseases Society of Taiwan (IDST). This guideline includes recommendations for selecting antimicrobial therapy for infections caused by carbapenem-resistant Acinetobacter baumannii, carbapenem-resistant Pseudomonas aeruginosa, carbapenem-resistant Enterobacterales, and vancomycin-resistant Enterococcus. The guideline takes into consideration the local epidemiology, and includes antimicrobial agents that may not yet be available in Taiwan. It is intended to serve as a clinical guide and not to supersede the clinical judgment of physicians in the management of individual patients.

Infectious Diseases Society of America 2022 Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa)

BACKGROUND

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant infections. The initial guidance document on infections caused by extended-spectrum β-lactamase producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa) was published on 17 September 2020. Over the past year, there have been a number of important publications furthering our understanding of the management of ESBL-E, CRE, and DTR-P. aeruginosa infections, prompting a rereview of the literature and this updated guidance document.

METHODS

A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections reviewed, updated, and expanded previously developed questions and recommendations about the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Because of differences in the epidemiology of resistance and availability of specific anti-infectives internationally, this document focuses on the treatment of infections in the United States.

RESULTS

Preferred and alternative treatment recommendations are provided with accompanying rationales, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, duration of therapy, and other management considerations are also discussed briefly. Recommendations apply for both adult and pediatric populations.

CONCLUSIONS

The field of antimicrobial resistance is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of antimicrobial-resistant infections. This document is current as of 24 October 2021. The most current versions of IDSA documents, including dates of publication, are available at www.idsociety.org/practice-guideline/amr-guidance/.

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.

Infectious Diseases Society of America Guidance on the Treatment of AmpC β-lactamase-Producing Enterobacterales, Carbapenem-Resistant Acinetobacter baumannii, and Stenotrophomonas maltophilia Infections

BACKGROUND

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant infections. A previous guidance document focused on infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa). Here, guidance is provided for treating AmpC β-lactamase-producing Enterobacterales (AmpC-E), carbapenem-resistant Acinetobacter baumannii (CRAB), and Stenotrophomonas maltophilia infections.

METHODS

A panel of six infectious diseases specialists with expertise in managing antimicrobial-resistant infections formulated questions about the treatment of AmpC-E, CRAB, and S. maltophilia infections. Answers are presented as suggestions and corresponding rationales. In contrast to guidance in the previous document, published data on optimal treatment of AmpC-E, CRAB, and S. maltophilia infections are limited. As such, guidance in this document is provided as "suggested approaches" based on clinical experience, expert opinion, and a review of the available literature. Because of differences in the epidemiology of resistance and availability of specific anti-infectives internationally, this document focuses on the treatment of infections in the United States.

RESULTS

Preferred and alternative treatment suggestions are provided, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, duration of therapy, and other management considerations are also discussed briefly. Suggestions apply for both adult and pediatric populations.

CONCLUSIONS

The field of antimicrobial resistance is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of antimicrobial-resistant infections. This document is current as of September 17, 2021 and will be updated annually. The most current versions of IDSA documents, including dates of publication, are available at www.idsociety.org/practice-guideline/amr-guidance-2.0/.

Pulmonary biofilm-based chronic infections and inhaled treatment strategies

Certain pulmonary diseases, such as cystic fibrosis (CF), non-CF bronchiectasis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia, are usually accompanied by respiratory tract infections due to the physiological alteration of the lung immunological defenses. Recurrent infections may lead to chronic infection through the formation of biofilms. Chronic biofilm-based infections are challenging to treat using antimicrobial agents. Therefore, effective ways to eradicate biofilms and thus relieve respiratory tract infection require the development of efficacious agents for biofilm destruction, the design of delivery carriers with biofilm-targeting and/or penetrating abilities for these agents, and the direct delivery of them into the lung. This review provides an in-depth description of biofilm-based infections caused by pulmonary diseases and focuses on current existing agents that are administered by inhalation into the lung to treat biofilm, which include i) inhalable antimicrobial agents and their combinations, ii) non-antimicrobial adjuvants such as matrix-targeting enzymes, mannitol, glutathione, cyclosporin A, and iii) liposomal formulations of anti-biofilm agents. Finally, novel agents that have shown promise against pulmonary biofilms as well as traditional and new devices for pulmonary delivery of anti-biofilm agents into the lung are also discussed.

Nebulized Colistin in Ventilator-Associated Pneumonia and Tracheobronchitis: Historical Background, Pharmacokinetics and Perspectives

Clinical evidence suggests that nebulized colistimethate sodium (CMS) has benefits for treating lower respiratory tract infections caused by multidrug-resistant Gram-negative bacteria (GNB). Colistin is positively charged, while CMS is negatively charged, and both have a high molecular mass and are hydrophilic. These physico-chemical characteristics impair crossing of the alveolo-capillary membrane but enable the disruption of the bacterial wall of GNB and the aggregation of the circulating lipopolysaccharide. Intravenous CMS is rapidly cleared by glomerular filtration and tubular excretion, and 20-25% is spontaneously hydrolyzed to colistin. Urine colistin is substantially reabsorbed by tubular cells and eliminated by biliary excretion. Colistin is a concentration-dependent antibiotic with post-antibiotic and inoculum effects. As CMS conversion to colistin is slower than its renal clearance, intravenous administration can lead to low plasma and lung colistin concentrations that risk treatment failure. Following nebulization of high doses, colistin (200,000 international units/24h) lung tissue concentrations are > five times minimum inhibitory concentration (MIC) of GNB in regions with multiple foci of bronchopneumonia and in the range of MIC breakpoints in regions with confluent pneumonia. Future research should include: (1) experimental studies using lung microdialysis to assess the PK/PD in the interstitial fluid of the lung following nebulization of high doses of colistin; (2) superiority multicenter randomized controlled trials comparing nebulized and intravenous CMS in patients with pandrug-resistant GNB ventilator-associated pneumonia and ventilator-associated tracheobronchitis; (3) non-inferiority multicenter randomized controlled trials comparing nebulized CMS to intravenous new cephalosporines/ß-lactamase inhibitors in patients with extensive drug-resistant GNB ventilator-associated pneumonia and ventilator-associated tracheobronchitis.

