Insufficient β-lactam concentrations in the early phase of severe sepsis and septic shock

Antibiotic Dosing in Patients With Acute Kidney Injury: "Enough But Not Too Much"

Increasing evidence suggests that antibiotic dosing in critically ill patients with acute kidney injury (AKI) often does not achieve pharmacodynamic goals, and the continued high mortality rate due to infectious causes appears to confirm these findings. Although there are compelling reasons why clinicians should use more aggressive antibiotic dosing, particularly in patients receiving aggressive renal replacement therapies, concerns for toxicity associated with higher doses are real. The presence of multisystem organ failure and polypharmacy predispose these patients to drug toxicity. This article examines the pharmacokinetic and pharmacodynamic consequences of critical illness, AKI, and renal replacement therapy and describes potential solutions to help clinicians give "enough but not too much" in these very complicated patients.

Early management of sepsis

Increased awareness of the signs and symptoms of sepsis and an emphasis on the importance of early treatment have helped to improve survival rates from this serious and frequent condition in recent years. With no specific, effective anti-sepsis therapies available, management focuses on early source control with adequate and appropriate antibiotics and removal of any source of infection, rapid resuscitation, hemodynamic stabilization and organ support. Use of dedicated teams to care for patients with sepsis can help optimize early management.

Emergency department antimicrobial considerations in severe sepsis

Severe sepsis and septic shock are common problems in the emergency department patient population and require expert clinical skill by members of the emergency department team to maximize optimal patient outcomes. Although various guidelines have been developed for the management of these patients, issues around antimicrobial-related considerations in critically ill patients require further evidence-based attention. In this review article, important factors related to patient illness, microorganism, timing of antimicrobial administration, and source control are discussed.

In vivo antibiotic removal during coupled plasma filtration adsorption: a retrospective study

Coupled plasma filtration adsorption (CPFA) is a blood purification therapy aimed at modulating the host inflammatory response involved in sepsis pathogenesis. One potential drawback of this technique is the unexpected elimination of antibiotics. The aim of this study was to assess the elimination of several antibiotics with CPFA. We performed a retrospective analysis of the serum and ultrafiltrate concentrations of different antibiotics routinely measured during CPFA sessions in five patients experiencing septic shock. The adsorbent extraction ratio (AER) for piperacillin and vancomycin 2 h into the CPFA session were high: 95.4 ± 6.9% and 99.6 ± 0.9%, respectively. These AER decreased significantly by 8 h (at 8 h: 6.3 ± 51.8% and -30.2 ± 25.6%, respectively), suggesting saturation of the resin cartridge. Conversely, the tazobactam AER was low (7.2 ± 15% after 2 h of CPFA). No significant changes in the mean serum concentrations of piperacillin, tazobactam, and vancomycin were observed. Thus, as opposed to tazobactam, we report high adsorption of piperacillin and vancomycin on the CPFA resin but with no reduction in serum concentrations.

Antibiotic stewardship in the intensive care unit

The rapid emergence and dissemination of antimicrobial-resistant microorganisms in ICUs worldwide constitute a problem of crisis dimensions. The root causes of this problem are multifactorial, but the core issues are clear. The emergence of antibiotic resistance is highly correlated with selective pressure resulting from inappropriate use of these drugs. Appropriate antibiotic stewardship in ICUs includes not only rapid identification and optimal treatment of bacterial infections in these critically ill patients, based on pharmacokinetic-pharmacodynamic characteristics, but also improving our ability to avoid administering unnecessary broad-spectrum antibiotics, shortening the duration of their administration, and reducing the numbers of patients receiving undue antibiotic therapy. Either we will be able to implement such a policy or we and our patients will face an uncontrollable surge of very difficult-to-treat pathogens.

Risk factors for target non-attainment during empirical treatment with β-lactam antibiotics in critically ill patients

PURPOSE

Risk factors for β-lactam antibiotic underdosing in critically ill patients have not been described in large-scale studies. The objective of this study was to describe pharmacokinetic/pharmacodynamic (PK/PD) target non-attainment envisioning empirical dosing in critically ill patients and considering a worst-case scenario as well as to identify patient characteristics that are associated with target non-attainment.

METHODS

This analysis uses data from the DALI study, a prospective, multi-centre pharmacokinetic point-prevalence study. For this analysis, we assumed that these were the concentrations that would be reached during empirical dosing, and calculated target attainment using a hypothetical target minimum inhibitory concentration (MIC), namely the susceptibility breakpoint of the least susceptible organism for which that antibiotic is commonly used. PK/PD targets were free drug concentration maintained above the MIC of the suspected pathogen for at least 50 % and 100 % of the dosing interval respectively (50 % and 100 % f T (>MIC)). Multivariable analysis was performed to identify factors associated with inadequate antibiotic exposure.

RESULTS

A total of 343 critically ill patients receiving eight different β-lactam antibiotics were included. The median (interquartile range) age was 60 (47-73) years, APACHE II score was 18 (13-24). In the hypothetical situation of empirical dosing, antibiotic concentrations remained below the MIC during 50 % and 100 % of the dosing interval in 66 (19.2 %) and 142 (41.4 %) patients respectively. The use of intermittent infusion was significantly associated with increased risk of non-attainment for both targets; creatinine clearance was independently associated with not reaching the 100 % f T( >MIC) target.

