DALI: defining antibiotic levels in intensive care unit patients: are current β-lactam antibiotic doses sufficient for critically ill patients?

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.

Sepsis Stewardship: The Puzzle of Antibiotic Therapy in the Context of Individualization of Decision Making

The main recent change observed in the field of critical patient infection has been universal awareness of the need to make better use of antimicrobials, especially for the most serious cases, beyond the application of simple and effective formulas or rigid protocols. The increase in resistant microorganisms, the quantitative increase in major surgeries and interventional procedures in the highest risk patients, and the appearance of a significant number of new antibiotics in recent years (some very specifically directed against certain mechanisms of resistance and others with a broader spectrum of applications) have led us to shift our questions from "what to deal with" to "how to treat". There has been controversy about how best to approach antibiotic treatment of complex cases of sepsis. The individualized and adjusted dosage, the moment of its administration, the objective, and the selection of the regimen are pointed out as factors of special relevance in a critically ill patient where the frequency of resistant microorganisms, especially among the Enterobacterales group, and the emergence of multiple and diverse antibiotic treatment alternatives have made the appropriate choice of antibiotic treatment more complex, requiring a constant updating of knowledge and the creation of multidisciplinary teams to confront new infections that are difficult to treat. In this article, we have reviewed the phenomenon of the emergence of resistance to antibacterials and we have tried to share some of the ideas, such as stewardship, sparing carbapenems, and organizational, microbiological, pharmacological, and knowledge tools, that we have considered most useful and effective for individualized decision making that takes into account the current context of multidrug resistance. The greatest challenge, therefore, of decision making in this context lies in determining an effective, optimal, and balanced empirical antibiotic treatment.

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.

First-in-human study to evaluate the safety, tolerability, and population pharmacokinetic/pharmacodynamic target attainment analysis of FL058 alone and in combination with meropenem in healthy subjects

FL058 is a novel diazabicyclooctane β-lactamase inhibitor. This first-in-human study evaluated the safety, tolerability, and population pharmacokinetic (PK)/pharmacodynamic target attainment analysis of FL058 alone and in combination with meropenem in healthy subjects. The results showed that the maximum tolerated dose of FL058 was 3,000 mg after single-dose infusion. FL058 in combination with meropenem did not cause any grade 3 or higher adverse event when the dose was escalated up to 1,000 mg/2,000 mg. FL058 exposure PK parameters showed dose proportionality. FL058 was excreted primarily in urine. No significant PK interaction was found between FL058 and meropenem. Population PK model analysis indicated that the PK profiles of FL058 and meropenem were consistent with the two-compartment model. The impact of covariates, creatinine clearance, concomitant use of meropenem, body weight, sex, and FL058 dose, on FL058 exposure was less than 10%. FL058/meropenem combination was safe and well tolerated up to a 1,000-mg/2,000-mg dose in healthy adults. The recommended minimum dose of FL058/meropenem combination was 500 mg/1,000 mg by intravenous infusion over 2 h every 8 h based on target attainment analysis. The good safety, tolerability, and satisfactory PK profiles of FL058 alone and in combination with meropenem in this first-in-human study will support further clinical development of FL058 in combination with meropenem in patients with target infections (ClinicalTrials.gov identifiers: NCT05055687, NCT05058118, and NCT05058105).

Population pharmacokinetics of fluconazole in critically ill patients receiving extracorporeal membrane oxygenation and continuous renal replacement therapy: an ASAP ECMO study

This multicenter study describes the population pharmacokinetics (PK) of fluconazole in critically ill patients receiving concomitant extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) and includes an evaluation of different fluconazole dosing regimens for achievement of target exposure associated with maximal efficacy. Serial blood samples were obtained from critically ill patients on ECMO and CRRT receiving fluconazole. Total fluconazole concentrations were measured in plasma using a validated chromatographic assay. A population PK model was developed and Monte Carlo dosing simulations were performed using Pmetrics in R. The probability of target attainment (PTA) of various dosing regimens to achieve fluconazole area under the curve to minimal inhibitory concentration ratio (AUC0-24/MIC) >100 was estimated. Eight critically ill patients receiving concomitant ECMO and CRRT were included. A two-compartment model including total body weight as a covariate on clearance adequately described the data. The mean (±standard deviation, SD) clearance and volume of distribution were 2.87 ± 0.63 L/h and 15.90 ± 13.29 L, respectively. Dosing simulations showed that current guidelines (initial loading dose of 12 mg/kg then 6 mg/kg q24h) achieved >90% of PTA for a MIC up to 1 mg/L. None of the tested dosing regimens achieved 90% of PTA for MIC above 2 mg/L. Current fluconazole dosing regimen guidelines achieved >90% PTA only for Candida species with MIC <1 mg/L and thus should be only used for Candida-documented infections in critically ill patients receiving concomitant ECMO and CRRT. Total body weight should be considered for fluconazole dose.

Pharmacokinetic Analysis of Intravenous Push Cefepime in Burn Patients with Augmented Renal Clearance

Patients with augmented renal clearance (ARC) are a subset of critically ill patients including burn patients that exhibit increased renal elimination of medications beyond that of similarly injured patients. Currently approved maximum regimens of medications primarily eliminated by the kidney, such as cefepime (>90% unchanged in the urine), may be inadequate (eg, compromising the bactericidal activity of cefepime) in patients with ARC. Due to recent resource limitations, centers have changed infusion practices of commonly prescribed medications to intravenous push (IVP), potentially exacerbating the problem of maintaining bactericidal cefepime concentrations. The hypothesis of the study was patients with ARC are not currently achieving adequate target attainment, when receiving cefepime 2 g every 8 h IVP. Eight blood samples were collected from each patient, and concentrations measured via LC-MS/MS. WinNonlin (version 8.3) was used to estimate the pharmacokinetic parameters of cefepime and simulate plasma concentrations of cefepime in each of the ten subjects. Simulations of cefepime plasma concentrations produced by a 2 g dose given every 8 h and a 1 g dose given every 4 h were performed and the time above a MIC of 4 mg/L, 8 mg/L, and 16 mg/L compared. The 2 g every 8 h regimen remained above the breakpoints for 92%, 85%, and 71% of the dosing interval, respectively. The 1 g every 4 h regimen remained above the same breakpoints at a frequency of 100%, 99%, and 92% of the dosing interval. Giving cefepime 1 g every 4 h is a simple approach to increase the likelihood of maintaining the optimal bactericidal activity of cefepime in patients with ARC.

Potential benefits of therapeutic drug monitoring for beta-lactam antibiotics in augmented renal clearance patients: a case report

Augmented renal clearance (ARC) is commonly described in critically ill patients, making drug pharmacokinetics even harder to predict in this population. This case report displays the value of therapeutic drug monitoring (TDM) of piperacillin/tazobactam (PTZ) in this population. We identified two patients with ARC and intermittent administration of PTZ who took part in a prospective, descriptive study conducted at Hôpital du Sacré-Cœur de Montréal. Both had plasma samples drawn at peak, middle, and end of their dosing intervals of PTZ. Minimal inhibitory concentrations (MICs) of 4 and 8 mg/L were chosen to evaluate therapeutic target attainment at middle and end of dosing interval. The first patient was a 52-year-old male with a renal clearance rate estimated at 147 mL/min who received 3.375 g PTZ every 6 h. The second patient, a 49-year-old male, had an estimated renal clearance rate of 163 mL/min and received the same regimen. Both patients had piperacillin concentrations above the target MICs at middle of the dosing interval, but they failed to reach a trough concentration above 8 mg/L. The present case report showcases two patients with subtherapeutic PTZ concentrations despite strict following of local administration protocols. This suboptimal administration could not only lead to treatment failure, but also to the selection and growth of resistant pathogens. Implementing TDM would offer the possibility to adjust drug regimens in real-time and prevent situations like these from occurring.

Which Are the Best Regimens of Broad-Spectrum Beta-Lactam Antibiotics in Burn Patients? A Systematic Review of Evidence from Pharmacology Studies

BACKGROUND

Burn injury causes profound pathophysiological changes in the pharmacokinetic/pharmacodynamic (PK/PD) properties of antibiotics. Infections are among the principal complications after burn injuries, and broad-spectrum beta-lactams are the cornerstone of treatment. The aim of this study was to review the evidence for the best regimens of these antibiotics in the burn patient population.

METHODS

We performed a systematic review of evidence available on MEDLINE (from its inception to 2023) of pharmacology studies that focused on the use of 13 broad-spectrum beta-lactams in burn patients. We extracted and synthetized data on drug regimens and their ability to attain adequate PK/PD targets.