Polymyxins for the treatment of lower respiratory tract infections: lessons learned from the integration of clinical pharmacokinetic studies and clinical outcomes

The global rise in nosocomial pneumonia caused by multidrug-resistant (MDR) Gram-negative pathogens and the increasingly limited antibiotic treatment options are growing threats to modern medicine. As a result, older antibiotics such as polymyxins are being used as last-resort drugs for MDR nosocomial pneumonia. Polymyxins are bactericidal against most aerobic Gram-negative bacilli. High-dose intravenous (IV) adminsitration of polymyxins, however, results in subtherapeutic concentrations at the site of infection making treatment challenging. Alternative forms of polymyxin delivery have been considered in order to better achieve the necessary concentrations at the site of infection. Several studies have evaluated the effectiveness of aerosolised polymyxins in patients with nosocomial pneumonia caused by MDR Gram-negative pathogens such as Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. Here we evaluated the pharmacokinetic data supporting the use of inhaled polymyxins in nosocomial pneumonia and provide insight into the limitations and challenges that future studies should address. We have also reviewed the literature published between 2006 and 2020 on the use of aerosolised polymyxins for the treatment of nosocomial pneumonia, including ventilator-associated pneumonia, in patients without cystic fibrosis to evaluate their safety and efficacy as monotherapy or as an adjunct to IV antimicrobials. This review highlights the need for well-designed multicentre studies with standardised methodologies to further evaluate the effectiveness of inhaled polymyxins and to provide reliable pharmacokinetic/pharmacodynamic data in order to redefine appropriate dosing strategies.

Efficacy of adjunctive nebulized colistin in critically ill patients with nosocomial carbapenem-resistant Gram-negative bacterial pneumonia: a multi-centre observational study

OBJECTIVES

To investigate the association between adjunctive nebulized colistin and treatment outcomes in critically ill patients with nosocomial carbapenem-resistant Gram-negative bacterial (CR-GNB) pneumonia.

METHODS

This retrospective, multi-centre, cohort study included individuals admitted to the intensive care unit with nosocomial pneumonia caused by colistin-susceptible CR-GNB. Enrolled patients were divided into groups with/without nebulized colistin as adjunct to at least one effective intravenous antibiotic. Propensity score matching was performed in the original cohort (model 1) and a time-window bias-adjusted cohort (model 2). The association between adjunctive nebulized colistin and treatment outcomes was analysed.

RESULTS

In total, 181 and 326 patients treated with and without nebulized colistin, respectively, were enrolled for analysis. The day 14 clinical failure rate and mortality rate were 41.4% (75/181) versus 46% (150/326), and 14.9% (27/181) versus 21.8% (71/326), respectively. In the propensity score-matching analysis, patients with nebulized colistin had lower day 14 clinical failure rates (model 1: 41% (68/166) versus 54.2% (90/166), p 0.016; model 2: 35.3% (41/116) versus 56.9% (66/116), p 0.001). On multivariate analysis, nebulized colistin was an independent factor associated with fewer day 14 clinical failures (model 1: adjusted odds ratio (aOR) 0.59, 95% CI 0.37-0.92; model 2: aOR 0.37, 95% CI 0.21-0.65). Nebulized colistin was not associated independently with a lower 14-day mortality rate in the time-dependent analysis in both models 1 and 2.

CONCLUSIONS

Adjunctive nebulized colistin was associated with lower day 14 clinical failure rate, but not lower 14-day mortality rate, in critically ill patients with nosocomial pneumonia caused by colistin-susceptible CR-GNB.

Intravenous vs intravenous plus aerosolized colistin for treatment of ventilator-associated pneumonia - a matched case-control study in neonates

BACKGROUND

Recently intravenous (IV) and aerosolized (ASZ) colistin have been used for treating ventilator-associated pneumonia (VAP) due to colistin susceptible multidrug-resistant Gram-negative bacteria (MDR-GNB). Colistin has limited lung penetration. We compared the efficacy and safety of IV-alone versus IV+ASZ-colistin for treating VAP in neonates.

METHODS

This retrospective matched case-control study was performed at NICU of the Aga Khan University Hospital, Pakistan between January 2015 and December 2018. Sixteen neonates with MDR-GNB associated VAP received IV-ASZ-colistin and were matched for date of birth, gestational age, birth weight, Apgar score, antenatal steroid history, disease severity, and duration of mechanical ventilation with 16 control neonates who received IV-colistin alone.

