Individualised antibiotic dosing for patients who are critically ill: challenges and potential solutions

Antimicrobial dosing recommendations during continuous renal replacement therapy: different databases, different doses

Meticulous antimicrobial management is essential among critically ill patients with acute kidney injury, particularly if renal replacement therapy is needed. Many factors affect drug removal in patients undergoing continuous renal replacement therapy CRRT. In this study, we aimed to compare current databases that are frequently used to adjust CRRT dosages of antimicrobial drugs with the gold standard. The dosage recommendations from various databases for antimicrobial drugs eliminated by CRRT were investigated. The book 'Renal Pharmacotherapy: Dosage Adjustment of Medications Eliminated by the Kidneys' was chosen as the gold standard. There were variations in the databases. Micromedex, UpToDate, and Sanford had similar rates to the gold standard of 45%, 35%, and 30%, respectively. The Micromedex database shows the most similar results to the gold standard source. In addition, a consensus was reached as a result of the expert panel meetings established to discuss the different antimicrobial dose recommendations of the databases.

The effects of single and multiple resistance mechanisms on bacterial response to meropenem

OBJECTIVES

Meropenem is commonly used against Pseudomonas aeruginosa. Traditionally, the time unbound antibiotic concentration exceeds the MIC (fT>MIC) is used to select carbapenem regimens. We aimed to characterize the effects of different baseline resistance mechanisms on bacterial killing and resistance emergence; evaluate whether fT>MIC can predict these effects; and, develop a novel Quantitative and Systems Pharmacology (QSP) model to describe the effects of baseline resistance mechanisms on the time-course of bacterial response.

METHODS

Seven isogenic P. aeruginosa strains with a range of resistance mechanisms and MICs were used in 10-day hollow-fiber infection model studies. Meropenem pharmacokinetic profiles were simulated for various regimens (t1/2,meropenem = 1.5 h). All viable counts on drug-free, 3 × MIC, and 5 × MIC meropenem-containing agar across all strains, five regimens, and control (n = 90 profiles) were simultaneously subjected to QSP modeling. Whole genome sequencing was completed for total population samples and emergent resistant colonies at 239 h.

RESULTS

Regimens achieving ≥98%fT>1×MIC suppressed resistance emergence of the mexR knockout strain. Even 100%fT>5 × MIC failed to achieve this against the strain with OprD loss and the ampD and mexR double-knockout strain. Baseline resistance mechanisms affected bacterial outcomes, even for strains with the same MIC. Genomic analysis revealed that pre-existing resistant subpopulations drove resistance emergence. During meropenem exposure, mutations in mexR were selected in strains with baseline oprD mutations, and vice versa, confirming these as major mechanisms of resistance emergence. Secondary mutations occurred in lysS or argS, coding for lysyl and arginyl tRNA synthetases, respectively.

DISCUSSION

The QSP model well-characterized all bacterial outcomes of the seven strains simultaneously, which fT>MIC could not.

Healthcare as a driver, reservoir and amplifier of antimicrobial resistance: opportunities for interventions

Antimicrobial resistance (AMR) is a global health challenge that threatens humans, animals and the environment. Evidence is emerging for a role of healthcare infrastructure, environments and patient pathways in promoting and maintaining AMR via direct and indirect mechanisms. Advances in vaccination and monoclonal antibody therapies together with integrated surveillance, rapid diagnostics, targeted antimicrobial therapy and infection control measures offer opportunities to address healthcare-associated AMR risks more effectively. Additionally, innovations in artificial intelligence, data linkage and intelligent systems can be used to better predict and reduce AMR and improve healthcare resilience. In this Review, we examine the mechanisms by which healthcare functions as a driver, reservoir and amplifier of AMR, contextualized within a One Health framework. We also explore the opportunities and innovative solutions that can be used to combat AMR throughout the patient journey. We provide a perspective on the current evidence for the effectiveness of interventions designed to mitigate healthcare-associated AMR and promote healthcare resilience within high-income and resource-limited settings, as well as the challenges associated with their implementation.

High-dose colistin pharmacokinetics in critically ill patients receiving continuous renal replacement therapy

BACKGROUND

Colistin, administered as intravenous colistimethate (CMS), is still used in the critical care setting and current guidelines recommend high dosage CMS in patients undergoing continuous renal replacement therapy (CRRT). Due to the paucity of real-life data, we aimed to describe colistin pharmacokinetic/pharmacodynamic (PK/PD) profile in a cohort of critically ill patients with infections due to carbapenem-resistant (CR) bacteria undergoing CRRT.

RESULTS

All consecutive patients admitted to three Intensive Care Units (ICUs) of a large metropolitan University Hospital, treated with colistin for at least 48 h at the dosage of 6.75 MUI q12, after 9 MIU loading dose, and undergoing CRRT were included. After the seventh dose, patients underwent blood serial sampling during a time frame of 24 h. We included 20 patients, who had CR-Acinetobacter baumannii ventilator-associated pneumonia and were characterized by a median SAPS II and SOFA score of 41 [34.5-59.3] and 9 [6.7-11], respectively. Fifteen patients died during ICU stay and six recovered renal function. Median peak and trough colistin concentrations were 16.6 mcg/mL [14.8-20.6] and 3.9 mcg/mL [3.3-4.4], respectively. Median area under the time-concentration curve (AUC0 - 24) and average steady-state concentration (Css, avg) were 193.9 mcg h/mL [170.6-208.6] and 8.07 mcg/mL [7.1-8.7]. Probability of target attainment of colistin pharmacodynamics according to the fAUC0 - 24/MIC target ≥ 12 was 100% for MIC ≤ 2 mcg/mL and 85% for MIC = 4 mcg/ML, although exceeding the toxicity limit of Css, avg 3-4 mcg/mL.

CONCLUSIONS

In critically ill patients with CR infections undergoing CRRT, recommended CMS dosage resulted in colistin plasmatic levels above bacterial MIC90, but exceeding the safety Css, avg. limit.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov on 23/07/2021 with the ID NCT04995133 (https//clinicaltrials.gov/study/NCT04995133).

Physiologically-based pharmacokinetic modelling in sepsis; a tool to elucidate how pathophysiology affects meropenem pharmacokinetics: A PBPK model of meropenem in sepsis

Applying physiologically-based pharmacokinetic (PBPK) modelling in sepsis could help to better understand how PK changes are influenced by drug- and patient-related factors. We aimed to elucidate the influence of sepsis pathophysiology on the PK of meropenem by applying PBPK modelling. A whole-body meropenem PBPK model was developed and evaluated in healthy individuals, and renally impaired non-septic patients. Sepsis-induced physiological changes in body composition, organ blood flow, kidney function, albumin, and haematocrit were implemented according to a previously proposed PBPK sepsis model. Model performance was evaluated, and a local sensitivity analysis was conducted. The model-predicted PK metrics (AUC, Cmax, CL, Vss) were within 1.33-fold-error margin of published data for 87.5% of the simulated profiles in healthy individuals. In sepsis, the model provided good predictions for literature-digitised average plasma and tissue exposure data, where the model-predicted AUC was within 1.33-fold-error margin for 9 out 11 simulated study profiles. Furthermore, the model was applied to individual plasma concentration data from 52 septic patients, where the model-predicted AUC, Cmax, and CL had a fold-error ratio range of 0.98-1.12, with alignment of the predicted and observed variability. For Vss, the fold-error ratio was 0.81, and the model underpredicted the population variability. CL was sensitive to renal plasma clearance, and kidney volume, whereas Vss was sensitive to the unbound fraction, organ volume fraction of the interstitial compartment, and the organ volume. These findings may be extended to more diverse drug types and support a more mechanistic understanding of the effect of sepsis on drug exposure.

Clinical pharmacokinetics of antimicrobials in critical care: a narrative review

INTRODUCTION

The management of critically ill septic patients presents considerable challenges due to multifaceted physiological alterations. Rapid changes such as fluid shifts, hyperdynamic states, and altered renal clearance often require special attention for better clinical outcomes. Vital organ dysfunction, with or without MODS, often necessitates supportive management like RRT, ventilatory support, and ECMO. These interventions can significantly affect the PK/PD of administered antimicrobials, complicating effective treatment.

AREA COVERED

Patient-specific parameters such as age, weight, and comorbid illnesses (e.g. cystic fibrosis, burns, and immunocompromised states) are critical determinants of antimicrobial pharmacokinetics. Understanding PK/PD determinants is crucial for developing optimized dosing regimens that enhance therapeutic efficacy and minimize toxicity in critically ill patients.

EXPERT OPINION

Incorporating pharmacometrics approaches in dose optimization can significantly improve patient outcomes. This review focuses on the nuances of PK/PD for optimized antimicrobial dosing in critically ill septic patients, emphasizing the importance of individualized treatment plans to address the complex and dynamic needs of this patient population. The adoption of these advanced pharmacokinetic and pharmacodynamic principles into clinical practice is essential for advancing patient care and optimizing therapeutic outcomes in critically ill patients.

Artificial Intelligence to Close the Gap between Pharmacokinetic/Pharmacodynamic Targets and Clinical Outcomes in Critically Ill Patients: A Narrative Review on Beta Lactams

Antimicrobial dosing can be a complex challenge. Although a solid rationale exists for a link between antibiotic exposure and outcome, conflicting data suggest a poor correlation between pharmacokinetic/pharmacodynamic targets and infection control. Different reasons may lead to this discrepancy: poor tissue penetration by β-lactams due to inflammation and inadequate tissue perfusion; different bacterial response to antibiotics and biofilms; heterogeneity of the host's immune response and drug metabolism; bacterial tolerance and acquisition of resistance during therapy. Consequently, either a fixed dose of antibiotics or a fixed target concentration may be doomed to fail. The role of biomarkers in understanding and monitoring host response to infection is also incompletely defined. Nowadays, with the ever-growing stream of data collected in hospitals, utilizing the most efficient analytical tools may lead to better personalization of therapy. The rise of artificial intelligence and machine learning has allowed large amounts of data to be rapidly accessed and analyzed. These unsupervised learning models can apprehend the data structure and identify homogeneous subgroups, facilitating the individualization of medical interventions. This review aims to discuss the challenges of β-lactam dosing, focusing on its pharmacodynamics and the new challenges and opportunities arising from integrating machine learning algorithms to personalize patient treatment.

