Renal Dosing of Antibiotics: Are We Jumping the Gun?

Unbound Ceftriaxone Concentrations in Plasma Measured Using Ultrafiltration Versus Equilibrium Dialysis

BACKGROUND

Ceftriaxone is a first-line beta-lactam antibiotic used in diverse clinical settings. Owing to pharmacokinetic alterations, ceftriaxone therapeutic drug monitoring is currently recommended for patients in the intensive care unit. Ultrafiltration is typically used to measure unbound ceftriaxone concentrations, as it is less costly and time-consuming compared with equilibrium dialysis. However, the reference method, equilibrium dialysis, has not been compared with equilibrium dialysis for ceftriaxone to measure the unbound ceftriaxone concentrations. Therefore, unbound ceftriaxone fractions measured by ultrafiltration versus equilibrium dialysis were compared in patients in the intensive care unit.

METHODS

Total and unbound ceftriaxone plasma fractions were measured by ultrafiltration (9500 g at 37°C for 30 minutes) and equilibrium dialysis (12 kDa, 37°C for 4 hours) in 32 plasma samples from 28 patients who were critically ill collected during a previous prospective pharmacokinetic study. Passing-Bablok regression and Bland-Altman analyses were performed to evaluate the agreements between both methods.

RESULTS

The median (range) total ceftriaxone plasma concentration was 108.6 (5.2-233) mg/L. The median unbound concentration measured by equilibrium dialysis and ultrafiltration was 14.5 (0.7-52.9) and 23.3 (0.9-79.2) mg/L, respectively, showing a significant difference. Passing-Bablok regression analysis revealed significant proportional and systematic bias. This result was confirmed by Bland-Altman analysis, with a mean relative bias of 43.3% and wide agreement limits (-21% to 108%).

CONCLUSIONS

Ultrafiltration substantially overestimates the unbound ceftriaxone fraction compared with equilibrium dialysis at 37°C. It is important to report methodological details and consider this information when interpreting unbound fractions of ceftriaxone and other drugs. These findings may impact the therapeutic drug monitoring of ceftriaxone.

Inadequate imipenem dosing in patients with decreased kidney function: A clinical pharmacokinetic study

OBJECTIVES

A number of population pharmacokinetic (popPK) models of imipenem in critically ill patients are available for dosing optimisation, but they represent only a narrow range of kidney functions. This study evaluates the target attainment of on-label regimens through popPK modelling and simulation in patients across different kidney functions.

METHODS

A popPK model was built based on two datasets from Switzerland (model development population, 151 patients, 322 concentrations) and externally validated on two datasets from the Czech Republic (19 patients, 111 concentrations) and Vietnam (43 patients, 85 concentrations). Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA) from a minimum inhibitory concentration (MIC) of 0.125 to 32 mg/L. We estimated the cumulative fraction of response (CFR) against Pseudomonas aeruginosa (the epidemiological cut-off value was 4 mg/L) across a broad range of Cockcroft-Gault creatinine clearance values (CLCRCG 15-130 mL/min). Targets of 40% and 100%ƒT>MIC (percentage of dosing interval estimated free concentrations above MIC) were investigated.

RESULTS

Decreased kidney function (eGFRCKD-EPI <90mL/min) was observed in 70/151 patients (46.4%) within the model development population, and in 11/19 (57.9%) and 24/43 (55.8%) patients in the Czech Republic and Vietnam, respectively. CLCRCG significantly influenced the imipenem clearance described by a two-compartment model. For PTA, all regimens achieved 40% ƒT>MIC2mg/L. With a 100%ƒT>MIC target, 500 mg q6h (CLCRCG 30-60 mL/min) could only cover a MIC of up to 1 mg/L, irrespective of infusion time. For CFR, no dosing regimen could cover susceptible P. aeruginosa for 100%ƒT>MIC.

CONCLUSIONS

The highest on-label imipenem dosing regimens failed to attain 100% ƒT>MIC4mg/L in patients with decreased kidney function. Higher dosing may be necessary to cover MIC of 4mg/L. Future trials should explore their efficacy, toxicity, and the utility of model-informed precision dosing in this population.

Utility of a TDM-Guided Expert Clinical Pharmacological Advice Program for Optimizing the Use of Novel Beta-Lactam/Beta-Lactamase Inhibitor Combinations and Cefiderocol in a Tertiary University Hospital: An Interim Analysis

BACKGROUND

This study assessed the utility of a therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program to optimize aggressive pharmacokinetic/pharmacodynamic (PK/PD) target attainment of novel beta-lactam/beta-lactamase inhibitor (BL/BLIc) combinations and cefiderocol.

METHODS

All hospitalized patients who received TDM-guided ECPA with BL/BLIc (ceftazidime-avibactam, ceftolozane-tazobactam, or meropenem-vaborbactam) or cefiderocol were assessed retrospectively. Three performance indicators were identified: the average number of ECPAs delivered per month of availability of the program and the ratio between the total number of ECPAs recommending dosing adjustment and the total number of ECPAs, at the first and at subsequent TDM assessments. The relationships between aggressive PK/PD target attainment and clinical and microbiological outcomes were assessed.

RESULTS

A total of 595 ECPAs were administered to 263 patients to optimize 319 treatment courses. Novel agents were mostly used for targeted therapy (79.6%) by continuous infusion (CI; 82.8%). In the first TDM assessment, dose increases were mostly required for patients receiving intermittent/extended infusion (II/EI) (51.9% vs. 6.4%; P < 0.0001), whereas dose decreases were mostly recommended for patients receiving CI (60.3% vs. 23.1%; P < 0.001). In subsequent TDM assessments, the overall proportion of ECPAs recommending dosing adjustments decreased in both groups (57.1% and 39.3% in the II/EI and CI groups, respectively). Aggressive PK/PD target attainment was associated with the highest microbiological eradication rate for ceftazidime-avibactam (79.6% out of 86.0%; P < 0.001), and the highest clinical cure rate for ceftazidime-avibactam (64.2% out of 78.1%; P < 0.001) and cefiderocol (50.0% out of 51.5%; P = 0.006).

CONCLUSIONS

A dedicated TDM-guided ECPA program may be helpful for optimizing the use of novel agents in settings with a high prevalence of multidrug-resistant pathogens.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Not "a cute" complication: phenotypic analysis of acute kidney injury in Staphylococcus aureus bacteraemia

OBJECTIVES

In this large retrospective cohort analysis, we aimed to determine the incidence of Kidney Disease Improving Global Outcomes (KDIGO)-defined acute kidney injury (AKI) within 14 days in patients with Staphylococcus aureus bacteraemia (SAB), and the association of AKI with 30-day mortality.

METHODS

A retrospective cohort study of adults with SAB between 1998 to 2023 admitted to a large regional Australian health service. Baseline creatinine was the lowest serum creatinine concentration in the 365 days before the day of index blood culture collection and AKI was defined and staged using the KGIDO criteria. AKIs were classified as early (within 48 hours of index blood culture) or late (48 hours to 14 days after index blood culture).

RESULTS

In those with SAB, AKI occurred in 46% (1255/2734) and was significantly linked to all-cause 30-day mortality (for patients with AKI, 354 died, 901 survived; without AKI 138 died and 1341 survived; OR, 3.81; 95% CI, 3.08-4.73; p ≤ 0.001). Overall 30-day mortality was 18% (492/2734). AKI resolution within 14 days occurred in 173/277 (62%) of those with an early AKI only, and in 101/435 (23%) of those with a late AKI only (p ≤ 0.001).

DISCUSSION

AKI is a frequent complication of SAB and is associated with 30-day mortality. Some AKI phenotypes have rapid resolution, which supports the consideration of delayed antimicrobial dose reduction.

Population Pharmacokinetics-Based Evaluation of Ceftazidime-Avibactam Dosing Regimens in Critically and Non-Critically Ill Patients With Carbapenem-Resistant Klebsiella pneumoniae

Purpose

This study aimed to describe the population pharmacokinetics (PopPK) of ceftazidime-avibactam (CAZ-AVI) in adult patients, and to develop optimal dosing regimens for both non-critically ill and critically ill patients by combining different pharmacokinetic/pharmacodynamic (PK/PD) targets.

Patients and Methods

A prospective, single-center study involving patients who were infected with CRKP and received CAZ-AVI therapy was conducted. Nonlinear mixed-effect modeling was used to develop a PopPK model. The optimal dosing regimen was assessed using Monte Carlo simulation.

Results

The PopPK analysis of CAZ-AVI included 91 steady-state concentrations from 45 adult patients. The data were modeled using a one-compartment model. The typical population values of CAZ and AVI clearances were 2.96 L/h and 3.09 L/h, and the volumes of distribution were 17.76 L and 18.25 L, respectively. Our study showed that creatinine clearance (CrCL) calculated using the Cockcroft-Gault equation significantly affected the pharmacokinetics of CAZ-AVI. The Monte Carlo simulation optimized the dosing regimen for both non-critically ill and critically ill patients with varying renal functions, providing detailed supplements to the instructions.

Conclusion

Our study established a PopPK model for CAZ-AVI and proposed a reference for dosing regimen adjustment based on the severity of the disease and renal functional status.