RESULTS

Both groups had similar MDR-GNB isolates and Acinetobacter baumannii (78%) was the most common pathogen. No colistin-resistant strain was isolated. Duration of IV-colistin and concomitant antibiotics use was significantly (p < 0.05) shorter in the IV-ASZ-colistin group. Significantly (p < 0.05) higher clinical cure and microbial eradication, along with lower ventilatory requirements, mortality rate, and colistin induced nephrotoxicity and electrolyte imbalance was observed in the IV-ASZ-colistin group.

CONCLUSIONS

With better lung penetration, ASZ-colistin offers effective and safe microbiological and clinical benefits as adjunctive or alternate treatment of VAP due to colistin susceptible MDR-GNB in neonates.

Inhalation with intravenous loading dose of colistin in critically ill patients with pneumonia caused by carbapenem-resistant gram-negative bacteria

Background:

Despite the increasing use of colistin in clinical practice, the optimal dosing, and administration route have not been established. This study aimed to evaluate the clinical outcome and safety of intravenous (IV) colistin with a loading dose (LD) and adjunctive aerosolized (AS) colistin administration in critically ill patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP) caused by carbapenem-resistant gram-negative bacteria (CRGNB).

Methods:

We retrospectively reviewed 191 critically ill patients who received colistin for the treatment of HAP or VAP caused by CRGNB. Patients were divided into three groups: non-LD IV (patients received only IV colistin without LD), LD IV (patients received only IV colistin with LD), and AS–LD (patients received IV colistin with LD and adjunctive AS colistin).

Results:

There was no difference in clinical response between the three groups. However, the rate of microbiological eradication was significantly higher in the AS–LD group (60%) than in the non-LD IV (31%), and LD IV (33%) groups (p = 0.010). Patients treated with adjunctive AS colistin in combination with LD IV had significantly lower 30-day mortality rates than patients treated with IV colistin alone (p = 0.027). After adjusting for potential confounding factors, adjunctive AS colistin was still significantly associated with lower mortality (adjusted OR 0.338, CI 95% 0.132–0.864, p = 0.024). However, nephrotoxicity did not change according to the use of LD regimen and AS colistin administration (p = 0.100).

Conclusions:

Adjunctive AS colistin in combination with IV colistin with LD was related to an improved 30-day mortality and microbiological outcome without an increase in nephrotoxicity in critically ill patients with HAP and VAP caused by CRGNB.

The reviews of this paper are available via the supplemental material section.

Aerosol delivery during invasive mechanical ventilation: development of a preclinical ex vivo respiratory model for aerosol regional deposition

In intensive care units, nebulization is a usual route for drug administration to patients under mechanical ventilation (MV). The effectiveness of inhalation devices as well as depositions sites of aerosols for ventilated patients remain poorly documented. In vivo human inhalation studies are scarce due to ethical restrictions because imaging techniques require radioaerosols to assess regional aerosol deposition. Thus, we developed an ex vivo respiratory model under invasive MV for preclinical aerosol deposition studies. The model was composed of ex vivo porcine respiratory tracts. MV was achieved thanks to a tracheal intubation and a medical ventilator under controlled conditions. Respiratory features were studied using analogical sensors. Then regional homogeneity of gas-ventilation was assessed with ^81mKrypton scintigraphies. Finally, a proof of concept study for aerosol deposition was performed. Obtained respiratory features as well as gamma-imaging techniques, which demonstrated a homogenous regional ventilation and about 18% ± 4% of the nebulized dose deposited the respiratory tract, were in good agreement with human data available in the literature. This original ex vivo respiratory model provides a feasible, reproducible and cost-effective preclinical tool to achieve aerosol deposition studies under MV.

Addressing clinical safety of antimicrobial resistance: personal perspectives

Introduction: Antimicrobial resistance is an important challenge for patients, societies, practicing physicians and health care organizations worldwide. Predictions in regard to the morbidity and mortality of antimicrobial resistance are grave especially in the setting of an era where the pipeline of production of antimicrobial agents is relatively dry.Areas covered: Herein, a viewpoint will be provided regarding antimicrobial bacterial resistance as a clinical safety need based on personal experience and data from the literature.Expert opinion: A variety of antibiotics has been produced during the last decade but novelty regarding truly new antimicrobial agents is rather little, as these new antibiotics are mainly based on modifications of known pharmaceutical molecules. Therefore, as there is still a desperate need to address optimal clinical safety in regard to antimicrobial resistance, we believe that strong financial incentives and rewards to producers of antimicrobial agents (especially new in concept) are necessary. Furthermore, global surveillance of antimicrobial resistance as suggested by the World Health Organization, coordination of measures of justified and appropriate use of antibiotics and application of strict infection control principles are needed to lessen the negative clinical impact of antimicrobial resistance.

Colistin for pneumonia involving multidrug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex

OBJECTIVES

To investigate clinical and microbiological response, and 30-day mortality of pneumonia involving multidrug-resistant (MDR) Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex treated with colistin, and identify associated factors of these outcomes.

METHODS

A retrospective study of 183 adult patients with colistin treatment for at least 7 days between January 2014 and October 2017.

