Prolonged infusion of beta-lactam antibiotics for Gram-negative infections: rationale and evidence base

Critical reappraisal of current issues for improving the proper clinical use of the incoming beta-lactam/beta-lactamase inhibitor combinations of tomorrow

INTRODUCTION

Although different novel beta-lactam/beta-lactamase inhibitor combinations (BL/BLIc) were recently licensed, resistance occurrence have been reported up to 15% of Gram-negative pathogens. For this reason, novel BL/BLIc of tomorrow will be released for managing difficult-to-treat resistance (DTR) Gram-negative infections.

AREAS COVERED

This review provides a critical reappraisal of current issues for improving the proper clinical use of the novel BL/BLIc of tomorrow. A literature search was performed on PubMed-MEDLINE (until December 2024) for retrieving available studies on cefepime-enmetazobactam, sulbactam-durlobactam, and cefepime-taniborbactam. Four different main areas were discussed according to available evidence: 1) translating findings coming from the randomized clinical trials into the real-world clinical practice; 2) defining the optimal joint pharmacokinetic/pharmacodynamic (PK/PD) target; 3) identifying proper dosing schedules in patients with renal dysfunction; 4) attributing proper relevance to the epithelial lining fluid (ELF) penetration rate in defining optimal dosing schedule for treating pneumonia.

EXPERT OPINION

Overall, old habits die hard and issues retrieved with licensed beta-lactams emerged also with novel BL/BLIc of tomorrow, potentially affecting their efficacy when used in real-world practice. Adopting appropriate corrective measures for overcoming these issues might increase the likelihood of preserving their efficacy in the future by minimizing the propensity risk of resistance development.

Reserve antibiotics: overcoming limitations of evidence generated from regulatory approval trials

New antibiotics active against multidrug resistant bacteria (MDR-B) are licensed by regulatory agencies based on pivotal trials that serve the primary purpose of obtaining marketing-authorization. There is increasing concern that they do not offer guidance on how to best use new antibiotics, in which population, and to what extent they overcome existing resistance. We reviewed the literature for pre-approval studies (phase 2 and 3 randomized controlled trials) and post-approval studies (randomized and non-randomized controlled trials) evaluating efficacy and safety of new antibiotics, classified by WHO as Reserve, approved in the European Union and the US from January 2010 to May 2023. Substantial failures occur in generating evidence to guide routine clinical use: preapproval studies lack representativeness, select outcomes and comparators to chase statistical significance, and often avoid using prespecified analytical methods. Three recommendations are key to enhance the quality and relevance of clinical data underpinning use of last resort molecules on the WHO AWaRe Reserve list active against carbapenem-resistant MDR-B i). separation of pivotal trials from post-approval studies, which should be funded by public programs and de-linked from commercial purposes, ii). development and maintenance of a global infrastructure to conduct post-approval public health focused studies, and iii). development of trial platforms that use efficient, adaptive designs to inform clinical decision making and country level technology appraisal. These solutions will allow clinicians to determine whether recently approved Reserve antibiotics are not only "newer" but also "better" for vulnerable patient populations at particular risk for infections by MDR-B.

[Epidemiology, diagnosis and treatment of adult patients with nosocomial pneumonia]

BACKGROUND

 Nosocomial pneumonia, encompassing hospital-acquired (HAP) and ventilator-associated pneumonia (VAP), remains a major cause of morbidity and mortality in hospitalized adults. In response to evolving pathogen profiles and emerging resistance patterns, this updated S3 guideline (AWMF Register No. 020-013) provides an evidence-based framework to enhance the diagnosis, risk stratification, and treatment of nosocomial pneumonia.

METHODS

 The guideline update was developed by a multidisciplinary panel representing key German professional societies. A systematic literature review was conducted with subsequent critical appraisal using the GRADE methodology. Structured consensus conferences and external reviews ensured that the recommendations were clinically relevant, methodologically sound, and aligned with current antimicrobial stewardship principles.