'Real-life' approach to applying PK/PD principles in infectious diseases clinical practice without access to prompt TDM

INTRODUCTION

Infectious disease treatments are transitioning from a one-size-fits-all approach to a more tailored approach. The increasing adoption of therapeutic drug monitoring (TDM) of antimicrobials is a clear example of this trend. Routine antimicrobial TDM in critically ill patients should be mandatory. Unfortunately, nowadays, only expert centers can provide it. Given the crucial nature of the first hours/days for achieving a favorable clinical outcome, empirical antibiotic therapy with an adequate choice of drug, dose and administration modalities is fundamental.

AREAS COVERED

We outline common scenarios encountered in clinical practice, such as in edematous patients, hypoalbuminemia, patients with liver and renal diseases, patients under renal replacement therapy or extracorporeal membrane oxygenation (ECMO), over or under-weight patients, in old adults and cases of infections caused by relatively high minimum inhibitory concentration (MIC) pathogens. Various clinical situations were analyzed with the help of the available literature (PubMed/MEDLINE/Google Scholar and books written by experts in pharmacology and infectious diseases).

EXPERT OPINION

In these different scenarios, we reported common examples of optimizing drug utilization to maximize therapeutic outcomes, reduce incorrect prescriptions and limit the emergence of antimicrobial resistance.

Translating PK-PD principles into improved methodology for clinical trials which compare intermittent with prolonged infusion of beta-lactam antibiotics

Based on the fact that beta-lactam antibiotics demonstrate time-dependent killing, different dosing strategies have been implemented to increase the time that free (f) (unbound) antibiotic concentrations remain above the Minimal Inhibitory Concentration (MIC), including prolonged and continuous infusion. Multiple studies have been performed that compared continuous with traditional intermittent infusion to improve outcomes in patients with severe sepsis and/or septic shock. These studies have yielded inconsistent results for patients as measured by clinical response to treatment and mortality due to heterogeneity of included patients, pathogens, dosing strategies and the absence of Therapeutic Drug Monitoring (TDM). The MERCY and BLING III studies failed to show a difference in mortality between patients randomized to receive continuous and intermittent infusion of beta-lactam antibiotics.
 A deeper understanding of pharmacokinetic (PK) and pharmacodynamic (PD) mechanisms that occur in critically ill patients should guide us in dose optimization and improvement in methodology for future clinical trials.

Impact of renal-adjusted ceftazidime/avibactam in patients with KPC-producing Klebsiella pneumoniae bloodstream infection: a retrospective cohort study

Background

Bloodstream infections (BSIs) caused by KPC-producing Klebsiella pneumoniae (KPC-Kp) are still associated with high mortality, and the game-changing drug ceftazidime/avibactam has shown suboptimal pharmacokinetics in some clinical settings. Ceftazidime/avibactam renal dose adjustment has recently been identified as an independent risk factor for mortality.

Objectives

To investigate the effect of ceftazidime/avibactam renal dose adjustment on mortality.

Methods

Patients with KPC-Kp BSI treated with a ceftazidime/avibactam-based regimen were retrospectively collected and analysed. The primary outcome was mortality at 7, 14 and 30 days after the start of definitive ceftazidime/avibactam antibiotic therapy. Renal function was estimated using the CKD-EPI equation.

Results

One hundred and ten patients with KPC-Kp BSI treated with a ceftazidime/avibactam-based regimen were included. Full-dose ceftazidime/avibactam (7.5 g daily) was prescribed to 82 patients (74.5%), while 28 patients (25.5%) received a renal-adjusted dose (17 patients due to chronic renal disease or haemodialysis, 11 patients due to infection-related acute kidney injury), with a median of 1.9 g daily. At multivariable analysis, receiving a reduced dose of ceftazidime/avibactam was independently associated with mortality (HR 4.47, 95% CI 1.09-18.03, P = 0.037), along with intra-abdominal or lower respiratory tract infections as source of BSI (HR 5.42, 95% CI 1.77-16.55, P = 0.003), septic shock (HR 6.99, 95% CI 1.36-35.87, P = 0.020) and SARS-CoV-2 coinfection (HR 10.23, 95% CI 2.69-38.85, P = 0.001).

Conclusions

Dose reduction of ceftazidime/avibactam according to renal function in patients with KPC-Kp BSI seems to be independently associated with higher mortality. This may be possibly due to inadequate exposure provided by the recommended doses for renal impairment.

Target-controlled dialysis for antibiotics (TCD-ABx)

BACKGROUND

Effective antimicrobial therapy is an essential part of intensive care medicine and renal replacement therapy is an important and common intervention which significantly affects the pharmacokinetics of many antimicrobials. This is especially critical for substances with a narrow therapeutic range, creating a dilemma of weighing the risk of toxicity from increased drug exposure against risk of ineffective treatment and promotion of antimicrobial resistance. To address this problem, we investigate a target-controlled dialysis by in vitro experiments - a novel technique in which drug is spiked into the dialysis solution to make use of the physicochemical properties of renal replacement therapy for solute transport, with the goal to reduce the risk of inadequate drug exposure.

METHODS

Five antibiotics (ceftazidime, meropenem, piperacillin/tazobactam, vancomycin, flucloxacillin) were dialyzed in an in vitro model of continuous veno-venous hemodialysis using 1 L of bovine serum albumin solution as simulated patient plasma compartment. This was done with and without antibiotics in target concentrations added to the dialysis solution, mimicking three clinically relevant scenarios: (i) target-controlled dialysis in a subject with sub-therapeutic drug levels, (ii) target-controlled dialysis in a subject with supra-therapeutic drug levels, and (iii) traditional dialysis of drugs starting at the target concentration. Drug levels were quantified by high-performance liquid chromatography. Additionally, the stability over 24 h of all antibiotics in two typical dialysis solutions was assessed.

RESULTS

Our data shows that with target-controlled dialysis, antibiotic concentrations will change in the desired direction towards the target concentration, depending on the patients' unbound drug levels in relation to the concentration in the dialysis solution. The desired target concentrations can be induced and maintained, regardless of the initial concentration. Furthermore, the stability tests revealed only a minor and clinically irrelevant loss in drug concentration (all < 10.2%) after 12 h.

CONCLUSIONS

We outlined the mechanistic plausibility and provided experimental evidence of the feasibility of the target-controlled dialysis concept, which could help to maintain therapeutic concentrations of many time-dependent antibiotics in critically ill patients under renal replacement therapy. The required stability in dialysis solutions was shown for a set of important antibiotics. The next step will be the prudent application of this concept to patients in clinical trials.

Validation of Cefiderocol Package Insert Dosing Recommendation for Patients Receiving Continuous Renal Replacement Therapy: A Prospective Multicenter Pharmacokinetic Study

Background

Cefiderocol is the first antibiotic with effluent flow rate-based dosing recommendations outlined in the product label for patients receiving continuous renal replacement therapy (CRRT). We aimed to investigate the population pharmacokinetics of cefiderocol among patients receiving CRRT and validate these dosing recommendations.

Methods

A multicenter, prospective cefiderocol pharmacokinetic study among intensive care unit patients receiving CRRT was conducted (2022-2023). Blood sampling was performed at steady-state and cefiderocol concentrations were assayed by validated liquid chromatography-tandem mass spectrometry. Population pharmacokinetic analyses were conducted in Pmetrics using R software. The free time above the minimum inhibitory concentration (f T > MIC) and total daily area under the concentration time curve (AUCdaily) were calculated.

Results

Fourteen patients with effluent flow rates ranging from 2.1 to 5.1 L/h were enrolled. Cefiderocol concentrations best fitted a 2-compartment model. Mean ± standard deviation (SD) parameter estimates for clearance, central compartment volume, and intercompartment transfer constants (k12 and k21) were 3.5 ± 1.5 L/hour, 10.7 ± 8.4 L, 3.9 ± 1.8 hours-1, and 2.2 ± 2.2 hours-1, respectively. With simulations based on product label dosing recommendations, all patients achieved 100% fT > MIC up to MIC 8 mg/L with an AUCdaily (mean ± SD) of 1444 ± 423 mg × hour/L. Cefiderocol was well tolerated among the 14 patients.

Conclusions

The current package insert dosing recommendations resulted in pharmacodynamically optimized cefiderocol exposures. Cefiderocol concentrations exceeded relevant MIC breakpoints in all patients at each effluent flow rate, and AUCdaily was within the range observed in patients in the phase 3 clinical trials, suggestive of a safe and therapeutic drug profile.

Development and validation of a deep learning algorithm for the prediction of serum creatinine in critically ill patients

Objectives

Serum creatinine (SCr) is the primary biomarker for assessing kidney function; however, it may lag behind true kidney function, especially in instances of acute kidney injury (AKI). The objective of the work is to develop Nephrocast, a deep-learning model to predict next-day SCr in adult patients treated in the intensive care unit (ICU).

Materials and Methods

Nephrocast was trained and validated, temporally and prospectively, using electronic health record data of adult patients admitted to the ICU in the University of California San Diego Health (UCSDH) between January 1, 2016 and June 22, 2024. The model features consisted of demographics, comorbidities, vital signs and laboratory measurements, and medications. Model performance was evaluated by mean absolute error (MAE) and root-mean-square error (RMSE) and compared against the prediction day's SCr as a reference.