RESULTS

The mean age was 76.8 years, and mean Acute Physiology and Chronic Health Evaluation II score was 17.7. Eighteen (9.8%) and 128 (69.9%) patients had intravenous (IV) colistin alone and inhaled (IH) colistin alone, respectively. Thirty-seven patients had both IV and IH colistin, including 5 (2.7%) with concurrent, and 32 (17.5%) with non-concurrent use of IV and IH colistin. The 30-day mortality rate was 19.1% and 131 (71.6%) patients had clinical response. In the 175 patients with available data, 126 (72%) had microbiological eradication. The multivariate analyses revealed that IH colistin alone was an independent predictor for 30-day survival, clinical response, and microbiological eradication, and IV colistin alone was an independent predictor for clinical failure. Patients with IV colistin alone had a significantly higher nephrotoxicity rate than IH colistin alone (37.5% vs 6.1%, P = 0.001). Sub-group analysis of 52 patients with IV colistin for ≧ 4 days revealed that 14 (26.9%) patients had inappropriate dose, and inappropriate dose was an independent predictor for 30-day mortality.

CONCLUSIONS

IH colistin provided good outcomes with few side effects, and appropriate dosing of IV colistin was important to avoid excess mortality.

Meta-analysis of Polymyxin Use in Patients

In this chapter, we systematically reviewed studies that assessed polymyxin's effectiveness and summarized results through meta-analysis. The outcomes addressed were all-cause mortality, assuming that for patients with severe multidrug-resistant infections survival is the most important outcome, and resistance development, important for future patients. Most clinical data on polymyxins in the literature are from retrospective, observational studies at high risk of bias. The majority of clinical studies were unpowered to examine mortality controlling for other risk factors. The studies had no control of dosage regimens and treatment modifications. We identified several areas of missing data, in particular randomized controlled trials (RCTs) examining treatment options for carbapenem-resistant Gram-negative bacteria, different dosage regimens, polymyxins versus alternative antibiotics (e.g. aminoglycosides, tigecycline), and monotherapy versus specific combination therapies. Ideally, mortality and development of resistance should be examined in RCTs, with further longitudinal studies required for the latter.

Why don't we have more inhaled antibiotics to treat ventilator-associated pneumonia?

BACKGROUND

The increasing prevalence of ventilator-associated pneumonia (VAP) due to either multidrug-resistant (MDR) organisms or infections with limited treatment options (i.e. susceptible to only aminoglycosides or colisitin) coupled with a dearth of new antimicrobials has led clinicians to pursue alternative management strategies including the use of inhaled antibiotics (IA).

OBJECTIVES

To review the evidence surrounding the use of IA in the treatment of VAP with a focus on establishing a path whereby adjunctive IA could become a standard therapy for the treatment of specific VAP patient populations.

SOURCES

A meta-analysis performed by the 2016 IDSA/ATS Hospital-acquired Pneumonia Guideline Committee; a PubMed and clinicaltrials.gov search for subsequent trials of IA for the treatment of VAP.

CONTENT

Based on a meta-analysis of nine studies (RR 1.29; 95% CI 1.13-1.47), the 2016 IDSA/ATS Hospital-acquired Pneumonia Guideline Committee recommended that adjunctive IA be used to treat VAP due to Gram-negative bacilli that are susceptible to only aminoglycosides or polymyxins. Two subsequent randomized trials of adjunctive IA for the treatment of mechanically ventilated patients with pneumonia failed to demonstrate a benefit. Despite these results, an updated meta-analysis (n = 11) including these two recent trials suggests a benefit of adjunctive IA for the treatment of VAP due to MDR and difficult-to-treat infections (RR 1.2; 95% CI 1.05-1.57).

IMPLICATIONS

Patients with VAP and limited intravenous antibiotic options are the individuals most likely to benefit from adjunctive IA and should be the focus of future investigative studies. Although vibrating mesh nebulizers predominate in pharmaceutical company-sponsored trials, these devices have not been directly compared with the traditional jet nebulizers in terms of efficacy or safety.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

A Breath of Fresh Air in the Fog of Antimicrobial Resistance: Inhaled Polymyxins for Gram-Negative Pneumonia

Despite advancements in therapy, pneumonia remains the leading cause of death due to infectious diseases. Novel treatment strategies are desperately needed to optimize the antimicrobial therapy of patients suffering from this disease. One such strategy that has recently garnered significant attention is the use of inhaled antibiotics to rapidly achieve therapeutic concentrations directly at the site of infection. In particular, there is significant interest in the role of inhaled polymyxins for the treatment of nosocomial pneumonia, including ventilator-associated pneumonia, due to their retained activity against multi-drug resistant Gram-negative pathogens, including Acinetobacter baumannii and Pseudomonas aeruginosa. This review will provide a comprehensive overview of the pharmacokinetic/pharmacodynamic profile, clinical outcomes, safety, and potential role of inhaled polymyxins in clinical practice.

Use of Colistin in Critically Ill Patients

Due to lack of better therapeutic options, colistin use for extensively drug-resistant Gram-negative organisms was revived in the past two decades, including in patients in intensive-care units (ICU). There are multiple knowledge gaps pertaining to the clinical use and utility of colistin in critically-ill patients, but due to lack of options, it is used in these high risk patients. In this chapter, we critically review the various topics pertaining to colistin use in critically-ill patients, while highlighting the (lack of) controlled evidence supporting common current practices pertaining to colistin use by clinicians.