RESULTS

We selected 35 studies for analysis. Overall, studies showed that both high doses and the continuous infusion (CI) of broad-spectrum beta-lactams were needed to achieve internationally-recognized PK/PD targets, ideally with therapeutic drug monitoring guidance. The most extensive evidence concerned meropenem, but similar conclusions could be drawn about piperacillin-tazobactam, ceftazidime, cefepime, imipenem-clinastatin and aztreonam. Insufficient data were available about new beta-lactam-beta-lactamase inhibitor combinations, ceftaroline, ceftobiprole and cefiderocol.

CONCLUSIONS

Both high doses and CI of broad-spectrum beta-lactams are needed when treating burn patients due to the peculiar changes in the PK/PD of antibiotics in this population. Further studies are needed, particularly about newer antibiotics.

Individual meropenem epithelial lining fluid and plasma PK/PD target attainment

It is unclear whether plasma is a reliable surrogate for target attainment in the epithelial lining fluid (ELF). The objective of this study was to characterize meropenem target attainment in plasma and ELF using prospective samples. The first 24-hour T>MIC was evaluated vs 1xMIC and 4xMIC targets at the patient (i.e., fixed MIC of 2 mg/L) and population [i.e., cumulative fraction of response (CFR) according to EUCAST MIC distributions] levels for both plasma and ELF. Among 65 patients receiving ≥24 hours of treatment, 40% of patients failed to achieve >50% T>4xMIC in plasma and ELF, and 30% of patients who achieved >50% T>4xMIC in plasma had <50% T>4xMIC in ELF. At 1xMIC and 4xMIC targets, 3% and 25% of patients with >95% T>MIC in plasma had <50% T>MIC in ELF, respectively. Those with a CRCL >115 mL/min were less likely to achieve >50%T>4xMIC in ELF (P < 0.025). In the population, CFR for Escherichia coli at 1xMIC and 4xMIC was >97%. For Pseudomonas aeruginosa, CFR was ≥90% in plasma and ranged 80%-85% in ELF at 1xMIC when a loading dose was applied. CFR was reduced in plasma (range: 75%-81%) and ELF (range: 44%-60%) in the absence of a loading dose at 1xMIC. At 4xMIC, CFR for P. aeruginosa was 60%-86% with a loading dose and 18%-62% without a loading dose. We found that plasma overestimated ELF target attainment inup to 30% of meropenem-treated patients, CRCL >115 mL/min decreased target attainment in ELF, and loading doses increased CFR in the population.

Interprofessional Therapeutic Drug Monitoring of Carbapenems Improves ICU Care and Guideline Adherence in Acute-on-Chronic Liver Failure

(1) Background: Acute-on-chronic liver failure (ACLF) is a severe, rapidly progressing disease in patients with liver cirrhosis. Meropenem is crucial for treating severe infections. Therapeutic drug monitoring (TDM) offers an effective means to control drug dosages, especially vital for bactericidal antibiotics like meropenem. We aimed to assess the outcomes of implementing TDM for meropenem using an innovative interprofessional approach in ACLF patients on a medical intensive care unit (ICU). (2) Methods: The retrospective study was conducted on a medical ICU. The outcomes of an interprofessional approach comprising physicians, hospital pharmacists, and staff nurses to TDM for meropenem in critically ill patients with ACLF were examined in 25 patients. Meropenem was administered continuously via an infusion pump after the application of an initial loading dose. TDM was performed weekly using high-performance liquid chromatography (HPLC). Meropenem serum levels, implementation of the recommendations of the interprofessional team, and meropenem consumption were analyzed. (3) Results: Initial TDM for meropenem showed a mean meropenem serum concentration of 20.9 ± 9.6 mg/L in the 25 analyzed patients. Of note, in the initial TDM, only 16.0% of the patients had meropenem serum concentrations within the respective target range, while 84.0% exceeded this range. Follow-up TDM showed serum concentrations of 15.2 ± 5.7 mg/L (9.0-24.6) in Week 2 and 11.9 ± 2.3 mg/L (10.2-13.5) in Week 3. In Week 2, 41.7% of the patients had meropenem serum concentrations that were within the respective target range, while 58.3% of the patients were above this range. In Week 3, 50% of the analyzed serum concentrations of meropenem were within the targeted range, and 50% were above the range. In total, 100% of the advice given by the interprofessional team regarding meropenem dosing or a change in antibiotic therapy was implemented. During the intervention period, the meropenem application density was 37.9 recommended daily doses (RDD)/100 patient days (PD), compared to 42.1 RDD/100 PD in the control period, representing a 10.0% decrease. (4) Conclusions: Our interprofessional approach to TDM significantly reduced meropenem dosing, with all the team's recommendations being implemented. This method not only improved patient safety but also considerably decreased the application density of meropenem.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impact of Beta-Lactam Target Attainment on Resistance Development in Patients with Gram-Negative Infections

BACKGROUND

The objective was to identify associations between beta-lactam pharmacokinetic/pharmacodynamic (PK/PD) targets and Gram-negative bacteria resistance emergence in patients.

METHODS

Retrospective data were collected between 2016 to 2019 at the University of Florida Health-Shands Hospital in Gainesville, FL. Adult patients with two Gram-negative isolates receiving cefepime, meropenem, or piperacillin-tazobactam and who had plasma beta-lactam concentrations were included. Beta-lactam exposures and time free drug concentrations that exceeded minimum inhibitory concentrations (ƒT > MIC), four multiples of MIC (ƒT > 4× MIC), and free area under the time concentration curve to MIC (ƒAUC/MIC) were generated. Resistance emergence was defined as any increase in MIC or two-fold increase in MIC. Multiple regression analysis assessed the PK/PD parameter impact on resistance emergence.

RESULTS

Two hundred fifty-six patients with 628 isolates were included. The median age was 58 years, and 59% were males. Cefepime was the most common beta-lactam (65%) and Pseudomonas aeruginosa the most common isolate (43%). The mean daily ƒAUC/MIC ≥ 494 was associated with any increase in MIC (p = 0.002) and two-fold increase in MIC (p = 0.004). The daily ƒAUC/MIC ≥ 494 was associated with decreased time on antibiotics (p = 0.008). P. aeruginosa was associated with any increase in MIC (OR: 6.41, 95% CI [3.34-12.28]) or 2× increase in MIC (7.08, 95% CI [3.56-14.07]).

CONCLUSIONS

ƒAUC/MIC ≥ 494 may be associated with decreased Gram-negative resistance emergence.

Efficiency of dosing software using Bayesian forecasting in achieving target antibiotic exposures in critically ill patients, a prospective cohort study

INTRODUCTION

Broad-spectrum antibiotics such as beta-lactams and vancomycin are frequently used to treat critically ill patients, however, a significant number do not achieve target exposures. Therapeutic drug monitoring (TDM) combined with Bayesian forecasting dosing software may improve target attainment in these patients. This study aims to describe the efficiency of dosing software for achieving target exposures of selected beta-lactam antibiotics and vancomycin in critically ill patients.

METHODS

A prospective cohort study was undertaken in an adult intensive care unit (ICU). Patients prescribed vancomycin, piperacillin-tazobactam and meropenem were included if they exhibited a subtherapeutic or supratherapeutic exposure informed by TDM. The dosing software, ID-ODS™, was used to generate dosing recommendations which could be either accepted or rejected by the treating team. Repeat antibiotic TDM were requested to determine if target exposures were achieved.

RESULTS

Between March 2020 and December 2021, 70 were included in the analysis. Software recommendations were accepted for 56 patients (80%) with 50 having repeated antibiotic measurements. Forty-three of the 50 patients (86%) achieved target exposures after one software recommendation, with 3 of the remaining 7 patients achieving target exposures after 2. Forty-seven patients out of the 50 patients (94%) achieved the secondary outcome of clinical cure. There were no antibiotic exposure-related adverse events reported.

CONCLUSION

The use of TDM combined with Bayesian forecasting dosing software increases the efficiency for achieving target antibiotic exposures in the ICU. Clinical trials comparing this approach with other dosing strategies are required to further validate these findings.

Swedish multicentre study of target attainments with β-lactams in the ICU: which MIC parameter should be used?

BACKGROUND

Therapeutic drug monitoring (TDM) has been suggested to optimize antimicrobial target attainment, typically using 100%T>MIC, in β-lactam treatment in the ICU. The MIC parameter used in this equation is mostly the worst case scenario MIC (MICWCS)-the highest MIC the empirical treatment should cover. However, the impact of the MIC parameter used in pharmacokinetic/pharmacodynamic calculations has been poorly investigated.