Results

A total of 28 191 encounters met the eligibility criteria, corresponding to 105 718 patient-days. The median (interquartile range [IQR]) MAE and RMSE in the internal test set were 0.09 (0.085-0.09) mg/dL and 0.15 (0.146-0.152) mg/dL, respectively. In the prospective validation, the MAE and RMSE were 0.09 mg/dL and 0.14 mg/dL, respectively. The model's performance was superior to the reference SCr.

Discussion and Conclusion

Our model demonstrated good performance in predicting next-day SCr by leveraging clinical data routinely collected in the ICU. The model could aid clinicians in in identifying high-risk patients for AKI, predicting AKI trajectory, and informing the dosing of renally eliminated drugs.

Drug-Drug Interactions in Nosocomial Infections: An Updated Review for Clinicians

Prevention, assessment, and identification of drug-drug interactions (DDIs) represent a challenge for healthcare professionals, especially in nosocomial settings. This narrative review aims to provide a thorough assessment of the most clinically significant DDIs for antibiotics used in healthcare-associated infections. Complex poly-pharmaceutical regimens, targeting multiple pathogens or targeting one pathogen in the presence of another comorbidity, have an increased predisposition to result in life-threatening DDIs. Recognising, assessing, and limiting DDIs in nosocomial infections offers promising opportunities for improving health outcomes. The objective of this review is to provide clinicians with practical advice to prevent or mitigate DDIs, with the aim of increasing the safety and effectiveness of therapy. DDI management is of significant importance for individualising therapy according to the patient, disease status, and associated comorbidities.

Outcomes and Predictors of Mortality in Patients With KPC-Kp Infections Treated With Meropenem Vaborbactam: An Observational Multicenter Study

Background

Meropenem-vaborbactam is a recent and promising option for the treatment of KPC-producing Klebsiella pneumoniae (KPC-Kp) infections, including those resistant to ceftazidime-avibactam.

Methods

We conducted a retrospective analysis of observational data from 19 Italian hospitals on use and outcomes of patients treated with meropenem-vaborbactam for at least ≥24 hours for KPC-Kp infections. Crude and propensity-weighted multiple Cox regression models were performed to ascertain risk factors independently associated with 30-day mortality.

Results

The cohort included 342 adults with bloodstream infections (n = 172) and nonbacteremic infections (n = 170), of which 107 were lower respiratory tract infections, 30 were complicated urinary tract infections, and 33 were infections involving other sites. Most infections (62.3%) were managed with meropenem-vaborbactam monotherapy, or in combination with at least 1 other active drug (usually fosfomycin, tigecycline, or gentamicin) (37.7%). The 30-day mortality rate was 31.6% (108/342). In multiple Cox regression model, 30-day mortality was independently associated with septic shock at infection onset, Charlson comorbidity index ≥ 3, dialysis, concomitant COVID-19, and INCREMENT score ≥ 8. Administration of meropenem-vaborbactam within 48 hours from infection onset was a negative predictor of mortality. All predictors, except administration of meropenem-vaborbactam within 48 hours, remained significant when the multiple Cox regression model was repeated after adjustment for the propensity score for receipt of combination therapy.

Conclusions

Despite the limits of a retrospective study, the data derived from this multicenter cohort provide additional evidence on the efficacy of meropenem-vaborbactam in treating severe KPC-Kp infections, even when used as monotherapy.

A New Dosing Frontier: Retrospective Assessment of Effluent Flow Rates and Residual Renal Function Among Critically Ill Patients Receiving Continuous Renal Replacement Therapy

OBJECTIVES

In 2020, cefiderocol became the first Food and Drug Administration-approved medication with continuous renal replacement therapy (CRRT) dosing recommendations based on effluent flow rates (QE). We aimed to evaluate the magnitude and frequency of factors that may influence these recommendations, that is, QE intrapatient variability and residual renal function.

DESIGN

Retrospective observational cohort study.

SETTING

ICUs within Hartford Hospital (890-bed, acute-care hospital) in Connecticut from 2017 to 2023.

PATIENTS

Adult ICU patients receiving CRRT for greater than 72 hours.

MEASUREMENTS AND MAIN RESULTS

CRRT settings including QE and urine output (UOP) were extracted from the time of CRRT initiation (0 hr) and trends were assessed. To assess the impact on antibiotic dosing, cefiderocol doses were assigned to 0 hour, 24 hours, 48 hours, and 72 hours QE values per product label, and the proportion of antibiotic dose changes required as a result of changes in inpatient's QE was evaluated. Among the 380 ICU patients receiving CRRT for greater than 72 hours, the median (interquartile range) 0 hour QE was 2.96 (2.35-3.29) L/hr. Approximately 9 QE values were documented per patient per 24-hour window. QE changes of greater than 0.75 L/hr were observed in 21.6% of patients over the first 24 hours and in 7.9% (24-48 hr) and 5.8% (48-72 hr) of patients. Approximately 40% of patients had UOP greater than 500 mL at 24 hours post-CRRT initiation. Due to QE changes within 24 hours of CRRT initiation, a potential cefiderocol dose adjustment would have been warranted in 38% of patients (increase of 21.3%; decrease of 16.6%). QE changes were less common after 24 hours, warranting cefiderocol dose adjustments in less than 15% of patients.

CONCLUSIONS

Results highlight the temporal and variable dynamics of QE and prevalence of residual renal function. Data also demonstrate a risk of antibiotic under-dosing in the first 24 hours of CRRT initiation due to increases in QE. For antibiotics with QE-based dosing recommendations, empiric dose escalation may be warranted in the first 24 hours of CRRT initiation.

Successful treatment of a unique case of solitary primary iliopsoas abscess caused by Streptococcus dysgalactiae subspecies equisimilis: A case report

RATIONALE

Iliopsoas abscess, mainly caused by Staphylococcus aureus, occurs via the bloodstream or spread from adjacent infected organs. Although a few cases regarding primary iliopsoas abscess caused by Streptococcus dysgalactiae subspecies equisimilis (SDSE) with accompanying disseminated foci have been reported to date, there has been no case report on solitary primary iliopsoas abscess caused by SDSE.

PATIENT CONCERNS

An 85-year-old Japanese woman presented with worsening right hip pain and fever after an exercise. Hip computed tomography revealed a right iliopsoas abscess (iliac fossa abscess), and intravenous cefazolin was started as a treatment based on the creatinine clearance level on admission.

DIAGNOSES

Blood cultures were positive for β-hemolytic Lancefield group G gram-positive cocci arranged in long chains, which were identified as SDSE by matrix-assisted laser desorption/ionization. No other disseminated foci were found upon performing whole computed tomography and transthoracic echocardiography. The patient was diagnosed with an SDSE solitary iliopsoas abscess.

INTERVENTIONS

The antimicrobial was appropriately switched to intravenous ampicillin on day 2, with the dosage adjusted to 2 g every 6 hours based on the preadmission creatinine clearance, followed by oral amoxicillin (1500 mg, daily).

OUTCOMES

The abscess disappeared without drainage on day 39, and the patient remained disease-free without recurrence or sequelae during a 6-month follow-up period.

LESSONS

SDSE can cause a solitary primary iliopsoas abscess, which can be successfully treated with an appropriate dose of antimicrobials without draining the abscess.

Early Versus Late Antipseudomonal β-Lactam Antibiotic Dose Adjustment in Critically Ill Sepsis Patients With Acute Kidney Injury: A Prospective Observational Cohort Study

Background

Acute kidney injury (AKI) is a common complication of sepsis, contributing to an increased mortality rate. However, some studies have demonstrated that renal function improves in sepsis patients with AKI within 48 hours, raising questions about the necessity for early antibiotic adjustment. This study evaluates the association between the timing of antipseudomonal β-lactam dose adjustment and the outcomes of critically ill sepsis patients with AKI.

Methods

A prospective, multicenter observational study of critically ill patients aged ≥18 years admitted to the intensive care unit with sepsis and AKI and started on antipseudomonal β-lactam therapy. After the initial dose, eligible patients were grouped as early β-lactam antibiotic (E-BLA) or late β-lactam antibiotic (L-BLA) dose adjustments based on the administration of subsequent renally adjusted doses within 24 hours and after 24 hours of sepsis recognition, respectively. The main outcome of interest was in-hospital mortality.

Results

Among 1185 patients screened, 224 (mean age, 62.7 ± 16.8 years; 62% were male) met inclusion criteria. Eighty-four and 140 patients were included in the E-BLA and L-BLA groups, respectively. Approximately half of the cohort presented with AKI stage II, and piperacillin-tazobactam was prescribed as initial empirical therapy in more than 50% of the cohort. In the multivariable Cox proportional hazards model, L-BLA was associated with a significant reduction in in-hospital mortality compared to E-BLA (hazard ratio, 0.588 [95% confidence interval, .355-.974]).

Conclusions

In sepsis patients with AKI, L-BLA was associated with in-hospital mortality benefits.

Ceftazidime-avibactam induced renal disorders: past and present

With the increasing prevalence of multidrug-resistant Gram-negative bacterial pathogens worldwide, antimicrobial resistance has become a significant public health concern. Ceftazidime-avibactam (CAZ-AVI) exhibited excellent in vitro activity against many carbapenemase-producing pathogens, and was widely used for the treatment of various complicated infections. CAZ-AVI is well tolerated across all dosing regimens, and its associated acute kidney injury (AKI) in phase II/III clinical trials is rare. However, recent real-world studies have demonstrated that CAZ-AVI associated AKI was more frequent in real-world than in phase II and III clinical trials, particularly in patients receiving concomitant nephrotoxic agents, with critically ill patients being at a higher risk. Herein, we reviewed the safety data related to renal impairment of CAZ-AVI, and discussed its pharmacokinetic/pharmacodynamic targets and dosage adjustment in patients with impaired renal function. This review aimed to emphasize the importance for healthcare professionals to be aware of this adverse event of CAZ-AVI and provide practical insights into the dosage optimization in critically ill patients with renal dysfunction.