Precision Dosing of Meropenem in Adults with Normal Renal Function: Insights from a Population Pharmacokinetic and Monte Carlo Simulation Study

This study aimed to develop a population pharmacokinetic (PK) model for meropenem in healthy adults and explore optimal dosing regimens for patients with normal renal function. PK samples were obtained from 12 healthy participants, which were analyzed using noncompartmental analysis and nonlinear mixed-effect modeling. The PK profiles of meropenem were characterized using a two-compartment model, and serum creatinine level was identified as a significant covariate affecting total clearance. Monte Carlo simulations were conducted using this model to inform dosing recommendations. The target index for meropenem efficacy was defined as the cumulative percentage over 24 h during which free (f) drug concentration exceeded the minimum inhibitory concentration (MIC) under steady state conditions (fT>MIC). These simulations indicated that the current dosage regimen of 1 g for 30 min infusions every 8 h achieved a 90% probability of target attainment (PTA) for 40%fT>MIC when the MIC was <2 mg/L. However, to achieve more stringent therapeutic targets, such as a 90%PTA for 100%fT>MIC or a 90%PTA for 100%fT>4MIC, higher doses administered as 3 h extended infusions or as continuous infusions may be necessary. These results highlight the need for model-informed precision dosing to enhance the efficacy of meropenem therapy across various MIC levels and therapeutic targets.

A Systematic Review of the Pharmacokinetics and Pharmacodynamics of Novel Beta-Lactams and Beta-Lactam with Beta-Lactamase Inhibitor Combinations for the Treatment of Pneumonia Caused by Carbapenem-Resistant Gram-Negative Bacteria

BACKGROUND

Novel beta-lactams show activity against many multidrug-resistant Gram-negative bacteria that cause severe lung infections. Understanding pharmacokinetic/pharmacodynamic characteristics of these agents may help optimise outcomes in the treatment of pneumonia.

OBJECTIVES

To describe and appraise studies that report pulmonary pharmacokinetic and pharmacodynamic data of cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam and meropenem/vaborbactam.

METHODS

MEDLINE (PubMed), Embase, Web of Science and Scopus libraries were used for the literature search. Pulmonary population pharmacokinetic and pharmacokinetic/pharmacodynamic studies on adult patients receiving cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam, and meropenem/vaborbactam published in peer-reviewed journals were included. Two independent authors screened, reviewed and extracted data from included articles. A reporting guideline for clinical pharmacokinetic studies (ClinPK statement) was used for bias assessment. Relevant outcomes were included, such as population pharmacokinetic parameters and probability of target attainment of dosing regimens.

RESULTS

Twenty-four articles were included. There was heterogeneity in study methods and reporting of results, with diversity across studies in adhering to the ClinPK statement checklist. Ceftolozane/tazobactam was the most studied agent. Only two studies collected epithelial lining fluid samples from patients with pneumonia. All the other phase I studies enrolled healthy subjects. Significant population heterogeneity was evident among available population pharmacokinetic models. Probabilities of target attainment rates above 90% using current licensed dosing regiments were reported in most studies.

CONCLUSIONS

Although lung pharmacokinetics was rarely described, this review observed high target attainment using plasma pharmacokinetic data for all novel beta-lactams. Future studies should describe lung pharmacokinetics in patient populations at risk of carbapenem-resistant pathogen infections.

Prediction of teicoplanin plasma concentration in critically ill patients: a combination of machine learning and population pharmacokinetics

BACKGROUND

Teicoplanin has been widely used in patients with infections caused by Staphylococcus aureus, especially for critically ill patients. The pharmacokinetics (PK) of teicoplanin vary between individuals and within the same individual. We aim to establish a prediction model via a combination of machine learning and population PK (PPK) to support personalized medication decisions for critically ill patients.

METHODS

A retrospective study was performed incorporating 33 variables, including PPK parameters (clearance and volume of distribution). Multiple algorithms and Shapley additive explanations were employed for feature selection of variables to determine the strongest driving factors.

RESULTS

The performance of each algorithm with PPK parameters was superior to that without PPK parameters. The composition of support vector regression, categorical boosting and a backpropagation neural network (7:2:1) with the highest R2 (0.809) was determined as the final ensemble model. The model included 15 variables after feature selection, of which the predictive performance was superior to that of models considering all variables or using only PPK. The R2, mean absolute error, mean squared error, absolute accuracy (±5 mg/L) and relative accuracy (±30%) of external validation were 0.649, 3.913, 28.347, 76.12% and 76.12%, respectively.

CONCLUSIONS

Our study offers a non-invasive, fast and cost-effective prediction model of teicoplanin plasma concentration in critically ill patients. The model serves as a fundamental tool for clinicians to determine the effective plasma concentration range of teicoplanin and formulate individualized dosing regimens accordingly.

Risk Factors Associated with Antibiotic Exposure Variability in Critically Ill Patients: A Systematic Review

(1) Background: Knowledge about the behavior of antibiotics in critically ill patients has been increasing in recent years. Some studies have concluded that a high percentage may be outside the therapeutic range. The most likely cause of this is the pharmacokinetic variability of critically ill patients, but it is not clear which factors have the greatest impact. The aim of this systematic review is to identify risk factors among critically ill patients that may exhibit significant pharmacokinetic alterations, compromising treatment efficacy and safety. (2) Methods: The search included the PubMed, Web of Science, and Embase databases. (3) Results: We identified 246 observational studies and ten clinical trials. The most studied risk factors in the literature were renal function, weight, age, sex, and renal replacement therapy. Risk factors with the greatest impact included renal function, weight, renal replacement therapy, age, protein or albumin levels, and APACHE or SAPS scores. (4) Conclusions: The review allows us to identify which critically ill patients are at a higher risk of not reaching therapeutic targets and helps us to recognize the extensive number of risk factors that have been studied, guiding their inclusion in future studies. It is essential to continue researching, especially in real clinical practice and with clinical outcomes.

Recommended doses of endovenous vancomycin are insufficient to achieve therapeutic concentrations in paediatric patients

OBJECTIVES

Vancomycin therapeutic drug monitoring is challenging, especially in the paediatric population where evidence is scarce. The main objective of this study was to analyse the achievement of therapeutic concentrations of vancomycin in paediatric patients and to evaluate the current monitoring method (trough levels), doses used, and the time required to achieve target concentrations.

METHODS

Paediatric patients on treatment and monitored with vancomycin from November 2019 to December 2021 were included. Those with only one determination of serum vancomycin concentration were excluded. Demographic variables, analytical and microbiological parameters and toxicity data were collected. Pharmacokinetic parameters were assessed at baseline and during treatment.

RESULTS

225 patients (40.9% female; 108 neonates, 49 infants and 68 children or adolescents) were included in the study. The main indications for vancomycin treatment were sepsis (33.9%) and fever of unknown origin (29.3%). Microbiological cultures were positive in 71.1%, mostly with Gram-positive bacteria (60.4%). Therapeutic levels of vancomycin were reached in only 20.1% of the participants in the first determination. After pharmacokinetic monitoring, 81.7% of patients reached therapeutic concentrations, requiring a 23% increase in the initial dose, a 2-day lag time and 1-2 dosage adjustments until the therapeutic concentration was reached. Of the total patients, 13 developed nephrotoxicity, nine neutropenia and one patient developed red man syndrome.

CONCLUSIONS

In our sample of paediatric patients, the recommended doses of vancomycin were insufficient to achieve therapeutic concentrations. Revision of the recommendations and/or a change in the method of pharmacokinetic monitoring is crucial to optimise treatment in this population.

Antimicrobial infusion practices within intensive care units: Carbapenem infusion preparation and administration process errors

OBJECTIVE

To describe nurse preparation and administration of intermittent carbapenem infusions.

RESEARCH METHODOLOGY/DESIGN

This observational study documented the carbapenem infusion process to adult patients in three general intensive care units.

MAIN OUTCOME MEASURES

Timing and duration of infusions were observed. Volumetric analysis of infusion items was conducted to determine loss of reconstituted carbapenem during preparation and administration phases.

RESULTS

Carbapenem infusions (n = 223) administered to twenty adult patients were observed. Infusion duration guidance was variable, with two ICUs following current literature recommendations, and one ICU referring to medication package insert information. Within these parameters, only 60 % of infusions complied with infusion duration. Non-compliance with planned time of administration impacted on desired dosing intervals. Incomplete delivery of intended dose was found during: sub-optimal reconstitution of vials, incorrect number of vials reconstituted, failure to administer a dose (missed dose), and discarding antibiotic residue in infusion items. Volumetric analysis of infusion items showed mean dose losses of 4.9 % and 1.2 % in discarded vials and syringes. Mean drug losses of 6.3 % and 30.8 % occurred in discarded infusion bags and infusion lines respectively. No flushing guidance or practice was observed.

CONCLUSION

Incorrect nurse administration of antibiotics resulted in varying durations of infusions and the non-delivery of prescribed dose. Under-dosing has the potential to contribute to selection pressure for bacterial antibiotic resistance. The increasing frequency of intravenous delivery of antimicrobial agents through infusions requires an understanding of the required duration of administration and how to manage residual drug remaining in the intravenous line once the infusion is completed.

IMPLICATIONS FOR CLINICAL PRACTICE

Flushing of administration lines is not common practice following intermittent antimicrobial infusions. Although there are multi-factorial risk factors for antimicrobial resistance in the critical care arena, nurse infusion practice must ensure that patients receive intended antimicrobial treatment. Attention must be given to the potential for antimicrobial resistance from environmental contamination with the disposal of infusion items containing undelivered antimicrobial medication.