Spotlight on inhaled ciprofloxacin and its potential in the treatment of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFB) is a severe chronic illness characterized by irreversible dilation of airways and thickening of bronchial walls, chronic inflammation, repeated infections, and progressive obstruction of the airways. In contrast to cystic fibrosis bronchiectasis (CFB), which is a well-defined genetic disorder, NCFB is a heterogeneous disease caused by many different medical entities. Inhaled antibiotics are effective for patients with CFB, but their efficacy in NCFB has not been proven. The main pathogens involved in the colonization of patients with bronchiectasis are Haemophilus influenza, Moraxella catarrhalis, Staphylococcus aureus, and Pseudomonas aeruginosa. The latter is associated with increased morbidity and mortality. In addition, in NCFB, P. aeruginosa strains are frequently more resistant than those in CFB. At present, there are no approved inhaled antibiotic therapies for NCFB patients. Inhaled ciprofloxacin has been under investigation in the last few years. In two phase II randomized, double-blind, placebo-controlled trials, the use of inhaled ciprofloxacin was significantly associated with reduction in sputum bacterial density and greater eradication rates. In four phase III randomized, double-blind, placebo-controlled trials, the results regarding the time of the first exacerbation and the rate of exacerbations were inconsistent. Specifically, ORBIT-4 and RESPIRE-1 trials showed clinical benefit (prolongation of the time of the first exacerbation and reduced rate of exacerbations in the treatment group compared to the placebo group), whereas the ORBIT-3 and RESPIRE-2 failed to achieve their primary endpoints. The RESPIRE-1 was the first trial that examined the 14-days on/off course separate from the standard 28-days on/off regimen, which is based on CFB protocol treatments. The current data on the efficacy of inhaled ciprofloxacin are encouraging, but further evaluation is needed to determine the appropriate target group and the ideal duration of treatment.

Aerosolized antibiotics for ventilator-associated pneumonia: a pairwise and Bayesian network meta-analysis

Background

Aerosolized antibiotics have been proposed as a novel and promising treatment option for the treatment of ventilator-associated pneumonia (VAP). However, the optimum aerosolized antibiotics for VAP remain uncertain.

Methods

We included studies from two systematic reviews and searched PubMed, EMBASE, and Cochrane databases for other studies. Eligible studies included randomized controlled trials and observational studies. Extracted data were analyzed by pairwise and network meta-analysis.

Results

Eight observational and eight randomized studies were identified for this analysis. By pairwise meta-analysis using intravenous antibiotics as the reference, patients treated with aerosolized antibiotics were associated with significantly higher rates of clinical recovery (risk ratio (RR) 1.21, 95% confidence interval (CI) 1.09–1.34; P = 0.001) and microbiological eradication (RR 1.42, 95% CI 1.22–1.650; P < 0.0001). There were no significant differences in the risks of mortality (RR 0.88, 95% CI 0.74–1.04; P = 0.127) or nephrotoxicity (RR 1.00, 95% CI 0.72–1.39; P = 0.995). Using network meta-analysis, clinical recovery benefits were seen only with aerosolized tobramycin and colistin (especially tobramycin), and microbiological eradication benefits were seen only with colistin. Aerosolized tobramycin was also associated with significantly lower mortality when compared with aerosolized amikacin and colistin and intravenous antibiotics. The assessment of rank probabilities indicated aerosolized tobramycin presented the greatest likelihood of having benefits for clinical recovery and mortality, and aerosolized colistin presented the best benefits for microbiological eradication.

Conclusions

Aerosolized antibiotics appear to be a useful treatment for VAP with respect to clinical recovery and microbiological eradication, and do not increase mortality or nephrotoxicity risks. Our network meta-analysis in patients with VAP suggests that clinical recovery benefits are associated with aerosolized tobramycin and colistin (especially tobramycin), microbiological eradication with aerosolized colistin, and survival with aerosolized tobramycin, mostly based on observational studies. Due to the low levels of evidence, definitive recommendations cannot be made before additional, large randomized studies are carried out.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2106-x) contains supplementary material, which is available to authorized users.

Treatment outcomes of patients with non-bacteremic pneumonia caused by extensively drug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolates: Is there any benefit of adding tigecycline to aerosolized colistimethate sodium?

Few therapeutic options exist for various infections caused by extensively drug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii (XDR-Acb) complex isolates, including pneumonia. This study investigated the clinical efficacy between aerosolized colistimethate sodium (AS-CMS, 2 million units thrice a day) treatment alone or in combination with standard-dose tigecycline (TGC) in patients with non-bacteremic pneumonia due to XDR-Acb, and explored the factors influencing patients' 30-day mortality.A 1:1 case (n = 106; receiving TGC plus AS-CMS) control (receiving AS-CMS alone with matching scores) observational study was conducted among adult patients with non-bacteremic XDR-Acb complex pneumonia in a Taiwanese medical center from January 2014 through December 2016. The clinically relevant data were retrospectively recorded. The primary endpoint was 30-day case fatality. Secondary endpoints investigated that if the co-morbidities, XDR-A. baumannii as a pneumonic pathogen, therapy-related factors, or airway colonization with colistin-resistant Acb negatively influenced the 14-day clinical condition of enrolled patients.A higher 30-day mortality rate was noted among the group receiving combination therapy (34.0% vs 22.6%; P = .17). The ≥7-day AS-CMS therapy successfully eradicated > 90% of airway XDR-Acb isolates. Nevertheless, follow-up sputum specimens from 10 (6.4% [10/156]) patients were colonized with colistin-resistant Acb isolates. After the conditional factors were adjusted by multivariate logistic analysis, the only factor independently predicting the 30-day case-fatality was the failure of treating XDR-Acb pneumonia at 14 days (adjusted odds ratio [aOR] = 38.2; 95% confidence interval [CI] = 9.96-142.29; P < .001). Cox proportional regression analysis found that chronic obstructive pulmonary disease (COPD) (adjusted hazard ratio [aHR] = 2.08; 95% CI = 1.05-4.10; P = .035), chronic renal failure (aHR = 3.00; 95% CI = 1.52-5.90; P = .002), non-invasive ventilation use (aHR = 2.68; 95% CI = 1.37-5.25; P = .004), and lack of TGC therapy (aHR = 0.52; 95% CI = 0.27-1.00; P = .049) adversely influenced the 14-day clinical outcomes. Conversely, the emergence of colistin-resistant Acb isolates in the follow-up sputum samples was not statistically significantly associated with curing or improving XDR-Acb pneumonia.In conclusion, aggressive pulmonary hygiene care, the addition of TGC, and corticosteroid dose tapering were beneficial in improving the 14-day patients' outcomes.