RESULTS

 For the management of nosocomial pneumonia patients should be divided in those with and without risk factors for multidrug-resistant pathogens and/or Pseudomonas aeruginosa. Bacterial multiplex-polymerase chain reaction (PCR) should not be used routinely. Bronchoscopic diagnosis is not considered superior to non-bronchoscopic sampling in terms of main outcomes. Combination antibiotic therapy is now reserved for patients in septic shock and high risk for multidrug-resistant pathogens, while select patients may be managed with monotherapy (e. g., meropenem). In clinically stabilized patients, antibiotic therapy should be de-escalated and focused, as well as duration shortened to 7-8 days. In critically ill patients, prolonged application of suitable beta-lactam antibiotics should be preferred. Patients on the intensive care unit (ICU) are at risk for invasive pulmonary aspergillosis (IPA). Diagnostics for Aspergillus should be performed with an antigen test from bronchial lavage fluid.

CONCLUSION

 This updated S3 guideline offers a comprehensive, multidisciplinary approach to the management of nosocomial pneumonia in adults. By integrating novel diagnostic modalities and refined therapeutic strategies, it aims to standardize care, improve patient outcomes, and enhance antimicrobial stewardship to curb the emergence of resistant pathogens.

Short, extended and continuous infusion of β-lactams: predicted impact on target attainment and risk for toxicity in an ICU patient cohort

OBJECTIVES

This study aimed to predict the impact of different infusion strategies on pharmacokinetic/pharmacodynamic (PK/PD) target attainment and the potential risk for toxicity in an ICU cohort treated with β-lactams.

METHOD

Using collected patient data from 137 adult ICU patients, and applying population PK models, individual PK parameters were estimated and used to predict concentrations and target attainment following cefotaxime 2 g q8h, piperacillin/tazobactam 4.5 g q6h and meropenem 1 g q8h, applying 15 min short infusions (SI), 3 h extended infusions (EI) and 24 h continuous infusion (CI). The MIC level of the most common primary pathogens, and the worst-case scenario (WCS) pathogen, were used in analyses.

RESULTS

For primary pathogens, target was reached in 94% (129/137) using SI. For WCS pathogens treated with piperacillin/tazobactam and meropenem, 78% (65/83) and 92% (76/83) reached target using SI and EI, respectively. However, target attainment was lower for cefotaxime [SI: 31% (17/54), EI: 44% (24/54)]. Overall, the number of individuals with potentially toxic concentrations was low, both in EI (n = 7) and SI (n = 5). For CI and WCS, target was reached in 50% (27/54), 96% (54/56) and 93% (25/27) for cefotaxime, piperacillin/tazobactam and meropenem, respectively.

CONCLUSIONS

In a Swedish ICU cohort target attainment rates for primary pathogens were high regardless of infusion strategy. In WCS pathogens, SI was insufficient, suggesting the benefit of routine use of EI or CI. However, for cefotaxime, target attainment remained low also with EI and CI. The use of CI might lead to unnecessarily high concentrations, but well-established toxicity levels are lacking and future studies are warranted.

Prolonged vs Intermittent Infusions of β-Lactam Antibiotics in Adults With Sepsis or Septic Shock: A Systematic Review and Meta-Analysis

Importance

There is uncertainty about whether prolonged infusions of β-lactam antibiotics improve clinically important outcomes in critically ill adults with sepsis or septic shock.

Objective

To determine whether prolonged β-lactam antibiotic infusions are associated with a reduced risk of death in critically ill adults with sepsis or septic shock compared with intermittent infusions.

Data Sources

The primary search was conducted with MEDLINE (via PubMed), CINAHL, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov from inception to May 2, 2024.

Study Selection

Randomized clinical trials comparing prolonged (continuous or extended) and intermittent infusions of β-lactam antibiotics in critically ill adults with sepsis or septic shock.

Data Extraction and Synthesis

Data extraction and risk of bias were assessed independently by 2 reviewers. Certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation approach. A bayesian framework was used as the primary analysis approach and a frequentist framework as the secondary approach.

Main Outcomes and Measures

The primary outcome was all-cause 90-day mortality. Secondary outcomes included intensive care unit (ICU) mortality and clinical cure.

Results

From 18 eligible randomized clinical trials that included 9108 critically ill adults with sepsis or septic shock (median age, 54 years; IQR, 48-57; 5961 men [65%]), 17 trials (9014 participants) contributed data to the primary outcome. The pooled estimated risk ratio for all-cause 90-day mortality for prolonged infusions of β-lactam antibiotics compared with intermittent infusions was 0.86 (95% credible interval, 0.72-0.98; I2 = 21.5%; high certainty), with a 99.1% posterior probability that prolonged infusions were associated with lower 90-day mortality. Prolonged infusion of β-lactam antibiotics was associated with a reduced risk of intensive care unit mortality (risk ratio, 0.84; 95% credible interval, 0.70-0.97; high certainty) and an increase in clinical cure (risk ratio, 1.16; 95% credible interval, 1.07-1.31; moderate certainty).