Physiologically-based pharmacokinetic/pharmacodynamic modeling of meropenem in critically ill patients

This study aimed to develop a physiologically based pharmacokinetic/pharmacodynamic model (PBPK/PD) of meropenem for critically ill patients. A PBPK model of meropenem in healthy adults was established using PK-Sim software and subsequently extrapolated to critically ill patients based on anatomic and physiological parameters. The mean fold error (MFE) and geometric mean fold error (GMFE) methods were used to compare the differences between predicted and observed values of pharmacokinetic parameters Cmax, AUC0-∞, and CL to evaluate the accuracy of the PBPK model. The model was verified using meropenem plasma samples obtained from Intensive Care Unit (ICU) patients, which were determined by HPLC-MS/MS. After that, the PBPK model was combined with a PKPD model, which was developed based on f%T > MIC. Monte Carlo simulation was utilized to calculate the probability of target attainment (PTA) in patients. The developed PBPK model successfully predicted the meropenem disposition in critically ill patients, wherein the MFE average and GMFE of all predicted PK parameters were within the 1.25-fold error range. The therapeutic drug monitoring (TDM) of meropenem was conducted with 92 blood samples from 31 ICU patients, of which 71 (77.17%) blood samples were consistent with the simulated value. The TDM results showed that meropenem PBPK modeling is well simulated in critically ill patients. Monte Carlo simulations showed that extended infusion and frequent administration were necessary to achieve curative effect for critically ill patients, whereas excessive infusion time (> 4 h) was unnecessary. The PBPK/PD modeling incorporating literature and prospective study data can predict meropenem pharmacokinetics in critically ill patients correctly. Our study provides a reference for dose adjustment in critically ill patients.

Model-informed precision dosing: State of the art and future perspectives

Model-informed precision dosing (MIPD) stands as a significant development in personalized medicine to tailor drug dosing to individual patient characteristics. MIPD moves beyond traditional therapeutic drug monitoring (TDM) by integrating mathematical predictions of dosing, and considering patient-specific factors (patient characteristics, drug measurements) as well as different sources of variability. For this purpose, rigorous model qualification is required for the application of MIPD in patients. This review delves into new methods in model selection and validation, also highlighting the role of machine learning in improving MIPD, the utilization of biosensors for real-time monitoring, as well as the potential of models integrating biomarkers for efficacy or toxicity for precision dosing. The clinical evidence of TDM and MIPD is discussed for various medical fields including infection medicine, oncology, transplant medicine, and inflammatory bowel diseases, thereby underscoring the role of pharmacokinetics/pharmacodynamics and specific biomarkers. Further research, particularly randomized clinical trials, is warranted to corroborate the value of MIPD in enhancing patient outcomes and advancing personalized medicine.

Physiologically Based Pharmacokinetic Modeling of Vancomycin in Critically Ill Neonates: Assessing the Impact of Pathophysiological Changes

Dosing vancomycin for critically ill neonates is challenging owing to substantial alterations in pharmacokinetics (PKs) caused by variability in physiology, disease, and clinical interventions. Therefore, an adequate PK model is needed to characterize these pathophysiological changes. The intent of this study was to develop a physiologically based pharmacokinetic (PBPK) model that reflects vancomycin PK and pathophysiological changes in neonates under intensive care. PK-sim software was used for PBPK modeling. An adult model (model 0) was established and verified using PK profiles from previous studies. A neonatal model (model 1) was then extrapolated from model 0 by scaling age-dependent parameters. Another neonatal model (model 2) was developed based not only on scaled age-dependent parameters but also on quantitative information on pathophysiological changes obtained via a comprehensive literature search. The predictive performances of models 1 and 2 were evaluated using a retrospectively collected dataset from neonates under intensive care (chictr.org.cn, ChiCTR1900027919), comprising 65 neonates and 92 vancomycin serum concentrations. Integrating literature-based parameter changes related to hypoalbuminemia, small-for-gestational-age, and co-medication, model 2 offered more optimized precision than model 1, as shown by a decrease in the overall mean absolute percentage error (50.6% for model 1; 37.8% for model 2). In conclusion, incorporating literature-based pathophysiological changes effectively improved PBPK modeling for critically ill neonates. Furthermore, this model allows for dosing optimization before serum concentration measurements can be obtained in clinical practice.

Novel Antibiotics for Gram-Negative Nosocomial Pneumonia

Nosocomial pneumonia, including hospital-acquired pneumonia and ventilator-associated pneumonia, is the leading cause of death related to hospital-acquired infections among critically ill patients. A growing proportion of these cases are attributed to multi-drug-resistant (MDR-) Gram-negative bacteria (GNB). MDR-GNB pneumonia often leads to delayed appropriate treatment, prolonged hospital stays, and increased morbidity and mortality. This issue is compounded by the increased toxicity profiles of the conventional antibiotics required to treat MDR-GNB infections. In recent years, several novel antibiotics have been licensed for the treatment of GNB nosocomial pneumonia. These novel antibiotics are promising therapeutic options for treatment of nosocomial pneumonia by MDR pathogens with certain mechanisms of resistance. Still, antibiotic resistance remains an evolving global crisis, and resistance to novel antibiotics has started emerging, making their judicious use crucial to prolong their shelf-life. This article presents an up-to-date review of these novel antibiotics and their current role in the antimicrobial armamentarium. We critically present data for the pharmacokinetics/pharmacodynamics, the in vitro spectrum of antimicrobial activity and resistance, and in vivo data for their clinical and microbiological efficacy in trials. Where possible, available data are summarized specifically in patients with nosocomial pneumonia, as this cohort may exhibit 'critical illness' physiology that affects drug efficacy.

Individualized, dynamic, and full-course vancomycin dosing prediction: a study on the customized dose model

Purpose

The single-point trough-based therapeutic drug monitoring (TDM) and Bayesian forecasting approaches are still limited in individualized and dynamic vancomycin delivery. Until recently, there has not yet been enough focus on the direct integration of pharmacokinetic/pharmacodynamic (PK/PD) and TDM to construct a customized dose model (CDM) for vancomycin to achieve individualized, dynamic, and full-course dose prediction from empirical to follow-up treatment. This study sought to establish CDM for vancomycin, test its performance and superiority in clinical efficacy prediction, formulate a CDM-driven full-course dosage prediction strategy to overcome the above challenge, and predict the empirical vancomycin dosages for six Staphylococci populations and four strains in patients with various creatinine clearance rates (CLcr).

Methods

The PK/PD and concentration models derived from our earlier research were used to establish CDM. The receiver operating characteristic (ROC) curve, with the area under ROC curve (AUCR) as the primary endpoint, for 21 retrospective cases was applied to test the performance and superiority of CDM in clinical efficacy prediction by comparison to the current frequently-used dose model (FDM). A model with an AUCR of at least 0.8 was considered acceptable. Based on the availability of TDM, the strategy of CDM-driven individualized, dynamic, and full-course dose prediction for vancomycin therapy was formulated. Based on the CDM, Monte Carlo simulation was used to predict the empirical vancomycin dosages for the target populations and bacteria.

Results

Four CDMs and the strategy of CDM-driven individualized, dynamic, and full-course dose prediction for vancomycin therapy from empirical to follow-up treatment were constructed. Compared with FDM, CDM showed a greater AUCR value (0.807 vs. 0.688) in clinical efficacy prediction. The empirical vancomycin dosages for six Staphylococci populations and four strains in patients with various CLcr were predicted.

Conclusion

CDM is a competitive individualized dose model. It compensates for the drawbacks of the existing TDM technology and Bayesian forecasting and offers a straightforward and useful supplemental approach for individualized and dynamic vancomycin delivery. Through mathematical modeling of the vancomycin dosage, this study achieved the goal of predicting doses individually, dynamically, and throughout, thus promoting "mathematical knowledge transfer and application" and also providing reference for quantitative and personalized research on similar drugs.

From Bed to Bench: Pre-analytical Stability of 29 Anti-infective Agents in Plasma and Whole Blood to Improve Accuracy of Therapeutic Drug Monitoring

BACKGROUND

Therapeutic drug monitoring requires a validated assay and appropriate conditions for sample shipment and storage based on the stability of the compound to be analyzed. This study evaluated the stability of 29 antimicrobial compounds in whole blood (WB) and plasma samples under various storage conditions.

METHODS

The pre-analytical stability of 22 antibiotics (amoxicillin, aztreonam, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftobiprole, ceftolozane, ceftriaxone, ciprofloxacin, clindamycin, cloxacillin, daptomycin, levofloxacin, linezolid, meropenem, metronidazole, moxifloxacin, piperacillin, sulfamethoxazole, and trimethoprim), 2 beta-lactamase inhibitors (avibactam, tazobactam), and 5 antituberculosis drugs (ethambutol, isoniazid, pyrazinamide, rifabutin, and rifampicin) was assessed by WB for up to 24 hours at room temperature (RT) and 72 hours at +4°C. The stability in plasma was evaluated for up to 6 hours at RT, 24 hours at +4°C, 1 month at -20°C, and 6 months at -80°C.

RESULTS

Concerning WB stability, all investigated compounds were stable for 24 hours at RT, except meropenem and isoniazid, which were stable for 6 hours; however, for 24 hours at +4°C, all the compounds were stable. For storage durations of 48 and 72 hours at +4°C, all compounds were stable, except for ciprofloxacin, cotrimoxazole, and isoniazid. Concerning stability in plasma, all compounds were stable for 6 hours at RT, and all except isoniazid were stable for 24 hours at +4°C. All the tested compounds were stable for 7 days at -20°C, except isoniazid, for which a degradation of approximately 20% was observed. An important degradation was observed for beta-lactam antibiotics after 1 month at -20°C. All compounds were stable at -80°C for 6 months.