CONCLUSIONS

This study found that-in empirical dosing and considering a worst--case scenario--19 % and 41 % of the patients would not achieve antibiotic concentrations above the MIC during 50 % and 100 % of the dosing interval. The use of intermittent infusion (compared to extended and continuous infusion) was the main determinant of non-attainment for both targets; increasing creatinine clearance was also associated with not attaining concentrations above the MIC for the whole dosing interval. In the light of this study from 68 ICUs across ten countries, we believe current empiric dosing recommendations for ICU patients are inadequate to effectively cover a broad range of susceptible organisms and need to be reconsidered.

Population pharmacokinetics and dosing simulations of cefuroxime in critically ill patients: non-standard dosing approaches are required to achieve therapeutic exposures

OBJECTIVES

To investigate the population pharmacokinetics of cefuroxime in critically ill patients.

METHODS

In this observational pharmacokinetic study, multiple blood samples were taken over one dosing interval of intravenous cefuroxime. Blood samples were analysed using a validated ultra HPLC tandem mass spectrometry technique. Population pharmacokinetic analysis and dosing simulations were performed using non-linear mixed-effects modelling.

RESULTS

One hundred and sixty blood samples were collected from 20 patients. CL(CR) ranged between 10 and 304 mL/min. A two-compartment model with between-subject variability on CL, V of the central compartment and V of the peripheral compartment described the data adequately. Twenty-four hour urinary CL(CR) was supported as a descriptor of drug CL. The population model for CL was CL = θ(1) × CL(CR)/100, where θ(1) is the typical cefuroxime CL in the population, which is 9.0 L/h. The mean V was 22.5 L. Dosing simulations showed failure to achieve the pharmacokinetic/pharmacodynamic target of 65% fT(>MIC) for an MIC of 8 mg/L with standard dosing regimens for patients with CL(CR) ≥50 mL/min.

CONCLUSIONS

Administration of standard doses by intermittent bolus is likely to result in underdosing for many critically ill patients. Continuous infusion of higher than normal doses after a loading dose is more likely to achieve pharmacokinetic/pharmacodynamic targets. However, even continuous infusion of high doses (up to 9 g per day) does not guarantee adequate levels for all patients with a CL(CR) of ≥300 mL/min if the MIC is 8 mg/L.

Does contemporary vancomycin dosing achieve therapeutic targets in a heterogeneous clinical cohort of critically ill patients? Data from the multinational DALI study

Introduction

The objective of this study was to describe the pharmacokinetics of vancomycin in ICU patients and to examine whether contemporary antibiotic dosing results in concentrations that have been associated with favourable response.

Methods

The Defining Antibiotic Levels in Intensive Care (DALI) study was a prospective, multicentre pharmacokinetic point-prevalence study. Antibiotic dosing was as per the treating clinician either by intermittent bolus or continuous infusion. Target trough concentration was defined as ≥15 mg/L and target pharmacodynamic index was defined as an area under the concentration-time curve over a 24-hour period divided by the minimum inhibitory concentration of the suspected bacteria (AUC_0–24/MIC ratio) >400 (assuming MIC ≤1 mg/L).

Results

Data of 42 patients from 26 ICUs were eligible for analysis. A total of 24 patients received vancomycin by continuous infusion (57%). Daily dosage of vancomycin was 27 mg/kg (interquartile range (IQR) 18 to 32), and not different between patients receiving intermittent or continuous infusion. Trough concentrations were highly variable (median 27, IQR 8 to 23 mg/L). Target trough concentrations were achieved in 57% of patients, but more frequently in patients receiving continuous infusion (71% versus 39%; P = 0.038). Also the target AUC_0–24/MIC ratio was reached more frequently in patients receiving continuous infusion (88% versus 50%; P = 0.008). Multivariable logistic regression analysis with adjustment by the propensity score could not confirm continuous infusion as an independent predictor of an AUC_0–24/MIC >400 (odds ratio (OR) 1.65, 95% confidence interval (CI) 0.2 to 12.0) or a C_min ≥15 mg/L (OR 1.8, 95% CI 0.4 to 8.5).

Conclusions

This study demonstrated large interindividual variability in vancomycin pharmacokinetic and pharmacodynamic target attainment in ICU patients. These data suggests that a re-evaluation of current vancomycin dosing recommendations in critically ill patients is needed to more rapidly and consistently achieve sufficient vancomycin exposure.

Antibiotic consumption and antibiotic stewardship in Swedish hospitals

BACKGROUND

The aim of this paper was to describe and analyze the effect of antibiotic policy changes on antibiotic consumption in Swedish hospitals and to review antibiotic stewardship in Swedish hospitals.