OBJECTIVES

To assess the influence of target attainment rates for two different MIC parameters using actual MICs of the causative pathogens as the primary reference.

METHODS

In a Swedish multicentre study of target attainment for 138 ICU patients treated with β-lactams, the causative pathogen was isolated and subjected to reference MIC testing. Whenever the strain belonged to the WT distribution, we assigned it to the category MICECOFF (epidemiological cut-off value). In the calculations we compared the MICECOFF and the MICWCS.

RESULTS

The proportion of patients with target attainment failure for all antibiotics using 100%T>MIC was 45% (95% CI, 37%-53%) for MICWCS and 23% (95% CI, 16%-31%) for MICECOFF. When the target 50%T>4×MIC was used, corresponding attainment failures were 57% (95% CI, 49%-66%) and 25% (95% CI, 17%-32%) for MICWCS and MICECOFF, respectively.

CONCLUSIONS

MICWCS can overestimate target attainment failure. The use of MICWCS could be one reason for the difficulties in establishing a relationship between target failure and mortality in other studies. Based on findings herein, the MICECOFF, which is based on the MIC of the causative pathogen, should be considered a more suitable alternative. When no pathogen is detected, the MICECOFF of likely pathogens according to infection type should be used.

Towards optimization of ceftazidime dosing in obese ICU patients: the end of the 'one-size-fits-all' approach?

BACKGROUND

Ceftazidime is commonly used as a key antibiotic against Pseudomonas aeruginosa in critically ill patients. ICU patients have severely altered and variable antibiotic pharmacokinetics, resulting in lower antimicrobial concentrations and potentially poor outcome. Several factors, including obesity and renal function, may influence pharmacokinetics. Thus, the objective of the study was to evaluate the impact of obesity and renal function on ceftazidime plasma concentrations and dosing regimen in ICU patients.

METHODS

All consecutive adult patients from six ICUs, treated with continuous ceftazidime infusion and under therapeutic drug monitoring evaluation, were included. Obesity was defined as BMI ≥30 kg/m². Glomerular filtration rate (GFR) was estimated by the Chronic Kidney Disease Epidemiology Collaboration formula. The ceftazidime recommended target for plasma concentrations was between 35 and 80 mg/L.

RESULTS

A total of 98 patients (45 obese), with an average weight of 90 (±25) kg, were included. Mean GFR was 84.1 (±40.4) mL/min/1.73 m2. Recommended ceftazidime plasma concentrations were achieved for only 48.0% of patients, with median dosing regimen of 6 g/day. Obese patients had lower ceftazidime plasma concentrations compared with non-obese patients (37.8 versus 56.3 mg/L; P = 0.0042) despite similar dosing regimens (5.83 g/day versus 5.52 g/day, P = 0.2529). Almost all augmented renal clearance patients were underdosed despite ceftazidime dosing of 6.6 (±0.8) g/day. Weight-based ceftazidime dosing seemed to attenuate such obesity-related discrepancies, regardless of GFR.

CONCLUSIONS

Obese ICU patients required significantly greater ceftazidime doses to achieve the target range. A tailored dosing regimen may be considered based on weight and GFR. Future prospective studies should be performed to confirm this individualized dosing approach.

Chemical stability and physical compatibility of meropenem in admixtures for continuous and extended intravenous infusions

INTRODUCTION

Prolonged intravenous infusion of beta-lactams increase the clinical cure rate compared to conventional administration in critical or septic patients. This study aimed to determine chemical stability and physical compatibility of meropenem at conditions used in clinical practice to evaluate the stability of the preparation during its administration and the possibility of anticipated preparation.

METHODS

Admixtures in study were: (i) meropenem 6g in 0.9% sodium chloride (NS) in infusor of 2mL/h 50mL or 10mL/h 240mL; (ii) meropenem 1 or 2g in NS in infusion bag of 250mL. Temperatures of study were: (i) infusor: 4.5°C, 32°C or 12h at 4.5°C followed by 32°C; (ii) Infusion bag: 4.5°C, 24.5°C or 6h at 4.5°C followed by 24.5°C. Time of study was 5-6 days in infusor and 1 day in infusion bag. Chemical stability was evaluated by high performance liquid chromatography and physical compatibility by measuring pH and visual inspection.

RESULTS

Chemical stability and physical compatibility of meropenem in admixtures in infusors were reduced at high meropenem concentration and high temperature. Admixtures in infusion bag show chemical stability and physical compatibility for at least 1 day.

CONCLUSION

Administration of meropenem 6g in infusion of 24h in 240mL of 0.9% NaCl in infusor of 10mL/h could be possible if the admixture is infused at 4.5°C. Extended infusion of meropenem 1 or 2g in 0.9% NaCl in infusion bag (250mL) in 3-4h is also feasible. Anticipated preparation of the admixtures in infusion bag is possible with a stability of 24h.

Clinical implications of augmented renal clearance after unrelated single cord blood transplantation in adults

Augmented renal clearance (ARC) is a phenomenon characterized by increased renal functionality, which can impact the pharmacokinetics and pharmacodynamics of antimicrobial drugs eliminated by the kidneys. It is a potential concern for infection treatment. Cord blood transplantation (CBT) is primarily impeded by delayed neutrophil recovery and immune reconstitution, thereby increasing susceptibility to infection. However, the clinical implications of ARC following CBT remain unexplored. We retrospectively assessed the influence of ARC on post-transplant outcomes at various time points in 194 adult recipients of single-unit unrelated CBT between 2007 and 2022 at our institution. ARC was observed in 52.9% of patients at 1 day, 39.8% at 15 days, and 26.5% at 29 days post-CBT. ARC was not significantly associated with bloodstream infection, acute graft-versus-host disease, or veno-occlusive disease/sinusoidal obstruction syndrome at any time point. ARC at 1 day, 15 days, and 29 days post-CBT was not significantly associated  with overall survival, non-relapse mortality, or relapse rates. These findings suggest that ARC is common in adults during the early stages of CBT, but does not discernibly influence clinical outcomes or post-CBT complications.

Impact of Various Estimated Glomerular Filtration Rate Equations on the Pharmacokinetics of Meropenem in Critically Ill Adults

IMPORTANCE

Meropenem dosing is typically guided by creatinine-based estimated glomerular filtration rate (eGFR), but creatinine is a suboptimal GFR marker in the critically ill.

OBJECTIVES

This study aimed to develop and qualify a population pharmacokinetic model for meropenem in critically ill adults and to determine which eGFR equation based on creatinine, cystatin C, or both biomarkers best improves model performance.

DESIGN SETTING AND PARTICIPANTS

This single-center study evaluated adults hospitalized in an ICU who received IV meropenem from 2018 to 2022. Patients were excluded if they had acute kidney injury, were on kidney replacement therapy, or were treated with extracorporeal membrane oxygenation. Two cohorts were used for population pharmacokinetic modeling: a richly sampled development cohort (n = 19) and an opportunistically sampled qualification cohort (n = 32).

MAIN OUTCOMES AND MEASURES

A nonlinear mixed-effects model was developed using parametric methods to estimate meropenem serum concentrations.

RESULTS

The best-fit structural model in the richly sampled development cohort was a two-compartment model with first-order elimination. The final model included time-dependent weight normalized to a 70-kg adult as a covariate for volume of distribution (Vd) and time-dependent eGFR for clearance. Among the eGFR equations evaluated, eGFR based on creatinine and cystatin C expressed in mL/min best-predicted meropenem clearance. The mean (se) Vd in the final model was 18.2 (3.5) liters and clearance was 11.5 (1.3) L/hr. Using the development cohort as the Bayesian prior, the opportunistically sampled cohort demonstrated good accuracy and low bias.

CONCLUSIONS AND RELEVANCE

Contemporary eGFR equations that use both creatinine and cystatin C improved meropenem population pharmacokinetic model performance compared with creatinine-only or cystatin C-only eGFR equations in adult critically ill patients.