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.

Inhaled Antibiotics for Ventilator-Associated Infections

Multidrug-resistant organisms are creating a challenge for physicians treating the critically ill. As new antibiotics lag behind the emergence of worsening resistance, intensivists in countries with high rates of extensively drug-resistant bacteria are turning to inhaled antibiotics as adjunctive therapy. These drugs can provide high concentrations of drug in the lung that could not be achieved with intravenous antibiotics without significant systemic toxicity. This article summarizes current evidence describing the use of inhaled antibiotics for the treatment of bacterial ventilator-associated pneumonia and ventilator-associated tracheobronchitis. Preliminary data suggest aerosolized antimicrobials may effectively treat resistant pathogens with high minimum inhibitory concentrations.

Nebulization of antimicrobial agents in mechanically ventilated adults in 2017: an international cross-sectional survey

2017 ESCMID practice guidelines reported safety concerns and weak evidence of benefit supporting use of aerosolized antibiotics in mechanically ventilated patients. Our primary goal was to assess current patterns of aerosolized antibiotic prescription in mechanically ventilated patients. A sequential global survey was performed prior to the release of the ESCMID guidelines, from the 1st of February to the 30th of April 2017, using an electronic platform. Responses were analyzed comparing geographical regions. A total of 410 units responded, with 261 (177 from Europe) being eligible for the full survey. 26.8% of units reported not using aerosolized antibiotics. The two major indications amongst prescribing units were ventilator-associated pneumonia and ventilator-associated tracheobronchitis (74.3% and 49.4%, respectively). 63.6% of units indicated prescription solely in response to multi-drug resistant organisms. In comparison with a survey undertaken in 2014, there was a significant reduction in use of aerosolized antibiotics for prophylaxis (50.6% vs 7.7%, p < 0.05) and colonization (52.9% vs 25.3%, p < 0.05). The large majority of units (91.7%) reported only prescribing in patients with positive pulmonary cultures. Asia appeared to be an outlier, with 53.3% of units reporting empirical use. The most commonly used device was the jet nebulizer. The most commonly prescribed drugs were colistin methanesulfonate (57.6%), colistin base (41.9%) and amikacin (31.4%), although there was considerable heterogeneity across geographical areas. A significant gap exists between ESCMID clinical practice recommendations and the use of aerosolized antibiotics in clinical practice. Our findings indicate an urgent need for high-quality education to bring practice into line with evidence-based guidelines.

Intravenous plus inhaled versus intravenous colistin monotherapy for lower respiratory tract infections: A systematic review and meta-analysis

OBJECTIVE

To evaluate whether intravenous plus inhaled combination (IV/INHCC) compared to intravenous monotherapy (IVCM) was associated with patient outcomes and identify factors influencing study outcomes.

METHODS

PubMed and Scopus were searched till November 2016. Studies were included if they evaluated adult patients with lower respiratory tract infections due to MDR/XDR Gram-negative bacteria and reported comparative mortality data (adjusted and unadjusted) for patients receiving IV/INHCC versus IVCM. Random effects meta-analyses were performed.

RESULTS

Thirteen studies (11 retrospective, 2 prospective) were included. The overall quality of data was low to very low and characterized by the lack of adjusted data. The majority of the studies were designed to evaluate the outcome of the meta-analysis. Both IV and inhaled colistin were administered at variable doses. There was no difference in mortality between IV/INHCC and IVCM when all studies were combined (13 studies, 1115 patients, risk ratio 0.94, 95% confidence interval 0.81-1.08). Only the analysis that included studies with low-dose IV colistin showed significant difference in favor of IV/INHCC versus IVCM (0.65, 0.45-0.94).

CONCLUSIONS

Overall, low quality data suggest that IV/INHCC did not lower mortality in patients with MDR Gram negative infections unless low IV colistin dose was administered.

Effect of extended infusion of meropenem and nebulized amikacin on Gram-negative multidrug-resistant ventilator-associated pneumonia

Background:

Ventilator-associated pneumonia (VAP) due to multidrug-resistant organisms (MDROs) is associated with a significant mortality in the Intensive Care Unit (ICU). The aim of this study was to compare the efficacy and safety of extended infusion of meropenem and nebulized amikacin on VAP caused by Gram-negative MDRO versus intravenous (IV) meropenem and amikacin alone.