RESULTS

The main findings were: 1) Antibiotic consumption has significantly increased in Swedish hospitals over the last decade. The consumption of cephalosporins has decreased, whereas that of most other drugs including piperacillin-tazobactam, carbapenems, and penicillinase-sensitive and -resistant penicillins has increased and replaced cephalosporins. 2) Invasive infections caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae have increased, but the proportion of pathogens resistant to third-generation cephalosporins causing invasive infections is still very low in a European and international perspective. Furthermore, the following gaps in knowledge were identified: 1) lack of national, regional, and local data on the incidence of antibiotic resistance among bacteria causing hospital-acquired infections e.g. bloodstream infections and hospital-acquired pneumonia-data on which standard treatment guidelines should be based; 2) lack of data on the incidence of Clostridium difficile infections and the effect of change of antibiotic policies on the incidence of C. difficile infections and infections caused by antibiotic-resistant pathogens; and 3) lack of prospective surveillance programs regarding appropriate antibiotic treatment, including selection of optimal antimicrobial drug regimens, dosage, duration of therapy, and adverse ecological effects such as increases in C. difficile infections and emergence of antibiotic-resistant pathogens.

CONCLUSIONS

Evidence-based actions to improve antibiotic use and to slow down the problem of antibiotic resistance need to be strengthened. The effect of such actions should be analyzed, and standard treatment guidelines should be continuously updated at national, regional, and local levels.

How severe is antibiotic pharmacokinetic variability in critically ill patients and what can be done about it?

The pharmacokinetics (PK) of antimicrobial agents administered to critically ill patients exhibit marked variability. This variability results from pathophysiological changes that occur in critically ill patients. Changes in volume of distribution, clearance, and tissue penetration all affect the drug concentrations at the site of infection. PK-pharmacodynamic indices (fCmax:MIC; AUC0-24:MIC; fT>MIC; fCmin:MIC) for both antimicrobial effect and suppression of emergence of resistance are described for many antimicrobial drugs. Changing the regimen by which antimicrobial drugs are delivered can help overcome the PK variability and optimise target attainment. This will deliver optimised antimicrobial chemotherapy to individual critically ill patients. Delivery of β-lactams antimicrobial agents by infusions, rather than bolus dosing, is effective at increasing the duration of the dosing interval that the drug concentration is above the MIC. Therapeutic drug monitoring, utilising population PK mathematical models with Bayesian estimation, can also be used to optimise regimens following measurement of plasma drug concentrations. Clinical trials are required to establish if patient outcomes can be improved by implementing these techniques.

Simultaneous determination of seven β-lactam antibiotics in human plasma for therapeutic drug monitoring and pharmacokinetic studies

There is strong evidence in literature supporting the benefit of monitoring plasma concentrations of β-lactam antibiotics in the critically ill to ensure appropriateness of dosing. The objective of this work was to develop a method for the simultaneous determination of total concentrations piperacillin, benzylpenicillin, flucloxacillin, meropenem, ertapenem, cephazolin and ceftazidime in human plasma. Sample preparation involved protein precipitation with acetonitrile containing 0.1% formic acid and subsequent dilution of supernatant with 0.1% formic acid in water. Chromatographic separation was achieved on a reversed phase column (C18, 2.6 μm, 2.1 × 50 mm) via gradient elution using water and acetonitrile, each containing 0.1% formic acid, as mobile phase. Tandem mass spectrometry (MSMS) analysis was performed, after electrospray ionization in the positive mode, with multiple reaction monitoring (MRM). The method is accurate with the inter-day and intra-day accuracies of quality control samples (QCs) ranging from 95 to 107% and 95 to 108%, respectively. It is also precise with intra-day and inter-day coefficient of variations ranging from 4 to 12% and 5 to 14%, respectively. The lower limit of quantification was 0.1 μg/mL for each antibiotic except flucloxacillin (0.25 μg/mL). Recovery was greater than 96% for all analytes except for ertapenem (78%). Coefficients of variation for the matrix effect were less than 10% over the six batches of plasma. Analytes were stable over three freeze-thaw cycles, and for reasonable hours on the bench top as well as post-preparation. This novel liquid chromatography tandem mass spectrometry method proved accurate, precise and applicable for therapeutic drug monitoring and pharmacokinetic studies of the selected β-lactam antibiotics.

Assessment of pharmacokinetic changes of meropenem during therapy in septic critically ill patients

Background

Meropenem is a carbapenem antibiotic commonly used in critically ill patients to treat severe infections. The available pharmacokinetic (PK) data has been mostly obtained from healthy volunteers as well as from clinical studies addressing selected populations, often excluding the elderly and also patients with renal failure. Our aim was to study PK of meropenem in a broader population of septic critically ill patients.

Methods

We characterized the PK of meropenem in 15 critically ill patients during the first 36 hrs of therapy. Aditionally, whenever possible, we collected a second set of late plasma samples after 5 days of therapy to evaluate PK intra-patient variability and its correlation with clinical course.

Patients received meropenem (1 g every 8 hrs IV). Drug plasma profiles were determined by high-performance liquid chromatography. The PK of meropenem was characterized and compared with clinical parameters.