Predicting Beta-Lactam Target Non-Attainment in ICU Patients at Treatment Initiation: Development and External Validation of Three Novel (Machine Learning) Models

In the intensive care unit (ICU), infection-related mortality is high. Although adequate antibiotic treatment is essential in infections, beta-lactam target non-attainment occurs in up to 45% of ICU patients, which is associated with a lower likelihood of clinical success. To optimize antibiotic treatment, we aimed to develop beta-lactam target non-attainment prediction models in ICU patients. Patients from two multicenter studies were included, with intravenous intermittent beta-lactam antibiotics administered and blood samples drawn within 12-36 h after antibiotic initiation. Beta-lactam target non-attainment models were developed and validated using random forest (RF), logistic regression (LR), and naïve Bayes (NB) models from 376 patients. External validation was performed on 150 ICU patients. We assessed performance by measuring discrimination, calibration, and net benefit at the default threshold probability of 0.20. Age, sex, serum creatinine, and type of beta-lactam antibiotic were found to be predictive of beta-lactam target non-attainment. In the external validation, the RF, LR, and NB models confirmed good discrimination with an area under the curve of 0.79 [95% CI 0.72-0.86], 0.80 [95% CI 0.73-0.87], and 0.75 [95% CI 0.67-0.82], respectively, and net benefit in the RF and LR models. We developed prediction models for beta-lactam target non-attainment within 12-36 h after antibiotic initiation in ICU patients. These online-accessible models use readily available patient variables and help optimize antibiotic treatment. The RF and LR models showed the best performance among the three models tested.

Population pharmacokinetic model of cefepime for critically ill adults: a comparative assessment of eGFR equations

Cefepime exhibits highly variable pharmacokinetics in critically ill patients. The purpose of this study was to develop and qualify a population pharmacokinetic model for use in the critically ill and investigate the impact of various estimated glomerular filtration rate (eGFR) equations using creatinine, cystatin C, or both on model parameters. This was a prospective study of critically ill adults hospitalized at an academic medical center treated with intravenous cefepime. Individuals with acute kidney injury or on kidney replacement therapy or extracorporeal membrane oxygenation were excluded. A nonlinear mixed-effects population pharmacokinetic model was developed using data collected from 2018 to 2022. The 120 included individuals contributed 379 serum samples for analysis. A two-compartment pharmacokinetic model with first-order elimination best described the data. The population mean parameters (standard error) in the final model were 7.84 (0.24) L/h for CL1 and 15.6 (1.45) L for V1. Q was fixed at 7.09 L/h and V2 was fixed at 10.6 L, due to low observed interindividual variation in these parameters. The final model included weight as a covariate for volume of distribution and the eGFRcr-cysC (mL/min) as a predictor of drug clearance. In summary, a population pharmacokinetic model for cefepime was created for critically ill adults. The study demonstrated the importance of cystatin C to prediction of cefepime clearance. Cefepime dosing models which use an eGFR equation inclusive of cystatin C are likely to exhibit improved accuracy and precision compared to dosing models which incorporate an eGFR equation with only creatinine.

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.

Efficacy of therapeutic drug monitoring-based antibiotic regimen in critically ill patients: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The efficacy of therapeutic drug monitoring (TDM)-based antimicrobial dosing optimization strategies on pharmacokinetics/pharmacodynamics and specific drug properties for critically ill patients is unclear. Here, we conducted a systematic review and meta-analysis of randomized controlled trials to evaluate the effectiveness of TDM-based regimen in these patients.

METHODS

Articles from three databases were systematically retrieved to identify relevant randomized control studies. Version two of the Cochrane tool for assessing risk of bias in randomized trials was used to assess the risk of bias in studies included in the analysis, and quality assessment of evidence was graded using the Grading of Recommendations Assessment, Development, and Evaluation approach. Primary outcome was the 28-day mortality and secondary outcome were in-hospital mortality, clinical cure, length of stay in the intensive care unit (ICU) and target attainment at day 1 and 3.

RESULTS

In total, 5 studies involving 1011 patients were included for meta-analysis of the primary outcome, of which no significant difference was observed between TDM-based regimen and control groups (risk ratio [RR] 0.94, 95% confidence interval [CI]: 0.77-1.14; I2 = 0%). In-hospital mortality (RR 0.96, 95% CI: 0.76-1.20), clinical cure (RR 1.23, 95% CI: 0.91-1.67), length of stay in the ICU (mean difference 0, 95% CI: - 2.18-2.19), and target attainment at day 1 (RR 1.14, 95% CI: 0.88-1.48) and day 3 (RR 1.35, 95% CI: 0.90-2.03) were not significantly different between the two groups, and all evidence for the secondary outcomes had a low or very low level of certainty because the included studies had serious risk of bias, variation of definition for outcomes, and small sample sizes.

CONCLUSION

TDM-based regimens had no significant efficacy for clinical or pharmacological outcomes. Further studies with other achievable targets and well-defined outcomes are required.

TRIAL REGISTRATION

Clinical trial registration; PROSPERO ( https://www.crd.york.ac.uk/prospero/ ), registry number: CRD 42022371959. Registered 24 November 2022.

Therapeutic Options for Adult Patients With Persistent Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Narrative Review

OBJECTIVE

To compare the efficacy of antimicrobial therapies used in the management of persistent methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.

DATA SOURCES

A literature search using the PubMed database (inception to December 2022) was conducted using the search terms "Staphylococcus aureus bacteremia," "methicillin-susceptible Staphylococcus aureus bacteremia," "persistent methicillin-susceptible Staphylococcus aureus bacteremia," and "refractory methicillin-susceptible Staphylococcus aureus bacteremia ." In addition, therapeutic agents which could be used as treatment for MSSA including "nafcillin," "oxacillin," "cefazolin," "ceftaroline," "gentamicin," "rifampin," and "daptomycin" were also combined with the aforementioned search terms to capture data using these agents.

STUDY SELECTION/DATA EXTRACTION

Clinical data were limited to those published in the English language. Articles and abstracts were considered for inclusion in addition to ongoing trials identified through ClinicalTrials.gov.

DATA SYNTHESIS

A total of 78 articles were reviewed including 17 in vitro or animal model studies and 39 studies including patient data. The remaining 22 articles included guidelines, review articles, and editorials. Recent data evaluating use of dual β-lactam regimens for persistent MSSA bacteremia were limited to 8 case reports or case series.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

At present, there is little guidance on how to best manage patients with persistent MSSA bacteremia. This narrative review collates the available data to assist clinicians in selecting the best possible antimicrobial regimen when facing this clinical conundrum.

CONCLUSIONS

Modification of antimicrobial therapy, in conjunction with source control and infectious diseases consultation, may all be necessary to sterilize blood cultures in patients with persistent MSSA bacteremia.

Extended infusion of β-lactams significantly reduces mortality and enhances microbiological eradication in paediatric patients: a systematic review and meta-analysis

Background

Paediatric patients are often exposed to subtherapeutic levels or treatment failure of β-lactams, and prolonged infusion may be beneficial. We aimed to investigate the efficacy and safety of extended infusion (EI; defined as ≥3 h) or continuous infusion vs. short, intermittent infusion (SI; defined as ≤60 min) of β-lactams in patients <21 years of age.

Methods

A systematic review and meta-analysis was conducted to compare EI and continuous infusion with SI of β-lactams in children. A systematic search was performed in MEDLINE (via PubMed), Embase, CENTRAL, and Scopus databases for randomised controlled trials (RCTs) and observational studies published from database inception up to August 22, 2023. Any comparative study concerned with mortality, clinical efficacy, adverse events, or plasma concentrations of β-lactams for any infection was eligible. Case reports, case series, and patients aged >21 years were excluded. Odds ratios (OR) and median differences with 95% confidence intervals (CI) were calculated using a random-effects model. Risk of bias (ROB) was assessed using ROB2 and ROBINS-I tools. The protocol was registered with PROSPERO, CRD42022375397.

Findings

In total, 19,980 articles were screened, out of which 19 studies (4195 patients) were included in the meta-analysis. EI administration was associated with a significantly lower all-cause mortality in both RCTs and non-RCTs [OR 0.74; CI 0.55-0.99; I2 = 0%; CI 0-58%]. Early microbiological eradication was higher with EI [OR 3.18; CI 2.24-4.51; I2 = 0%; CI 0-90%], but the clinical cure did not differ significantly between the two groups [OR 1.20; CI 0.17-8.71; I2 = 79%; CI 32-93%]. Achieving the optimal plasma level (50-100% fT > MIC) appeared favourable in the EI group compared to the SI. No significant differences were observed in the adverse events. The overall ROB was high because of the small sample sizes and clinically heterogeneous populations.

Interpretation

Our findings suggest that extended infusion of β-lactams was associated with lower mortality and increased microbiological eradication and was considered safe compared to short-term infusion.

Funding

None.

In silico evaluation of a beta-lactam dosing guideline among adults with serious infections

STUDY OBJECTIVE

The aim of this study was to compare the achievement of therapeutic pharmacokinetic-pharmacodynamic (PK-PD) exposure targets for beta-lactam antibiotics using product information dosing or guideline-based dosing for the treatment of serious infections.

DESIGN

In silico study.

DATA SOURCE

ID-ODSTM (Individually Designed Optimum Dosing Strategies).