Conclusions and Relevance

Among adults in the intensive care unit who had sepsis or septic shock, the use of prolonged β-lactam antibiotic infusions was associated with a reduced risk of 90-day mortality compared with intermittent infusions. The current evidence presents a high degree of certainty for clinicians to consider prolonged infusions as a standard of care in the management of sepsis and septic shock.

Trial Registration

PROSPERO Identifier: CRD42023399434.

Prolonged versus intermittent β-lactam infusion in sepsis: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The two latest studies on prolonged versus intermittent use of β-lactam antibiotics in patients with sepsis did not reach consistent conclusions, further contributing to the controversy surrounding the effectiveness of the prolonged β-lactam antibiotics infusion strategy. We conducted a systemic review and meta-analysis to evaluate the efficacy and safety of prolonged and intermittent β-lactam infusion in adult patients with sepsis.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane Library databases for original randomized controlled trials comparing prolonged and intermittent β-lactam infusion in sepsis patients. A random-effects model was used to evaluate mortality, clinical success, microbiological success, and adverse events. We also conducted subgroup analyses to explore the impact of various factors on the mortality rates. Relative risk (RR) and corresponding 95% confidence intervals (CIs) were used to calculate the overall effect sizes for dichotomous outcomes. This meta-analysis was registered in PROSPERO (CRD42023463905).

RESULTS

We assessed 15 studies involving 2130 patients. In our comprehensive assessment, we found a significant reduction in all-cause mortality (RR, 0.83; 95% CI 0.72-0.97; P = 0.02) and a notable improvement in clinical success (RR, 1.16; 95% CI 1.03-1.31; P = 0.02) in the prolonged infusion group compared to the intermittent infusion group, whereas microbiological success did not yield statistically significant results (RR, 1.10; 95% CI 0.98-1.23; P = 0.11). No significant differences in adverse events were observed between the two groups (RR, 0.91; 95% CI 0.64-1.29; P = 0.60). Additionally, remarkable conclusions were drawn from subgroup analyses including studies with sample sizes exceeding 20 individuals per group (RR, 0.84; 95%CI 0.72-0.98; P = 0.03), research conducted post-2010 (RR, 0.84; 95%CI 0.72-0.98; P = 0.03), cases involving infections predominantly caused by Gram-negative bacteria (RR, 0.81; 95%CI 0.68-0.96; P = 0.02), as well as the administration of a loading dose (RR, 0.84; 95% CI 0.72-0.97; P = 0.02) and the use of penicillin (RR, 0.61; 95% CI 0.38-0.98; P = 0.04).

CONCLUSIONS

Compared to intermittent infusion, prolonged infusion of β-lactam antibiotics significantly decreases all-cause mortality among patients with sepsis and enhances clinical success without increasing adverse events.

Prolonged vs intermittent intravenous infusion of β-lactam antibiotics for patients with sepsis: a systematic review of randomized clinical trials with meta-analysis and trial sequential analysis

BACKGROUND

The prolonged β-lactam antibiotics infusion has been an attractive strategy in severe infections, because it provides a more stable free drug concentration and a longer duration of free drug concentration above the minimum inhibitory concentration (MIC). We conducted this systematic review of randomized clinical trials (RCTs) with meta-analysis and trial sequential analysis (TSA) to compare the effects of prolonged vs intermittent intravenous infusion of β-lactam antibiotics for patients with sepsis.

METHODS

This study was prospectively registered on PROSPERO database (CRD42023447692). We searched EMBASE, PubMed, and Cochrane Library to identify eligible studies (up to July 6, 2023). Any study meeting the inclusion and exclusion criteria would be included. The primary outcome was all-cause mortality within 30 days. Two authors independently screened studies and extracted data. When the I2 values < 50%, we used fixed-effect mode. Otherwise, the random effects model was used. TSA was also performed to search for the possibility of false-positive (type I error) or false-negative (type II error) results.

