Optimization of the treatment with beta-lactam antibiotics in critically ill patients-guidelines from the French Society of Pharmacology and Therapeutics (Société Française de Pharmacologie et Thérapeutique-SFPT) and the French Society of Anaesthesia and Intensive Care Medicine (Société Française d'Anesthésie et Réanimation-SFAR)

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.

Frequency of pharmacological target attainment with flucloxacillin and cefazolin in invasive methicillin-susceptible Staphylococcus aureus infection: a prospective cohort study in hospitalized patients

BACKGROUND

The proportion of patients with invasive methicillin-susceptible Staphylococcus aureus (MSSA) infection who achieve target concentrations of flucloxacillin or cefazolin with standard dosing regimens is uncertain. This study measured drug concentrations in a prospective cohort of patients with invasive S. aureus infections to determine the frequency of target concentration attainment, and risk factors for failure to achieve target concentrations.

PATIENTS AND METHODS

Unbound flucloxacillin and cefazolin plasma concentrations were measured at the midpoint between intravenous doses. Adequate and optimal targets were defined as an unbound plasma concentration of ≥1 and ≥2 times the minimum inhibitory concentration (MIC) (flucloxacillin 0.5 mg/L, cefazolin 2 mg/L), respectively (50%fT_≥1MIC, 50%fT_≥2MIC).

RESULTS

There were 50 patients in each of the flucloxacillin and cefazolin groups. Eighty-five (85%) patients met the target of 50%fT_≥2MIC and 95 (95%) patients met the target of 50%fT_≥1MIC. The median unbound flucloxacillin concentration was 2.6 mg/L [interquartile range (IQR) 1.0-8.1]. The median unbound cefazolin concentration was 15.4 mg/L (IQR 8.8-28.2). A higher proportion of patients in the flucloxacillin group failed to achieve the optimal target compared with the cefazolin group [13 (26%) vs 2 (4%); P=0.002]. Younger age and higher creatinine clearance were associated with lower plasma concentrations.

CONCLUSIONS

Standard dosing of flucloxacillin and cefazolin in the treatment of invasive MSSA infections may not achieve target plasma concentrations for a subgroup of patients. Measuring drug concentrations identifies this subgroup and facilitates dose individualization.

Circulatory shock in adults in emergency department

Circulatory shock is a common condition that carries high morbidity and mortality. This review aims to update the critical steps in managing common types of shock in adult patients admitted to medical emergency and intensive care units. A literature review was performed by searching PubMed, EMBASE Ovid, and Cochrane Library, using the following search items: ("shock" OR "circulatory shock" OR "septic shock" OR "cardiogenic shock") AND ("management" OR "treatment" OR "resuscitation"). The review emphasizes prompt shock identification with tissue hypoperfusion, knowledge of the underlying pathophysiological mechanism, initial fluid resuscitation with balanced crystalloids, norepinephrine as the preferred vasopressor in septic and profound cardiogenic shock, and tailored intervention addressing specific etiologies. Point-of-care ultrasound may help evaluate an undifferentiated shock and determine fluid responsiveness. The approach to septic shock is improving; however, confirmatory studies are required for many existing (e.g., amount of initial fluids and steroids) and emerging (e.g., angiotensin II) therapies. Knowledge gaps and wide variations persist in managing cardiogenic shock that needs urgent addressing to improve outcomes.

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.

Continuous Infusion of High Doses of Cefepime in Intensive Care Unit: Assessment of Steady-State Plasma Level and Incidence on Neurotoxicity

Continuous infusion (CI) with high doses of cefepime is recommended in the empirical antimicrobial regimen of critically ill patients with suspected Gram-negative sepsis. This study aimed to determine factors associated with cefepime overdosing and the incidence of cefepime-induced neurotoxicity (CIN) in these patients. We performed a retrospective study including all patients receiving cefepime treatment between January 2019 and May 2022. The plasma level of cefepime defining overdosing was over 35 mg/L. Neurotoxicity was defined according to strict criteria and correlated with concomitant steady-state concentration of cefepime. Seventy-eight courses of cefepime treatment were analyzed. The mean cefepime plasma level at steady state was 59.8 ± 29.3 mg/L, and overdosing occurred in 80% of patients. Renal failure and a daily dose > 5 g were independently associated with overdosing. CIN was present in 30% of patients. In multivariate analysis, factors associated with CIN were chronic renal failure and a cefepime plasma concentration ≥ 60 mg/L. CIN was not associated with mortality. Overdosing is frequent in patients receiving high doses of cefepime by CI. Steady-state levels are higher than targeted therapeutic pharmacokinetic/pharmacodynamic objectives. The risk of CIN is important when the plasma concentration is ≥60 mg/L.

Diffusion of amoxicillin into heart valves from infective endocarditis patients

OBJECTIVES

Amoxicillin is the drug of choice in the management of streptococcal and enterococcal infective endocarditis (IE) but little is known regarding amoxicillin diffusion into infected heart valves. Herein, we assessed amoxicillin valvular distribution and related pharmacokinetic/pharmacodynamic (PK/PD) target attainment in IE patients undergoing heart valve surgery.

PATIENTS AND METHODS

In this 2-year prospective study, patients with IE treated by continuous infusion of amoxicillin and undergoing a surgical valve replacement were included. Both amoxicillin plasma and tissue concentrations were measured the day of surgery. Amoxicillin concentration in plasma and crushed heart valves were measured by a validated liquid chromatography method coupled with ultra-violet and tandem mass spectrometry, respectively. MIC and MBC of amoxicillin were determined for all available isolates. The rate of achievement of PK/PD efficacy parameters were assessed.

RESULTS

Twenty-two heart valves were removed from 20 patients. Bacterial aetiology was streptococcal (n = 17) and enterococcal (n = 3). Amoxicillin mean daily dose was 12 ± 3 g/24 h, mean plasma concentration was 29 ± 21 mg/L (n = 15), mean tissue concentration was 23 ± 15 mg/L (n = 22). Median diffusion rate was 62%. Patients reached a plasma concentration target >4XCMI (n = 13). Tissue concentrations were bactericidal for all streptococcal IE but not for enterococcal IE.

CONCLUSIONS

Amoxicillin intravalvular measurements in IE treated patients showed significant penetration into the infectious site. These data are reassuring that in situ bactericidal concentrations can be largely achieved in the management of streptococcal IE and support the need for combination antibiotic therapy for enterococcal IE.

Total and Unbound Pharmacokinetics of Cefiderocol in Critically Ill Patients

BACKGROUND

Cefiderocol is a siderophore cephalosporin antibiotic active against Gram-negative bacteria, including extended-spectrum beta-lactamase and carbapenemase-producing strains. The pharmacokinetics of cefiderocol has been studied in healthy subjects and particularly in phase II and III studies. This retrospective study investigated intravenous cefiderocol population pharmacokinetics in adult patients treated by cefiderocol.

METHODS

We studied 55 consecutive patients hospitalized in an intensive care unit. Cefiderocol plasma samples were obtained on different occasions during treatment. Plasma concentration was assayed using mass spectrometry. Data analysis was performed using a non-linear mixed-effect approach via Monolix 2020R1.