PATIENTS AND INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

In silico product information and guideline-based dosing simulations for cefepime, ceftazidime, flucloxacillin, meropenem, and piperacillin/tazobactam were performed using pharmacokinetic models from seriously ill patient populations. The median simulated concentration at 48 and 96 h was used to measure the probability of target attainment (PTA) to achieve predefined therapeutic and toxicity PK-PD targets. A multiple linear regression model was constructed to identify the effect of guideline-based dosing covariates on achieving pre-defined therapeutic targets. In total, 480 dosing simulations were performed. The PTA percentage with guideline-based dosing at 48 and 96 h was 80% and 68%, respectively, yielding significantly higher results when compared to product information dosing (48.45% and 49%, respectively), p < 0.001 at both time points. At 48 h, predefined toxicity thresholds were exceeded in 4.7% and 0% of simulations for guideline-based and product information-based dosing, respectively (p = 0.002). eGFR was significantly associated with the % PTA by guideline-based dosing, with eGFR values of 20 and 50 ml/min both statistically significant in leading to an increase in PTA.

CONCLUSIONS

Our study demonstrated that achievement of PK-PD exposures associated with an increased likelihood of effectiveness was more likely to occur with guideline-based dosing; especially at 48 h.

Antimicrobial pharmacokinetics and dosing in critically ill adults receiving prolonged intermittent renal replacement therapy: A systematic review

Prolonged intermittent renal replacement therapy (PIRRT) is gaining popularity as a renal replacement modality in intensive care units, but there is a relative lack of guidance regarding antimicrobial clearance and dosing when compared with other modalities. The objectives of this systematic review were to: (1) identify and describe the pharmacokinetics (PK) of relevant antimicrobials used in critically ill adults receiving PIRRT, (2) evaluate the quality of evidence supporting these data, and (3) propose dosing recommendations based on the synthesis of these data. A search strategy for multiple databases was designed and executed to identify relevant published evidence describing the PK of antimicrobials used in critically ill adults receiving PIRRT. Quality assessment, evaluation of reporting, and relevant data extraction were conducted in duplicate. Synthesis of PK/pharmacodynamic (PD) outcomes, dosing recommendations from study authors, and physicochemical properties of included antibiotics were assessed by investigators in addition to the quality of evidence to develop dosing recommendations. Thirty-nine studies enrolling 452 patients met criteria for inclusion and provided PK and/or PD data for 20 antimicrobials in critically ill adults receiving PIRRT. Nineteen studies describe both PK and PD outcomes. Vancomycin (12 studies, 171 patients), meropenem (7 studies, 84 patients), and piperacillin/tazobactam (5 studies, 56 patients) were the most frequent antimicrobials encountered. The quality of evidence was deemed strong for 7/20 antimicrobials, and strong dosing recommendations were determined for 9/20 antimicrobials. This systematic review updates and addresses issues of quality in previous systematic reviews on this topic. Despite an overall low quality of evidence, strong recommendations were able to be made for almost half of the identified antimicrobials. Knowledge gaps persist for many antimicrobials, and higher quality studies (i.e., population PK studies with assessment of PD target attainment) are needed to address these gaps.

Practical considerations for individualizing drug dosing in critically ill adults receiving renal replacement therapy

Critically ill patients with sepsis admitted to the intensive care unit (ICU) often present with or develop renal dysfunction requiring renal replacement therapy (RRT) in addition to antimicrobial therapy. While early and appropriate antimicrobials for sepsis have been associated with an increased probability of survival, adequate dosing is also required in these patients. Adequate dosing of antimicrobials refers to dosing strategies that achieve serum drug levels at the site of infection that are able to provide a microbiological and/or clinical response while avoiding toxicity from excessive antibiotic exposure. Therapeutic drug monitoring (TDM) is the recommended strategy to achieve this goal, however, TDM is not routinely available in all ICUs and for all antimicrobials. In the absence of TDM, clinicians are therefore required to make dosing decisions based on the clinical condition of the patient, the causative organism, the characteristics of RRT, and an understanding of the physicochemical properties of the antimicrobial. Pharmacokinetics (PK) of antimicrobials can be highly variable between critically ill patients and also within the same patient over the course of their ICU stay. The initiation of RRT, which can be in the form of intermittent hemodialysis, continuous, or prolonged intermittent therapy, further complicates the predictability of drug disposition. This variability highlights the need for individualized dosing. This review highlights the practical considerations for the clinician for antimicrobial dosing in critically ill patients receiving RRT.

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.

Cefepime Daily Exposure and the Associated Impact on the Change in Sequential Organ Failure Assessment Scores and Vasopressors Requirement in Critically Ill Patients Using Repeated-Measures Mixed-Effect Modeling

IMPORTANCE

Sepsis and septic shock are major healthcare problems that need early and appropriate management.

OBJECTIVES

To evaluate the association of daily cefepime pharmacokinetic/pharmacodynamic (PK/PD) parameters with change in Sequential Organ Failure Assessment (SOFA) score and vasopressors requirement.

DESIGN SETTING AND PARTICIPANTS

This is a retrospective study. Adult ICU patients who received cefepime for Gram-negative pneumonia or bloodstream infection (BSI) and had cefepime concentrations measured were included. Daily cefepime exposure was generated and PK/PD parameters calculated for patients. Repeated-measures mixed-effect modeling was used to evaluate the impact of PK/PD on the outcomes.

MAIN OUTCOMES AND MEASURES

Change in daily SOFA score and vasopressors requirement.

RESULTS

A total of 394 and 207 patients were included in the SOFA and vasopressors analyses, respectively. The mean (±sd) age was 55 years (19) and weight 81 kg (29). For the change in SOFA score, daily SOFA score, mechanical ventilation, renal replacement therapy, and number of vasopressors were included. In the vasopressors analysis, daily SOFA score, day of therapy, and hydrocortisone dose were significant covariates in the final model. Achieving cefepime concentrations above the minimum inhibitory concentration (MIC) (T>MIC) for 100% of the dosing interval was associated with 0.006 µg/kg/min decrease in norepinephrine-equivalent dose. Cefepime PK/PD did not have an impact on the daily change in SOFA score.

CONCLUSIONS AND RELEVANCE

Achieving 100% T>MIC was associated with negligible decrease in vasopressors requirement in ICU patients with Gram-negative pneumonia and BSI. There was no impact on the change in SOFA score.

Inoculum-Based Dosing: A Novel Concept for Combining Time with Concentration-Dependent Antibiotics to Optimize Clinical and Microbiological Outcomes in Severe Gram Negative Sepsis

Certain classes of antibiotics show "concentration dependent" antimicrobial activity; higher concentrations result in increased bacterial killing rates, in contrast to "time dependent antibiotics", which show antimicrobial activity that depends on the time that antibiotic concentrations remain above the MIC. Aminoglycosides and fluoroquinolones are still widely used concentration-dependent antibiotics. These antibiotics are not hydrolyzed by beta-lactamases and are less sensitive to the inoculum effect, which can be defined as an increased MIC for the antibiotic in the presence of a relatively higher bacterial load (inoculum). In addition, they possess a relatively long Post-Antibiotic Effect (PAE), which can be defined as the absence of bacterial growth when antibiotic concentrations fall below the MIC. These characteristics make them interesting complementary antibiotics in the management of Multi-Drug Resistant (MDR) bacteria and/or (neutropenic) patients with severe sepsis. Global surveillance studies have shown that up to 90% of MDR Gram-negative bacteria still remain susceptible to aminoglycosides, depending on the susceptibility breakpoint (e.g., CLSI or EUCAST) being applied. This percentage is notably lower for fluoroquinolones but depends on the region, type of organism, and mechanism of resistance involved. Daily (high-dose) dosing of aminoglycosides for less than one week has been associated with significantly less nephro/oto toxicity and improved target attainment. Furthermore, higher-than-conventional dosing of fluoroquinolones has been linked to improved clinical outcomes. Beta-lactam antibiotics are the recommended backbone of therapy for severe sepsis. Since these antibiotics are time-dependent, the addition of a second concentration-dependent antibiotic could serve to quickly lower the bacterial inoculum, create PAE, and reduce Penicillin-Binding Protein (PBP) expression. Inadequate antibiotic levels at the site of infection, especially in the presence of high inoculum infections, have been shown to be important risk factors for inadequate resistance suppression and therapeutic failure. Therefore, in the early phase of severe sepsis, effort should be made to optimize the dose and quickly lower the inoculum. In this article, the authors propose a novel concept of "Inoculum Based Dosing" in which the decision for antibiotic dosing regimens and/or combination therapy is not only based on the PK parameters of the patient, but also on the presumed inoculum size. Once the inoculum has been lowered, indirectly reflected by clinical improvement, treatment simplification should be considered to further treat the infection.