RESULTS

A total of 4355 studies were identified in our search, and nine studies with 1762 patients were finally included. The pooled results showed that, compared with intermittent intravenous infusion, prolonged intravenous infusion of beta-lactam antibiotics resulted in a significant reduction in all-cause mortality within 30 days in patients with sepsis (RR 0.82; 95%CI 0.70-0.96; P = 0.01; TSA-adjusted CI 0.62-1.07). However, the certainty of the evidence was rated as low, and the TSA results suggested that more studies were needed to further confirm our conclusion. In addition, it is associated with lower hospital mortality, ICU mortality, and higher clinical cure. No significant reduction in 90-day mortality or the emergence of resistance bacteria was detected between the two groups.

CONCLUSIONS

Prolonged intravenous infusion of beta-lactam antibiotics in patients with sepsis was associated with short-term survival benefits and higher clinical cure. However, the TSA results suggested that more studies are needed to reach a definitive conclusion. In terms of long-term survival benefits, we could not show an improvement.

Real-Life Experience of Continuously Infused Ceftolozane/Tazobactam in Patients with Bronchiectasis and Multidrug-Resistant Pseudomonas aeruginosa Infection in the Outpatient Setting

(1) Background: Ceftolozane/tazobactam (C/T) is a novel β-lactam/β-lactamase inhibitor with excellent activity against the multidrug-resistant (MDR) P. aeruginosa. Continuous infusion (CI) dosing allows the optimization of pharmacokinetic and pharmacodynamic (PK/PD) properties of β-lactam antibiotics and may support patients' treatment as outpatients. (2) Methods: Adult patients receiving their entire course of C/T as a CI in the outpatient setting were retrospectively included in the study. The primary outcome evaluated was clinical resolution. The secondary outcomes evaluated were PK/PD target attainment (ƒT > 4 × MIC) and microbiologic clearance at the end of treatment. Therapeutic drug monitoring to assess C/T concentration was performed. (3) Results: Three patients were enrolled in the study and received 9 g of C/T in CI every 24 h. One patient received an additional course of antimicrobial therapy due to disease exacerbation six months after initial treatment, accounting for four evaluated treatments. The primary outcome was achieved in 3/4 treatments and the secondary outcome was achieved in 4/4 and 3/3, respectively. In all patients, free ceftolozane concentrations were >10 times higher than the EUCAST breakpoint (4 mg/L). (4) Conclusions: Elastomeric infusion of C/T delivered in CI can be an effective and convenient way to treat acute diseases caused by MDR-P. aeruginosa, avoid hospital admission, and contribute to infection control strategies. Despite the small number of enrolled patients, clinical and microbiological results support this strategy.

Extended and Continuous Infusion of Novel Protected β-Lactam Antibiotics: A Narrative Review

Consolidated data from pharmacokinetic and pharmacodynamic studies support the administration of β-lactam antibiotics in prolonged infusion (i.e., extended or continuous) to optimize therapeutic efficacy by increasing the probability of attaining maximal bactericidal activity. This is the longest possible time during which the free drug concentrations are approximately four-fold the minimum inhibitory concentration between dosing intervals. In the context of antimicrobial stewardship strategies, achieving aggressive pharmacokinetic and pharmacodynamic targets is an important tool in the management of multi-drug resistant (MDR) bacterial infections and in the attainment of mutant preventing concentrations. However, prolonged infusion remains an unexploited resource. Novel β-lactam/β-lactamase inhibitor (βL/βLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-cilastatin-relebactam) have been released in recent years to face the emerging challenge of MDR Gram-negative bacteria. Pre-clinical and real-life evidence has confirmed the promising role of prolonged infusion of these molecules in specific settings and clinical populations. In this narrative review we have summarized available pharmacological and clinical data, future perspectives, and current limitations of prolonged infusion of the novel protected β-lactams, their application in hospital settings and in the context of outpatient parenteral antimicrobial therapy.