CONCLUSIONS

The pre-analytical stabilities of several anti-infective compounds was described. The present results can be used to determine the appropriate conditions for shipping and storing samples dedicated to therapeutic drug monitoring of the investigated compounds.

Population pharmacokinetics of daptomycin in critically ill patients receiving extracorporeal membrane oxygenation

BACKGROUND

Daptomycin is widely used in critically ill patients for Gram-positive bacterial infections. Extracorporeal membrane oxygenation (ECMO) is increasingly used in this population and can potentially alter the pharmacokinetic (PK) behaviour of antibiotics. However, the effect of ECMO has not been evaluated in daptomycin. Our study aims to explore the effect of ECMO on daptomycin in critically ill patients through population pharmacokinetic (PopPK) analysis and to determine optimal dosage regimens based on both efficacy and safety considerations.

METHODS

A prospective, open-label PK study was carried out in critically ill patients with or without ECMO. The total concentration of daptomycin was determined by UPLC-MS/MS. NONMEM was used for PopPK analysis and Monte Carlo simulations.

RESULTS

Two hundred and ninety-three plasma samples were collected from 36 critically ill patients, 24 of whom received ECMO support. A two-compartment model with first-order elimination can best describe the PK of daptomycin. Creatinine clearance (CLCR) significantly affects the clearance of daptomycin while ECMO has no significant effect on the PK parameters. Monte Carlo simulations showed that, when the MICs for bacteria are  ≥1 mg/L, the currently recommended dosage regimen is insufficient for critically ill patients with CLCR > 30 mL/min. Our simulations suggest 10 mg/kg for patients with CLCR between 30 and 90 mL/min, and 12 mg/kg for patients with CLCR higher than 90 mL/min.

CONCLUSIONS

This is the first PopPK model of daptomycin in ECMO patients. Optimal dosage regimens considering efficacy, safety, and pathogens were provided for critical patients based on pharmacokinetic-pharmacodynamic analysis.

Integrating microneedles and sensing strategies for diagnostic and monitoring applications: The state of the art

Microneedles (MNs) offer minimally-invasive access to interstitial fluid (ISF) - a potent alternative to blood in terms of monitoring physiological analytes. This property is particularly advantageous for the painless detection and monitoring of drugs and biomolecules. However, the complexity of the skin environment, coupled with the inherent nature of the analytes being detected and the inherent physical properties of MNs, pose challenges when conducting physiological monitoring using this fluid. In this review, we discuss different sensing mechanisms and highlight advancements in monitoring different targets, with a particular focus on drug monitoring. We further list the current challenges facing the field and conclude by discussing aspects of MN design which serve to enhance their performance when monitoring different classes of analytes.

Development and Quality Control of a Population Pharmacokinetic Model Library for Caspofungin

BACKGROUND

Caspofungin is an echinocandin antifungal agent commonly used as the first-line therapy for invasive candidiasis, salvage therapy for invasive aspergillosis, and empirical therapy for presumed fungal infections. Pharmacokinetic (PK) variabilities and suboptimal exposure have been reported for caspofungin, increasing the risk of insufficient efficacy.

OBJECTIVE

This work aimed to develop a caspofungin population pharmacokinetic (popPK) library and demonstrate its utility by assessing the probability of target attainment across diverse settings.

METHODS

We established a caspofungin popPK model library following a rigorous literature review, re-implementing selected models in R with rxode2. Quality control procedures included a comparison of different studies and assessing covariate impacts. Model libraries were primarily used to perform Monte Carlo simulations to estimate target attainment and guide personalized dosing in Candida infections.

RESULTS

A total of 13 models, one- or two-compartment models, were included. The most significant covariates were body size (weight and body surface area), liver function, and albumin level. The results show that children and adults showed considerable differences in pharmacokinetics. For C. albicans and C. parapsilosis, none of the populations achieved a PTA of ≥90% at their respective susceptible MIC values. In contrast, for C. glabrata, 70% of the adult studies reached a PTA of ≥90%, while all pediatric studies achieved the same PTA level.

CONCLUSION

At the recommended dosage, adult patients showed notably lower exposure to caspofungin compared to pediatric patients. Considering body size, liver function, and serum albumin is crucial when determining caspofungin dosage regimens. Furthermore, further research is required to comprehensively understand the pharmacokinetics of caspofungin in pediatric patients.

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients

INTRODUCTION

Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients, effective monitoring assays and dose adjustment strategies are needed.

AREAS COVERED

This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients.

EXPERT OPINION

Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appear to favor using anti-Xa assay monitoring for heparin anticoagulation, which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Review article: Evaluation and care of the critically ill patient with cirrhosis

BACKGROUND

The increase in prevalence of liver disease globally will lead to a substantial incremental burden on intensive care requirements. While liver transplantation offers a potential life-saving intervention, not all patients are eligible due to limitations such as organ availability, resource constraints, ongoing sepsis or multiple organ failures. Consequently, the focus of critical care of patients with advanced and decompensated cirrhosis turns to liver-centric intensive care protocols, to mitigate the high mortality in such patients.

AIM

Provide an updated and comprehensive understanding of cirrhosis management in critical care, and which includes emergency care, secondary organ failure management (mechanical ventilation, renal replacement therapy, haemodynamic support and intensive care nutrition), use of innovative liver support systems, infection control, liver transplantation and palliative and end-of life care.

METHODS

We conducted a structured bibliographic search on PubMed, sourcing articles published up to 31 March 2024, to cover topics addressed. We considered data from observational studies, recommendations of society guidelines, systematic reviews, and meta-analyses, randomised controlled trials, and incorporated our clinical expertise in liver critical care.

RESULTS

Critical care management of the patient with cirrhosis has evolved over time while mortality remains high despite aggressive management with liver transplantation serving as a crucial but not universally available resource.

CONCLUSIONS

Implementation of organ support therapies, intensive care protocols, nutrition, palliative care and end-of-life discussions and decisions are an integral part of critical care of the patient with cirrhosis. A multi-disciplinary approach towards critical care management is likely to yield better outcomes.

A high performance liquid chromatography-tandem mass spectrometry assay for therapeutic drug monitoring of 10 drug compounds commonly used for antimicrobial therapy in plasma and serum of critically ill patients: Method optimization, validation, cross-validation and clinical application

BACKGROUND AND AIMS

Intensive care antibiotic treatment faces challenges due to substantial pharmacokinetic differences in critically ill patients. Individualized antibiotic dosing guided by therapeutic drug monitoring (TDM) is considered to minimize the risk of treatment failure and toxicity. This study aimed to develop a valid method for simultaneous LC-MS/MS quantification of 10 drugs frequently used in intensive care antibiotic therapy for which TDM-guided dosing is recommended: piperacillin, meropenem, flucloxacillin, cefuroxime, vancomycin, colistin A and B, linezolid, ciprofloxacin and tazobactam.

METHODS AND RESULTS

Thorough optimization of sample preparation and chromatography resulted in a fast and simple method based on protein precipitation of 50 µL plasma or serum and gradient elution using an Acquity UPLC HSS-T3 column. Electrospray ionization-triple quadrupole mass spectrometry in dynamic multiple reaction monitoring was used for quantification, covering the therapeutic range of each drug compound. Validation following EMA and FDA recommendations, including inter-platform validation and inter-laboratory comparison, demonstrated high accuracy, precision and robustness of the new method. The assay was successfully used to monitor plasma antibiotic levels of critically ill patients (n = 35).

CONCLUSION

The established multiplex method covers major drug classes with documented dosing challenges, provides a reliable basis for the implementation of high-throughput TDM, and its application confirmed the clinical impact of TDM in a real-world setting.

Renal Replacement Therapy as a New Indicator of Voriconazole Clearance in a Population Pharmacokinetic Analysis of Critically Ill Patients

AIMS

The pharmacokinetic (PK) profiles of voriconazole in intensive care unit (ICU) patients differ from that in other patients. We aimed to develop a population pharmacokinetic (PopPK) model to evaluate the effects of using extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) and those of various biological covariates on the voriconazole PK profile.

METHODS

Modeling analyses of the PK parameters were conducted using the nonlinear mixed-effects modeling method (NONMEM) with a two-compartment model. Monte Carlo simulations (MCSs) were performed to observe the probability of target attainment (PTA) when receiving CRRT or not under different dosage regimens, different stratifications of quick C-reactive protein (qCRP), and different minimum inhibitory concentration (MIC) ranges.

RESULTS

A total of 408 critically ill patients with 746 voriconazole concentration-time data points were included in this study. A two-compartment population PK model with qCRP, CRRT, creatinine clearance rate (CLCR), platelets (PLT), and prothrombin time (PT) as fixed effects was developed using the NONMEM.

CONCLUSIONS

We found that qCRP, CRRT, CLCR, PLT, and PT affected the voriconazole clearance. The most commonly used clinical regimen of 200 mg q12h was sufficient for the most common sensitive pathogens (MIC ≤ 0.25 mg/L), regardless of whether CRRT was performed and the level of qCRP. When the MIC was 0.5 mg/L, 200 mg q12h was insufficient only when the qCRP was <40 mg/L and CRRT was performed. When the MIC was ≥2 mg/L, a dose of 300 mg q12h could not achieve ≥ 90% PTA, necessitating the evaluation of a higher dose.

Production of antibody and development of enzyme-linked immunosorbent assay for therapeutic drug monitoring of eravacycline

Eravacycline (ERC) was approved for clinical use in 2018. It is more potent than other tetracyclines and can overcome resistance, making it an attractive option for combating multidrug-resistant bacterial infections. Intensive pharmacokinetic (PK) studies are currently being conducted to ensure the effectiveness and safety of ERC in various groups of patients, including those undergoing extracorporeal therapies. This study is the first attempt to develop a simple, efficient, and high-throughput immunoassay for quantifying ERC in human or animal serum. BSA-ERC conjugate as immunogen elicited antibody production in rabbits. Monitoring of the immune response and comparison of homologous and heterologous coating antigens allowed selection of immunoreagents and development of an assay that was selective for ERC possessing sensitivity (IC50), dynamic range (IC20-IC80) and detection limit equal to 3.3 ng/mL, 0.27-54 ng/mL and 0.09 ng/mL, respectively. The developed ELISA showed acceptable recovery of ERC (85-105 %) from rabbit and human serum in the clinically relevant concentration range of 0.1-3.0 mg/L. The method was used to quantify serum ERC concentration in the pilot PK study in Soviet chinchilla rabbits. The results were confirmed by HPLC-MS/MS.