Results

Fifteen septic critically ill patients (8 male, median age 73 yrs) were included. The geometric mean of the volume of distribution at the steady state (V_ss)/weight was 0.20 (0.15-0.27) L/kg. No correlation of V_ss/weight with severity or comorbidity scores was found. However the Sequential Organ Failure Assessment score correlated with the V_ss/weight of the peripheral compartment (r² = 0.55, p = 0.021). The median meropenem clearance (Cl) was 73.3 (45–120) mL/min correlated with the creatinine (Cr) Cl (r² = 0.35, p = 0.033).

After 5 days (N = 7) although V_ss remained stable, a decrease in the proportion of the peripheral compartment (V_ss2) was found, from 61.3 (42.5-88.5)% to 51.7 (36.6-73.1)%. No drug accumulation was noted.

Conclusions

In this cohort of septic, unselected, critically ill patients, large meropenem PK heterogeneity was noted, although neither underdosing nor accumulation was found. However, Cr Cl correlated to meropenem Cl and the V_ss2 decreased with patient’s improvement.

The influence of acute kidney injury on antimicrobial dosing in critically ill patients: are dose reductions always necessary?

Optimal dosing of antimicrobial therapy is pivotal to increase the likelihood of survival in critically ill patients with sepsis. Drug exposure that maximizes bacterial killing, minimizes the development of antimicrobial resistance, and avoids concentration-related toxicities should be considered the target of therapy. However, antimicrobial dosing is problematic as pathophysiological factors inherent to sepsis that alter may result in reduced concentrations. Alternatively, sepsis may evolve to multiple-organ dysfunction including acute kidney injury (AKI). In this case, decreased clearance of renally cleared drugs is possible, which may lead to increased concentrations that may cause drug toxicities. Consequently, when dosing antibiotics in septic patients with AKI, one should consider factors that may lead to underdosing and overdosing. Drug-specific pharmacokinetic and pharmacodynamic data may be helpful to guide dosing in these circumstances. Yet, because of the high interpatient variability in pharmacokinetics of antibiotics during sepsis, this issue remains a significant challenge.

Therapeutic drug monitoring-based dose optimisation of piperacillin and meropenem: a randomised controlled trial

PURPOSE

There is variability in the pharmacokinetics (PK) of antibiotics (AB) in critically ill patients. Therapeutic drug monitoring (TDM) could overcome this variability and increase PK target attainment. The objective of this study was to analyse the effect of a dose-adaption strategy based on daily TDM on target attainment.

METHODS

This was a prospective, partially blinded, and randomised controlled trial in patients with normal kidney function treated with meropenem (MEM) or piperacillin/tazobactam (PTZ). The intervention group underwent daily TDM, with dose adjustment when necessary. The predefined PK/pharmacodynamic (PK/PD) target was 100% fT>4MIC [percentage of time during a dosing interval that the free (f) drug concentration exceeded 4 times the MIC]. The control group received conventional treatment. The primary endpoint was the proportion of patients that reached 100% fT>4MIC and 100 % fT>MIC at 72 h.

RESULTS

Forty-one patients (median age 56 years) were included in the study. Pneumonia was the primary infectious diagnosis. At baseline, 100% fT>4MIC was achieved in 21% of the PTZ patients and in none of the MEM patients; 100% fT>MIC was achieved in 71% of the PTZ patients and 46 % of the MEM patients. Of the patients in the intervention group, 76 % needed dose adaptation, and five required an additional increase. At 72 h, target attainment rates for 100% fT>4MIC and 100% fT>MIC were higher in the intervention group: 58 vs. 16%, p = 0.007 and 95 vs. 68%, p = 0.045, respectively.

CONCLUSIONS

Among critically ill patients with normal kidney function, a strategy of dose adaptation based on daily TDM led to an increase in PK/PD target attainment compared to conventional dosing.

Clinical pharmacodynamics of antipseudomonal cephalosporins in patients with ventilator-associated pneumonia

Advanced-generation cephalosporins are frequently used for empirical coverage of ventilator-associated pneumonia (VAP) due to their activity against a broad spectrum of Gram-positive and Gram-negative aerobic bacteria, including Pseudomonas aeruginosa and Enterobacteriaceae. Providing optimal antibiotic exposure is essential to achieving successful response in patients with VAP. We evaluated exposures of two antipseudomonal cephalosporins, ceftazidime and cefepime, in patients with VAP due to Gram-negative bacilli to identify the pharmacodynamic parameter predictive of microbiological success. Population pharmacokinetic models were used to estimate individual free drug exposures. Pharmacodynamic indices were determined for each patient using the baseline Gram-negative bacilli with the highest drug MIC. Classification and regression tree analysis was utilized to partition exposure breakpoints, and multivariate logistic regression was conducted to identify predictors of microbiological success. A total of 73 patients (18 receiving ceftazidime therapy and 55 receiving cefepime therapy) were included. MICs ranged widely from 0.047 to 96 μg/ml. The microbiological success rate was 58.9%. Predictive breakpoints were identified for all pharmacodynamic parameters, including a serum fT>MIC greater than 53% (P=0.02). When controlling for APACHE II (odds ratio [OR], 1.01; 95% confidence interval, 0.93 to 1.09; P=0.85) and combination therapy (OR, 0.74; 95% confidence interval, 0.25 to 2.19; P=0.59), achieving a greater than 53% fT>MIC remained a significant predictor of success (OR, 10.3; 95% confidence interval, 1.1 to 92.3; P=0.04). In patients with VAP due to Gram-negative bacilli, serum exposure of greater than 53% fT>MIC was found to be a significant predictor of favorable microbiological response for antipseudomonal cephalosporins. These data are useful when determining dosing regimens for cephalosporin agents under development for pneumonia.