Update on Therapeutic Drug Monitoring of Beta-Lactam Antibiotics in Critically Ill Patients—A Narrative Review

Beta-lactam antibiotics remain one of the most preferred groups of antibiotics in critical care due to their excellent safety profiles and their activity against a wide spectrum of pathogens. The cornerstone of appropriate therapy with beta-lactams is to achieve an adequate plasmatic concentration of a given antibiotic, which is derived primarily from the minimum inhibitory concentration (MIC) of the specific pathogen. In a critically ill patient, the plasmatic levels of drugs could be affected by many significant changes in the patient’s physiology, such as hypoalbuminemia, endothelial dysfunction with the leakage of intravascular fluid into interstitial space and acute kidney injury. Predicting antibiotic concentration from models based on non-critically ill populations may be misleading. Therapeutic drug monitoring (TDM) has been shown to be effective in achieving adequate concentrations of many drugs, including beta-lactam antibiotics. Reliable methods, such as high-performance liquid chromatography, provide the accurate testing of a wide range of beta-lactam antibiotics. Long turnaround times remain the main drawback limiting their widespread use, although progress has been made recently in the implementation of different novel methods of antibiotic testing. However, whether the TDM approach can effectively improve clinically relevant patient outcomes must be proved in future clinical trials.

Treatment Failure Due to Adaptive Resistance Mechanisms in a Severe and Complicated Bloodstream Infection Due to Elizabethkingia meningoseptica

Elizabethkingia meningoseptica is an uncommonly encountered multidrug-resistant gram-negative bacterium that causes infections primarily among vulnerable hosts. A true opportunistic pathogen, its ability to cause severe sepsis and complicated infection in selected patients has been noted. Very limited preclinical and clinical data exist with regard to suitable therapeutic options. In this study, we present the case of prolonged bloodstream and central nervous system infection due to E. meningoseptica treated with dose-optimized combination antibiotic therapy, with evidence of microbiological (including development of adaptive resistance mechanisms) and clinical failure.

Antimicrobial stewardship

PURPOSE OF REVIEW

The optimal use of antimicrobials is necessary to slow resistance development and improve patient outcomes. Antimicrobial stewardship (AMS) is a bundle of interventions aimed at promoting the responsible use of antiinfectives. The ICU is an important field of activity for AMS because of high rates of antimicrobial use, high prevalence of resistant pathogens and complex pharmacology. This review discusses aims and interventions of AMS with special emphasis on the ICU.

RECENT FINDINGS

AMS-interventions can improve the quality and quantity of antimicrobial prescribing in the ICU without compromising patient outcomes. The de-escalation of empiric therapy according to microbiology results and the limitation of treatment duration are important steps to reduce resistance pressure. Owing to the complex nature of critical illness, the pharmacological optimization of antimicrobial therapy is an important goal in the ICU. AMS-objectives and strategies are also applicable to patients with sepsis. This is reflected in the most recent guidelines by the Surviving Sepsis Campaign. AMS-interventions need to be adapted to their respective setting and be mindful of local prescribing cultures and prescribers' attitudes.

SUMMARY

AMS in the ICU is effective and safe. Intensivists should be actively involved in AMS-programs and propagate responsible use of antimicrobials.

Self-Expandable Metal Stent in the Management of Malignant Airway Disorders

Background

Self-expanding metallic stent (SEMS) is a palliative therapy for patients with malignant central airway obstruction (CAO) or tracheoesophageal fistula (TEF). Despite this, many patients experience death shortly after SEMS placement.

Aims

We aimed to investigate the effect of SEMS on the palliative treatment between malignant CAO and malignant TEF patients and investigate the associated prognostic factors of the 3-month survival.

Methods

We performed a single-center, retrospective study of malignant CAO or TEF patients receiving SEMS placement. Clinical data were collected using the standardized data abstraction forms. Data were analyzed using SPSS 22.0. A two-sided P-value &lt;0.05 was statistically significant.

Results

106 malignant patients (82 CAO and 24 TEF) receiving SEMS placement were included. The body mass index (BMI), hemoglobin levels, and albumin levels in the malignant TEF group were lower than in the malignant CAO group (all P &lt; 0.05). The procalcitonin levels, C-reactive protein levels, and the proportion of inflammatory lesions were higher in the malignant TEF group than in the malignant CAO group (all P &lt; 0.05). The proportion of symptomatic improvement after the SEMS placement was 97.6% in the malignant CAO group, whereas 50.0% in the malignant TEF group, with a significant difference (P = 0.000). Three months after SEMS placement, the survival rate at was 67.0%, significantly lower in the malignant TEF group than in the malignant CAO group (45.8% vs. 73.2%, P = 0.013). Multivariate analysis revealed that BMI [odds ratio (OR) = 1.841, 95% certificated interval (CI) (1.155-2.935), P = 0.010] and neutrophil percentage [OR = 0.936, 95% CI (0.883–0.993), P = 0.027] were the independent risk factors for patients who survived three months after SEMS placement.