Can linezolid be validly measured in endotracheal aspiration in critically ill patients? A proof-of-concept trial

BACKGROUND

Therapeutic drug monitoring (TDM) of anti-infectives such as linezolid is routinely performed in blood of intensive care unit (ICU) patients to optimize target attainment. However, the concentration at the site of infection is considered more important for a successful therapy. Until now, bronchoalveolar lavage (BAL) is the gold standard to measure intrapulmonary concentrations of anti-infective agents. However, it is an invasive method and unsuitable for regular TDM. The aim of this proof-of-concept study was to investigate whether it is possible to reliably determine the intrapulmonary concentration of linezolid from endotracheal aspiration (ENTA).

METHODS

Intubated ICU patients receiving 600 mg intravenous linezolid twice daily were examined in steady state. First, preliminary experiments were performed in six patients to investigate which patients are suitable for linezolid measurement in ENTA. In a second step, trough and peak linezolid concentrations of plasma and ENTA were determined in nine suitable patients.

RESULTS

Linezolid can validly be detected in ENTA with viscous texture and > 0.5 mL volume. The mean (SD) linezolid trough concentration was 2.02 (1.27) mg/L in plasma and 1.60 (1.36) mg/L in ENTA, resulting in a median lung penetration rate of 104%. The mean (SD) peak concentration in plasma and ENTA was 10.77 (5.93) and 4.74 (2.66) mg/L.

CONCLUSIONS

Linezolid can validly be determined in ENTA with an adequate texture and volume. The penetration rate is comparable to already published BAL concentrations. This method might offer a simple and non-invasive method for TDM at the site of infection "lung". Due to promising results of the feasibility study, comparison of ENTA and BAL in the same patient should be investigated in a further trial.

Imipenem/relebactam pharmacokinetics in critically ill patients supported on extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a life-saving modality but has the potential to alter the pharmacokinetics (PK) of antimicrobials. Imipenem/cilastatin/relebactam is an antibiotic with utility in treating certain multi-drug resistant Gram-negative infections. Herein, we describe the population pharmacokinetics of imipenem and relebactam in critically ill patients supported on ECMO.

METHODS

Patients with infection supported on ECMO received 4-6 doses of imipenem/cilastatin/relebactam per current prescribing information based on estimated creatinine clearance. Blood samples were collected following the final dose of the antibiotic. Concentrations were determined via LC-MS/MS. Population PK models were fit with and without covariates using Pmetrics. Monte Carlo simulations of 1000 patients assessed joint PTA of fAUC0-24/MIC ≥ 8 for relebactam, and ≥40% fT > MIC for imipenem for each approved dosing regimen.

RESULTS

Seven patients supported on ECMO were included in PK analyses. A two-compartment model with creatinine clearance as a covariate on clearance for both imipenem and relebactam fitted the data best. The mean ± standard deviation parameters were: CL0, 15.21 ± 6.52 L/h; Vc, 10.13 ± 2.26 L; K12, 2.45 ± 1.16 h-1 and K21, 1.76 ± 0.49 h-1 for imipenem, and 6.95 ± 1.34 L/h, 9.81 ± 2.69 L, 2.43 ± 1.13 h-1 and 1.52 ± 0.67 h-1 for relebactam. Simulating each approved dose of imipenem/cilastatin/relebactam according to creatinine clearance yielded PTAs of ≥90% up to an MIC of 2 mg/L.

CONCLUSIONS

Imipenem/cilastatin/relebactam dosed according to package insert in patients supported on ECMO is predicted to achieve exposures sufficient to treat susceptible Gram-negative isolates, including Pseudomonas aeruginosa.

Determinants of clinical response to empirical antibiotic treatment in patients with cirrhosis and bacterial and fungal infections-Results from the ICA "Global Study" (EABCIR-Global Study)

BACKGROUND

The administration of an appropriate empirical antibiotic treatment is essential in cirrhosis and severe bacterial infections. We aimed to investigate the predictors of clinical response of empirical antibiotic treatment in a prospective cohort of patients with cirrhosis and bacterial and fungal infections included in the International Club of Ascites "Global Study."

METHODS

Patients hospitalized with cirrhosis and bacterial/fungal infection were prospectively enrolled at 46 centers. Clinical response to antibiotic treatment was defined according to changes in markers of infection/inflammation, vital signs, improvement of organ failure, and results of cultures.

RESULTS

From October 2015 to September 2016, 1302 patients were included at 46 centers. A clinical response was achieved in only 61% of cases. Independent predictors of lack of clinical response to empirical treatment were C-reactive protein (OR = 1.16; 95% CI = 1.02-1.31), blood leukocyte count (OR = 1.39;95% CI = 1.09-1.77), serum albumin (OR = 0.70; 95% CI = 0.55-0.88), nosocomial infections (OR = 1.96; 95% CI = 1.20-2.38), pneumonia (OR = 1.75; 95% CI = 1.22-2.53), and ineffective treatment according to antibiotic susceptibility test (OR = 5.32; 95% CI = 3.47-8.57). Patients with a lack of clinical response to first-line antibiotic treatment had a significantly lower resolution rate of infections (55% vs. 96%; p < 0.001), a higher incidence of second infections (29% vs. 15%; p < 0.001), shock (35% vs. 7%; p < 0.001) and new organ failures (52% vs. 19 %; p < 0.001) than responders. Clinical response to empirical treatment was an independent predictor of 28-day survival ( subdistribution = 0.20; 95% CI = 0.14-0.27).

CONCLUSIONS

Four out of 10 patients with cirrhosis do not respond to the first-line antibiotic therapy, leading to lower resolution of infections and higher mortality. Broader-spectrum antibiotics and strategies targeting systemic inflammation may improve prognosis in patients with a high degree of inflammation, low serum albumin levels, and severe liver impairment.

No Sequestration of Commonly Used Anti-Infectives in the Extracorporeal Membrane Oxygenation (ECMO) Circuit-An Ex Vivo Study

Patients undergoing extracorporeal membrane oxygenation (ECMO) often require therapy with anti-infective drugs. The pharmacokinetics of these drugs may be altered during ECMO treatment due to pathophysiological changes in the drug metabolism of the critically ill and/or the ECMO therapy itself. This study investigates the latter aspect for commonly used anti-infective drugs in an ex vivo setting. A fully functional ECMO device circulated an albumin-electrolyte solution through the ECMO tubes and oxygenator. The antibiotic agents cefazolin, cefuroxim, cefepime, cefiderocol, linezolid and daptomycin and the antifungal agent anidulafungin were added. Blood samples were taken over a period of four hours and drug concentrations were measured via high-pressure liquid chromatography (HPLC) with UV detection. Subsequently, the study analyzed the time course of anti-infective concentrations. The results showed no significant changes in the concentration of any tested anti-infectives throughout the study period. This ex vivo study demonstrates that the ECMO device itself has no impact on the concentration of commonly used anti-infectives. These findings suggest that ECMO therapy does not contribute to alterations in the concentrations of anti-infective medications in severely ill patients.

The Impact of Augmented Renal Clearance on Vancomycin Pharmacokinetics and Pharmacodynamics in Critically Ill Patients

Augmented renal clearance (ARC), defined as a creatinine clearance (CrCl) > 130 mL/min/1.73 m2, is observed in 30-65% of critically ill patients. When following standard dosage guidelines, patients with ARC often experience subtherapeutic vancomycin levels, resulting in treatment failure due to accelerated drug elimination. This review aims to explore ARC's impact on vancomycin pharmacokinetics and pharmacodynamics (PK/PD) indices in ARC patients, seeking to identify an accurate dose adjustment method for this patient population. In September 2023, a comprehensive literature search was conducted on the MEDLINE and EMBASE databases to include all available studies providing information on the impact of ARC on vancomycin therapy in critically ill adults. Articles that studied the pediatric population and those with insufficient PK data were excluded. A total of 21 articles met the inclusion criteria. The findings revealed a positive correlation between CrCl and vancomycin clearance, indicating low serum concentrations. Therefore, upward dosing adjustments are necessary to improve treatment success. Younger age consistently emerged as a major contributor to ARC and vancomycin PK/PD alterations. This study summarizes the PK/PD alterations, current dosage recommendations and proposes preliminary recommendations on possible dosing approaches to decrease the risk of subtherapeutic exposure in this patient population.

The chain of survival and rehabilitation for sepsis: concepts and proposals for healthcare trajectory optimization

This article describes the structures and processes involved in healthcare delivery for sepsis, from the prehospital setting until rehabilitation. Quality improvement initiatives in sepsis may reduce both morbidity and mortality. Positive outcomes are more likely when the following steps are optimized: early recognition, severity assessment, prehospital emergency medical system activation when available, early therapy (antimicrobials and hemodynamic optimization), early orientation to an adequate facility (emergency room, operating theater or intensive care unit), in-hospital organ failure resuscitation associated with source control, and finally a comprehensive rehabilitation program. Such a trajectory of care dedicated to sepsis amounts to a chain of survival and rehabilitation for sepsis. Implementation of this chain of survival and rehabilitation for sepsis requires full interconnection between each link. To date, despite regular international recommendations updates, the adherence to sepsis guidelines remains low leading to a considerable burden of the disease. Developing and optimizing such an integrated network could significantly reduce sepsis related mortality and morbidity.