Antimicrobial Multidrug Resistance: Clinical Implications for Infection Management in Critically Ill Patients

The increasing incidence of antimicrobial resistance (AMR) worldwide represents a serious threat in the management of sepsis. Due to resistance to the most common antimicrobials prescribed, multidrug-resistant (MDR) pathogens have been associated with delays in adequate antimicrobial therapy leading to significant increases in mortality, along with prolonged hospital length of stay (LOS) and increases in healthcare costs. In response to MDR infections and the delay of microbiological results, broad-spectrum antibiotics are frequently used in empirical antimicrobial therapy. This can contribute to the overuse and misuse of antibiotics, further promoting the development of resistance. Multiple measures have been suggested to combat AMR. This review will focus on describing the epidemiology and trends concerning MDR pathogens. Additionally, it will explore the crucial aspects of identifying patients susceptible to MDR infections and optimizing antimicrobial drug dosing, which are both pivotal considerations in the fight against AMR. Expert commentary: The increasing AMR in ICUs worldwide makes the empirical antibiotic therapy challenging in septic patients. An AMR surveillance program together with improvements in MDR identification based on patient risk stratification and molecular rapid diagnostic tools may further help tailoring antimicrobial therapies and avoid unnecessary broad-spectrum antibiotics. Continuous infusions of antibiotics, therapeutic drug monitoring (TDM)-based dosing regimens and combination therapy may contribute to optimizing antimicrobial therapy and limiting the emergence of resistance.

Extended Versus Intermittent Meropenem Infusion in the Treatment of Nosocomial Pneumonia: A Retrospective Single-Center Study

The efficacy of extended meropenem infusions in patients with nosocomial pneumonia is not well defined. Therefore, we compared the clinical outcomes of extended versus intermittent meropenem infusions in the treatment of nosocomial pneumonia. We performed a retrospective analysis of extended versus intermittent meropenem infusions in adult patients who had been treated for nosocomial pneumonia at a medical ICU between 1 May 2018 and 30 April 2020. The primary outcome was mortality at 14 days. Overall, 64 patients who underwent an extended infusion and 97 with an intermittent infusion were included in this study. At 14 days, 10 (15.6%) patients in the extended group and 22 (22.7%) in the intermittent group had died (adjusted hazard ratio (HR), 0.55; 95% confidence interval (CI): 0.23-1.31; p = 0.174). In the subgroup analysis, significant differences in mortality at day 14 were observed in patients following empirical treatment with meropenem (adjusted HR, 0.17; 95% CI: 0.03-0.96; p = 0.045) and in Gram-negative pathogens identified by blood or sputum cultures (adjusted HR, 0.01; 95% CI: 0.01-0.83; p = 0.033). Extended infusion of meropenem compared with intermittent infusion as a treatment option for nosocomial pneumonia may have a potential advantage in specific populations.

24/7 Therapeutic Drug Monitoring of Beta-Lactam Antibiotics with CLAM-2000

BACKGROUND

The aim of this study was to evaluate the CLAM-2000 automated preanalytical sample preparation module with integrated liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) as a method for 24/7 therapeutic drug monitoring (TDM) of beta-lactam antibiotics in routine clinical diagnostics.

METHODS

Method validation was performed using quality control samples. Method comparison was performed with routine samples from patients treated with beta-lactam antibiotics.

RESULTS

The determination of piperacillin, meropenem, ceftazidime, flucloxacillin, and cefotaxime was performed using D5-piperacillin and D6-meropenem as internal standards. The linearity of the method was within the therapeutic range of beta-lactam antibiotics. The imprecision and accuracy data obtained from quality control samples were within 15%, and the imprecision of patient samples on the instrument was less than the 5% coefficient of variation (CV). Internal standards stored in the instrument at 9 °C for at least one week were stable, which facilitated reagent use and storage.

CONCLUSION

The CLAM-2000 (Shimadzu, Kyoto, Japan) provides reproducible results as an established routine instrument and is a useful tool for 24/7 TDM of beta-lactam antibiotics in routine clinical diagnostics.

The clinical application of beta-lactam antibiotic therapeutic drug monitoring in the critical care setting

Critically ill patients have increased variability in beta-lactam antibiotic (beta-lactam) exposure due to alterations in their volume of distribution and elimination. Therapeutic drug monitoring (TDM) of beta-lactams, as a dose optimization and individualization tool, has been recommended to overcome this variability in exposure. Despite its potential benefit, only a few centres worldwide perform beta-lactam TDM. An important reason for the low uptake is that the evidence for clinical benefits of beta-lactam TDM is not well established. TDM also requires the availability of specific infrastructure, knowledge and expertise. Observational studies and systematic reviews have demonstrated that TDM leads to an improvement in achieving target concentrations, a reduction in potentially toxic concentrations and improvement of clinical and microbiological outcomes. However, a small number of randomized controlled trials have not shown a mortality benefit. Opportunities for improved study design are apparent, as existing studies are limited by their inclusion of heterogeneous patient populations, including patients that may not even have infection, small sample size, variability in the types of beta-lactams included, infections caused by highly susceptible bacteria, and varied sampling, analytical and dosing algorithm methods. Here we review the fundamentals of beta-lactam TDM in critically ill patients, the existing clinical evidence and the practical aspects involved in beta-lactam TDM implementation.

Developing a Method for Quantifying Meropenem in Children-Volumetric Adsorptive Microsampling Versus Plasma Sampling

BACKGROUND

Meropenem is a carbapenem antibiotic often used in pediatric intensive care units due to its broad spectrum of activity. Therapeutic drug monitoring (TDM) is a useful tool to increase the effectiveness of meropenem by adjusting the dose based on plasma levels; however, the relatively large sample volume required for TDM can limit its use in children. Therefore, this study aimed to determine meropenem concentrations and consequently perform TDM effectively using the smallest possible sample volume. Volumetric absorptive microsampling (VAMS) is a sampling technology developed to collect a small, precise volume of blood. For the applicability of VAMS in TDM, plasma concentrations must be reliably calculated from whole blood (WB) collected by VAMS.

METHODS

VAMS technology using 10 µL of WB was evaluated and compared with EDTA-plasma sampling. High-performance liquid chromatography with UV detection was applied to quantify meropenem in VAMS and plasma samples after the removal of proteins by precipitation. Ertapenem was used as the internal standard. Samples were collected simultaneously from critically ill children receiving meropenem using VAMS and traditional sampling.

RESULTS

It was found that no consistent factor could be determined to calculate meropenem plasma concentrations from the WB, indicating that VAMS was not reliable in the TDM of meropenem. Therefore, to reduce the required sample amount in pediatric patients, a method for quantifying meropenem from 50 µL of plasma with a lower limit of quantification of 1 mg/L was developed and successfully validated.

CONCLUSIONS

A simple, reliable, and low-cost method was established using high-performance liquid chromatography-UV to determine the concentration of meropenem in 50 µL of plasma. VAMS using WB does not seem to be suitable for TDM of meropenem.

A three-level model for therapeutic drug monitoring of antimicrobials at the site of infection

The silent pandemic of bacterial antimicrobial resistance is a leading cause of death worldwide, prolonging hospital stays and raising health-care costs. Poor incentives to develop novel pharmacological compounds and the misuse of antibiotics contribute to the bacterial antimicrobial resistance crisis. Therapeutic drug monitoring (TDM) based on blood analysis can help alleviate the emergence of bacterial antimicrobial resistance and effectively decreases the risk of toxic drug concentrations in patients' blood. Antibiotic tissue penetration can vary in patients who are critically or chronically ill and can potentially lead to treatment failure. Antibiotics such as β-lactams and glycopeptides are detectable in non-invasively collectable biofluids, such as sweat and exhaled breath. The emergence of wearable sensors enables easy access to these non-invasive biofluids, and thus a laboratory-independent analysis of various disease-associated biomarkers and drugs. In this Personal View, we introduce a three-level model for TDM of antibiotics to describe concentrations at the site of infection (SOI) by use of wearable sensors. Our model links blood-based drug measurement with the analysis of drug concentrations in non-invasively collectable biofluids stemming from the SOI to characterise drug concentrations at the SOI. Finally, we outline the necessary clinical and technical steps for the development of wearable sensing platforms for SOI applications.

Diagnostic Value and Clinical Application of Metagenomic Next-Generation Sequencing for Infections in Critically Ill Patients

Objective

To evaluate the diagnostic value and clinical application of metagenomic next-generation sequencing (mNGS) for infections in critically ill patients.