Clinical efficacy of ceftazidime/avibactam combination therapy for severe hospital-acquired pulmonary infections caused by carbapenem-resistant and difficult-to-treat Pseudomonas aeruginosa

OBJECTIVES

This retrospective study aimed to identify the effectiveness of ceftazidime/avibactam (CAZ/AVI) and its optimisation programs for severe hospital-acquired pulmonary infections (sHAPi) caused by carbapenem-resistant and difficult-to-treat Pseudomonas aeruginosa (CRPA and DTR-P. aeruginosa).

METHODS

We retrospectively analysed observational data on treatment and outcomes of CAZ/AVI for sHAPi caused by CRPA or DTR-P. aeruginosa. The primary study outcomes were to evaluate the clinical and microbiology efficacy of CAZ/AVI.

RESULTS

The cohort consisted of 84 in-patients with sHAPi caused by CRPA (n = 39) and DTR-P. aeruginosa (n = 45) who received at least 72 h of CAZ/AVI therapy. The clinical cure rate was 63.1% in total. There was no significant difference in study outcomes between patients treated with CAZ/AVI monotherapy and those managed with combination regimens. CAZ/AVI as first-line therapy possessed prominent clinical benefits regarding infections caused by DTR-P. aeruginosa. The clinical cure rate was positively relevant with loading dose for CAZ/AVI (odds ratio [OR] 0.03; 95% confidence interval [CI] 0.004-0.19; P < 0.001) and with CAZ/AVI administration by prolonged infusion (odds ratio 0.15; 95% confidence interval 0.03-0.77; P = 0.002). APACHE II score>15 (P = 0.013), septic shock at infection onset (P = 0.001), and CAZ/AVI dose adjustment for renal dysfunction (P = 0.003) were negative predictors of clinical cure.

CONCLUSION

CAZ/AVI is a valid alternative for sHAPi caused by CPRA and DTR-P. aeruginosa, even when used alone. Optimisations of the treatment with CAZ/AVI in critically ill patients, including loading dose, adequate maintenance dose and prolonged infusion, were positively associated with potential clinical benefits.

State of the Management of Infections Caused by Multidrug-Resistant Gram-Negative Organisms

In the past decade, the prevalence of multidrug-resistant gram-negative (MDR-GN) bacterial infections has increased significantly, leading to higher rates of morbidity and mortality. Treating these infections poses numerous challenges, particularly when selecting appropriate empiric therapy for critically ill patients for whom the margin for error is low. Fortunately, the availability of new therapies has improved the treatment landscape, offering safer and more effective options. However, there remains a need to establish and implement optimal clinical and therapeutic approaches for managing these infections. Here, we review strategies for identifying patients at risk for MDR-GN infections, propose a framework for the choice of empiric and definitive treatment, and explore effective multidisciplinary approaches to managing patients in the hospital while ensuring a safe transition to outpatient settings.

Adequacy of cefepime concentrations in the early phase of critical illness: A case for precision pharmacotherapy

STUDY OBJECTIVE

In critically ill patients, adequacy of early antibiotic exposure has been incompletely evaluated. This study characterized factors associated with inadequate cefepime exposure in the first 24 h of critical illness.

DESIGN

Prospective cohort study.

SETTING

Academic Medical Center.

PATIENTS

Critically ill adults treated with cefepime. Patients with acute kidney injury or treated with kidney replacement therapy or extracorporeal membrane oxygenation were excluded.

INTERVENTION

None.

MEASUREMENTS

A nonlinear mixed-effects pharmacokinetic (PK) model was developed to estimate cefepime concentrations for each patient over time. The percentage of time the free drug concentration exceeded 8 mg/L during the first 24 h of therapy was calculated (%ƒT>8; appropriate for the susceptible breakpoint for Pseudomonas aeruginosa). Factors predictive of low %ƒT>8 were explored with multivariable regression.

MAIN RESULTS

In the 100 included patients, a one-compartment PK model was developed with first-order elimination with covariates for weight and estimated glomerular filtration rate based on creatinine and cystatin C (eGFRSCr-CysC). The median (interquartile range) %ƒT>8 for cefepime in the first 24 h of therapy based on this model was 85% (66%, 100%). Less than 100% ƒT>8 during first 24 h of therapy occurred in 70 (70%) individuals. Lower Sequential Organ Failure Assessment score (p = 0.032) and higher eGFRSCr-CysC (p < 0.001) predicted a lower %ƒT>8. Central nervous system infection source was protective (i.e., associated with a higher %ƒT>8; p = 0.008).

CONCLUSIONS

During early critical illness, cefepime concentrations were inadequate in a significant proportion of patients. Antimicrobial optimization is needed to improve the precision of pharmacotherapy in the critically ill patients.

The Significance of Bayesian Pharmacokinetics in Dosing for Critically Ill Patients: A Primer for Clinicians Using Vancomycin as an Example

Antibiotic use is becoming increasingly challenging with the emergence of multidrug-resistant organisms. Pharmacokinetic (PK) alterations result from complex pathophysiologic changes in some patient populations, particularly those with critical illness. Therefore, antibiotic dose individualization in such populations is warranted. Recently, there have been advances in dose optimization strategies to improve the utilization of existing antibiotics. Bayesian-based dosing is one of the novel approaches that could help clinicians achieve target concentrations in a greater percentage of their patients earlier during therapy. This review summarizes the advantages and disadvantages of current approaches to antibiotic dosing, with a focus on critically ill patients, and discusses the use of Bayesian methods to optimize vancomycin dosing. The Bayesian method of antibiotic dosing was developed to provide more precise predictions of drug concentrations and target achievement early in therapy. It has benefits such as the incorporation of personalized PK/PD parameters, improved predictive abilities, and improved patient outcomes. Recent vancomycin dosing guidelines emphasize the importance of using the Bayesian method. The Bayesian method is able to achieve appropriate antibiotic dosing prior to the patient reaching the steady state, allowing the patient to receive the right drug at the right dose earlier in therapy.

Ceftolozane-Tazobactam Versus Ceftazidime-Avibactam for the Treatment of Infections Caused by Multidrug-Resistant Pseudomonas aeruginosa: a Multicenter Cohort Study

Ceftolozane-tazobactam (C-T) and ceftazidime-avibactam (CAZ-AVI) are two novel antimicrobials that retain activity against resistant Pseudomonas aeruginosa. The comparative effectiveness and safety of C-T versus CAZ-AVI remain unknown. A retrospective, multicenter cohort study was performed in six tertiary centers in Saudi Arabia and included patients who received either C-T or CAZ-AVI for infections due to multidrug-resistant (MDR) P. aeruginosa. Overall in-hospital mortality, 30-day mortality, and clinical cure were the main study outcomes. Safety outcomes were also evaluated. A multivariate analysis using logistic regression was used to determine the independent impact of treatment on the main outcomes of interest. We enrolled 200 patients in the study (100 in each treatment arm). A total of 56% were in the intensive care unit, 48% were mechanically ventilated, and 37% were in septic shock. Approximately 19% of patients had bacteremia. Combination therapy was administered to 41% of the patients. The differences between the C-T and CAZ-AVI groups did not reach statistical significance in the overall in-hospital mortality (44% versus 37%; P = 0.314; OR, 1.34; 95% CI, 0.76 to 2.36), 30-day mortality (27% versus 23%; P = 0.514; OR, 1.24; 95% CI, 0.65 to 2.35), clinical cure (61% versus 66%; P = 0.463; OR, 0.81; 95% CI, 0.43 to 1.49), or acute kidney injury (23% versus 17%; P = 0.289; OR, 1.46; 95% CI, 0.69 to 3.14), even after adjusting for differences between the two groups. C-T and CAZ-AVI did not significantly differ in terms of safety and effectiveness, and they serve as potential options for the treatment of infections caused by MDR P. aeruginosa.

Medication Management in the Critically Ill Patient with Acute Kidney Injury

ABSTRACT

AKI occurs frequently in critically ill patients. Patients with AKI, including those who require KRT, experience multiple pharmacokinetic and pharmacodynamic perturbations that dynamically influence medication effectiveness and safety. Patients with AKI may experience both subtherapeutic drug concentrations, which lead to ineffective therapy, and supratherapeutic drug concentrations, which increase the risk for toxicity. In critically ill patients with AKI not requiring KRT, conventional GFR estimation equations, especially those based on serum creatinine, have several limitations that can limit the accuracy when used for medication dosing. Alternative methods to estimate kidney function may be informative, including use of measured urinary creatinine clearance, kinetic eGFR, and equations that integrate novel kidney biomarkers. For critically ill patients with AKI requiring KRT, physicochemical properties of the drug, the KRT prescription and circuit configuration, and patient-specific factors each contribute to medication clearance. Evidence-based guidance for medication dosing during AKI requiring KRT is often limited. A working knowledge of the basic tenets of drug elimination during KRT can provide a framework for how to approach decision making when the literature is lacking. Iterative re-evaluation of a patient's progress toward therapeutic goals with a medication must occur over the arc of critical illness, including and especially in the setting of dynamic kidney function.