RESULTS

A total of 205 plasma samples were obtained from 55 patients. Eighty percent of patients received cefiderocol for ventilator-associated pneumonia due to carbapenem-resistant Pseudomonas aeruginosa infection. Cefiderocol concentration time-courses were best fit to a two-compartment open model with first-order elimination. Elimination clearance was positively related to renal function (estimated by the CKD formula). Adding albumin plasma binding in the model significantly improved the model assuming a ~40% unbound drug fraction given a ~40 g/L albuminemia. The final model included CKD plus cefiderocol plasma binding effects. Fat-free mass was better than total body weight to influence, via the allometric rule, clearance and volume terms, but this effect was negligible. The final clearance based on free circulating drug (CL_U) for a typical patient, CKD = 90, was 7.38 L/h [relative standard error, RSE, 22%] with a between-subject variability of 0.47 [RSE 10%] (exponential distribution).

CONCLUSION

This study showed that albumin binding and CKD effects were significant predictors of unbound and total plasma cefiderocol concentrations. Our results indicate that individual adjustment of cefiderocol can be used to reach high minimum inhibitory concentrations based on an estimation of unbound drug concentration and optimize therapeutic efficacy.

When and How to Use MIC in Clinical Practice?

Bacterial resistance to antibiotics continues to be a global public health problem. The choice of the most effective antibiotic and the use of an adapted dose in the initial phase of the infection are essential to limit the emergence of resistance. This will depend on (i) the isolated bacteria and its resistance profile, (ii) the pharmacodynamic (PD) profile of the antibiotic used and its level of toxicity, (iii) the site of infection, and (iv) the pharmacokinetic (PK) profile of the patient. In order to take account of both parameters to optimize the administered treatment, a minimal inhibitory concentration (MIC) determination associated with therapeutic drug monitoring (TDM) and their combined interpretation are required. The objective of this narrative review is thus to suggest microbiological, pharmacological, and/or clinical situations for which this approach could be useful. Regarding the microbiological aspect, such as the detection of antibiotic resistance and its level, the preservation of broad-spectrum β-lactams is particularly discussed. PK-PD profiles are relevant for difficult-to-reach infections and specific populations such as intensive care patients, cystic fibrosis patients, obese, or elderly patients. Finally, MIC and TDM are tools available to clinicians, who should not hesitate to use them to manage their patients.

Pharmacokinetic/Pharmacodynamic Analysis of Continuous-Infusion Fosfomycin in Combination with Extended-Infusion Cefiderocol or Continuous-Infusion Ceftazidime-Avibactam in a Case Series of Difficult-to-Treat Resistant Pseudomonas aeruginosa Bloodstream Infections and/or Hospital-Acquired Pneumonia

Objectives: To perform a pharmacokinetic/pharmacodynamic (PK/PD) analysis of continuous-infusion (CI) fosfomycin combined with extended-infusion (EI) cefiderocol or CI ceftazidime-avibactam in a case series of severe difficult-to-treat Pseudomonas aeruginosa (DTR-PA) infections. Methods: A single-center retrospective study of patients who were treated with CI fosfomycin plus EI cefiderocol or CI ceftazidime-avibactam for severe DTR-PA infections and who underwent therapeutic drug monitoring (TDM), from 1 September 2021 to 30 June 2022 was performed. Concentrations were measured at steady-state (Css) for CI fosfomycin and ceftazidime-avibactam and at trough (Cmin) for EI cefiderocol. Joint PK/PD targets of combination therapy were analyzed (thresholds: area-under-the curve to minimum inhibitory concentration (AUC/MIC) ratio > 40.8 for fosfomycin; ceftazidime Css/MIC ratio ≥ 4 coupled with avibactam Css > 4 mg/L for ceftazidime-avibactam; Cmin/MIC ratio ≥ 4 for cefiderocol). Joint PK/PD targets of the combination therapy were analyzed and defined as optimal when both were achieved, quasi-optimal if only one of the two was achieved, and suboptimal if none of the two was achieved). The relationship between joint PK/PD target attainment and microbiological response was assessed. Results: Six patients (three pneumonia, two BSI + pneumonia, and one BSI) were included. The joint PK/PD targets were optimal in four cases and quasi-optimal in the other two. Microbiological eradication (ME) occurred in 4/4 of patients with optimal joint PK/PD targets and in one of the two patients with quasi-optimal joint PK/PD targets. Conclusions: Attaining optimal joint PK/PD targets with a combo-therapy of CI fosfomycin plus EI cefiderocol or CI ceftazidime-avibactam could represent an effective strategy for granting favorable microbiological outcomes in patients with DTR-PA pneumonia and/or BSI.

Optimal antipseudomonal ꞵ-lactam drug dosing recommendations in critically-ill Asian patients receiving CRRT

INTRODUCTION

The average body weight is smaller in Asian patients compared with Western patients, but influence of body weight in antibiotic dosing is unknown. This study was to predict the optimal ceftazidime, cefepime, meropenem, piperacillin/tazobactam doses in Asian patients undergoing continuous venovenous hemofiltration (CVVH).

METHODS

Monte Carlo simulations (MCS) were performed using published Asian demographics and pharmacokinetics parameters in 5000 virtual patients at three CVVH effluent rates (Qeff; 20, 30, 40 mL/kg/h). Various dosing regimens were assessed for the probability of target attainments using 60% fT > 1 × MIC or 4xMIC and neurotoxicity risk at 48-h using suggested neurotoxicity thresholds.

RESULTS

Ceftazidime 1 g q12h, meropenem 1 g q12h, and piperacillin/tazobactam 3.375 g q6h were optimal for all Qeff settings against fT > 1 × MIC. Cefepime 2 g q24h and 2 g q12h were optimal at 20 and 30-40 mL/kg/h respectively. For the aggressive PD target (4 × MIC), optimal ceftazidime regimens were 1.25 g q8h (20-30 mL/kg/h) and 1.5 g q8h (40 mL/kg/h). Cefepime 2 g q8h and meropenem 1 g q8h were optimal at all Qeff settings. No simulated piperacillin doses attained the aggressive PD target. Increased neurotoxicity risk was predicted with ceftazidime and cefepime doses attaining the efficacy.

CONCLUSION

MCS enabled the prediction of optimal β-lactam dosing regimens for Asian patients receiving CVVH at varying Qeff. Clinical validation is warranted.

Model-informed precision dosing of beta-lactam antibiotics and ciprofloxacin in critically ill patients: a multicentre randomised clinical trial

PURPOSE

Individualising drug dosing using model-informed precision dosing (MIPD) of beta-lactam antibiotics and ciprofloxacin has been proposed as an alternative to standard dosing to optimise antibiotic efficacy in critically ill patients. However, randomised clinical trials (RCT) on clinical outcomes have been lacking.

METHODS

This multicentre RCT, including patients admitted to the intensive care unit (ICU) who were treated with antibiotics, was conducted in eight hospitals in the Netherlands. Patients were randomised to MIPD with dose and interval adjustments based on monitoring serum drug levels (therapeutic drug monitoring) combined with pharmacometric modelling of beta-lactam antibiotics and ciprofloxacin. The primary outcome was ICU length of stay (LOS). Secondary outcomes were ICU mortality, hospital mortality, 28-day mortality, 6-month mortality, delta sequential organ failure assessment (SOFA) score, adverse events and target attainment.

RESULTS

In total, 388 (MIPD n = 189; standard dosing n = 199) patients were analysed (median age 64 [IQR 55-71]). We found no significant differences in ICU LOS between MIPD compared to standard dosing (10 MIPD vs 8 standard dosing; IRR = 1.16; 95% CI 0.96-1.41; p = 0.13). There was no significant difference in target attainment before intervention at day 1 (T1) (55.6% MIPD vs 60.9% standard dosing; p = 0.24) or at day 3 (T3) (59.5% vs 60.4%; p = 0.84). There were no significant differences in other secondary outcomes.