Beta-lactam antibiotic concentrations in critically ill patients with standard and adjusted dosages: A prospective observational study

INTRODUCTION

Antibiotic concentration target attainment is known to be poor in critically ill patients. Dose adjustment is recommended in patients with altered clearance, obesity and those with bacterial species with intermediate susceptibility. The aim of this study was to investigate the variation of antibiotic concentration in critically ill patients with standard or adjusted dosing regimens.

METHODS

The concentration of three beta-lactam antibiotics used in the intensive care unit (ICU) setting, cefotaxime, piperacillin/tazobactam, and meropenem, was measured in patients with confirmed or suspected infection. Mid-dose and trough values were collected during a single dosing interval. The pharmacokinetic endpoints were a free antibiotic concentration that, during the whole dosing interval, was above MIC (100% ƒT > MIC, primary endpoint) or above four times MIC (100% ƒT > 4MIC, secondary endpoint). Non-species related MIC breakpoints were used (1 mg/L for cefotaxime, 8 mg/L for piperacillin/tazobactam, and 2 mg/L for meropenem).

RESULTS

We included 102 patients (38 cefotaxime, 30 piperacillin/tazobactam, and 34 meropenem) at a single ICU, with a median age of 66 years. In total, 73% were males, 40% were obese (BMI ≥30) and the median SAPS 3 score was 63 points. Of all patients, 78 patients (76%) reached the primary endpoint (100%ƒT > MIC), with 74% for cefotaxime, 67% for piperacillin/tazobactam and 88% for meropenem. Target attainment for 100% ƒT > 4MIC was achieved in 40 (39%) patients, overall, with 34% for cefotaxime, 30% for piperacillin/tazobactam and 53% for meropenem. In patients with standard dose 71% attained 100%ƒT > MIC and 37% for 100%ƒT > 4MIC. All patients with reduced dose attained 100%ƒT > MIC and 27% attained 100% ƒT > 4MIC. In patients with increased dose 79% attained 100%ƒT > MIC and 48% 100%ƒT > 4MIC respectively.

CONCLUSIONS

Beta-lactam antibiotics concentration vary widely in critically ill patients. The current standard dosing regimens employed during the study were not sufficient to reach 100% ƒT > MIC in approximately a quarter of the patients. In patients where dose adjustment was performed, the group with increased dose also had low target attainment, as opposed to patients with dose reduction, who all reached target. This suggests the need for further individualization of dosing where therapeutic drug monitoring can be an alternative to further increase target attainment.

Simulation-based evaluation of personalized dosing approaches for anti-FGFR/KLB bispecific antibody fazpilodemab

Personalized dosing approaches play important roles in clinical practices to improve benefit: risk profiles. Whereas this is also important for drug development, especially in the context of drugs with narrow therapeutic windows, such approaches have not been fully evaluated during clinical development. Fazpilodemab (BFKB8488A) is an agonistic bispecific antibody which was being developed for the treatment of nonalcoholic steatohepatitis. The objective of this study was to characterize the exposure-response relationships of fazpilodemab with the purpose of guiding dose selection for a phase II study, as well as to evaluate various personalized dosing strategies to optimize the treatment benefit. Fazpilodemab exhibited clear exposure-response relationships for a pharmacodynamic (PD) biomarker and gastrointestinal adverse events (GIAEs), such as nausea and vomiting. Static exposure-response analysis, as well as longitudinal adverse event (AE) analysis using discrete-time Markov model, were performed to characterize the observations. Clinical trial simulations were performed based on the developed exposure-response models to evaluate probability of achieving target PD response and the frequency of GIAEs to inform phase II dose selection. Dynamic simulation of personalized dosing strategies demonstrated that the AE-based personalized dosing is the most effective approach for optimizing the benefit-risk profiles. The approach presented here can be a useful framework for quantifying the benefit of personalized dosing for drugs with narrow therapeutic windows.

Identifying patients with difficult-to-treat acute bacterial skin infections

PURPOSE OF REVIEW

The early recognition of acute bacterial skin infections (ABSIs) and their swift and adequate care are the major determinants of success. The features that can hamper or delay surgical and medical management can lead to 'difficult-to-treat' ABSIs.

RECENT FINDINGS

Delayed diagnosis and belated management are the key obstacles to be overcome. Clinicians should be careful about underestimating the severity of ABSIs and overlooking comorbidities, especially immunosuppression. Many conditions can lead to delayed source control, including a misdiagnosis, interhospital transfers, delayed re-exploration, or extensive injuries. Difficult therapeutic issues can occur, including rapidly destructive infections from highly pathogenic microorganisms (Group-A-streptococci, Vibrio spp., Clostridium spp. and Staphylococcus aureus ) or inadequate antibiotic therapy resulting from multidrug-resistant bacteria. Impaired pharmacokinetic capacities of antibiotic agents should also be considered as a source of clinical failure due to insufficient antimicrobial activity at the site of infection.

SUMMARY

Microbiological samples should be used for guiding antimicrobial therapy. Risk factors for multidrug-resistant bacteria should be considered, including local epidemiology and comorbidities. The optimization of antibiotic therapy should be achieved. Optimized care should be achieved through multidisciplinary management involving professionals with sufficient and appropriate training.

Meropenem pharmacokinetic/pharmacodynamic target attainment and clinical response in ICU patients: A prospective observational study

BACKGROUND

Several studies report lack of meropenem pharmacokinetic/pharmacodynamic (PK/PD) target attainment (TA) and risk of therapeutic failure with intermittent bolus infusions in intensive care unit (ICU) patients. The aim of this study was to describe meropenem TA in an ICU population and the clinical response in the first 72 h after therapy initiation.

METHODS

A prospective observational study of ICU patients ≥18 years was conducted from 2014 to 2017. Patients with normal renal clearance (NRC) and augmented renal clearance (ARC) and patients on continuous renal replacement therapy (CRRT) were included. Meropenem was administered as intermittent bolus infusions, mainly at a dose of 1 g q6h. Peak, mid, and trough levels were sampled at 24, 48, and 72 h after therapy initiation. TA was defined as 100% T > 4× MIC or trough concentration above 4× MIC. Meropenem PK was estimated using traditional calculation methods and population pharmacokinetic modeling (P-metrics®). Clinical response was evaluated by change in C-reactive protein (CRP), Sequential Organ Failure Assessment (SOFA) score, leukocyte count, and defervescence.

RESULTS

Eighty-seven patients were included, with a median Simplified Acute Physiology (SAPS) II score 37 and 90 days mortality rate of 32%. Median TA was 100% for all groups except for the ARC group with 45.5%. Median CRP fell from 175 (interquartile range [IQR], 88-257) to 70 (IQR, 30-114) (p < .001) in the total population. A reduction in SOFA score was observed only in the non-CRRT groups (p < .001).

CONCLUSION

Intermittent meropenem bolus infusion q6h gives satisfactory TA in an ICU population with variable renal function and CRRT modality, except for ARC patients. No consistent relationship between TA and clinical endpoints were observed.

Achievement of therapeutic antibiotic exposures using Bayesian dosing software in critically unwell children and adults with sepsis

PURPOSE

Early recognition and effective treatment of sepsis improves outcomes in critically ill patients. However, antibiotic exposures are frequently suboptimal in the intensive care unit (ICU) setting. We describe the feasibility of the Bayesian dosing software Individually Designed Optimum Dosing Strategies (ID-ODS™), to reduce time to effective antibiotic exposure in children and adults with sepsis in ICU.

METHODS

A multi-centre prospective, non-randomised interventional trial in three adult ICUs and one paediatric ICU. In a pre-intervention Phase 1, we measured the time to target antibiotic exposure in participants. In Phase 2, antibiotic dosing recommendations were made using ID-ODS™, and time to target antibiotic concentrations were compared to patients in Phase 1 (a pre-post-design).

RESULTS

175 antibiotic courses (Phase 1 = 123, Phase 2 = 52) were analysed from 156 participants. Across all patients, there was no difference in the time to achieve target exposures (8.7 h vs 14.3 h in Phase 1 and Phase 2, respectively, p = 0.45). Sixty-one courses in 54 participants failed to achieve target exposures within 24 h of antibiotic commencement (n = 36 in Phase 1, n = 18 in Phase 2). In these participants, ID-ODS™ was associated with a reduction in time to target antibiotic exposure (96 vs 36.4 h in Phase 1 and Phase 2, respectively, p < 0.01). These patients were less likely to exhibit subtherapeutic antibiotic exposures at 96 h (hazard ratio (HR) 0.02, 95% confidence interval (CI) 0.01-0.05, p < 0.01). There was no difference observed in in-hospital mortality.

CONCLUSIONS

Dosing software may reduce the time to achieve target antibiotic exposures. It should be evaluated further in trials to establish its impact on clinical outcomes.