Prolonging β-lactam infusion: a review of the rationale and evidence, and guidance for implementation

Given the sparse antibiotic pipeline and the increasing prevalence of resistant organisms, efforts should be made to optimise the pharmacodynamic exposure of currently available agents. Prolonging the infusion duration is a strategy used to increase the percentage of the dosing interval that free drug concentrations remain above the minimum inhibitory concentration (fT>MIC), the pharmacodynamic efficacy driver for time-dependent antibiotics such as β-lactams. β-Lactams, the most commonly prescribed class of antibiotics owing to their efficacy and safety profile, have been the mainstay of therapy since the discovery of penicillin over 60 years ago. Mounting evidence, including the use of population pharmacokinetic modelling and Monte Carlo simulation, suggests that prolonging the infusion time of β-lactam antibiotics may have advantages over standard infusion techniques, including an enhanced probability of achieving requisite fT>MIC exposures, lower mortality and potentially reductions in infection/antibiotic-related costs. As a result of these favourable attributes, clinical practice guidelines support the use of prolonged-infusion β-lactams in the treatment of many severe infections. This article discusses the rationale and evidence for prolonging the infusion of β-lactam antibiotics and provides guidance for the implementation of a prolonged-infusion programme.

An alternate pathophysiologic paradigm of sepsis and septic shock: implications for optimizing antimicrobial therapy

The advent of modern antimicrobial therapy following the discovery of penicillin during the 1940s yielded remarkable improvements in case fatality rate of serious infections including septic shock. Since then, pathogens have continuously evolved under selective antimicrobial pressure resulting in a lack of significant improvement in clinical effectiveness in the antimicrobial therapy of septic shock despite ever more broad-spectrum and potent drugs. In addition, although substantial effort and money has been expended on the development novel non-antimicrobial therapies of sepsis in the past 30 years, clinical progress in this regard has been limited. This review explores the possibility that the current pathophysiologic paradigm of septic shock fails to appropriately consider the primacy of the microbial burden of infection as the primary driver of septic organ dysfunction. An alternate paradigm is offered that suggests that has substantial implications for optimizing antimicrobial therapy in septic shock. This model of disease progression suggests the key to significant improvement in the outcome of septic shock may lie, in great part, with improvements in delivery of existing antimicrobials and other anti-infectious strategies. Recognition of the role of delays in administration of antimicrobial therapy in the poor outcomes of septic shock is central to this effort. However, therapeutic strategies that improve the degree of antimicrobial cidality likely also have a crucial role.

Pharmacokinetic behavior presents drug therapy challenges

There are conditions that cause a substantial change in drug clearance to such a degree that how a specific drug is managed to optimize drug response and minimize drug toxicity presents a challenge. This review will focus on recent literature (within the past 5 years) that evaluates pathophysiologic and genetic conditions and drug interactions which can change drug clearance to the magnitude that response is affected. Situations discussed that cause an increase in drug clearance will include: augmented renal clearance in critically ill patients; ultrafast drug metabolism caused by gene duplication; and enzyme induction interactions caused by rifampin. Situations discussed that result in a reduction in clearance will include: multiple organ failure in critically ill, patients with non-functioning CYP2D6 and CYP2C8/9 alleles, and CYP3A4 drug interactions with erythromycin and clarithromycin. In each case evaluated clearance is changed to the magnitude such that managing drug therapy can be difficult.

Ceftazidime dosage recommendations in burn patients: from a population pharmacokinetic approach to clinical practice via Monte Carlo simulations

BACKGROUND

Ceftazidime dosage regimen recommendations based on pharmacokinetic/pharmacodynamic approaches are not available for burn patients.

OBJECTIVE

The goal of this study was to propose a continuous dosage regimen of ceftazidime in burn patients, taking into account different MICs and pharmacokinetic covariates.

METHODS

The population pharmacokinetic analysis was conducted by using software dedicated to the analysis of nonlinear mixed effects models. The population pharmacokinetic model was first developed and validated in 70 adult burn patients. Taking into account various MICs of pathogens, 3 Monte Carlo simulation trials were conducted by using target concentration intervals (10-100, 20-100, and 40-100 mg/L). The recommended dosages were defined as the minimum dose leading to the highest percentage of patients whose ceftazidime concentrations were included in the target interval.

RESULTS

Serum creatinine and age were identified as covariates of ceftazidime clearance. Age was also involved in volume of distribution. The simulations showed that a dose of 6 g/d did not allow achievement of the target interval in most patients. Regardless of dosage regimen, age, and serum creatinine, the mean percentage of patients reaching the 10- to 100-mg/L and the 20- to 100-mg/L target intervals were 99.4% (0.3%) and 96.1% (0.8%), respectively. For the 40- to 100-mg/L target interval, this percentage was only 76.4% (2.1%) (range, 65%-80%).