Rationale and evidence for the use of new beta-lactam/beta-lactamase inhibitor combinations and cefiderocol in critically ill patients

BACKGROUND

Healthcare-associated infections involving Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) phenotype are associated with impaired patient-centered outcomes and poses daily therapeutic challenges in most of intensive care units worldwide. Over the recent years, four innovative β-lactam/β-lactamase inhibitor (BL/BLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of certain DTR-GNB infections. The literature addressing their microbiological spectrum, pharmacokinetics, clinical efficacy and safety was exhaustively audited by our group to support the recent guidelines of the French Intensive Care Society on their utilization in critically ill patients. This narrative review summarizes the available evidence and unanswered questions on these issues.

METHODS

A systematic search for English-language publications in PUBMED and the Cochrane Library database from inception to November 15, 2022.

RESULTS

These drugs have demonstrated relevant clinical success rates and a reduced renal risk in most of severe infections for whom polymyxin- and/or aminoglycoside-based regimen were historically used as last-resort strategies-namely, ceftazidime-avibactam for infections due to Klebsiella pneumoniae carbapenemase (KPC)- or OXA-48-like-producing Enterobacterales, meropenem-vaborbactam for KPC-producing Enterobacterales, ceftazidime-avibactam/aztreonam combination or cefiderocol for metallo-β-lactamase (MBL)-producing Enterobacterales, and ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam for non-MBL-producing DTR Pseudomonas aeruginosa. However, limited clinical evidence exists in critically ill patients. Extended-infusion scheme (except for imipenem-relebactam) may be indicated for DTR-GNB with high minimal inhibitory concentrations and/or in case of augmented renal clearance. The potential benefit of combining these agents with other antimicrobials remains under-investigated, notably for the most severe presentations. Other important knowledge gaps include pharmacokinetic information in particular situations (e.g., pneumonia, other deep-seated infections, and renal replacement therapy), the hazard of treatment-emergent resistance and possible preventive measures, the safety of high-dose regimen, the potential usefulness of rapid molecular diagnostic tools to rationalize their empirical utilization, and optimal treatment durations. Comparative clinical, ecological, and medico-economic data are needed for infections in whom two or more of these agents exhibit in vitro activity against the causative pathogen.

CONCLUSIONS

New BL/BLI combinations and cefiderocol represent long-awaited options for improving the management of DTR-GNB infections. Several research axes must be explored to better define the positioning and appropriate administration scheme of these drugs in critically ill patients.

The place of new antibiotics for Gram-negative bacterial infections in intensive care: report of a consensus conference

INTRODUCTION

New beta-lactams, associated or not with beta-lactamase inhibitors (NBs/BIs), can respond to the spread of carbapenemase-producing enterobacteriales and nonfermenting carbapenem-resistant bacteria. The risk of emergence of resistance to these NBs/BIs makes guidelines necessary. The SRLF organized a consensus conference in December 2022.

METHODS

An ad hoc committee without any conflict of interest (CoI) with the subject identified the molecules (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-cilastatin-relebactam, meropenem-vaborbactam and cefiderocol); defined 6 generic questions; drew up a list of subquestions according to the population, intervention, comparison and outcomes (PICO) model; and reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Seven experts in the field proposed their own answers to the questions in a public session and answered questions from the jury (a panel of 10 critical-care physicians without any CoI) and the public. The jury then met alone for 48 h to write its recommendations. Due to the frequent lack of powerful studies that have used clinically important criteria of judgment, the recommendations were formulated as expert opinions as often as necessary.

RESULTS

The jury provided 17 statements answering 6 questions: (1) Is there a place in the ICU for the probabilistic use of new NBs/IBs active against Gram-negative bacteria? (2) In the context of documented infections with sensitivity to several of these molecules, are there pharmacokinetic, pharmacodynamic, ecological or medico-economic elements for prioritization? (3) What are the possible combinations with these molecules and in what context? (4) Should we integrate these new molecules into a carbapenem-sparing strategy? (5) What pharmacokinetic and pharmacodynamic data are available to optimize their mode of administration in critically ill patients? (6) What are the dosage adaptations in cases of renal insufficiency, hepatocellular insufficiency or obesity?

CONCLUSION

These recommendations should optimize the use of NBs/BIs in ICU patients.

Optimizing the Use of Beta-Lactam Antibiotics in Clinical Practice: A Test of Time

Despite their limitations, the pharmacokinetics (PK) and pharmacodynamics (PD) indices form the basis for our current understanding regarding antibiotic development, selection, and dose optimization. Application of PK-PD in medicine has been associated with better clinical outcome, suppression of resistance, and optimization of antibiotic consumption. Beta-lactam antibiotics remain the cornerstone for empirical and directed therapy in many patients. The percentage of time of the dosing interval that the free (unbound) drug concentration remains above the minimal inhibitory concentration (MIC) (%fT > MIC) has been considered the PK-PD index that best predicts the relationship between antibiotic exposure and killing for the beta-lactam antibiotics. Time dependence of beta-lactam antibiotics has its origin in the acylation process of the serine active site of penicillin-binding proteins, which subsequently results in bacteriostatic and bactericidal effects during the dosing interval. To enhance the likelihood of target attainment, higher doses, and prolonged infusion strategies, with/or without loading doses, have been applied to compensate for subtherapeutic levels of antibiotics related to PK-PD changes, especially in the early phase of severe sepsis. To minimize resistance and maximize clinical outcome, empirical therapy with a meropenem loading dose followed by high-dose-prolonged infusion should be considered in patients with high inoculum infections presenting as severe (Gram negative) sepsis. Subsequent de-escalation and dosing of beta-lactam antibiotics should be considered as an individualized dynamic process that requires dose adjustments throughout the time course of the disease process mediated by clinical parameters that indirectly assess PK-PD alterations.

The expert clinical pharmacological advice program for tailoring on real-time antimicrobial therapies with emerging TDM candidates in special populations: how the ugly duckling turned into a swan

INTRODUCTION

The growing spread of infections caused by multidrug-resistant pathogens makes the need of tailoring antimicrobial therapies by means of a 'patient-centered' approach fundamental. In this scenario, therapeutic drug monitoring (TDM) of emerging antimicrobial candidates may be a valuable approach, but expert interpretation of TDM results should be granted for making them more clinically useful. The MD Clinical Pharmacologist may take over this task since this specialist may couple PK/PD expertise on drugs with a medical background and may provide expert interpretation of TDM results of antimicrobials for tailoring therapy on real-time in each single patient based on specific both drug/pathogen issues and patient issues.

AREAS COVERED

This article aims to highlight the main key-points and organizational aspects for implementing a successful TDM-based expert clinical pharmacological advice (ECPA) program for tailoring antimicrobial therapies on real-time in different hospitalized patient special populations.

EXPERT OPINION

TDM-based ECPA programs lead by the MD Clinical Pharmacologist may represent a way forward for maximizing clinical efficacy and for minimizing the risk of resistance developments and/or toxicity of antimicrobials. Stakeholders should be aware of the fact that this innovative approach may be cost-effective.

Software- and TDM-Guided Dosing of Meropenem Promises High Rates of Target Attainment in Critically Ill Patients

Various studies have reported insufficient beta-lactam concentrations in critically ill patients. The optimal dosing strategy for beta-lactams in critically ill patients, particularly in septic patients, is an ongoing matter of discussion. This retrospective study aimed to evaluate the success of software-guided empiric meropenem dosing (CADDy, Calculator to Approximate Drug-Dosing in Dialysis) with subsequent routine meropenem measurements and expert clinical pharmacological interpretations. Adequate therapeutic drug exposure was defined as concentrations of 8-16 mg/L, whereas concentrations of 16-24 mg/L were defined as moderately high and concentrations >24 mg/L as potentially harmful. A total of 91 patients received meropenem as a continuous infusion (229 serum concentrations), of whom 60% achieved 8-16 mg/L, 23% achieved 16-24 mg/L, and 10% achieved unnecessarily high and potentially harmful meropenem concentrations >24 mg/L in the first 48 h using the dosing software. No patient showed concentrations <2 mg/L using the dosing software in the first 48 h. With a subsequent TDM-guided dose adjustment, therapeutic drug exposure was significantly (p ≤ 0.05) enhanced to 70%. No patient had meropenem concentrations >24 mg/L with TDM-guided dose adjustments. The combined use of dosing software and consecutive TDM promised a high rate of adequate therapeutic drug exposures of meropenem in patients with sepsis and septic shock.