Methods

Comparison of diagnostic performance of mNGS and conventional microbiological testing for pathogens was analyzed in 234 patients. The differences between immunocompetent and immunocompromised individuals in mNGS-guided anti-infective treatment adjustment were also analyzed.

Results

The sensitivity and specificity of mNGS for bacterial and fungal detection were 96.6% (95% confidence interval [CI], 93.5%-99.6%) and 83.1% (95% CI, 75.2%-91.1%), and 85.7% (95% CI, 71.9%-99.5%) and 93.2% (95% CI, 89.7%-96.7%), respectively. Overall, 152 viruses were detected by mNGS, but in which 28 viruses were considered causative agents. The proportion of mNGS-guided beneficial anti-infective therapy adjustments in the immunocompromised group was greater than in the immunocompetent group (48.5% vs 30.1%; P=0.008). In addition, mNGS-guided anti-infective regimens with peripheral blood and BALF specimens had the highest proportion (39.0%; 40.0%), but the proportion of patients not helpful due to peripheral blood mNGS was also as high as 22.0%.

Conclusion

mNGS might be a promising technology to provide precision medicine for critically ill patients with infection.

Probiotics and Their Bioproducts: A Promising Approach for Targeting Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus

Antibiotic resistance is a serious global health problem that poses a threat to the successful treatment of various bacterial infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). Conventional treatment of MRSA and VRE infections is challenging and often requires alternative or combination therapies that may have limited efficacy, higher costs, and/or more adverse effects. Therefore, there is an urgent need to find new strategies to combat antibiotic-resistant bacteria. Probiotics and antimicrobial peptides (AMPs) are two promising approaches that have shown potential benefits in various diseases. Probiotics are live microorganisms that confer health benefits to the host when administered in adequate amounts. AMPs, usually produced with probiotic bacteria, are short amino acid sequences that have broad-spectrum activity against bacteria, fungi, viruses, and parasites. Both probiotics and AMPs can modulate the host immune system, inhibit the growth and adhesion of pathogens, disrupt biofilms, and enhance intestinal barrier function. In this paper, we review the current knowledge on the role of probiotics and AMPs in targeting multi-drug-resistant bacteria, with a focus on MRSA and VRE. In addition, we discuss future directions for the clinical use of probiotics.

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.

Making the case for precision dosing: visualizing the variability of cefepime exposures in critically ill adults

OBJECTIVE

To investigate and describe the variability in cefepime exposures among 'real-world', critically ill patients by using population pharmacokinetic modelling and simulations, and with translation of these findings to visualizations.

METHODS

A cohort of adult medical ICU patients who received cefepime with therapeutic drug monitoring was studied. Two compartment models were developed to estimate cefepime clearance (Model 1) and simulate cefepime exposures among 1000 patients, each with identical creatinine clearance of 60 mL/min and receiving a regimen of cefepime 1 gram IV over 30 minutes, every 8 hours (Model 2). Variability in the relationship between cefepime clearance and creatinine clearance (CrCL) was visualized, and a random, representative sample of 10 simulated patients was utilized to illustrate variability in cefepime exposures.

RESULTS

A total of 75 adult medical ICU patients (52% female) and 98 serum cefepime samples were included in the study. Population parameter estimates for cefepime displayed a wide range of variation in Model 1 (CV: 45% to 95%), with low bias at the individual level at 0.226 mg/L but high bias in the population model 10.6 mg/L. Model 2 displayed similar fits, demonstrating that correcting for individual patient creatinine clearance slightly improves the bias of the population model (bias = 4.31 mg/L). Among 10 simulated patients that a clinician would deem similar from a dosing perspective (i.e. equivalent creatinine clearance), maximum concentrations after three simulated doses varied more than 8-fold from 41.2 to 339 mg/L at the 5th and 95th percentiles, and clearance profiles were highly different.

CONCLUSION

Creatinine clearance estimates alone are inadequate for predicting cefepime exposures. Wide variations in cefepime exposure exist among ICU patients, even for those with similar kidney function estimates. Current population adjustment schemes based solely on creatinine clearance will result in unintended high and low exposures leading to safety and efficacy concerns, respectively.

The Neonatal and Paediatric Pharmacokinetics of Antimicrobials study (NAPPA): investigating amoxicillin, benzylpenicillin, flucloxacillin and piperacillin pharmacokinetics from birth to adolescence

BACKGROUND

Pharmacokinetic (PK) data underlying paediatric penicillin dosing remain limited, especially in critical care.

OBJECTIVES

The primary objective of the Neonatal and Paediatric Pharmacokinetics of Antimicrobials study (NAPPA) was to characterize PK profiles of commonly used penicillins using data obtained during routine care, to further understanding of PK variability and inform future evidence-based dosing.

METHODS

NAPPA was a multicentre study of amoxicillin, co-amoxiclav, benzylpenicillin, flucloxacillin and piperacillin/tazobactam. Patients were recruited with informed consent. Antibiotic dosing followed standard of care. PK samples were obtained opportunistically or at optimal times, frozen and analysed using UPLC with tandem MS. Pharmacometric analysis was undertaken using NONMEM software (v7.3). Model-based simulations (n = 10 000) tested PTA with British National Formulary for Children (BNFC) and WHO dosing. The study had ethical approval.

RESULTS

For the combined IV PK model, 963 PK samples from 370 participants were analysed simultaneously incorporating amoxicillin, benzylpenicillin, flucloxacillin and piperacillin data. BNFC high-dose regimen simulations gave these PTA results (median fT>MIC at breakpoints of specified pathogens): amoxicillin 100% (Streptococcus pneumoniae); benzylpenicillin 100% (Group B Streptococcus); flucloxacillin 48% (MSSA); and piperacillin 100% (Pseudomonas aeruginosa). Oral population PK models for flucloxacillin and amoxicillin enabled estimation of first-order absorption rate constants (1.16 h-1 and 1.3 h-1) and bioavailability terms (62.7% and 58.7%, respectively).

CONCLUSIONS

NAPPA represents, to our knowledge, the largest prospective combined paediatric penicillin PK study undertaken to date, and the first paediatric flucloxacillin oral PK model. The PTA results provide evidence supportive of BNFC high-dose IV regimens for amoxicillin, benzylpenicillin and piperacillin.

Loading dose plus continuous/extended infusion versus intermittent bolus of β-lactams for the treatment of Gram-negative bacteria bloodstream infections: a propensity score-adjusted retrospective cohort study

BACKGROUND

Optimal β-lactam dosing for the treatment of Gram-negative bacteria bloodstream infections (GNB-BSIs) remains a debated issue. Herein, the efficacy and safety of a loading dose (LD) followed by extended/continuous infusion (EI/CI) versus intermittent bolus (IB) of these drugs for the treatment of GNB-BSIs was evaluated.

METHODS

This is a retrospective observational study enrolling patients with GNB-BSIs treated with β-lactams from 1 October 2020 to 31 March 2022. The 30 day infection-related mortality rate was assessed with Cox regression, while mortality risk reduction was evaluated by an inverse probability of treatment weighting regression adjustment (IPTW-RA) model.

RESULTS

Overall, 224 patients were enrolled: 140 and 84 in the IB and EI/CI groups, respectively. β-Lactam regimens were chosen according to pathogen antibiogram, clinical judgement and current guidelines. Interestingly, the LD + EI/CI regimen was associated with a significant lower mortality rate (17% versus 32%, P = 0.011). Similarly, β-lactam LD + EI/CI was significantly associated with a reduced risk of mortality at multivariable Cox regression [adjusted HR (aHR) = 0.46; 95%CI = 0.22-0.98; P = 0.046]. Finally, the IPTW-RA (adjusted for multiple covariates) was performed, showing a significant risk reduction in the overall population [-14% (95% CI = -23% to -5%)]; at the subgroup restricted analysis, a significant risk reduction (>15%) was observed in the case of GNB-BSI in severely immunocompromised patients (P = 0.003), for SOFA score > 6 (P = 0.014) and in septic shock (P = 0.011).

CONCLUSIONS

The use of LD + EI/CI of β-lactams in patients with a GNB-BSI may be associated with reduced mortality; also in patients with severe presentation of infection or with additional risk factors, such as immunodepression.