CONCLUSIONS

We could not show a beneficial effect of MIPD of beta-lactam antibiotics and ciprofloxacin on ICU LOS in critically ill patients. Our data highlight the need to identify other approaches to dose optimisation.

Pharmacokinetics, Pharmacodynamics, and Dosing Considerations of Novel β-Lactams and β-Lactam/β-Lactamase Inhibitors in Critically Ill Adult Patients: Focus on Obesity, Augmented Renal Clearance, Renal Replacement Therapies, and Extracorporeal Membrane Oxygenation

OBJECTIVE

Dose optimization of novel β-lactam antibiotics (NBLA) has become necessary given the increased prevalence of multidrug-resistant infections in intensive care units coupled with the limited number of available treatment options. Unfortunately, recommended dose regimens of NBLA based on PK/PD indices are not well-defined for critically ill patients presenting with special situations (i.e., obesity, extracorporeal membrane oxygenation (ECMO), augmented renal clearance (ARC), and renal replacement therapies (RRT)). This review aimed to discuss and summarize the available literature on the PK/PD attained indices of NBLA among critically ill patients with special circumstances.

DATA SOURCES

PubMed, MEDLINE, Scopus, Google Scholar, and Embase databases were searched for studies published between January 2011 and May 2022.

STUDY SELECTION AND DATA EXTRACTION

Articles relevant to NBLA (i.e., ceftolozane/tazobactam, ceftazidime/avibactam, cefiderocol, ceftobiprole, imipenem/relebactam, and meropenem/vaborbactam) were selected. The MeSH terms of "obesity", "augmented renal clearance", "renal replacement therapy", "extracorporeal membrane oxygenation", "pharmacokinetic", "pharmacodynamic" "critically ill", and "intensive care" were used for identification of articles. The search was limited to adult humans' studies that were published in English. A narrative synthesis of included studies was then conducted accordingly.

DATA SYNTHESIS

Available evidence surrounding the use of NBLA among critically ill patients presenting with special situations was limited by the small sample size of the included studies coupled with high heterogeneity. The PK/PD target attainments of NBLA were reported to be minimally affected by obesity and/or ECMO, whereas the effect of renal functionality (in the form of either ARC or RRT) was more substantial.

CONCLUSION

Critically ill patients presenting with special circumstances might be at risk of altered NBLA pharmacokinetics, particularly in the settings of ARC and RRT. More robust, well-designed trials are still required to define effective dose regimens able to attain therapeutic PK/PD indices of NBLA when utilized in those special scenarios, and thus aid in improving the patients' outcomes.

Prompt and Appropriate Antimicrobial Therapy Improves Outcomes of NDM-Producing and KPC-Producing Klebsiella pneumoniae Bloodstream Infections in Patients Hospitalized for COVID-19: A Comparative Retrospective Case-Series

Secondary bloodstream infections (BSIs) caused by KPC- and NDM-producing Klebsiella pneumoniae (K.p.) during the course of COVID-19 infections lead to significant mortality. Herein, a comparative retrospective case series of KPC- or NDM-K.p. BSIs occurring in COVID-19 subjects treated with Ceftazidime/Avibactam (CAZ/AVI) for KPC-K.p., or CAZ/AVI+ Aztreonam (ATM) for NDM-K.p is reported. All patients hospitalized for COVID-19 in two Italian hospitals with a BSI between March and September 2021 were included. The main outcome was 14-day mortality. Overall, 44 patients were included: 23 with KPC-K.p. and 21 with NDM-K.p. BSIs. The median (q1–q3) age was 67 (57–75) years, and 32 (72%) were males. The two groups were similar in terms of baseline comorbidity, or severity of COVID-19. Notably, 14-day mortality of KPC-K.p. BSIs and NDM-K.p. BSIs (26% vs. 38%, p = 0.521) and 28-day mortality (35% vs. 48%, p = 0.541) were similar. A Cox regression model of delayed initiation of an appropriate antibiotic therapy after the onset of symptoms independently predicted mortality: initiation between 24 and 72 h (aHR = 12.03; 95% CI = 1.10–130, p = 0.041); and initiation after 72h (aHR = 36.9, 95% CI = 3.22–424, p = 0.004). Moreover, a trend towards an increased risk of mortality was observed for polymicrobial infections (aHR = 3.73, 95% CI = 0.87–15.8, p = 0.074), while a protective effect was observed for a beta-lactam loading dose at the start of treatment (aHR = 0.16, 95% CI = 0.02–1.10, p = 0.064). The high mortality of KPC and NDM-K.p. BSIs in COVID-19 patients may be reduced by an early and appropriate antibiotic therapy. Further efforts should be made to develop antimicrobial stewardship and infection control programs in COVID-19 wards.

Antimicrobial Stewardship during COVID-19 Outbreak: A Retrospective Analysis of Antibiotic Prescriptions in the ICU across COVID-19 Waves

The demographics and outcomes of ICU patients admitted for a COVID-19 infection have been characterized in extensive reports, but little is known about antimicrobial stewardship for these patients. We designed this retrospective, observational study to investigate our hypothesis that the COVID-19 pandemic has disrupted antimicrobial stewardship practices and likely affected the rate of antibiotic de-escalation (ADE), patient outcomes, infection recurrence, and multidrug-resistant bacteria acquisition. We reviewed the prescription of antibiotics in three ICUs during the pandemic from March 2020 to December 2021. All COVID-19 patients with suspected or proven bacterial superinfections who received antibiotic treatment were included. The primary outcome was the rate of ADE, and secondary outcomes included the rate of appropriate empirical treatment, mortality rates and a comparison with a control group of infected patients before the COVID-19 pandemic. We included 170 COVID-19 patients who received antibiotic treatment for a suspected or proven superinfection, of whom 141 received an empirical treatment. For the latter, antibiotic treatment was de-escalated in 47 (33.3%) patients, escalated in 5 (3.5%) patients, and continued in 89 (63.1%) patients. The empirical antibiotic treatment was appropriate for 87.2% of cases. ICU, hospital, and day 28 and day 90 mortality rates were not associated with the antibiotic treatment strategy. The ADE rate was 52.2% in the control group and 27.6% in the COVID-19 group (p < 0.001). Our data suggest that empirical antibiotic treatment was appropriate in most cases. The ADE rates were lower in the COVID-19 group than in the control group, suggesting that the stress associated with COVID-19 affected our practices.

Continuous Piperacillin-Tazobactam Infusion Improves Clinical Outcomes in Critically Ill Patients with Sepsis: A Retrospective, Single-Centre Study

Continuous infusion of beta-lactam antibiotics has emerged as an alternative for the treatment of sepsis because of the favourable pharmacokinetics of continuous infusion. This study aimed to evaluate the survival benefits of continuous vs. intermittent infusion of piperacillin-tazobactam in critically ill patients with sepsis. We retrospectively conducted a single-centre study of continuous infusion vs. intermittent infusion of piperacillin-tazobactam for adult patients who met the Sepsis-3 criteria and were treated at a medical ICU within 48 h after hospitalisation between 1 May 2018 and 30 April 2020. The primary outcome was mortality at 28 days. A total of 157 patients (47 in the continuous group and 110 in the intermittent group) met the inclusion criteria for evaluation. The 28-day mortality rates were 12.8% in the continuous group and 27.3% in the intermittent group (p = 0.07). However, after adjustment for potential covariables, patients in the continuous group (12.8%) showed significantly lower mortality at 28 days than those in the intermittent group (27.3%; adjusted hazard ratio (HR), 0.31; 95% confidence interval (CI), 0.13-0.79; p = 0.013). In sepsis patients, continuous infusion of piperacillin-tazobactam may confer a benefit regarding the avoidance of mortality at 28 days compared with intermittent infusion.