Comparative Impact of an Optimized PK/PD Target Attainment of Piperacillin-Tazobactam vs. Meropenem on the Trend over Time of SOFA Score and Inflammatory Biomarkers in Critically Ill Patients Receiving Continuous Infusion Monotherapy for Treating Documented Gram-Negative BSIs and/or VAP

(1) Background: The advantage of using carbapenems over beta-lactam/beta-lactamase inhibitor combinations in critically ill septic patients still remains a debated issue. We aimed to assess the comparative impact of an optimized pharmacokinetic/pharmacodynamic (PK/PD) target attainment of piperacillin-tazobactam vs. meropenem on the trend over time of both Sequential Organ Failure Assessment (SOFA) score and inflammatory biomarkers in critically ill patients receiving continuous infusion (CI) monotherapy with piperacillin-tazobactam or meropenem for treating documented Gram-negative bloodstream infections (BSI) and/or ventilator-associated pneumonia (VAP). (2) Methods: We performed a retrospective observational study comparing critically ill patients receiving targeted treatment with CI meropenem monotherapy for documented Gram-negative BSIs or VAP with a historical cohort of critical patients receiving CI piperacillin-tazobactam monotherapy. Patients included in the two groups were admitted to the general and post-transplant intensive care unit in the period July 2021-September 2023 and fulfilled the same inclusion criteria. The delta values of the SOFA score between the baseline of meropenem or piperacillin-tazobactam treatment and those at 48-h (delta 48-h SOFA score) or at 7-days (delta 7-days SOFA) were selected as primary outcomes. Delta 48-h and 7-days C-reactive protein (CRP) and procalcitonin (PCT), microbiological eradication, resistance occurrence, clinical cure, multi-drug resistant colonization at 90-day, ICU, and 30-day mortality rate were selected as secondary outcomes. Univariate analysis comparing primary and secondary outcomes between critically ill patients receiving CI monotherapy with piperacillin-tazobactam vs. meropenem was carried out. (3) Results: Overall, 32 critically ill patients receiving CI meropenem monotherapy were compared with a historical cohort of 43 cases receiving CI piperacillin-tazobactam monotherapy. No significant differences in terms of demographics and clinical features emerged at baseline between the two groups. Optimal PK/PD target was attained in 83.7% and 100.0% of patients receiving piperacillin-tazobactam and meropenem, respectively. No significant differences were observed between groups in terms of median values of delta 48-h SOFA (0 points vs. 1 point; p = 0.89) and median delta 7-days SOFA (2 points vs. 1 point; p = 0.43). Similarly, no significant differences were found between patients receiving piperacillin-tazobactam vs. meropenem for any of the secondary outcomes. (4) Conclusion: Our findings may support the contention that in critically ill patients with documented Gram-negative BSIs and/or VAP, the decreases in the SOFA score and in the inflammatory biomarkers serum levels achievable with CI piperacillin-tazobactam monotherapy at 48-h and at 7-days may be of similar extent and as effective as to those achievable with CI meropenem monotherapy provided that optimization on real-time by means of a TDM-based expert clinical pharmacological advice program is granted.

Impact of a multidisciplinary management team on clinical outcome in ICU patients affected by Gram-negative bloodstream infections: a pre-post quasi-experimental study

BACKGROUND

Bloodstream infections (BSIs) by Gram-negative pathogens play a major role in intensive care patients, both in terms of prevalence and severity, especially if multi-drug resistant pathogens are involved. Early appropriate antibiotic therapy is therefore a cornerstone in the management of these patients, and growing evidence shows that implementation of a multidisciplinary team may improve patients' outcomes. Our aim was to evaluate the clinical and microbiological impact of the application of a multidisciplinary team on critically ill patients.

METHODS

Pre-post study enrolling critically ill patients with Gram negative bloodstream infection in intensive care unit. In the pre-intervention phase (from January until December 2018) patients were managed with infectious disease consultation on demand, in the post-intervention phase (from January until December 2022) patients were managed with a daily evaluation by a multidisciplinary team composed of intensivist, infectious disease physician, clinical pharmacologist and microbiologist.

RESULTS

Overall, 135 patients were enrolled during the study period, of them 67 (49.6%) in the pre-intervention phase and 68 (50.4%) in the post-intervention phase. Median age was 67 (58-75) years, sex male was 31.9%. Septic shock, the need for continuous renal replacement therapy and mechanical ventilation at BSI onset were similar in both groups, no difference of multidrug-resistant organisms (MDRO) prevalence was observed. In the post-phase, empirical administration of carbapenems decreased significantly (40.3% vs. 62.7%, p = 0.02) with an increase of appropriate empirical therapy (86.9% vs. 55.2%, p < 0.001) and a decrease of overall antibiotic treatment (12 vs. 16 days, p < 0.001). Despite no differences in delta SOFA and all-cause 30-day mortality, a significant decrease in microbiological failure (10.3% vs. 29.9%, p = 0.005) and a new-onset 30-day MDRO colonization (8.3% vs. 36.6%, p < 0.001) in the post-phase was reported. At multivariable analysis adjusted for main covariates, the institution of a multidisciplinary management team (MMT) was found to be protective both for new MDRO colonization [OR 0.17, 95%CI(0.05-0.67)] and microbiological failure [OR 0.37, 95%CI (0.14-0.98)].

CONCLUSIONS

The institution of a MMT allowed for an optimization of antimicrobial treatments, reflecting to a significant decrease in new MDRO colonization and microbiological failure among critically ill patients.

Removal of common antimicrobial agents by sustained low-efficiency dialysis

Adequate dosing of antimicrobials is paramount for treating infections in critically ill patients undergoing kidney replacement therapy; however, little is known about antimicrobial removal by sustained low-efficiency dialysis (SLED). The objective was to quantify the removal of cefepime, daptomycin, meropenem, piperacillin-tazobactam, and vancomycin in patients undergoing SLED. Adult patients ≥18 years with acute kidney injury (AKI) or end-stage kidney disease receiving one of the select antimicrobials and requiring SLED were included. Blood and dialysate flow rates were maintained at 250 and 100 mL/min, respectively. Simultaneous arterial and venous blood samples for the analysis of antibiotic concentrations were collected hourly for 8 hours during SLED (on-SLED). Arterial samples were collected every 2 hours for up to 6 hours while not receiving SLED (off-SLED) for the calculation of SLED clearance, half-life (t1/2) on-SLED and off-SLED, and the fraction of removal by SLED (fD). Twenty-one patients completed the study: 52% male, mean age (±SD) 53 ± 13 years, and mean weight of 98 ± 30 kg. Eighty-six percent had AKI, and 4 patients were receiving cefepime, 3 daptomycin, 10 meropenem, 6 piperacillin-tazobactam, and 13 vancomycin. The average SLED time was 7.3 ± 1.1 hours, and the mean ultrafiltration rate was 95 ± 52 mL/hour (range 10-211). The t1/2 on-SLED was substantially lower than the off-SLED t1/2 for all antimicrobials, and the SLED fD varied between 44% and 77%. An 8-hour SLED session led to significant elimination of most antimicrobials evaluated. If SLED is performed, modification of the dosing regimen is warranted to avoid subtherapeutic concentrations.

Factors Influencing Integration and Usability of Model-Informed Precision Dosing Software in the Intensive Care Unit

BACKGROUND

 Antimicrobial dosing in critically ill patients is challenging and model-informed precision dosing (MIPD) software may be used to optimize dosing in these patients. However, few intensive care units (ICU) currently adopt MIPD software use.

OBJECTIVES

 To determine the usability of MIPD software perceived by ICU clinicians and identify implementation barriers and enablers of software in the ICU.

METHODS

 Clinicians (pharmacists and medical staff) who participated in a wider multicenter study using MIPD software were invited to participate in this mixed-method study. Participants scored the industry validated Post-study System Usability Questionnaire (PSSUQ, assessing software usability) and Technology Acceptance Model 2 (TAM2, assessing factors impacting software acceptance) survey. Semistructured interviews were used to explore survey responses. The framework approach was used to identify factors influencing software usability and integration into the ICU from the survey and interview data.

RESULTS

 Seven of the eight eligible clinicians agreed to participate in the study. The PSSUQ usability scores ranked poorer than the reference norms (2.95 vs. 2.62). The TAM2 survey favorably ranked acceptance in all domains, except image. Qualitatively, key enablers to workflow integration included clear and accessible data entry, visual representation of recommendations, involvement of specialist clinicians, and local governance of software use. Barriers included rigid data entry systems and nonconformity of recommendations to local practices.

CONCLUSION

 Participants scored the MIPD software below the threshold that implies good usability. Factors such as availability of software support by specialist clinicians was important to participants while rigid data entry was found to be a deterrent.

Daily fluid intake as a novel covariate affecting the population pharmacokinetics of polymyxin B in patients with sepsis

BACKGROUND

Polymyxin B dosing in patients with sepsis is difficult because pathophysiological changes and supportive therapies alter drug pharmacokinetics (PK). This study aimed to investigate the impact of fluid management and renal function on the PK of polymyxin B and to propose alternative dosing regimens.

METHODS

Patients (aged ≥ 18 y) with sepsis and receiving intravenous polymyxin B for ≥ 96 h were enrolled. Blood samples were collected at steady state. Plasma concentrations were measured by liquid chromatography-tandem mass spectrometry and subjected to population PK modelling. Monte Carlo simulations were used to optimise dosage regimens.

RESULTS

Eighty-three patients with a median (range) daily fluid intake of 4.2 (1.3-8.4) L and a creatinine clearance (CrCL) of 87.5 (17.3-309.7) mL/min were included. Polymyxin B PK was adequately characterised by a two-compartment model. The PK covariate analysis revealed daily fluid intake statistically significantly affected central volume of distribution and central compartment clearance (CL), and CrCL influenced CL. Simulation indicated that a decreased dosing would be suitable for patients with renal dysfunction (CrCL < 40 mL/min), and therapeutic drug monitoring is recommended to avoid exposure fluctuation when patients have fluid overload.

CONCLUSIONS

Fluid management as well as renal function are essential factors affecting polymyxin B PK for patients with sepsis, which can help optimise dosage regimens.

Therapeutic drug monitoring of imipenem/cilastatin and meropenem in critically ill adult patients

OBJECTIVES

To investigate the factors influencing imipenem/cilastatin (IMI) and meropenem (MEM) concentrations in critically ill adult patients and the role of these concentrations in the clinical outcome.

METHODS

Plasma trough concentrations of IMI and MEM were detected by high-performance liquid chromatography. A target value of 100%-time above MIC was used for the drugs.