Conclusions

We observed symptom improvement in malignant CAO and TEF patients after SEMS placement. The survival rate in malignant TEF patients after SEMS placement was low, probably due to aspiration pneumonitis and malnutrition. Therefore, we recommend more aggressive treatment modalities in patients with malignant TEF, such as strong antibiotics, nutrition support, and strategic ventilation. More studies are needed to investigate the prognostic factors in patients with malignant airway disorders receiving SEMS placement.

Treatment of ventilator-associated pneumonia due to carbapenem-resistant Gram-negative bacteria with novel agents: a contemporary, multidisciplinary ESGCIP perspective

INTRODUCTION

: In the past 15 years, treatment of VAP caused by carbapenem-resistant Gram-negative bacteria (CR-GNB) has represented an intricate challenge for clinicians.

AREAS COVERED

In this perspective article, we discuss the available clinical data about novel agents for the treatment of CR-GNB VAP, together with general PK/PD principles for the treatment of VAP, in the attempt to provide some suggestions for optimizing antimicrobial therapy of CR-GNB VAP in the daily clinical practice.

EXPERT OPINION

Recently, novel BL and BL/BLI combinations have become available that have shown potent in vitro activity against CR-GNB and have attracted much interest as novel, less toxic, and possibly more efficacious options for the treatment of CR-GNB VAP compared with previous standard of care. Besides randomized controlled trials, a good solution to enrich our knowledge on how to use these novel agents at best in the near future, while at the same time remaining adherent to current evidence-based guidelines, is to improve our collaboration to conduct larger multinational observational studies to collect sufficiently large populations treated in real life with those novel agents for which guidelines currently do not provide a recommendation (in favor or against) for certain causative organisms.

Are Antibiotics Appropriately Dosed in Critically Ill Patients with Augmented Renal Clearance? A Narrative Review

AIMS

Augmented renal clearance (ARC), which is commonly defined as increased renal clearance above 130 ml/min/1.73 m², is a common phenomenon among critically ill patients. The increased elimination rate of drugs through the kidneys in patients with ARC can increase the risk of treatment failure due to the exposure to subtherapeutic serum concentrations of medications and affect the optimal management of infections, length of hospital stay, and outcomes. The main goal of this review article is to summarize the recommendations for appropriate dosing of antibiotics in patients with ARC.

METHODS

This article is a narrative review of the articles that evaluated different dosing regimens of antibiotics in patients with ARC. The keywords "Augmented Renal Clearance," "Critically ill patients," "Drug dosing," "Serum concentration," "Beta-lactams," "Meropenem," "Imipenem," "Glycopeptide," "Vancomycin," "Teicoplanin," "Linezolid," "Colistin," "Aminoglycosides," "Amikacin," "Gentamycin," "Fluoroquinolones," "Ciprofloxacin," and "Levofloxacin" were searched in Scopus, Medline, PubMed, and Google Scholar databases, and pediatric, nonhuman, and non-English studies were excluded.

RESULTS

PK properties of antibiotics including lipophilicity or hydrophilicity, protein binding, the volume of distribution, and elimination rate that affect drug concentration should be considered along with PD parameters for drug dosing in critically ill patients with ARC.

CONCLUSION

This review recommends a dosing protocol for some antibiotics to help the appropriate dosing of antibiotics in ARC and decrease the risk of subtherapeutic exposure that may be observed while receiving conventional dosing regimens in critically ill patients with ARC.

Continuous versus intermittent infusion of antibiotics in Gram-negative multidrug-resistant infections

PURPOSE OF REVIEW

The aim of this review was to perform a critical reappraisal of the real-world evidence supporting administration by prolonged infusion of novel beta-lactams for the management of multidrug-resistant Gram-negative infections.