Individual target pharmacokinetic/pharmacodynamic attainment rates among meropenem-treated patients admitted to the ICU with hospital-acquired pneumonia

OBJECTIVES

Critical illness reduces β-lactam pharmacokinetic/pharmacodynamic (PK/PD) attainment. We sought to quantify PK/PD attainment in patients with hospital-acquired pneumonia.

METHODS

Meropenem plasma PK data (n = 70 patients) were modelled, PK/PD attainment rates were calculated for empirical and definitive targets, and between-patient variability was quantified [as a coefficient of variation (CV%)].

RESULTS

Attainment of 100% T&gt;4×MIC was variable for both empirical (CV% = 92) and directed (CV% = 33%) treatment.

CONCLUSIONS

Individualization is required to achieve suggested PK/PD targets in critically ill patients.

A Narrative Review of the Impact of Extracorporeal Membrane Oxygenation on the Pharmacokinetics and Pharmacodynamics of Critical Care Therapies

Objective:

Extracorporeal membrane oxygenation (ECMO) utilization is increasing on a global scale, and despite technological advances, minimal standardized approaches to pharmacotherapeutic management exist. This objective was to create a comprehensive review for medication dosing in ECMO based on the most current evidence.

Data Sources:

A literature search of PubMed was performed for all pertinent articles prior to 2022. The following search terms were utilized: ECMO, pharmacokinetics, pharmacodynamics, sedation, analgesia, antiepileptic, anticoagulation, antimicrobial, antifungal, nutrition. Retrospective cohort studies, case-control studies, case series, case reports, and ex vivo investigations were reviewed.

Study Selection and Data Extraction:

PubMed (1975 through July 2022) was the database used in the literature search. Non-English studies were excluded. Search terms included both drug class categories, specific drug names, ECMO, and pharmacokinetics.

Data Synthesis:

Medications with high protein binding (>70%) and high lipophilicity (logP > 2) are associated with circuit sequestration and the potential need for dose adjustment. Volume of distribution changes with ECMO may also impact dosing requirements of common critical care medications. Lighter sedation targets and analgosedation may help reduce sedative and analgesia requirements, whereas higher antiepileptic dosing is recommended. Vancomycin is minimally affected by the ECMO circuit and recommendations for dosing in critically ill adults are reasonable. Anticoagulation remains challenging as optimal aPTT goals have not been established.

Relevance to Patient Care and Clinical Practice:

This review describes the anticipated impacts of ECMO circuitry on sedatives, analgesics, anticoagulation, antiepileptics, antimicrobials, antifungals, and nutrition support and provides recommendations for drug therapy management.

Conclusions:

Medication pharmacokinetic/pharmacodynamic parameters should be considered when determining the potential impact of the ECMO circuit on attainment of therapeutic effect and target serum drug concentrations, and should guide therapy choices and/or dose adjustments when data are not available.

Population Pharmacokinetics/Pharmacodynamics and Clinical Outcomes of Meropenem in Critically Ill Patients

Several pathophysiological changes can alter meropenem pharmacokinetics in critically ill patients, thereby increasing the risk of subtherapeutic concentrations and affecting therapeutic outcomes. This study aimed to characterize the population pharmacokinetic (PPK) parameters of meropenem, evaluate the relationship between the pharmacokinetic/pharmacodynamic index of meropenem and treatment outcomes, and evaluate the different dosage regimens that can achieve 40%, 75%, and 100% of the dosing interval for which the free plasma concentrations remain above the MIC of the pathogens (fT_>MIC) targets. Critically ill adult patients treated with meropenem were recruited for this study. Five blood samples were collected from each patient. PPK models were developed using a nonlinear mixed-effects modeling approach, and the final model was subsequently used for Monte Carlo simulations to determine the optimal dosage regimens. A total of 247 concentrations from 52 patients were available for analysis. The two-compartment model with linear elimination adequately described the data. The mean PPK parameters were clearance (CL) of 4.8 L/h, central volume of distribution (V_C) of 11.4 L, peripheral volume of distribution (V_P) of 14.6 L, and intercompartment clearance of 10.5 L/h. Creatinine clearance was a significant covariate affecting CL, while serum albumin level and shock status were factors influencing V_C and V_P, respectively. Although 75% of the drug-resistant infection patients had fT_>MIC values of >40%, approximately 83% of them did not survive the infection. Therefore, 40% fT_>MIC might not be sufficient for critically ill patients, and a higher target, such as 75 to 100% fT_>MIC, should be considered for optimizing therapy. A 75% fT_>MIC could be reached using approved doses administered via a 3-h infusion.

Current Aspects of Pediatric Pharmacokinetics and Pharmacodynamics of Antimicrobials in Japan: Importance of the Promotion of Population PK/PD Analysis

Pharmacologic knowledge is important for pediatricians conducting feasible pharmacokinetic or pharmacodynamic (PK/PD) studies or applying effective antimicrobial therapies in children. Because of the difficulties in conducting PK/PD studies in children, antimicrobial PK/PD data in children are still limited. To fill in the lack of knowledge, promotion of population PK/PD analysis, which allows us to handle sparse sampling data from individual patients, is important because it is considered a suitable methodology to conduct PK/PD studies in children with limited blood drug concentration data for PK/PD analysis. Population PK/PD analysis is also useful in the clinical setting to provide individualized optimal dosage for each patient with various conditions. Here we summarized the current aspects of pediatric PK/PD studies of antimicrobials in Japan from clinical and research perspectives, specifically focusing on the importance of population PK/PD analysis.

Dose optimization of β-lactams antibiotics in pediatrics and adults: A systematic review

Background: β-lactams remain the cornerstone of the empirical therapy to treat various bacterial infections. This systematic review aimed to analyze the data describing the dosing regimen of β-lactams.

Methods: Systematic scientific and grey literature was performed in accordance with Preferred Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The studies were retrieved and screened on the basis of pre-defined exclusion and inclusion criteria. The cohort studies, randomized controlled trials (RCT) and case reports that reported the dosing schedule of β-lactams are included in this study.

Results: A total of 52 studies met the inclusion criteria, of which 40 were cohort studies, 2 were case reports and 10 were RCTs. The majority of the studies (34/52) studied the pharmacokinetic (PK) parameters of a drug. A total of 20 studies proposed dosing schedule in pediatrics while 32 studies proposed dosing regimen among adults. Piperacillin (12/52) and Meropenem (11/52) were the most commonly used β-lactams used in hospitalized patients. As per available evidence, continuous infusion is considered as the most appropriate mode of administration to optimize the safety and efficacy of the treatment and improve the clinical outcomes.

Conclusion: Appropriate antibiotic therapy is challenging due to pathophysiological changes among different age groups. The optimization of pharmacokinetic/pharmacodynamic parameters is useful to support alternative dosing regimens such as an increase in dosing interval, continuous infusion, and increased bolus doses.