Simulation of Vancomycin Exposure Using Trough and Peak Levels Achieves the Target Area under the Steady-State Concentration-Time Curve in ICU Patients

The therapeutic drug monitoring (TDM) of vancomycin (VCM) in critically ill patients often results in the estimated area being under the concentration-time curve (AUC) values that deviate from individual observations. In this study, we investigated the factors influencing the achievement of the target AUC of VCM at steady-state in critically ill patients. We retrospectively collected data from patients treated with VCM in an intensive care unit (ICU). Multivariate analysis was used to adjust for significant factors with p < 0.05 and identify new factors affecting the achievement of the target AUC at steady-state for VCM. Among the 113 patients included in this study, 72 (64%) were in the 1-point group (trough only), whereas 41 (36%) were in the 2-point group (trough/peak). The percentage of patients achieving the target AUC at the follow-up TDM evaluation was significantly higher in the two-point group. Multivariate analysis showed that being in the 2-point group and those with a 20% or more increase (or decrease) in creatinine clearance (CCr) were both significantly associated with the success rate of achieving the target AUC at the follow-up TDM. Novel findings revealed that in patients admitted to the ICU, changes in renal function were a predictor of AUC deviation, with a 20% or more increase (or decrease) in CCr being an indicator. We believe the indicators obtained in this study are simple and can be applied clinically in many facilities. If changes in renal function are anticipated, we recommend an AUC evaluation of VCM with a two-point blood collection, close monitoring of renal function, and dose adjustment based on reanalyzing the serum concentrations of VCM.

Effectiveness of First-Line Therapy with Old and Novel Antibiotics in Ventilator-Associated Pneumonia Caused by Carbapenem-Resistant Acinetobacter baumannii: A Real Life, Prospective, Observational, Single-Center Study

Evidence-based, standard antibiotic therapy for ventilator-associated pneumonia (VAP) caused by carbapenem-resistant Acinetobacter baumannii (CRAB) is a relevant unmet clinical need in the intensive care unit (ICU). We aimed to evaluate the effectiveness of first-line therapy with old and novel CRAB active antibiotics in monomicrobial VAP caused by CRAB. A prospective, observational study was performed in a mixed non-COVID-19 ICU. The primary outcome measure was clinical failure upon first-line targeted therapy. Features independently influencing failure occurrence were also investigated via Cox proportional multivariable analysis. To account for the imbalance in antibiotic treatment allocation, a propensity score analysis with an inverse probability treatment weighting approach was adopted. Of the 90 enrolled patients, 34 (38%) experienced clinical failure. Compared to patients who experienced a clinical resolution of VAP, those who had clinical failure were of an older age (median age 71 (IQR 64-78) vs. 62 (IQR 52-69) years), and showed greater burden of comorbidities (median Charlson comorbidity index 8 (IQR 6-8) vs. 4 (IQR 2-6)), higher frequency of immunodepression (44% vs. 21%), and greater clinical severity at VAP onset (median SOFA score 10 (IQR 9-11) vs. 9 (IQR 7-11)). Lower rates of use of fast molecular diagnostics for nosocomial pneumonia (8.8% vs. 30.3%) and of timely CRAB active therapy administration (65% vs. 89%), and higher rates of colistin-based targeted therapy (71% vs. 46%) were also observed in patients who failed first-line therapy. Overall, CRAB active iv regimens were colistin-based in 50 patients and cefiderocol-based in 40 patients, both always combined with inhaled colistin. According to the backbone agent of first-line regimens, clinical failure was lower in the cefiderocol group, compared to that in the colistin group (25% vs. 48%, respectively). In multivariable Cox regression analysis, the burden of comorbid conditions independently predicted clinical failure occurrence (Charlson index aHR = 1.21, 95% CI = 1.04-1.42, p = 0.01), while timely targeted antibiotic treatment (aHR = 0.40, 95% CI = 0.19-0.84, p = 0.01) and cefiderocol-based first-line regimens (aHR = 0.38, 95% CI = 0.17-0.85, p = 0.02) strongly reduced failure risk. In patients with VAP caused by CRAB, timely active therapy improves infection outcomes and cefiderocol holds promise as a first-line therapeutic option.

Impact of Piperacillin-Tazobactam Dosing in Septic Shock Patients Using Real-World Evidence: An Observational, Retrospective Cohort Study

BACKGROUND

Sepsis and septic shock are associated with significant morbidity and mortality. Rapid initiation of appropriate antibiotic therapy is essential, as inadequate therapy early during septic shock has been shown to increase the risk of mortality. However, despite the importance of appropriate antibiotic initiation, in clinical practice, concerns for renal dysfunction frequently lead to antibiotic dose reduction, with scant evidence on the impact of this practice in septic shock patients.

OBJECTIVE

The purpose if this article is to investigate the rate and impact of piperacillin-tazobactam dose adjustment in early phase septic shock patients using real-world electronic health record (EHR) data.

METHODS

A multicenter, observational, retrospective cohort study was conducted of septic shock patients who received at least 48 hours of piperacillin-tazobactam therapy and concomitant receipt of norepinephrine. Subjects were stratified into 2 groups according to their cumulative 48-hour piperacillin-tazobactam dose: low piperacillin-tazobactam dosing (LOW; <27 g) group and normal piperacillin-tazobactam dosing (NORM; ≥27 g) group. To account for potential confounding variables, propensity score matching was used. The primary study outcome was 28-day norepinephrine-free days (NFD).

RESULTS

In all, 1279 patients met study criteria. After propensity score matching (n = 608), the NORM group had more median NFD (23.9 days [interquartile range, IQR: 0-27] vs 13.6 days [IQR: 0-27], P = 0.021). The NORM group also had lower rates of in-hospital mortality/hospice disposition (25.9% [n = 79] vs 35.5% [n = 108]), P = 0.014). Other secondary outcomes were similar between the treatment groups.

CONCLUSIONS AND RELEVANCE

In the propensity score-matched cohort, the NORM group had significantly more 28-day NFD. Piperacillin-tazobactam dose reduction in early phase septic shock is associated with worsened clinical outcomes. Clinicians should be vigilant to avoid piperacillin-tazobactam dose reduction in early phase septic shock.

Association between emergency department sepsis order set design and delay to second dose piperacillin-tazobactam administration

BACKGROUND

Delay to first antibiotic dose in patients with sepsis has been associated with increased mortality. Second dose antibiotic delay has also been linked to worsened patient outcomes. Optimal methods to decrease second dose delay are currently unclear. The primary objective of this study was to evaluate the association between updating an emergency department (ED) sepsis order set design from one-time doses to scheduled antibiotic frequencies and delay to administration of second piperacillin-tazobactam dose.

METHODS

This retrospective cohort study was conducted at eleven hospitals in a large, integrated health system and included adult patients treated in the ED with at least one dose of piperacillin-tazobactam ordered through an ED sepsis order set over a two year period. Patients were excluded if they received less than two doses of piperacillin-tazobactam. Midway through the study period, the enterprise-wide ED sepsis order set was updated to include scheduled antibiotic frequencies. Two patient cohorts receiving piperacillin-tazobactam were compared: those in the year before the order set update and those in the year post-update. The primary outcome was major delay, defined as an administration delay >25% of the recommended dosing interval, which was evaluated with multivariable logistic regression and interrupted time series analysis.

RESULTS

3219 patients were included: 1222 in the pre-update group and 1997 in the post-update group. The proportion of patients who experienced major second dose delay was significantly lower in the post-update group (32.7% vs 25.6%, p < 0.01; adjusted OR 0.64, 95% CI 0.52 to 0.78). No between-group difference was detected in the slope of monthly major delay frequency, but there was a significant level change (post-update change -10%, 95% CI -17.9% to -1.9%).

CONCLUSIONS

Including scheduled antibiotic frequencies in ED sepsis order sets is a pragmatic mechanism to decrease delays in second antibiotic doses.

Review of novel β-lactams and β-lactam/β-lactamase inhibitor combinations with implications for pediatric use

Antimicrobial resistance continues to surmount increasing concern globally, and treatment of difficult-to-treat (DTR) Pseudomonas aeruginosa, carbapenem-resistant (CR) Acinetobacter baumannii (CRAB), and CR Enterobacterales (CRE) remains a challenge for clinicians. Although previously rare, the incidence of multidrug-resistant (MDR) and CR infections in pediatric patients has increased drastically in the last decade and is associated with increased morbidity and mortality. To combat this issue, 14 novel antibiotics, including three β-lactam/novel β-lactamase inhibitor combinations (βL-βLIs) and two novel β-lactams (βLs), have received approval from the United States Food and Drug Administration since 2010. Improving clinician understanding of the utility of these novel therapies is imperative to improve judicious decision-making and prevent societal regression to a pre-penicillin era. In this review, we summarize the pharmacokinetic/pharmacodynamic (PK/PD) properties, clinical efficacy and safety data, dosing considerations, and subsequent role in therapy for ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MER-VAB), imipenem-cilastatin-relebactam (IMI-REL), ceftolozane-tazobactam (TOL-TAZ), and cefiderocol in pediatric patients.

Clinical efficacy of renal dosing adjustments of ceftazidime-avibactam in patients affected by carbapenem-resistant Gram-negative infections: A systematic review and meta-analysis of observational studies

AIMS

The aim of this study is to assess clinical efficacy of ceftazidime-avibactam for the management of carbapenem-resistant Gram-negative infections in renal patients receiving recommended dosing adjustments compared to those treated with scheduled full-dose.

METHODS

Two authors independently searched PubMed-MEDLINE and Scopus database from inception to 31 December 2021, to retrieve randomized controlled trials or observational studies comparing clinical efficacy of ceftazidime-avibactam in patients affected by carbapenem-resistant Gram-negative infections receiving recommended renal dosing adjustments compared to those treated with scheduled full-dose. Data were independently extracted by the 2 authors, and the quality of included studies was independently assessed according to ROBINS-I tool for observational studies. Mortality rate was selected as primary outcome. Meta-analysis was conducted by including only studies at low or moderate risk of bias providing adjustment for confounders.