RECENT FINDINGS

Real-world evidence support the use of novel beta-lactams by prolonged infusion over intermittent infusion in terms of achieving aggressive pharmacokinetic/pharmacodynamic (PK/PD) target for either maximizing efficacy and clinical outcome or suppressing the emergence of resistance development. Continuous infusion of ceftolozane-tazobactam showed a marked superiority toward both intermittent and extended infusion (EI) in achieving a PK/PD target of 100%fT> 4 X MIC in infections caused by less-susceptible Pseudomonas aeruginosa isolates. No resistance development was found in critically ill or immunocompromised patients treated with EI ceftolozane-tazobactam compared to intermittent infusion. Prolonged infusion of ceftazidime-avibactam was negatively associated with mortality in patients affected by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae infections. Different challenging scenarios (patients showing augmented renal clearance of affected by deep-seated infections) could benefit from prolonged infusion to optimize the efficacy of novel agents.

SUMMARY

Although available data are still limited, real-world evidence regarding mainly ceftolozane-tazobactam and ceftazidime-avibactam could support the administration of novel beta-lactams by prolonged infusion in some specific scenarios in which achievement of aggressive PK/PD target is quite challenging.

Contemporary Perspective on the Treatment of Acinetobacter baumannii Infections: Insights from the Society of Infectious Diseases Pharmacists

The purpose of this narrative review is to bring together the most recent epidemiologic, preclinical, and clinical findings to offer our perspective on best practices for managing patients with A. baumannii infections with an emphasis on carbapenem-resistant A. baumannii (CRAB). To date, the preferred treatment for CRAB infections has not been defined. Traditional agents with retained in vitro activity (aminoglycosides, polymyxins, and tetracyclines) are limited by suboptimal pharmacokinetic characteristics, emergence of resistance, and/or toxicity. Recently developed and US Food and Drug Administration (FDA)-approved β-lactam/β-lactamase inhibitor agents do not provide enhanced activity against CRAB. On balance, cefiderocol and eravacycline demonstrate potent in vitro activity and are well tolerated, but clinical data for patients with CRAB infections do not yet support widespread use. Given that CRAB has the capacity to infect vulnerable patients and preferred regimens have not been identified, we advocate for combination therapy. Our preferred regimen for critically ill patients infected, or considered to be at high risk for CRAB, includes meropenem, polymyxin B, and ampicillin/sulbactam. Importantly, site of infection, severity of illness, and local epidemiology are essential factors to be considered in selecting combination therapies. Molecular mechanisms of resistance may unveil preferred combinations at individual centers; however, such data are often unavailable to treating clinicians and have not been linked to improved clinical outcomes. Combination strategies may also pose an increased risk for antibiotic toxicity and Clostridioides difficile infection, and should therefore be balanced by understanding patient goals of care and underlying health conditions. Promising therapies that are in clinical development and/or under investigation include durlobactam-sulbactam, cefiderocol combination regimens, and bacteriophage therapy, which may over time eliminate the need for the continued use of polymyxins. Future goals for CRAB management include pathogen-focused treatment paradigms that are based on molecular mechanisms of resistance, local susceptibility rates, and the availability of well-tolerated, effective treatment options.

Pharmacokinetics of meropenem in critically ill patients in Saudi Arabia

Background

Meropenem is commonly used in the ICU to treat gram-negative infections. Due to various pathophysiological changes, critically ill patients are at higher risk of having subtherapeutic concentrations and hence have a higher risk of treatment failure—especially in regions where gram-negative drug resistance is increasing, such as Saudi Arabia. No studies have evaluated the pharmacokinetics of meropenem in critically ill patients in Saudi Arabia. Our primary objective is to assess the percentage of patients achieving the therapeutic target for meropenem.

Methods

This prospective observational study was conducted in the ICUs of King Khalid University Hospital. Patient were included if >18 years-of-age and received meropenem for a clinically suspected or proven bacterial infection. The primary outcome was to assess the percentage of patients who achieved the pharmacokinetic/pharmacodynamic (PKPD) therapeutic target of a free trough concentration four times the MIC. The secondary outcome was to estimate the pharmacokinetics of meropenem. Pharmacokinetic analysis was performed using Monolix Suite 2020R1 (Lixoft, France).

Results

Trough concentrations were highly variable and ranged from <0.5 µg/mL to 39 µg/mL, with a mean ± SD trough concentration of 8.5 ± 8 µg/mL. Only 46% of patients achieved the therapeutic target. The only significant predictor of failing to achieve the PKPD target was augmented renal clearance.

Conclusion

In conclusion, more than half of our patients did not achieve the PKPD target. Thus, there is a need for better dosing strategies of meropenem in critically ill patients in Saudi Arabia such as extended and continuous infusion.