RESULTS

A total of 186 patients were included, with 87 receiving IMI and 99 receiving MEM. The percentages of patients reaching the target IMI and MEM concentrations were 44.8% and 38.4%, respectively. The proportions of patients infected with drug-resistant bacteria were 57.5% and 69.7% in the IMI group and MEM group, respectively. In the multivariate analysis, the risk factors for an IMI concentration that did not reach the target were infection with drug-resistant bacteria, and those for MEM were infection with drug-resistant bacteria, estimated glomerular filtration rate, and diabetes mellitus. A total of 47.1% of patients had good outcomes in the IMI cohort, and 38.1% of patients had good outcomes in the MEM cohort. The duration of mechanical ventilation and IMI concentration were associated with ICU stay in patients in the IMI cohort, while MEM concentration and severe pneumonia affected the clinical outcome of patients in the MEM cohort.

CONCLUSION

Infection with drug-resistant bacteria is an important factor influencing whether IMI and MEM concentrations reach the target. Furthermore, IMI and MEM concentrations are associated with the clinical outcome, and elevated doses of IMI and MEM should be given to patients who are infected with drug-resistant bacteria.

Practical Lessons on Antimicrobial Therapy for Critically Ill Patients

Sepsis stands as a formidable global health challenge, with persistently elevated mortality rates in recent decades. Each year, sepsis not only contributes to heightened morbidity but also imposes substantial healthcare costs on survivors. This narrative review aims to highlight the targeted measures that can be instituted to alleviate the incidence and impact of sepsis in intensive care. Here we discuss measures to reduce nosocomial infections and the prevention of equipment and patient colonisation by resilient pathogens. The overarching global crisis of bacterial resistance to newly developed antimicrobial agents intensifies the imperative for antimicrobial stewardship and de-escalation. This urgency has been accentuated in recent years, notably during the COVID-19 pandemic, as high-dose steroids and opportunistic infections presented escalating challenges. Ongoing research into airway colonisation's role in influencing disease outcomes among critically ill patients underscores the importance of tailoring treatments to disease endotypes within heterogeneous populations, which are important lessons for intensivists in training. Looking ahead, the significance of novel antimicrobial delivery systems and drug monitoring is poised to increase. This narrative review delves into the multifaceted barriers and facilitators inherent in effectively treating critically ill patients vulnerable to nosocomial infections. The future trajectory of intensive care medicine hinges on the meticulous implementation of vigilant stewardship programs, robust infection control measures, and the continued exploration of innovative and efficient technological solutions within this demanding healthcare landscape.

Predictors of Treatment Failure and Mortality among Patients with Septic Shock Treated with Meropenem in the Intensive Care Unit

Background

The aim of the study was to determine the predictors of meropenem treatment failure and mortality in the Intensive Care Unit (ICU).

Methods

This was a retrospective study, involving sepsis and septic shock patients who were admitted to the ICU and received intravenous meropenem. Treatment failure is defined as evidence of non-resolved fever, non-reduced total white cell (TWC), non-reduced C-reactive protein (CRP), subsequent culture negative and death in ICU.

Results

An Acute Physiology and Chronic Health Evaluation II (APACHE II) and duration of antibiotic treatment less than 5 days were associated with treatment failure with adjusted OR = 1.24 (95% CI: 1.15, 1.33; P < 0.001), OR = 65.43 (95% CI: 21.70, 197.23; P < 0.001). A higher risk of mortality was observed with higher APACHE and Sequential Organ Failure Assessment (SOFA) scores, initiating antibiotics > 72 h of sepsis, duration of antibiotic treatment less than 5 days and meropenem with renal adjustment dose with an adjusted OR = 1.21 (95% CI: 1.12, 1.30; P < 0.001), adjusted OR = 1.23 (95% CI: 1.08, 1.41; P < 0.001), adjusted OR = 6.38 (95% CI: 1.67, 24.50; P = 0.007), adjusted OR = 0.03 (95% CI: 0.01, 0.14; P < 0.001), adjusted OR = 0.30 (95% CI: 0.14, 0.64; P = 0.002).

Conclusion

A total of 50 (14.12%) patients had a treatment failure with meropenem with 120 (48.02%) ICU mortality. The predictors of meropenem failure are higher APACHE score and shorter duration of meropenem treatment. The high APACHE, high SOFA score, initiating antibiotics more than 72 h of sepsis, shorter duration of treatment and meropenem with renal adjustment dose were predictors of mortality.

Multistate modeling for survival analysis in critically ill patients treated with meropenem

Appropriate antibiotic dosing to ensure early and sufficient target attainment is crucial for improving clinical outcome in critically ill patients. Parametric survival analysis is a preferred modeling method to quantify time-varying antibiotic exposure - response effects, whereas bias may be introduced in hazard functions and survival functions when competing events occur. This study investigated predictors of in-hospital mortality in critically ill patients treated with meropenem by pharmacometric multistate modeling. A multistate model comprising five states (ongoing meropenem treatment, other antibiotic treatment, antibiotic treatment termination, discharge, and death) was developed to capture the transitions in a cohort of 577 critically ill patients treated with meropenem. Various factors were investigated as potential predictors of the transitions, including patient demographics, creatinine clearance calculated by Cockcroft-Gault equation (CLCRCG ), time that unbound concentrations exceed the minimum inhibitory concentration (fT>MIC ), and microbiology-related measures. The probabilities to transit to other states from ongoing meropenem treatment increased over time. A 10 mL/min decrease in CLCRCG was found to elevate the hazard of transitioning from states of ongoing meropenem treatment and antibiotic treatment termination to the death state by 18%. The attainment of 100% fT>MIC significantly increased the transition rate from ongoing meropenem treatment to antibiotic treatment termination (by 9.7%), and was associated with improved survival outcome. The multistate model prospectively assessed predictors of death and can serve as a useful tool for survival analysis in different infection scenarios, particularly when competing risks are present.

Antibiotics in anesthesia and critical care

Sepsis is life-threatening organ dysfunction due to a dysregulated host response to an underlying acute infection. Sepsis is a major worldwide healthcare problem. An annual estimated 48.9 million incident cases of sepsis is reported, with 11 million (20%) sepsis-related deaths. Administration of appropriate antimicrobials is one of the most effective therapeutic interventions to reduce mortality. The severity of illness informs the urgency of antimicrobial administration. Nevertheless, even used properly, they cause adverse effects and contribute to the development of antibiotic resistance. Both inadequate and unnecessarily broad empiric antibiotics are associated with higher mortality and also select for antibiotic-resistant germs. In this narrative review, we will first discuss important factors and potential confounders which may influence the occurrence of surgical site infection (SSI) and which should be considered in the provision of perioperative antibiotic prophylaxis (PAP). Then, we will summarize recent advances and perspectives to optimize antibiotic therapy in the intensive care unit (ICU). Finally, the major role of the microbiota and the impact of antimicrobials on it will be discussed. While expert recommendations help guide daily practice in the operating theatre and ICU, a thorough knowledge of pharmacokinetic/pharmacodynamic (PK/PD) rules is critical to optimize the management of complex patients and minimize the emergence of multidrug-resistant organisms.

Unveiling Synergistic Potency: Exploring Butyrolactone I to Enhance Gentamicin Efficacy against Methicillin-Resistant Staphylococcus aureus (MRSA) Strain USA300

Staphylococcus aureus, including MRSA strains, poses significant health risks, imposing a significant disease burden and mortality. We investigate butyrolactone I (BL-1), a marine-derived metabolite from Aspergillus terreus, enhancing aminoglycoside efficacy against MRSA. A promising synergy is observed with BL-1 and various aminoglycosides, marked by low fractional inhibitory concentration indexes (FICIs < 0.5). Comprehensive studies utilizing USA300 MRSA and gentamicin reveal a remarkable one-fourth reduction in minimum inhibitory concentration (MIC) with 20 μg/mL BL-1. A relative abundance assay indicates that BL-1 enhances gentamicin uptake while restraining extracellular presence, involving intricate transmembrane signaling and molecular interactions. RNA-Seq analysis yielded an unexpected revelation, unveiling a distinctive gene expression profile and distinguishing it from other treatment approaches. Furthermore, meticulous analyses validated the extensive perturbations induced by BL-1 exposure, affecting diverse biological functions, encompassing glycolysis, amino acid metabolisms, substance transmembrane transport, and virulence generation. These valuable insights inspired further confirmation of bacterial virulence and the modulation of membrane permeability resulting from BL-1 treatment. Phenotypic validations corroborated our observations, revealing reduced membrane permeability and hemolytic toxicity, albeit demanding a deeper comprehension of the intricate interplay underlying these actions. Our study contributes crucial mechanistic insights to the development of therapeutic strategies against this notorious pathogen and the judicious employment of aminoglycosides. Additionally, it elucidates marine-derived metabolites' ecological and functional roles, exemplified by fungal quorum sensing signals. These compounds could give producers a competitive edge, inhibiting microorganism proliferation and suggesting novel approaches for combating resistant pathogens.

Translational PK/PD for the Development of Novel Antibiotics-A Drug Developer's Perspective

Antibiotic development traditionally involved large Phase 3 programs, preceded by Phase 2 studies. Recognizing the high unmet medical need for new antibiotics and, in some cases, challenges to conducting large clinical trials, regulators created a streamlined clinical development pathway in which a lean clinical efficacy dataset is complemented by nonclinical data as supportive evidence of efficacy. In this context, translational Pharmacokinetic/Pharmacodynamic (PK/PD) plays a key role and is a major contributor to a "robust" nonclinical package. The classical PK/PD index approach, proven successful for established classes of antibiotics, is at the core of recent antibiotic approvals and the current antibacterial PK/PD guidelines by regulators. Nevertheless, in the case of novel antibiotics with a novel Mechanism of Action (MoA), there is no prior experience with the PK/PD index approach as the basis for translating nonclinical efficacy to clinical outcome, and additional nonclinical studies and PK/PD analyses might be considered to increase confidence. In this review, we discuss the value and limitations of the classical PK/PD approach and present potential risk mitigation activities, including the introduction of a semi-mechanism-based PK/PD modeling approach. We propose a general nonclinical PK/PD package from which drug developers might choose the studies most relevant for each individual candidate in order to build up a "robust" nonclinical PK/PD understanding.