CONCLUSIONS

Age and serum creatinine level can be used at the bedside to determine the initial doses of ceftazidime. These Monte Carlo simulations highlight the need of a reappraisal of ceftazidime's use in burn patients. Doses between 3 and 16 g/d are proposed, taking into account the pathogens' MICs. However, for sepsis caused by a pathogen with an MIC ≥ 8 mg/L, an insufficient percentage of burn patients will reach the therapeutic target with the recommended dosages.

Can changes in renal function predict variations in β-lactam concentrations in septic patients?

This study investigated whether variations in creatinine clearance (CLCr) are correlated with changes in β-lactam concentrations or pharmacokinetics in septic patients. Data for 56 adult patients admitted to the ICU in whom routine therapeutic drug monitoring (TDM) of broad-spectrum β-lactams (ceftazidime, cefepime, piperacillin or meropenem) was performed were reviewed. Patients were included if they had at least two TDM during their ICU stay for the same antibiotic and were not concomitantly treated with any extracorporeal replacement therapy. Serum drug concentrations were measured by HPLC-UV. Antibiotic pharmacokinetics were calculated using a one-compartment model and the percentage of time spent above four times the MIC (%T>4×MIC) for Pseudomonas aeruginosa and the antibiotic clearance (ATB-CL) were obtained. CLCr was measured on the same day as the TDM using 24-h urine collection. The %T>4×MIC and ATB-CL were significantly correlated with CLCr at the first (r=-0.41, P=0.002; r=0.56, P<0.001, respectively) and second (r=-0.61, P<0.001; r=0.63, P<0.001, respectively) TDM. However, changes in ATB-CL were only weakly correlated with changes in CLCr (r=0.34, P=0.01). The proportion of patients with insufficient β-lactam concentrations at the first and second TDM were 39% and 30%, respectively, and increased proportionally to CLCr. Although CLCr was significantly correlated with concentrations and clearance of broad-spectrum β-lactams, changes in CLCr did not reliably predict variations in drug pharmacokinetics/pharmacodynamics. Routine TDM should be considered to adapt β-lactam doses in this setting.

The clinical relevance of plasma protein binding changes

Controversy reigns as to how protein binding changes alter the time course of unbound drug concentrations in patients. Given that the unbound concentration is responsible for drug efficacy and potential drug toxicity, this area is of significant interest to clinicians and academics worldwide. The present uncertainty means that many questions relating to this area exist, including "How important is protein binding?", "Is protein binding always constant?", "Do pH and temperature changes alter binding?" and "How do protein binding changes affect dosing requirements?". In this paper, we seek to address these questions and consider the data associated with altered pharmacokinetics in the presence of changes in protein binding and the clinical consequences that these may have on therapy, using examples from the critical care area. The published literature consistently indicates that a change in the protein binding and unbound concentrations of some drugs are common in certain specific patient groups such as the critically ill. Changes in pharmacokinetic parameters, including clearance and apparent volume of distribution (V(d)), may be dramatic. Drugs with high protein binding, high intrinsic clearance (e.g. clearance by glomerular filtration) and where dosing is not titrated to effect are most likely to be affected in a clinical context. Drugs such as highly protein bound antibacterials with multiple half-lives within a dosing interval and that have some level of renal clearance, such as ertapenem, teicoplanin, ceftriaxone and flucloxacillin, are commonly affected. In response to these challenges, clinicians need to adapt dosing regimens rationally based on the pharmacokinetic/pharmacodynamic characteristics of the drug. We propose that further pharmacokinetic modelling-based research is required to enable the design of robust dosing regimens for drugs affected by altered protein binding.

Augmented renal clearance is a common finding with worse clinical outcome in critically ill patients receiving antimicrobial therapy

INTRODUCTION

We describe incidence and patient factors associated with augmented renal clearance (ARC) in adult intensive care unit (ICU) patients.

MATERIALS AND METHODS

A prospective observational study in a mixed cohort of surgical and medical ICU patients receiving antimicrobial therapy at the Ghent University Hospital, Belgium. Kidney function was assessed by the 24-hour creatinine clearance (Ccr); ARC defined as at least one Ccr of >130 mL/min per 1.73 m2. Multivariate logistic regression analysis: to assess variables associated with ARC occurrence. Therapeutic failure (TF): an impaired clinical response and need for alternate antimicrobial therapy.

RESULTS

Of the 128 patients and 599 studied treatment days, ARC was present in 51.6% of the patients. Twelve percent permanently expressed ARC. ARC patients had a median Ccr of 144 mL/min per 1.73 m2 (IQR 98-196). Median serum creatinine concentration on the first day of ARC was 0.54 mg/dL (IQR 0.48-0.69). Patients with ARC were significantly younger (P<.001). Age and male gender were independently associated with ARC whereas the APACHE II score was not. ARC patients had more TF (18 (27.3%) vs. 8 (12.9%); P=.04).