A personalised approach to antibiotic pharmacokinetics and pharmacodynamics in critically ill patients

Critically ill patients admitted to intensive care unit (ICU) with severe infections, or those who develop nosocomial infections, have poor outcomes with substantial morbidity and mortality. Such patients commonly have suboptimal antibiotic exposures at routinely used antibiotic doses related to an increased volume of distribution and altered clearance due to their underlying altered physiology. Furthermore, the use of extracorporeal devices such as renal replacement therapy and extracorporeal membrane oxygenation in these group of patients also has the potential to alter in vivo drug concentrations. Moreover, ICU patients are likely to be infected with less-susceptible pathogens. Therefore, one potential contributing cause to the poor outcomes observed in critically ill patients may be related to subtherapeutic antibiotic exposures. Newer concepts include the clinician considering optimised dosing based on a blood antibiotic exposure defined by pharmacokinetic modelling and therapeutic drug monitoring, combined with a knowledge of the antibiotic penetration into the site of infection, thereby achieving optimal bacterial killing. Such optimised dosing is likely to improve patient outcomes. The aim of this review is to highlight key aspects of antibiotic pharmacokinetics and pharmacodynamics (PK/PD) in critically ill patients and provide a PK/PD approach to tailor antibiotic dosing to the individual patient.

Prolonged Infusion of β-Lactams Decreases Mortality in Patients with Septic Shock: A Retrospective before-and-after Study

Septic shock substantially alters the pharmacokinetic properties of β-lactams with a subsequently high risk of insufficiently low serum concentrations and treatment failure. Considering their pharmacokinetic (PK)/pharmacodynamic (PD) index, prolonged infusions (PI) of β-lactams extend the time that the unbound fraction of the drug remains above the minimal inhibitory concentration MIC (ft _>MIC) and may improve patient survival. The present study is a monocentric, retrospective before-and-after analysis of septic shock patients treated with β-lactams. Patients of the years 2015–2017 received intermittent bolus application whereas patients of 2017–2020 received PI of β-lactams. The primary outcome was mortality at day 30 and 90 after diagnosis of septic shock. Mortality rates in the PI group were significantly lower on day 30 (PI: 41%, n = 119/290 vs. IB: 54.8%, n = 68/114; p = 0.0097) and day 90 (PI: 47.9%, n = 139/290 vs. IB: 62.9%, n = 78/124; p = 0.005). After propensity-score matching, 30- and 90-day mortality remained lower for the PI group (−10%, p = 0.14). PI was further associated with a reduction in the duration of invasive ventilation and a stronger decrease in SOFA scores within a 14 day-observation period. PI of β-lactams was associated with a significant reduction of mortality in patients with septic shock and may have beneficial effects on invasive ventilation and recovery from sepsis-related organ failure.

Pharmacokinetic/pharmacodynamic target attainment in critically ill renal patients on antimicrobial usage: focus on novel beta-lactams and beta lactams/beta-lactamase inhibitors

INTRODUCTION

Several novel beta-lactams (BLs) and/or beta lactams/beta-lactamase inhibitors (BL/BLIs) have been recently developed for the management of multidrug-resistant bacterial infections. Data concerning dose optimization in critically ill patients with altered renal function are scanty.

AREAS COVERED

This article provides a critical reappraisal of pharmacokinetic and clinical issues emerged with novel BLs and/or BL/BLIs in renal critically ill patients. Clinical and pharmacokinetic studies published in English until December 2020 were searched on the PubMed-MEDLINE database.

EXPERT OPINION

Several issues emerged with the use of novel BLs and/or BL/BLIs in critically ill renal patients. Suboptimal clinical response rate with ceftazidime-avibactam and ceftolozane-tazobactam was reported in phase II-III trials in patients with moderate kidney injury; data on patients undergoing renal replacement therapy are limited to some case reports; dose adjustment in augmented renal clearance is provided only for cefiderocol. Implementation of altered dosing strategies (prolonged infusion and/or higher dosage) coupled with adaptive real-time therapeutic drug monitoring could represent the most effective approach in warranting optimal pharmacokinetic/pharmacodynamic targets with novel BLs and/or BL/BLIs in challenging scenarios, thus minimizing the risk of clinical failure and/or of resistance selection.