RESULTS

In total, 1794 articles were screened, and 11 observational studies (1 prospective and 10 retrospective) were included. Serious or critical risk of bias was found in 4 studies, while the other 7 were classified at moderate risk of bias and included in the meta-analysis. Renal dosing adjustments of ceftazidime-avibactam were associated with higher risk of mortality (odds ratio 1.79; 95% confidence interval 1.18-2.72).

CONCLUSION

Renal dosing adjustment of ceftazidime-avibactam seems to be associated with a higher risk of mortality in patients affected by carbapenem-resistant Gram-negative infections. However, residual confounder associated with baseline conditions cannot be excluded. Further prospective studies including larger samples are warranted to definitively address this unmet clinical need.

Jumping into the future: overcoming pharmacokinetic/pharmacodynamic hurdles to optimize the treatment of severe difficult to treat-Gram-negative infections with novel beta-lactams

INTRODUCTION

The choice of best therapeutic strategy for difficult-to-treat resistance (DTR) Gram-negative infections currently represents an unmet clinical need.

AREAS COVERED

This review provides a critical reappraisal of real-world evidence supporting the role of pharmacokinetic/pharmacodynamic (PK/PD) optimization of novel beta-lactams in the management of DTR Gram-negative infections. The aim was to focus on prolonged and/or continuous infusion administration, penetration rates into deep-seated infections, and maximization of PK/PD targets in special renal patient populations. Retrieved findings were applied to the three most critical clinical scenarios of Gram-negative resistance phenotypes (i.e. carbapenem-resistant Enterobacterales; difficult-to-treat resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii).

EXPERT OPINION

Several studies supported the role of PK/PD optimization of beta-lactams in the management of DTR Gram-negative infections for both maximizing clinical efficacy and preventing resistance emergence. Optimizing antimicrobial therapy with novel beta-lactams based on the so called 'antimicrobial therapy puzzle' PK/PD concepts may represent a definitive jump into the future toward a personalized patient management of DTR Gram negative infections. Establishing a dedicated and coordinated multidisciplinary team and implementing a real-time TDM-guided personalized antimicrobial exposure optimization of novel beta-lactams based on expert clinical pharmacological interpretation, could represent crucial cornerstones for the proper management of DTR Gram-negative infections.

Risk of bleeding with factor Xa inhibitors versus unfractionated heparin in patients with acute kidney injury

STUDY OBJECTIVE

To compare bleeding and thromboembolic events in patients receiving therapeutic doses of apixaban or rivaroxaban versus unfractionated heparin (UFH) in patients with acute kidney injury (AKI).

DESIGN

Single-center, retrospective, observational study.

SETTING

Ascension St. John Hospital in Detroit, Michigan.

PATIENTS

Hospitalized adult patients who received therapeutic doses of factor Xa inhibitors (n = 250) or UFH (n = 250) for at least 24 h in the setting of AKI.

MEASUREMENTS AND MAIN RESULTS

After adjusting for confounding factors, patients who received a factor Xa inhibitor experienced a lower risk of composite major and clinically relevant nonmajor bleeding (CRNMB) events compared with UFH (OR: 0.57, 95% CI: 0.34-0.94; p = 0.03). There was a significantly decreased risk of CRNMB events in the factor Xa inhibitor group (OR: 0.55, 95% CI: 0.33-0.91, p = 0.02); however, no significant differences in major bleeding or venous thromboembolism (VTE) were noted.

CONCLUSIONS

Our results suggest that it may be preferable to continue patients in AKI on factor Xa inhibitors versus transitioning to UFH due to the lower risk of bleeding events.

A descriptive pharmacokinetic/pharmacodynamic analysis of continuous infusion ceftazidime-avibactam in a case series of critically ill renal patients treated for documented carbapenem-resistant Gram-negative bloodstream infections and/or ventilator-associated pneumonia

OBJECTIVES

To describe the pharmacokinetic/pharmacodynamic (PK/PD) behaviour of continuous infusion (CI) ceftazidime-avibactam and the microbiological outcome in a case series of critically ill renal patients treated for documented carbapenem-resistant Gram-negative (CR-GN) bloodstream infections (BSI) and/or ventilator-associated pneumonia (VAP).

METHODS

Critically ill patients with different degrees of renal function who were treated with CI ceftazidime-avibactam for documented CR-GN infections, and who underwent therapeutic drug monitoring from April 2021 to March 2022, were retrospectively assessed. Ceftazidime and avibactam concentrations were determined at steady-state, and the free fraction (fC_ss) was calculated. The joint PK/PD target of ceftazidime-avibactam was considered as optimal when both C_ss/MIC ratio for ceftazidime ≥4 (equivalent to 100%fT>_4xMIC) and C_ss/C_T ratio for avibactam >1 (equivalent to 100% fT>C_T of 4.0 mg/L) were simultaneously achieved (quasi-optimal if only one of the two was achieved, and suboptimal if neither of the two was achieved). The relationship between ceftazidime-avibactam PK/PD targets and microbiological outcome was assessed.

RESULTS

Ten patients with documented CR-GN infections (5 BSIs, 4 VAP, 1 BSI+VAP) were retrieved. The joint PK/PD targets of ceftazidime-avibactam were optimal and quasi-optimal in eight and two cases, respectively. Microbiological failure occurred in two patients (one with VAP, one with BSI+VAP), one of whom developed ceftazidime-avibactam resistance. Both underwent renal replacement therapy, and failed despite attaining optimal joint PK/PD target and receiving fosfomycin co-treatment.

CONCLUSION

CI administration may enable optimal joint PK/PD targets of ceftazidime-avibactam to be achieved in most critical renal patients with CR-GN infections, and may help to minimize the risk of microbiological failure.

A Proof of Concept of the Usefulness of a TDM-Guided Strategy for Optimizing Pharmacokinetic/Pharmacodynamic Target of Continuous Infusion Ampicillin-Based Regimens in a Case Series of Patients with Enterococcal Bloodstream Infections and/or Endocarditis

(1) Objective: To describe the usefulness of a real-time therapeutic drug monitoring (TDM)-based strategy for optimizing pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) ampicillin-based regimens in a case series of patients affected by suspected or documented enterococcal bloodstream infections (BSIs) and/or infective endocarditis (IE). (2) Methods: Patients treated with CI ampicillin-based regimens for documented or suspected enterococcal BSI/IE who underwent real-time therapeutic drug monitoring (TDM)-based expert clinical pharmacological advice (ECPA) between June 2021 and May 2022 were retrospectively assessed. Ampicillin concentrations were determined at steady state, and the free fraction (fCss) was calculated according to a plasma protein binding of 20%. The fCss/MIC ratio was selected as the PD parameter for ampicillin efficacy and was defined as optimal for values between 4 and 8. The requirement for TDM-guided ampicillin dosing adjustments was assessed. (3) Results: Data for 12 patients with documented (n = 10) or suspected (n = 2) enterococcal infections (7 with BSIs and 5 with IE) were retrieved. The ampicillin PK/PD target was optimal over time in all of the 10 documented infections. None of the enterococcal BSIs persisted. Following the first real-time TDM-based ECPA, ampicillin dosage was decreased by >50% in 11 out of 12 patients (91.7%). (4) Conclusions: CI may be helpful in attaining aggressive ampicillin PK/PD targets in patients affected by enterococcal BSIs and/or IE. Administration of CI ampicillin after loading coupled with real-time TDM-based ECPA could be a valuable strategy for managing enterococcal infections.

Optimization of antimicrobial dosing in patients with acute kidney injury: a single-centre observational study

Background

Acute kidney injury (AKI) is a potential complication of systemic infection. Optimizing antimicrobial dosing in this dynamic state can be challenging with sub- or supra-therapeutic dosing risking treatment failure or toxicity, respectively. Locally, unadjusted renal dosing for the first 48 h of infection is recommended.

Objectives

To determine the outcomes associated with this dosing strategy.

Methods

A retrospective cohort analysis was undertaken in patients treated for Gram-negative bacteraemia with concurrent non-filtration dependent AKI from a single-centre NHS acute hospital (April 2016–March 2020). Patient demographics, microbiology data, antimicrobial treatment and patient outcome (in-hospital mortality and kidney function) were analysed.

Results

In total, 647 episodes of Gram-negative bacteraemia (608 patients) were included; 305/608 (50.2%) were male with median age 71 years (range 18–100). AKI was present in 235/647 (36.3%); 78/647 (12.1%) and 45/647 (7.0%) having Kidney Disease Improving Global Outcomes-defined injury (stage 2) or failure (stage 3), respectively. In-hospital 30 day mortality was 25/352 (7.1%), 14/112 (12.5%), 26/123 (21.1%) and 11/60(18.3%) in patients with normal renal function, AKI stage 1, AKI stage ≥2 and established chronic kidney disease, respectively. Recovery of renal function at Day 21 or discharge was present in 105/106 surviving patients presenting with AKI stage ≥2. Time to recovery of AKI was similar in patients receiving full, low or no aminoglycoside (3 versus 4 versus 3 days, P = 0.612) and those receiving full- and low-dose β-lactam (3 versus 5 days, P = 0.077).