Comparison of different equations for renal function evaluation as proxies for antibiotic drug clearance: the examples of amoxicillin and cloxacillin

The most appropriate renal function estimation equation to predict drug clearance is a matter of debate. In this study, we compare the Modification of Diet in Renal Disease (MDRD), the Chronic Kidney Disease Epidemiology collaboration (CKD-EPI) and the Cockroft-Gault (CG) equations to predict amoxicillin and cloxacillin clearance among hospitalized patients receiving high doses of these antibiotic treatments. This study aimed to compare different equations used to predict amoxicillin and cloxacillin clearance among hospitalized patients receiving amoxicillin or cloxacillin treatments outside the intensive care unit. Data from 128 patients contributing 268 plasma samples was analyzed, and correlations between the equations and the amoxicillin and cloxacillin antibiotic clearance rates were calculated. We found a correlation between antibiotic clearance and all the renal function estimation equations, CG being the best, with a R² of 0.35 for amoxicillin and 0.29 for cloxacillin (compared to 0.26 and 0.21 for MDRD and 0.12 and 0.24 for CKD-EPI). CG should be preferentially used as a proxy for amoxicillin and cloxacillin drug clearance, but the use of completely different tools such as therapeutic drug monitoring could help individualize antibiotic dosage.

Assessment of current practice for β-lactam therapeutic drug monitoring in French ICUs in 2021: a nationwide cross-sectional survey

BACKGROUND

Current guidelines and literature support the use of therapeutic drug monitoring (TDM) to optimize β-lactam treatment in adult ICU patients.

OBJECTIVES

To describe the current practice of β-lactam monitoring in French ICUs.

METHODS

A nationwide cross-sectional survey was conducted from February 2021 to July 2021 utilizing an online questionnaire that was sent as an email link to ICU specialists (one questionnaire per ICU).

RESULTS

Overall, 119 of 221 (53.8%) French ICUs participated. Eighty-seven (75%) respondents reported having access to β-lactam TDM, including 52 (59.8%) with on-site access. β-Lactam concentrations were available in 24-48 h and after 48 h for 36 (41.4%) and 26 (29.9%) respondents, respectively. Most respondents (n = 61; 70.1%) reported not knowing whether the β-lactam concentrations in the TDM results were expressed as unbound fractions or total concentrations. The 100% unbound fraction of the β-lactam above the MIC was the most frequent pharmacokinetic and pharmacodynamic target used (n = 62; 73.0%).

CONCLUSIONS

Despite the publication of international guidelines, β-lactam TDM is not optimally used in French ICUs. The two major barriers are β-lactam TDM interpretation and the required time for results.

Tissue Penetration of Antimicrobials in Intensive Care Unit Patients: A Systematic Review—Part I

The challenging severity of some infections, especially in critically ill patients, makes the diffusion of antimicrobial drugs within tissues one of the cornerstones of chemotherapy. The knowledge of how antibacterial agents penetrate tissues may come from different sources: preclinical studies in animal models, phase I–III clinical trials and post-registration studies. However, the particular physiopathology of critically ill patients may significantly alter drug pharmacokinetics. Indeed, changes in interstitial volumes (the third space) and/or in glomerular filtration ratio may influence the achievement of bactericidal concentrations in peripheral compartments, while inflammation can alter the systemic distribution of some drugs. On the contrary, other antibacterial agents may reach high and effective concentrations thanks to the increased tissue accumulation of macrophages and neutrophils. Therefore, the present review explores the tissue distribution of beta-lactams and other antimicrobials acting on the cell wall and cytoplasmic membrane of bacteria in critically ill patients. A systematic search of articles was performed according to PRISMA guidelines, and tissue/plasma penetration ratios were collected. Results showed a highly variable passage of drugs within tissues, while large interindividual variability may represent a hurdle which must be overcome to achieve therapeutic concentrations in some compartments. To solve that issue, off-label dosing regimens could represent an effective solution in particular conditions.

Population-Based Pharmacokinetics and Dose Optimization of Imipenem in Vietnamese Critically-Ill Patients

Purpose

The purpose of this study was to characterize the population-based pharmacokinetic (POP-PK) profile of imipenem in Vietnamese adult patients and to assess the probability of target attainment (PTA) of the pharmacokinetic/pharmacodynamic (PK/PD) parameter to determine the optimal dose.

Patients and Methods

A POP-PK model of imipenem was developed in patients with severe infection from a 1500-bed general hospital in Vietnam, using MONOLIX 2019. After the initial dose infusion, 6 blood samples per patient were collected to measure plasma imipenem levels. Eight covariates (eg, age, weight) were investigated to ascertain their influence on imipenem’s PK. Monte Carlo simulations were performed to determine the PTA for the time in which the total steady-state imipenem concentrations remained above the MIC (T>MIC) for 40% and 100% of the dosing interval.

Results

The best fit to the PK data was a two-compartment model with inter-individual variability (IIV) in clearance (CL), central volume of distribution (Vc), intercompartmental clearance (Q), and peripheral volume of distribution (Vp). Only creatinine clearance was retained as a covariate on CL in the final model. The typical value of CL and Vc were estimated to be 4.79 L/h and 11.1 L, respectively. The between-subject variability in this population was noted to be high (>38%, especially for IIV on Q at 110%). Prolonged or continuous infusion demonstrated efficacy (40% T>MIC) against bacteria with a MIC of 4mg/L. To achieve 100% T>MIC or bacteria with MIC>4 mg/L, however, the number of doses must be increased while maintaining the same daily dose for the 3-hour prolonged infusion regimen.

Conclusion

A population pharmacokinetic model of imipenem was developed for Vietnamese adult patients with severe illness. By using Monte Carlo simulation, the appropriate dose has been suggested based on the bacterial MIC value and the targeted PK/PD goal.

Implementation of Model-Based Dose Adjustment of Tobramycin in Adult Patients with Cystic Fibrosis

Therapeutic drug monitoring (TDM) of tobramycin is widely performed in patients with cystic fibrosis (CF), but little is known about the value of model-informed precision dosing (MIPD) in this setting. We aim at reporting our experience with tobramycin MIPD in adult patients with CF. We analyzed data from adult patients with CF who received IV tobramycin and had model-guided TDM during the first year of implementation of MIPD. The predictive performance of a pharmacokinetic (PK) model was assessed. Observed maximal (Cmax) and minimal (Cmin) concentrations after initial dosing were compared with target values. We compared the initial doses and adjusted doses after model-based TDM, as well as renal function at the beginning and end of therapy. A total of 78 tobramycin courses were administered in 61 patients. After initial dosing set by physicians (mean, 9.2 ± 1.4 mg/kg), 68.8% of patients did not achieve the target Cmax ≥ 30 mg/L. The PK model fit the data very well, with a median absolute percentage error of 4.9%. MIPD was associated with a significant increase in tobramycin doses (p < 0.001) without significant change in renal function. Model-based dose suggestions were wellaccepted by the physicians and the expected target attainment for Cmax was 83%. To conclude, the implementation of MIPD was effective in changing prescribing practice and was not associated with nephrotoxic events in adult patients with CF.