CONCLUSION

ARC was documented in approximately 52% of a mixed ICU patient population receiving antibiotic treatment with worse clinical outcome. Young age and male gender were independently associated with ARC presence.

Meropenem and piperacillin/tazobactam prescribing in critically ill patients: does augmented renal clearance affect pharmacokinetic/pharmacodynamic target attainment when extended infusions are used?

Background

Correct antibiotic dosing remains a challenge for the clinician. The aim of this study was to assess the influence of augmented renal clearance on pharmacokinetic/pharmacodynamic target attainment in critically ill patients receiving meropenem or piperacillin/tazobactam, administered as an extended infusion.

Methods

This was a prospective, observational, pharmacokinetic study executed at the medical and surgical intensive care unit at a large academic medical center. Elegible patients were adult patients without renal dysfunction receiving meropenem or piperacillin/tazobactam as an extended infusion. Serial blood samples were collected to describe the antibiotic pharmacokinetics. Urine samples were taken from a 24-hour collection to measure creatinine clearance. Relevant data were drawn from the electronic patient file and the intensive care information system.

Results

We obtained data from 61 patients and observed extensive pharmacokinetic variability. Forty-eight percent of the patients did not achieve the desired pharmacokinetic/pharmacodynamic target (100% fT_>MIC), of which almost 80% had a measured creatinine clearance >130 mL/min. Multivariate logistic regression demonstrated that high creatinine clearance was an independent predictor of not achieving the pharmacokinetic/pharmacodynamic target. Seven out of nineteen patients (37%) displaying a creatinine clearance >130 mL/min did not achieve the minimum pharmacokinetic/pharmacodynamic target of 50% fT_>MIC.

Conclusions

In this large patient cohort, we observed significant variability in pharmacokinetic/pharmacodynamic target attainment in critically ill patients. A large proportion of the patients without renal dysfunction, most of whom displayed a creatinine clearance >130 mL/min, did not achieve the desired pharmacokinetic/pharmacodynamic target, even with the use of alternative administration methods. Consequently, these patients may be at risk for treatment failure without dose up-titration.

Prognostic value of serum paraoxonase and arylesterase activity in patients with sepsis

Objective

To determine whether serum paraoxonase (PON) and arylesterase (ARE) activity might predict sepsis mortality.

Methods

Patients with sepsis and healthy control subjects were enrolled in this retrospective study. Serum PON and ARE activity levels were measured. Patients were stratified according to 30-day mortality rates.

Results

Serum PON and ARE activity levels were significantly lower in patients with sepsis ( n = 61) than in healthy controls ( n = 32), and were significantly lower in nonsurviving patients ( n = 22) than in surviving patients ( n = 39). Low PON and ARE activity levels were significantly correlated with poor overall survival in patients with sepsis.

Conclusions

Decreased serum PON and ARE activity is related to poor prognosis in patients with sepsis. Measuring the activity of PON and ARE may represent a new method for evaluating the prognosis of sepsis. In addition, both PON and ARE are potential molecular treatment targets for sepsis.

Infusional β-lactam antibiotics in febrile neutropenia: has the time come?

PURPOSE OF REVIEW

Febrile neutropenia presents a clinical challenge in which timely and appropriate antibiotic exposure is crucial. In the context of altered pharmacokinetics and rising bacterial resistance, standard antibiotic doses are unlikely to be sufficient. This review explores the potential utility of altered dosing approaches of β-lactam antibiotics to optimize treatment in febrile neutropenia.

RECENT FINDINGS

There is a dynamic relationship between the antibiotic, the infecting pathogen, and the host. Great advancements have been made in the understanding of the pharmacokinetic changes in critical illness and the pharmacodynamic relationships of antibiotics in these settings.

SUMMARY

Antibiotic treatment in febrile neutropenia is becoming increasingly difficult. Patients are of higher acuity, receive more intensive chemotherapy regimens leading to prolonged neutropenia, and are often exposed to multiple antibiotic courses. These patients display significant variability in antibiotic clearances and increases in volume of distribution compared with standard ward-based patients. Rising antibiotic resistance and a lack of new antibiotics in production have prompted alternative dosing strategies based on pharmacokinetic/pharmacodynamic data, such as extended or continuous infusions of β-lactam antibiotics, to maximize the likelihood of treatment success. A definitive study that describes a mortality benefit of such dosing regimens remains elusive and the theoretical advantages require testing in well designed clinical trials.

β-lactam pharmacokinetics and pharmacodynamics in critically ill patients and strategies for dose optimization: a structured review

1. Infections and related sepsis are two of the most prevalent issues in the care of critically ill patients, with mortality as high as 70%. Appropriate antibiotic selection, as well as adequate dosing, is important to improve the clinical outcome for these patients. 2. β-Lactams are the most common antibiotic class used in critically ill sepsis patients because of their broad spectrum of activity and high tolerability. β-Lactams exhibit time-dependent antibacterial activity. Therefore, concentrations need to be maintained above the minimum inhibitory concentration (MIC) of pathogenic bacteria. β-Lactams are hydrophilic antibiotics with small distribution volumes similar to extracellular water and are predominantly excreted through the renal system. 3. Critically ill patients experience a myriad of physiological changes that result in changes in the pharmacokinetics (PK) of hydrophilic drugs such as β-lactams. A different approach to dosing with β-lactams may increase the likelihood of positive outcomes considering the pharmacodynamics (PD) of β-lactams, as well as the changes in PK in critically ill patients. 4. The present review describes the strategies for dose optimization of β-lactams in critically ill patients in line with the PK and PD of these drugs.