Conclusions

There is a high burden of AKI in patients with Gram-negative bacteraemia. Dose adjustments of β-lactams may not be necessary in the first 48 h of infection-induced AKI and single-dose aminoglycosides may be considered for early empirical coverage.

β-Lactam Therapeutic Drug Monitoring in Critically Ill Patients: Weighing the Challenges and Opportunities to Assess Clinical Value

OBJECTIVE

β-lactams are the cornerstone of empiric and targeted antibiotic therapy for critically ill patients. Recently, there have been calls to use β-lactam therapeutic drug monitoring (TDM) within 24-48 hours after the initiation of therapy in critically ill patients. In this article, we review the dynamic physiology of critically ill patients, β-lactam dose response in critically ill patients, the impact of pathogen minimum inhibitory concentration (MIC) on β-lactam TDM, and pharmacokinetics in critically ill patients. Additionally, we highlight available clinical data to better inform β-lactam TDM for critically ill patients.

DATA SOURCES

We retrospectively analyzed patients admitted for sepsis or septic shock at a single academic medical center who were treated with β-lactam antibiotics.

STUDY SELECTION

Indexed studies in PubMed in English language were selected for review on topics relative to critical care physiology, β-lactams, pharmacokinetics/pharmacodynamics, TDM, and antibiotic susceptibility.

DATA EXTRACTION

We reviewed potentially related studies on β-lactams and TDM and summarized their design, patients, and results. This is a synthetic, nonsystematic, review.

DATA SYNTHESIS

In the retrospective analysis of patients treated with β-lactam antibiotics, approximately one-third of patients received less than 48 hours of β-lactam therapy. Of those who continued beyond 48 hours, only 13.7% had patient-specific factors (augmented renal clearance, fluid overload, morbid obesity, and/or surgical drain), suggesting a potential benefit of β-lactam TDM.

CONCLUSIONS

These data indicate that a strategy of comprehensive β-lactam TDM for critically ill patients is unwarranted as it has not been shown yet to improve patient-oriented outcomes. This review demonstrates that β-lactam TDM in the ICU, while laudable, layers ambiguous β-lactam exposure thresholds upon uncertain/unknown MIC data within a dynamic, unpredictable patient population for whom TDM results will not be available fast enough to significantly affect care. Judicious, targeted TDM for those with risk factors for β-lactam over- or underexposure is a better approach but requires further study. Clinically, choosing the correct antibiotic and dosing β-lactams aggressively, which have a wide therapeutic index, to overcome critical illness factors appears to give critically ill patients the best likelihood of survival.

Antimicrobial safety considerations in critically ill patients: part I: focused on acute kidney injury

INTRODUCTION

Antibiotic prescription is a challenging issue in critical care settings. Different pharmacokinetic and pharmacodynamic properties, polypharmacy, drug interactions, and high incidence of multidrug-resistant microorganisms in this population can influence the selection, safety, and efficacy of prescribed antibiotics.

AREAS COVERED

In the current article, we searched PubMed, Scopus, and Google Scholar for estimating renal function in acute kidney injury, nephrotoxicity of commonly used antibiotics, and nephrotoxin stewardship in intensive care units.

EXPERT OPINION

Early estimation of kidney function with an accurate method may be helpful to optimize antimicrobial treatment in critically ill patients. Different antibiotic dosing regimens may be required for patients with acute kidney injury. In many low-resource settings, therapeutic drug monitoring is not available for antibiotics. Acute kidney injury may influence treatment effectiveness and patient outcome.

Expert clinical pharmacological advice may make an antimicrobial TDM program for emerging candidates more clinically useful in tailoring therapy of critically ill patients

Background

Therapeutic drug monitoring (TDM) may represent an invaluable tool for optimizing antimicrobial therapy in septic patients, but extensive use is burdened by barriers. The aim of this study was to assess the impact of a newly established expert clinical pharmacological advice (ECPA) program in improving the clinical usefulness of an already existing TDM program for emerging candidates in tailoring antimicrobial therapy among critically ill patients.

Methods

This retrospective observational study included an organizational phase (OP) and an assessment phase (AP). During the OP (January–June 2021), specific actions were organized by MD clinical pharmacologists together with bioanalytical experts, clinical engineers, and ICU clinicians. During the AP (July–December 2021), the impact of these actions in optimizing antimicrobial treatment of the critically ill patients was assessed. Four indicators of performance of the TDM-guided real-time ECPA program were identified [total TDM-guided ECPAs July–December 2021/total TDM results July–December 2020; total ECPA dosing adjustments/total delivered ECPAs both at first assessment and overall; and turnaround time (TAT) of ECPAs, defined as optimal (< 12 h), quasi-optimal (12–24 h), acceptable (24–48 h), suboptimal (> 48 h)].

Results

The OP allowed to implement new organizational procedures, to create a dedicated pathway in the intranet system, to offer educational webinars on clinical pharmacology of antimicrobials, and to establish a multidisciplinary team at the morning bedside ICU meeting. In the AP, a total of 640 ECPAs were provided for optimizing 261 courses of antimicrobial therapy in 166 critically ill patients. ECPAs concerned mainly piperacillin–tazobactam (41.8%) and meropenem (24.9%), and also other antimicrobials had ≥ 10 ECPAs (ceftazidime, ciprofloxacin, fluconazole, ganciclovir, levofloxacin, and linezolid). Overall, the pre–post-increase in TDM activity was of 13.3-fold. TDM-guided dosing adjustments were recommended at first assessment in 61.7% of ECPAs (10.7% increases and 51.0% decreases), and overall in 45.0% of ECPAs (10.0% increases and 35.0% decreases). The overall median TAT was optimal (7.7 h) and that of each single agent was always optimal or quasi-optimal.

Conclusions

Multidisciplinary approach and timely expert interpretation of TDM results by MD Clinical Pharmacologists could represent cornerstones in improving the cost-effectiveness of an antimicrobial TDM program for emerging TDM candidates.

Measured versus estimated creatinine clearance in critically ill patients with acute kidney injury: an observational study

Background

Acute kidney injury (AKI) commonly occurs in critically ill patients. Estimation of renal function and antibiotics dose adjustment in patients with AKI is a challenging issue.

Methods

Urinary creatinine clearance was measured in a 6-hour urine collection from patients with acute kidney injuries. The correlations between different formulas including the modified Cockcroft-Gault, modification of diet in renal disease, chronic kidney disease-epidemiology collaboration, Jelliffe, kinetic-glomerular filtration rate (GFR), Brater, and Chiou formulas were considered. The pattern of the prescribed antimicrobial agents was also compared with the patterns in the available resources.

Results

Ninety-five patients with acute kidney injuries were included in the research. The mean age of the participants was 63.11±17.58 years old. The most patients (77.89%) were in stage 1 of AKI according to the Acute Kidney Injury Network criteria, followed by stage 2 (14.73%) and stage 3 (7.36), respectively. None of the formulations had a high or very high correlation with the measured creatinine clearance. In stage 1, Chiou (r=0.26), and in stage 2 and 3, kinetic-GFR (r=0.76 and r=0.37) had the highest correlation coefficient. Antibiotic over- and under-dosing were frequently observed in the study.

Conclusions

The results showed that none of the static methods can predict the measured creatinine clearance in the critically ill patients. The dynamic methods such as kinetic-GFR can be helpful for patients who do not receive diuretics and vasopressors. Further studies are needed to confirm our results.

Drug Regimens of Novel Antibiotics in Critically Ill Patients with Varying Renal Functions: A Rapid Review

There is currently an increase in the emergence of multidrug-resistant bacteria (MDR) worldwide, requiring the development of novel antibiotics. However, it is not only the choice of antibiotic that is important in treating an infection; the drug regimen also deserves special attention to avoid underdosing and excessive concentrations. Critically ill patients often have marked variation in renal function, ranging from augmented renal clearance (ARC), defined as a measured creatinine clearance (CrCL) ≥ 130 mL/min*1.73 m², to acute kidney injury (AKI), eventually requiring renal replacement therapy (RRT), which can affect antibiotic exposure. All novel beta-lactam (BLs) and/or beta-lactam/beta-lactamases inhibitors (BL/BLIs) antibiotics have specific pharmacokinetic properties, such as hydrophilicity, low plasma–protein binding, small volume of distribution, low molecular weight, and predominant renal clearance, which require adaptation of dosage regimens in the presence of abnormal renal function or RRT. However, there are limited data on the topic. The aim of this review was therefore to summarize available PK studies on these novel antibiotics performed in patients with ARC or AKI, or requiring RRT, in order to provide a practical approach to guide clinicians in the choice of the best dosage regimens in critically ill patients.

Pharmacokinetics and pharmacodynamics of peptide antibiotics

Antimicrobial resistance is a major global health challenge. As few new efficacious antibiotics will become available in the near future, peptide antibiotics continue to be major therapeutic options for treating infections caused by multidrug-resistant pathogens. Rational use of antibiotics requires optimisation of the pharmacokinetics and pharmacodynamics for the treatment of different types of infections. Toxicodynamics must also be considered to improve the safety of antibiotic use and, where appropriate, to guide therapeutic drug monitoring. This review focuses on the pharmacokinetics/pharmacodynamics/toxicodynamics of peptide antibiotics against multidrug-resistant Gram-negative and Gram-positive pathogens. Optimising antibiotic exposure at the infection site is essential for improving their efficacy and minimising emergence of resistance.