Relationship between Pharmacokinetic/Pharmacodynamic Target Attainment and Microbiological Outcome in Critically Ill COVID-19 Patients with Documented Gram-Negative Superinfections Treated with TDM-Guided Continuous-Infusion Meropenem

Objectives: The objective of this study was to explore the relationship between pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous-infusion (CI) meropenem and microbiological outcome in critical COVID-19 patients with documented Gram-negative superinfections. Methods: Patients receiving CI meropenem for documented Gram-negative infections at the COVID ICU of the IRCCS Azienda Ospedaliero-Universitaria di Bologna and undergoing therapeutic drug monitoring from January 2021 to February 2022 were retrospectively assessed. Average steady-state meropenem concentrations (Css) were calculated and the Css/MIC ratio was selected as a pharmacodynamic parameter of meropenem efficacy. The Css/MIC ratio was defined as optimal if ≥4, quasi-optimal if between 1 and 4, and suboptimal if <1. The relationship between Css/MIC and microbiological outcome was assessed. Results: Overall, 43 critical COVID-19 patients with documented Gram-negative infections were retrieved. Combination therapy was implemented in 26 cases. Css/MIC ratios were optimal in 27 (62.8%), quasi-optimal in 7 (16.3%), and suboptimal in 9 cases (20.9%). Microbiological failure occurred in 21 patients (48.8%), with no difference between monotherapy and combination therapy (43.8% vs. 53.8%; p = 0.53). The microbiological failure rate was significantly lower in patients with an optimal Css/MIC ratio compared to those with a quasi-optimal or suboptimal Css/MIC ratio (33.3% vs. 75.0%; p = 0.01). Conclusion: Suboptimal attainment of meropenem PK/PD targets may be a major determinant impacting on microbiological failure in critical COVID-19 patients with Gram-negative superinfections.

Barriers and facilitators for therapeutic drug monitoring of beta-lactams and ciprofloxacin in the ICU: a nationwide cross-sectional study

Background

Recent studies demonstrated that failure of achieving pharmacodynamic targets of commonly used antibiotics is common in critically ill patients. Therapeutic drug monitoring (TDM) can contribute to optimize the exposure of beta-lactams and ciprofloxacin. While evidence for TDM of these antibiotics is growing, translation into clinical implementation remains limited. Therefore, perceived barriers and facilitators are important for implementing TDM in this population. The primary aim of this study was to identify healthcare professionals’ barriers and facilitators for the implementation of TDM of beta-lactams and ciprofloxacin in Dutch intensive care units (ICU).

Methods

We conducted a nationwide cross-sectional online survey among healthcare professionals (HCPs) involved in antibiotic treatment of ICU patients. An adapted version of the Measurement Instrument for Determinants of Innovations was sent out. Items were considered barriers when ≥ 20% of participants responded with a negative answer. If ≥ 80% of the participants responded with a positive answer, the item was considered a facilitator.

Results

Sixty-four HCPs completed the survey, of which 14 were from academic hospitals, 25 from general hospitals, and 25 from teaching hospitals. Most participants were hospital pharmacists (59%) or medical specialists (23%). Eleven barriers and four facilitators for implementation of TDM of beta-lactams were identified; 17 barriers for TDM of ciprofloxacin and no facilitators. The most important barriers were a lack of conclusive evidence, organizational support, and low availability of assays. Additional barriers were a lack of consensus on which specific patients to apply TDM and which pharmacodynamic targets to use. Identified facilitators for beta-lactam TDM implementation are low complexity and high task perception, combined with the perception that TDM is important to prevent side effects and to adequately treat infections. Twenty-eight percent of participants reported that flucloxacillin could be analyzed in their hospital. Assay availability of other beta-lactams and ciprofloxacin was lower (3–17%).

Conclusion

Several barriers were identified that could obstruct the implementation of TDM of beta-lactams and ciprofloxacin in the ICU. In particular, education, clear guidelines, and organizational support should be considered when creating tailored implementation strategies. Finally, evidence of beneficial clinical outcomes on TDM of beta-lactams and ciprofloxacin can enhance further implementation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07587-w.

Ceftriaxone dosing based on the predicted probability of augmented renal clearance in critically ill patients with pneumonia

OBJECTIVES

PTA of protein-unbound ceftriaxone may be compromised in critically ill patients with community-acquired pneumonia (CAP) with augmented renal clearance (ARC). We aimed to determine an optimized ceftriaxone dosage regimen based on the probability of developing ARC on the next day (PARC,d+1; www.arcpredictor.com).

PATIENTS AND METHODS

Thirty-three patients enrolled in a prospective cohort study were admitted to the ICU with severe CAP and treated with ceftriaxone 2 g once daily. Patients contributed 259 total ceftriaxone concentrations, collected during 1 or 2 days (±7 samples/day). Unbound fractions of ceftriaxone were determined in all peak and trough samples (n = 76). Population pharmacokinetic modelling and simulation were performed using NONMEM7.4. Target attainment was defined as an unbound ceftriaxone concentration >4 mg/L throughout the dosing interval.

RESULTS

A two-compartment population pharmacokinetic model described the data well. The maximal protein-bound ceftriaxone concentration decreased with lower serum albumin. Ceftriaxone clearance increased with body weight and PARC,d+1 determined on the previous day. A high PARC,d+1 was identified as a clinically relevant predictor for underexposure on the next day (area under the receiver operating characteristics curve 0.77). Body weight had a weak predictive value and was therefore considered clinically irrelevant. Serum albumin had no predictive value. An optimal PARC,d+1 threshold of 5.7% was identified (sensitivity 73%, specificity 69%). Stratified once- or twice-daily 2 g dosing when below or above the 5.7% PARC,d+1 cut-off, respectively, was predicted to result in 81% PTA compared with 47% PTA under population-level once-daily 2 g dosing.

CONCLUSIONS

Critically ill patients with CAP with a high PARC,d+1 may benefit from twice-daily 2 g ceftriaxone dosing for achieving adequate exposure on the next day.

[Therapeutic drug monitoring and pharmacokinetic models as a strategy for rational antibiotic therapy in intensive care patients]

BACKGROUND AND OBJECTIVE

Antibiotic dosing in intensive care patients is complex due to pharmacokinetic (PK) alterations. The aim of this article is to illustrate the role of therapeutic drug monitoring (TDM) and PK models to individualize antibiotic dosing.

MATERIAL AND METHODS

Guidelines and recommendations are discussed in the context of clinical practice and the prerequisites for routine TDM of different antibiotics are presented. In addition, the benefits and limitations of TDM are discussed. The advantages and disadvantages of TDM and PK models are described and the resulting future options are presented.

RESULTS

In the clinical routine, the peak or trough concentrations of antibiotics in blood are measured depending on the antibiotic class. Prerequisites for a purposeful TDM are a coordinated blood sampling and a prompt reporting of findings. As target ranges are not uniformly defined following rules, dosage adjustments are difficult. The PK models offer a valid possibility to individualize the antibiotic therapy of intensive care patients. Areas of application are the calculation of the loading dose and the combination with TDM for treatment control. For whom and how often TDM is necessary and how it can best be combined with PK models or even replace them should be investigated in the future, in addition to evaluation of the optimal target area.

CONCLUSION

The routine use of TDM for antibiotics in intensive care patients is only effective under the abovementioned conditions. By combination with PK models the treatment could be optimized in the future.