Development and Validation of a Strong Cation Exchange Chromatographic Column Coupled with High-Performance Liquid Chromatography Method for Meropenem and Evaluation of Its Stability in Human Plasma: Application to the Therapeutic Drug Monitoring

Meropenem is a wide inter-individual variability in the pharmacokinetic, and standard dosing may not be adequate in critically ill patients. Therapeutic drug monitoring is a useful tool to optimize dosing. Meropenem is the amphoteric compound with an isoelectric point of 5.15. The secondary amino group of meropenem is positively charged when pH ≤ 5.4, thus we attempted to separate by strong cation exchange (SCX) column using acetonitrile/25-mM potassium dihydrogen phosphate (pH 3.0; 60:40) as mobile phase, and good peak shape and effective separation obtained. Generally, meropenem were unstable in plasma. We try to investigate stability of plasma samples using the medium QC sample with or without 3-(N-morpholino) propanesulfonic acid (MOPS) as stabilizer solutions at possible conditions during handling and storage. Meropenem showed higher stability at -80°C, and addition of MOPS might increase the short-term and extracted samples stability. This method is suitable for the quantification of meropenem in human plasma from 0.5 to 100 μg/mL. The accuracy was ranged from 96.53 to 101.11% with relative standard deviation ≤ 4.76%. The method has been used for determined 63 critically ill patients treated with meropenem. During the first measurement, 11 patients showed trough levels below the target ranges despite standard dosing. Through continuous or prolonged infusion, 8/11 patients (72.73%) led to adequate trough levels. The described SCX-high-performance liquid chromatography method for meropenem in human plasma is a powerful tool for therapeutic drug monitoring.

'How to' Guide for Pharmacist-led Implementation of Beta-Lactam Therapeutic Drug Monitoring in the Critically Ill

Beta-lactam therapeutic drug monitoring (TDM) can improve precision dosing and clinical outcomes in critically ill patients, but has not been implemented widely in the United States. Mayo Clinic recently implemented a beta-lactam TDM program. This single-center experience forms the basis of the manuscript which outlines practical considerations involved with implementation, including the pharmacist's role as a leader. Our implementation effort focused on three primary domains. First, we aimed to ensure a supportive organizational infrastructure. Early leadership engagement by the pharmacist-led core team facilitated advocacy for the clinical need, allocation of resources, and assay development. Second, core clinical workflows were developed that addressed the preferred patient population for use, desirable pharmacokinetic and pharmacodynamic targets, and the preferred sampling strategy. Clinical tools to guide pharmacists in interpreting the results (e.g., pharmacokinetics calculator) and documenting decisions were developed. Third, stakeholders were offered repeated exposure to evidence and expertise to facilitate understanding and application of the new practice. This act of 'individual internalization' seems to be uniquely important to beta-lactam TDM implementation compared with implementation of other antimicrobial TDM programs. Educational strategies and supportive materials that were developed were focused on providing substantive and varied information tailored to the stakeholders' role in the process. For pharmacists, this included both clinical and operational considerations. A continuous improvement plan to support management of the process was instituted to address necessary updates and changes that inevitably emerged. In summary, the described approach to implementation of a pharmacist led beta-lactam TDM program could be used as a roadmap to aid other institutions that aim to develop such a program.

Pharmacokinetics of ampicillin during venovenous extracorporeal membrane oxygenation: A case report

The presence of extracorporeal membrane oxygenation (ECMO) in addition to underlying critical illness can affect the pharmacokinetics and pharmacodynamics of drugs that are often required to treat this patient population. While ampicillin is the preferred agent for the treatment of susceptible Enterococcus faecalis infections, there are no in vivo pharmacokinetic studies regarding ampicillin dosing in patients receiving ECMO. This case report consists of two patients on venovenous ECMO with E. faecalis bloodstream infections in which ampicillin serum concentrations were measured. Pharmacokinetic parameters were calculated using a one compartment open model. Ampicillin trough levels were 5.87 and 39.2 mg/L for patients A and B, respectively. Based on these results, ampicillin concentrations were found to be above the minimum inhibitory concentration (MIC) for 100% of the dosing interval. The findings of this case report demonstrate that therapeutic concentrations of ampicillin can be obtained in patients on ECMO and therapeutic drug monitoring can be utilized to ensure adequate serum concentrations are achieved.

Why is the Implementation of Beta-Lactam Therapeutic Drug Monitoring for the Critically Ill Falling Short? A Multicenter Mixed-Methods Study

BACKGROUND

Beta-lactam therapeutic drug monitoring (BL TDM; drug level testing) can facilitate improved outcomes in critically ill patients. However, only 10%-20% of hospitals have implemented BL TDM. This study aimed to characterize provider perceptions and key considerations for successfully implementing BL TDM.

METHODS

This was a sequential mixed-methods study from 2020 to 2021 of diverse stakeholders at 3 academic medical centers with varying degrees of BL TDM implementation (not implemented, partially implemented, and fully implemented). Stakeholders were surveyed, and a proportion of participants completed semistructured interviews. Themes were identified, and findings were contextualized with implementation science frameworks.

RESULTS

Most of the 138 survey respondents perceived that BL TDM was relevant to their practice and improved medication effectiveness and safety. Integrated with interview data from 30 individuals, 2 implementation themes were identified: individual internalization and organizational features. Individuals needed to internalize, make sense of, and agree to BL TDM implementation, which was positively influenced by repeated exposure to evidence and expertise. The process of internalization appeared more complex with BL TDM than with other antibiotics (ie, vancomycin). Organizational considerations relevant to BL TDM implementation (eg, infrastructure, personnel) were similar to those identified in other TDM settings.

CONCLUSIONS

Broad enthusiasm for BL TDM among participants was found. Prior literature suggested that assay availability was the primary barrier to implementation; however, the data revealed many more individual and organizational attributes, which impacted the BL TDM implementation. Internalization should particularly be focused on to improve the adoption of this evidence-based practice.

Towards model-informed precision dosing of piperacillin: multicenter systematic external evaluation of pharmacokinetic models in critically ill adults with a focus on Bayesian forecasting

PURPOSE

Inadequate piperacillin (PIP) exposure in intensive care unit (ICU) patients threatens therapeutic success. Model-informed precision dosing (MIPD) might be promising to individualize dosing; however, the transferability of published models to external populations is uncertain. This study aimed to externally evaluate the available PIP population pharmacokinetic (PopPK) models.

METHODS

A multicenter dataset of 561 ICU patients (11 centers/3654 concentrations) was used for the evaluation of 24 identified models. Model performance was investigated for a priori (A) predictions, i.e., considering dosing records and patient characteristics only, and for Bayesian forecasting, i.e., additionally including the first (B1) or first and second (B2) therapeutic drug monitoring (TDM) samples per patient. Median relative prediction error (MPE) [%] and median absolute relative prediction error (MAPE) [%] were calculated to quantify accuracy and precision.

RESULTS

The evaluation revealed a large inter-model variability (A: MPE - 135.6-78.3% and MAPE 35.7-135.6%). Integration of TDM data improved all model predictions (B1/B2 relative improvement vs. A: |MPE|median_all_models 45.1/67.5%; MAPEmedian_all_models 29/39%). The model by Kim et al. was identified to be most appropriate for the total dataset (A/B1/B2: MPE - 9.8/- 5.9/- 0.9%; MAPE 37/27.3/23.7%), Udy et al. performed best in patients receiving intermittent infusion, and Klastrup et al. best predicted patients receiving continuous infusion. Additional evaluations stratified by sex and renal replacement therapy revealed further promising models.

CONCLUSION

The predictive performance of published PIP models in ICU patients varied considerably, highlighting the relevance of appropriate model selection for MIPD. Our differentiated external evaluation identified specific models suitable for clinical use, especially in combination with TDM.

Individualized antibiotic dosage regimens for patients with augmented renal clearance

Objectives: Augmented renal clearance (ARC) is a state of enhanced renal function commonly observed in 30%-65% of critically ill patients despite normal serum creatinine levels. Using unadjusted standard dosing regimens of renally eliminated drugs in ARC patients often leads to subtherapeutic concentrations, poor clinical outcomes, and the emergence of multidrug-resistant bacteria. We summarized pharmaceutical, pharmacokinetic, and pharmacodynamic research on the definition, underlying mechanisms, and risk factors of ARC to guide individualized dosing of antibiotics and various strategies for optimizing outcomes. Methods: We searched for articles between 2010 and 2022 in the MEDLINE database about ARC patients and antibiotics and further provided individualized antibiotic dosage regimens for patients with ARC. Results: 25 antibiotic dosage regimens for patients with ARC and various strategies for optimization of outcomes, such as extended infusion time, continuous infusion, increased dosage, and combination regimens, were summarized according to previous research. Conclusion: ARC patients, especially critically ill patients, need to make individualized adjustments to antibiotics, including dose, frequency, and method of administration. Further comprehensive research is required to determine ARC staging, expand the range of recommended antibiotics, and establish individualized dosing guidelines for ARC patients.