Methodology:

A randomized nonblinded controlled trial was performed on ninety patients with VAP. Patients were randomized into three equal groups: Group I received IV amikacin 20 mg/kg/24 h and meropenem 2 g over 30 min/8 h. Group II received the same as Group I in addition to nebulized amikacin 25 mg/kg/day every 8 h. Group III received IV amikacin 20 mg/kg/24 h, nebulized amikacin 25 mg/kg/day every 8 h, and meropenem 2 g diluted in 240 ml normal saline over 3 h/8 h. The primary outcome was the clinical outcome of VAP. Secondary outcomes were microbiological outcome, VAP-related mortality, duration of MV, ICU stay, and nephrotoxicity.

Results:

Group II and Group III compared to Group I showed higher incidence of clinical cure (53.33% in Group II and 66.67% in Group III vs. 26.67% in Group I, P = 0.007). Group II compared to Group I showed significant reduction in ventilator days (5.32 ± 1.86 vs. 7.3 ± 2.1 days, respectively, P < 0.001) and reduction in ICU days (11.87 ± 2.6 vs. 15.3 ± 3.1 days, respectively, P < 0.001). Group III compared to Group II showed significant reduction in ventilator days (4.22 ± 1.32 vs. 5.32 ± 1.86, respectively, P = 0.011) and highly significant reduction in ICU days (9.21 ± 1.17 vs. 11.87 ± 2.6, respectively, P < 0.001). All groups were comparable as regards nephrotoxicity or mortality.

Conclusions:

Adding nebulized amikacin to systemic antibiotics in patients with VAP caused by Gram-negative MDRO may offer efficacy benefits, and the use of extended infusions of meropenem could improve the clinical outcomes in critically ill populations.

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.

Antimicrobials for the treatment of drug-resistant Acinetobacter baumannii pneumonia in critically ill patients: a systemic review and Bayesian network meta-analysis

BACKGROUND

An optimal therapy for the treatment of pneumonia caused by drug-resistant Acinetobacter baumannii remains unclear. This study aims to compare various antimicrobial strategies and to determine the most effective therapy for pneumonia using a network meta-analysis.

METHODS

Systematic search and quality assessment were performed to select eligible studies reporting one of the following outcomes: all-cause mortality, clinical cure, and microbiological eradication. The primary outcome was all-cause mortality. A network meta-analysis was conducted with a Bayesian approach. Antimicrobial treatments were ranked based on surface under the cumulative ranking curve (SUCRA) value along with estimated median outcome rate and corresponding 95% credible intervals (CrIs). Two treatments were considered significantly different if a posterior probability of superiority (P) was greater than 97.5%.

RESULTS

Twenty-three studies evaluating 15 antimicrobial treatments were included. Intravenous colistin monotherapy (IV COL) was selected as a common comparator, serving as a bridge for developing the network. Five treatments ranked higher than IV COL (SUCRA, 57.1%; median all-cause mortality 0.45, 95% CrI 0.41-0.48) for reducing all-cause mortality: sulbactam monotherapy (SUL, 100.0%; 0.18, 0.04-0.42), high-dose SUL (HD SUL, 85.7%; 0.31, 0.07-0.71), fosfomycin plus IV COL (FOS + IV COL, 78.6%; 0.34, 0.19-0.54), inhaled COL plus IV COL (IH COL + IV COL, 71.4%; 0.39, 0.32-0.46), and high-dose tigecycline (HD TIG, 71.4%; 0.39, 0.16-0.67). Those five treatments also ranked higher than IV COL (SUCRA, 45.5%) for improving clinical cure (72.7%, 72.7%, 63.6%, 81.8%, and 90.9%, respectively). Among the five treatments, SUL (P = 98.1%) and IH COL + IV COL (P = 99.9%) were significantly superior to IV COL for patient survival and clinical cure, respectively. In terms of microbiological eradication, FOS + IV COL (P = 99.8%) and SUL (P = 98.9%) were significantly superior to IV COL.

CONCLUSIONS

This Bayesian network meta-analysis demonstrated the comparative effectiveness of fifteen antimicrobial treatments for drug-resistant A. baumannii pneumonia in critically ill patients. For survival benefit, SUL appears to be the best treatment followed by HD SUL, FOS + IV COL, IH COL + IV COL, HD TIG, and IV COL therapy, in numerical order.

Major publications in the critical care pharmacotherapy literature: January-December 2016

PURPOSE

To summarize select critical care pharmacotherapy guidelines and studies published in 2016.

SUMMARY

The Critical Care Pharmacotherapy Literature Update (CCPLU) Group screened 31 journals monthly for relevant pharmacotherapy articles and selected 107 articles for review over the course of 2016. Of those included in the monthly CCPLU, three guidelines and seven primary literature studies are reviewed here. The guideline updates included are as follows: hospital-acquired pneumonia and ventilator-associated pneumonia management, sustained neuromuscular blocking agent use, and reversal of antithrombotics in intracranial hemorrhage (ICH). The primary literature summaries evaluate the following: dexmedetomidine for delirium prevention in post-cardiac surgery, dexmedetomidine for delirium management in mechanically ventilated patients, high-dose epoetin alfa after out-of-hospital cardiac arrest, ideal blood pressure targets in ICH, hydrocortisone in severe sepsis, procalcitonin-guided antibiotic de-escalation, and empiric micafungin therapy.

CONCLUSION

The review provides a synopsis of select pharmacotherapy publications in 2016 applicable to clinical practice.