Clinical Pharmacokinetics and Pharmacodynamics of Cefepime

Cefepime is a broad-spectrum fourth-generation cephalosporin with activity against Gram-positive and Gram-negative pathogens. It is generally administered as an infusion over 30-60 min or as a prolonged infusion with infusion times from 3 h to continuous administration. Cefepime is widely distributed in biological fluids and tissues with an average volume of distribution of ~ 0.2 L/kg in healthy adults with normal renal function. Protein binding is relatively low (20%), and elimination is mainly renal. About 85% of the dose is excreted unchanged in the urine, with an elimination half-life of 2-2.3 h. The pharmacokinetics of cefepime is altered under certain pathophysiological conditions, resulting in high inter-individual variability in cefepime volume of distribution and clearance, which poses challenges for population dosing approaches. Consequently, therapeutic drug monitoring of cefepime may be beneficial in certain patients including those who are critically ill, have life-threatening infections, or are infected with more resistant pathogens. Cefepime is generally safe and efficacious, with a goal exposure target of 70% time of the free drug concentration over the minimum inhibitory concentration for clinical efficacy. In recent years, reports of neurotoxicity have increased, specifically in patients with impaired renal function. This review summarizes the pharmacokinetics, pharmacodynamics, and toxicodynamics of cefepime contemporarily in the setting of increasing cefepime exposures. We explore the potential benefits of extended or continuous infusions and therapeutic drug monitoring in special populations.

Drug Dosing in Critically Ill Adult Patients with Augmented Renal Clearance

Augmented renal clearance (ARC) is a phenomenon of enhanced renal function seen in critically ill patients. ARC alters the disposition of renally eliminated medications currently used in the intensive care unit, resulting in underdosing and potential therapy failure. Our review addresses the rising concern of inadequate dosing in patients with ARC by summarizing the currently available evidence. To our knowledge, this guide is the first to provide clinicians with dose recommendation insights for renally eliminated agents in adult critically ill patients with ARC. A comprehensive literature search using MEDLINE, Embase, Cochrane Library, CINAHL, Scopus, and ProQuest Dissertations and Theses Global was conducted until 3 November 2021. Screening and data extraction were conducted in two steps: title and abstract screening followed by full-text review. Full text review resulted in a total of 51 studies included in this review. The results demonstrated the need for higher-than-standard doses for meropenem, imipenem, and vancomycin and reduced dosing intervals for ceftriaxone in patients with ARC. The potential need for increased dosing frequency in patients with ARC was also found for both enoxaparin and levetiracetam. In conclusion, ARC has been shown to influence the probability of target attainment in several medications requiring dosing changes to mitigate the risk of therapeutic failure.

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.

Therapeutic Drug Monitoring of Ceftazidime-Avibactam Concentrations in Carbapenem-Resistant K. pneumoniae-Infected Patients With Different Kidney Statuses

Aims: Carbapenem-resistant K. pneumoniae (CRKP) is the most common carbapenem-resistant Enterobacteriaceae with high mortality. Ceftazidime-avibactam (CAZ-AVI) has exhibited excellent in vitro activity in vivo against CRKP. However, the efficacy of CAZ-AVI in KPC-producing CRKP-infected patients with different kidney statuses varies, such as renal insufficiency, normal renal function, and augmented renal clearance (ARC). We explored the use of therapeutic drug monitoring (TDM) to evaluate the concentration and efficacy of CAZ-AVI in CRKP-infected patients with different kidney statuses.

Methods: Serum concentrations for CAZ and AVI were determined by the high-performance liquid chromatography method. Bacterial identification, routine susceptibility testing, renal function index, and others were performed in standard protocols in the hospital’s clinical laboratories.

Results: In the two patients with ARC, in case 1, CAZ-AVI 2.5g q6h was used with good efficacy, and the concentrations were up to the pharmacokinetics/pharmacodynamics targets. In Case 2, 2.5 g q8h was used with invalid effectiveness, and AVI C_min was only 0.797 mg/l, which is lower than the PK/PD target. Case 3 was renal insufficiency using CAZ-AVI 1.25 q8h, and case 4 was normal renal function using 2.5 g q8h. Their concentrations were both up to the PK/PD targets.

Conclusion: TDM results demonstrated that CAZ-AVI steady-state plasma concentration varies among patients with different kidney statuses, providing evidence for the utility of TDM of CAZ-AVI in individualized drug dose adjustment. ARC patients may need more CAZ-AVI daily doses than the standard dose.

Evaluation of 4 quantification methods for monitoring 16 antibiotics and 1 beta-lactamase inhibitor in human serum by high-performance liquid chromatography with tandem mass spectrometry detection

Antibiotic (ATB) prescription in an intensive care unit (ICU) requires continuous monitoring of serum dosages due to the patient's pathophysiological condition. Dosing adjustment is necessary to achieve effective targeted concentrations. Since ICUs routinely use a large number of ATBs, global monitoring needs to be developed. In the present study, we developed a global analytical method for extracting, separating and quantifying the most widely used ATBs in ICUs: amoxicillin, piperacillin, cefazolin, cefepime, cefotaxime, ceftazidime, ceftolozane, ceftriaxone, ertapenem, meropenem, ciprofloxacin, moxifloxacin, levofloxacin, daptomycin, dalbavancin, linezolid and a beta-lactamase inhibitor: tazobactam. To guarantee the robustness of the quantification, we differentiated the 16 ATBs and the beta lactamase inhibitor into 4 pools (ATB1 to ATB4), taking into account prescription frequency in the ICU, the physicochemical properties and the calibration ranges of the ATBs selected. The whole ATB was then separated with two LC columns in reversed phase: Kinetex Polar-C18 100 Å and Polar-RP-80 synergy, in less than 6.5 min. Detection was carried out by electrospray in positive ion mode, by tandem mass spectrometry (LC-MS/MS. The four quantification methods were validated according to the European guidelines on bioanalytical method validation (EMEA guide), after determining the extraction yields, matrix effects, recovery, precision, accuracy, within-run precision and between-run precision. For all analyses, bias is < 15% and is comparable to the literature and LOQs vary from 0.05 mg.L^-1 for ciprofloxacin to 1.00 mg.L^-1 for ceftriaxone and dalbavancin. The stability time of cefepime and piperacillin is 3 hrs and for the other ATBs 6 hrs in serum at room temperature. For long-term stability, freezing at - 80 °C guarantees 3 months of stability for ceftriaxone and dalbavancin and more than 6 months for the other ATBs.

Implementation of a β-lactam therapeutic drug monitoring program: Experience from a large academic medical center

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To describe the implementation and operationalization of a β-lactam (BL) therapeutic drug monitoring(TDM) program at a large academic center.

SUMMARY

BLs are the most used class of antibiotics. Suboptimal antibiotic exposure is a significant concern in hospitalized patients, particularly in those with altered pharmacokinetics. BL-TDM provides clinicians the opportunity to optimize drug concentrations to ensure maximal therapeutic efficacy while minimizing toxicity. However, BL-TDM has not been widely adopted due to the lack of access to assays. The University of Florida Shands Hospital developed a BL-TDM program in 2015. This is a consultative service primarily run by pharmacists and is conducted in all patient care areas. An analysis was performed on the first BL-TDM encounter for 1,438 patients. BL-TDM was most frequently performed for cefepime (61%, n = 882), piperacillin (15%, n = 218), and meropenem (11%, n = 151). BL-TDM was performed a median of 3 days (interquartile range, 1-5 days) from BL initiation. Among patients with available minimum inhibitory concentration (MIC) values and trough concentrations, the pharmacokinetic/pharmacodynamic (PK/PD) target of 100% fT>MIC was attained in 308 patients (88%). BL-TDM resulted in a dosage adjustment in 25% (n = 361) of patients.

CONCLUSION

Implementation of a BL-TDM program requires the concerted efforts of physicians, pharmacists, nursing staff, phlebotomists, and personnel in the analytical laboratory. Standard antibiotic dosing failed to achieve optimal PK/PD targets in all patients; utilizing BL-TDM, dose adjustments were made in 1 of every 4 patients.

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.

Diagnosis and management of infections caused by multidrug-resistant bacteria: guideline endorsed by the Italian Society of Infection and Tropical Diseases (SIMIT), the Italian Society of Anti-Infective Therapy (SITA), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Association of Clinical Microbiologists (AMCLI) and the Italian Society of Microbiology (SIM)

Management of patients with infections caused by multidrug-resistant organisms is challenging and requires a multidisciplinary approach to achieve successful clinical outcomes. The aim of this paper is to provide recommendations for the diagnosis and optimal management of these infections, with a focus on targeted antibiotic therapy. The document was produced by a panel of experts nominated by the five endorsing Italian societies, namely the Italian Association of Clinical Microbiologists (AMCLI), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Society of Microbiology (SIM), the Italian Society of Infectious and Tropical Diseases (SIMIT) and the Italian Society of Anti-Infective Therapy (SITA). Population, Intervention, Comparison and Outcomes (PICO) questions about microbiological diagnosis, pharmacological strategies and targeted antibiotic therapy were addressed for the following pathogens: carbapenem-resistant Enterobacterales; carbapenem-resistant Pseudomonas aeruginosa; carbapenem-resistant Acinetobacter baumannii; and methicillin-resistant Staphylococcus aureus. A systematic review of the literature published from January 2011 to November 2020 was guided by the PICO strategy. As data from randomised controlled trials (RCTs) were expected to be limited, observational studies were also reviewed. The certainty of evidence was classified using the GRADE approach. Recommendations were classified as strong or conditional. Detailed recommendations were formulated for each pathogen. The majority of available RCTs have serious risk of bias, and many observational studies have several limitations, including small sample size, retrospective design and presence of confounders. Thus, some recommendations are based on low or very-low certainty of evidence. Importantly, these recommendations should be continually updated to reflect emerging evidence from clinical studies and real-world experience.

Optimal dosing of cefotaxime and desacetylcefotaxime for critically ill paediatric patients. Can we use microsampling?

Objectives

To describe the population pharmacokinetics of cefotaxime and desacetylcefotaxime in critically ill paediatric patients and provide dosing recommendations. We also sought to evaluate the use of capillary microsampling to facilitate data-rich blood sampling.

Methods

Patients were recruited into a pharmacokinetic study, with cefotaxime and desacetylcefotaxime concentrations from plasma samples collected at 0, 0.5, 2, 4 and 6 h used to develop a population pharmacokinetic model using Pmetrics. Monte Carlo dosing simulations were tested using a range of estimated glomerular filtration rates (60, 100, 170 and 200 mL/min/1.73 m²) and body weights (4, 10, 15, 20 and 40 kg) to achieve pharmacokinetic/pharmacodynamic (PK/PD) targets, including 100% ƒT_>MIC with an MIC breakpoint of 1 mg/L.

Results

Thirty-six patients (0.2–12 years) provided 160 conventional samples for inclusion in the model. The pharmacokinetics of cefotaxime and desacetylcefotaxime were best described using one-compartmental model with first-order elimination. The clearance and volume of distribution for cefotaxime were 12.8 L/h and 39.4 L, respectively. The clearance for desacetylcefotaxime was 10.5 L/h. Standard dosing of 50 mg/kg q6h was only able to achieve the PK/PD target of 100% ƒT_>MIC in patients >10 kg and with impaired renal function or patients of 40 kg with normal renal function.

Conclusions

Dosing recommendations support the use of extended or continuous infusion to achieve cefotaxime exposure suitable for bacterial killing in critically ill paediatric patients, including those with severe or deep-seated infection. An external validation of capillary microsampling demonstrated skin-prick sampling can facilitate data-rich pharmacokinetic studies.

Evaluation of a Meropenem and Piperacillin Monitoring Program in Intensive Care Unit Patients Calls for the Regular Assessment of Empirical Targets and Easy-to-Use Dosing Decision Tools

The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1–5 × MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8–40 mg/L and 16–80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0%, piperacillin: 93.9%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7%, piperacillin 50.5%) with the lowest TA for severely impaired renal function (meropenem: 13.9%, piperacillin: 29.2%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13%, piperacillin: 4.78%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.

Rapid, simple, and economical LC-MS/MS method for simultaneous determination of ceftazidime and avibactam in human plasma and its application in therapeutic drug monitoring

WHAT IS KNOWN AND OBJECTIVE

Carbapenem-resistant Gram-negative bacterial pathogens continue to threaten public health. Avibactam (AVI), a novel non-β-lactam β-lactamase inhibitor, has been approved for use with ceftazidime (CAZ) mainly against carbapenem-resistant Enterobacteriaceae. Therapeutic drug monitoring (TDM) is urgently needed to optimize dosage regimens to maximize efficacy, minimize toxicity, and delay the emergence of resistance. This study aims to develop and validate a rapid, simple, and economical LC-MS/MS method for simultaneous determination of CAZ/AVI in human plasma.

METHODS

Samples were processed by simple protein precipitation, and gradient elution strategy was applied to separate CAZ and AVI on a reverse-phase C18 column; with subsequent detection by the mass spectrometer in a positive and negative ion switching mode. Plasma samples from patients were analysed.

RESULTS AND DISCUSSION

A 4-min run of LC-MS/MS was developed. The precision, trueness, matrix effect, extraction recovery, carry-over, dilution integrity, and stability were all acceptable for a bioanalytical method. The method was successfully applied to the determination of CAZ and AVI in patients, and a considerable PK variability of CAZ/AVI was observed among patients.

WHAT IS NEW AND CONCLUSION

A robust, rapid, simple, and economical LC-MS/MS method for the simultaneous determination of CAZ and AVI was developed. The considerable PK variability of CAZ/AVI among patients demonstrates the clinical significance of TDM.

Cefepime population pharmacokinetics and dosing regimen optimization in critically ill children with different renal function

OBJECTIVE

Cefepime is commonly used in pediatric intensive care units (PICUs), where unpredictable variations in the patients' pharmacokinetic (PK) variables may require drug dose adjustments. The objectives of the present study were to build a population PK model for cefepime in critically ill children and to optimize individual initial dosing regimens.

METHODS

Children (aged from 1 month to 18 years; bodyweight >3 kg) receiving cefepime were included. Cefepime total plasma concentrations were measured using high performance liquid chromatography. Data were modelled using non-linear, mixed-effect modeling software, and Monte Carlo simulations were performed with a PK target of 100% fT _{> MIC}.

RESULTS

Fifty-nine patients (median (range) age: 13.5 months (1.1 month-17.6 years)) and 129 cefepime concentration measurements were included. The cefepime concentration data were best fitted by a one-compartment model. The selected covariates were body weight with allometric scaling and estimated glomerular filtration rate on clearance. Mean population values for clearance and volume were 1.21 L.h^-1 and 4.8 L, respectively. According to the simulations, a regimen of 100 mg.kg^-1.day^-1 q12 h over 30 min or 100 mg.kg^-1.day^-1 as a continuous infusion was more likely to achieve the PK target in patients with renal failure and in patients with normal or augmented renal clearance, respectively.

CONCLUSIONS

Appropriate cefepime dosing regimens should take renal function into account. Continuous infusions are required in critically ill children with normal or augmented renal clearance, while intermittent infusions are adequate for children with acute renal failure. Close therapeutic drug monitoring is mandatory, given cefepime's narrow therapeutic window.