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.

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.

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.

Inhaled colistin monotherapy for respiratory tract infections in adults without cystic fibrosis: a systematic review and meta-analysis

BACKGROUND

Inhaled colistin is becoming increasingly popular against respiratory tract infections caused by multidrug resistant (MDR) Gram-negative bacteria because it may overcome the problems associated with intravenous (IV) administration.

OBJECTIVE

To investigate the effectiveness and safety of inhaled colistin as monotherapy (without concomitant IV administration of colistin) in the treatment of respiratory tract infections caused by MDR or colistin-only susceptible Gram-negative bacteria.

METHODS

PubMed and Scopus databases were searched. A systematic review and meta-analysis were conducted.

RESULTS

Twelve studies (373 patients receiving inhaled colistin for respiratory tract infection) were included. Ten studies evaluated patients with pneumonia (including 8 studies with ventilator-associated pneumonia) and 2 studies evaluated patients with ventilator-associated tracheobronchitis. Patients with infections due to MDR Acinetobacter baumannii and Pseudomonas aeruginosa were mainly studied. Daily dose of inhaled colistin and treatment duration varied in the individual studies. The pooled all-cause mortality was 33.8% (95% CI 24.6% - 43.6%), clinical success was 70.4% (58.5% - 81.1%) and eradication of Gram-negative bacteria was shown in 71.3% (57.6% - 83.2%) of cases.

CONCLUSIONS

Inhaled colistin monotherapy may deserve further consideration as a mode for colistin administration for the treatment of respiratory tract infections caused by MDR A. baumannii and P. aeruginosa.

Efficacy and toxicity of high-dose nebulized colistin for critically ill surgical patients with ventilator-associated pneumonia caused by multidrug-resistant Acinetobacter baumannii

PURPOSE

Few studies have compared nebulized and intravenous (IV) colistin for multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa pneumonia. This study compared the nephrotoxicity and clinical outcomes for these two delivery routes.

METHODS

This study retrospectively compared 95 critically ill surgical patients who were diagnosed with Acinetobacter baumannii ventilator associated pneumonia and received colistin between March 2013 and January 2016.

RESULTS

The most common diagnoses were brain hemorrhage (27.4%), traumatic brain injury (20%), traumatic thoracic injury (15.8%), and secondary peritonitis (11.6%). Compared to the IV group, the nebulizer group was significantly older (60.0 vs. 67.5years, p=0.010), had higher APACHE II scores (16.3 vs. 19.9, p=0.001), and more frequently had diabetes mellitus (6.8% vs. 21.6%, p=0.043). Nephrotoxicity was more common in the IV group (60.5% vs. 15.7%, p<0.0001). Both groups had similar microbiological and clinical outcomes (p=0.921 and p=0.719, respectively). Patients with nephrotoxicity exhibited prolonged IV or nebulized colistin treatment and more frequent combination with vancomycin. Nephrotoxicity was independently associated with IV delivery (odds ratio: 8.48, 95% confidence interval: 2.95-24.39, p<0.0001).

CONCLUSIONS

Nebulized colistin may have less nephrotoxicity and provide similar clinical results, compared to IV colistin.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

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.

Colistin combination therapy improves microbiologic cure in critically ill patients with multi-drug resistant gram-negative pneumonia

Currently, in vitro synergy with colistin has not translated into improved clinical outcomes. This study aimed to compare colistin combination therapy to colistin monotherapy in critically ill patients with multi-drug resistant gram-negative (MDR-GN) pneumonia. This was a retrospective analysis of critically ill adult patients receiving intravenous colistin for MDR-GN pneumonia comparing colistin combination therapy to colistin monotherapy with a primary endpoint of clinical cure. Combination therapy was defined by administration of another antibiotic to which the MDR-GN pathogen was reported as susceptible or intermediate. Ninety patients were included for evaluation (41 combination therapy and 49 monotherapy). Baseline characteristics were similar between groups. No difference in clinical cure was observed between combination therapy and monotherapy in univariate analysis, nor when adjusted for APACHE II score and time to appropriate antibiotic therapy (57.1 vs. 63.4 %, adjusted OR 1.15, p = 0.78). Microbiological cure was significantly higher for combination therapy (87 vs. 35.5 %, p < 0.001). Colistin combination therapy was associated with a significant improvement in microbiological cure, without improvement in clinical cure. Based on the in vitro synergy and improvement in microbiological clearance, colistin combination therapy should be prescribed for MDR-GN pneumonia. Further research is warranted to determine if in vitro synergy with colistin translates into improved clinical outcomes.

Advances in antibiotic therapy in the critically ill

Infections occur frequently in critically ill patients and their management can be challenging for various reasons, including delayed diagnosis, difficulties identifying causative microorganisms, and the high prevalence of antibiotic-resistant strains. In this review, we briefly discuss the importance of early infection diagnosis, before considering in more detail some of the key issues related to antibiotic management in these patients, including controversies surrounding use of combination or monotherapy, duration of therapy, and de-escalation. Antibiotic pharmacodynamics and pharmacokinetics, notably volumes of distribution and clearance, can be altered by critical illness and can influence dosing regimens. Dosing decisions in different subgroups of patients, e.g., the obese, are also covered. We also briefly consider ventilator-associated pneumonia and the role of inhaled antibiotics. Finally, we mention antibiotics that are currently being developed and show promise for the future.