Risk factors for a low linezolid trough plasma concentration in acute infections

Linezolid is an antibiotic with time-dependent activity, and both the percentage of time that plasma concentrations exceed the MIC and the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC24/MIC ratio) are associated with clinical response. The aim of this study was to analyze the linezolid trough plasma concentration (C(min)) and to determine factors associated with a C(min) < 2 mg/liter and other clinically relevant thresholds. Characteristics of 78 patients receiving 600 mg/12 h of linezolid with a C(min) determination at the steady state and within the first 10 days of treatment were retrospectively reviewed. Concentrations were measured using high-pressure liquid chromatography. Univariate and multivariate analysis were performed to identify risk factors of low C(min). A total of 29.5% of patients had a C(min) < 2 mg/liter. The percentage was significantly higher in patients with an estimated glomerular filtration (eGF) > 80 ml/min, in intensive care unit (ICU) patients, and in patients with an infection due to Staphylococcus aureus. The independent predictors of C(min) < 2 mg/liter were an eGF > 80 ml/min (odds ratio [OR], 10; 95% confidence interval [CI], 2.732 to 37.037; P = 0.001) and infection due to S. aureus (OR, 5.906; 95% CI, 1.651 to 21.126; P = 0.006). A linezolid C(min) of <2 mg/liter was found in 29.5% of cases, and the risk was significantly higher among those with an eGF > 80 ml/min and in infections due to S. aureus. In patients with severe sepsis, a loading dose or continuous infusion and drug monitoring could improve the pharmacodynamic parameters associated with linezolid efficacy.

Prolonged infusion antibiotics for suspected gram-negative infections in the ICU: a before-after study

BACKGROUND

ß-Lactam antibiotics demonstrate time-dependent killing. Prolonged infusion of these agents is commonly performed to optimize the time the unbound concentration of an antibiotic remains greater than the minimum inhibitory concentration and decrease costs, despite limited evidence suggesting improved clinical results.

OBJECTIVE

To determine whether prolonged infusion of ß-lactam antibiotics improves outcomes in critically ill patients with suspected gram-negative infection.

METHODS

We conducted a single-center, before-after, comparative effectiveness trial between January 2010 and January 2011 in the intensive care units at Barnes-Jewish Hospital, an urban teaching hospital affiliated with the Washington University School of Medicine in St. Louis, MO. Outcomes were compared between patients who received standardized dosing of meropenem, piperacillin-tazobactam, or cefepime as an intermittent infusion over 30 minutes (January 1, 2010, to June 30, 2010) and patients who received prolonged infusion over 3 hours (August 1, 2010, to January 31, 2011).

RESULTS

A total of 503 patients (intermittent infusion, n = 242; prolonged infusion, n = 261) treated for gram-negative infection were included in the clinically evaluable population. Approximately 50% of patients in each group received cefepime and 20% received piperacillin-tazobactam. More patients in the intermittent infusion group received meropenem (35.5% vs 24.5%; p = 0.007). Baseline characteristics were similar between groups, with the exception of a greater occurrence of chronic obstructive pulmonary disease (COPD) in the intermittent infusion group. Treatment success rates in the clinically evaluable group were 56.6% for intermittent infusion and 51.0% for prolonged infusion (p = 0.204), and in the microbiologically evaluable population, 55.2% for intermittent infusion and 49.5% for prolonged infusion (p = 0.486). Fourteen-day, 30-day, and inhospital mortality rates in the clinically evaluable population for the intermittent and prolonged infusion groups were 13.2% versus 18.0% (p = 0.141), 23.6% versus 25.7% (p = 0.582), and 19.4% versus 23.0% (p = 0.329).

CONCLUSIONS

Routine use of prolonged infusion of time-dependent antibiotics for the empiric treatment of gram-negative bacterial infections offers no advantage over intermittent infusion antibiotic therapy with regard to treatment success, mortality, or hospital length of stay. These results were confirmed after controlling for potential confounders in a multivariate analysis.

Dose modulation: a new concept of antibiotic therapy in the critically ill patient?

Considerable evidence has shown that adequate antibiotic therapy is of utmost importance in the critically ill septic patient. However, antibiotic concentration may be insufficient early in infection course. We propose the concept of dose modulation, meaning front-line variability of antibiotic dose, according to patient and microorganism characteristics, followed by its reduction after clinical response and patient recovery. Therefore, dose modulation means concentrating the largest weight of antibiotics at the front-end, when the microbial load is higher and the pharmacokinetic changes poses the highest risk of underdosing and nibbling off antibiotic dose, when the sepsis syndrome is improving, guided by pharmacokinetic and pharmacodynamic data.

2013 WSES guidelines for management of intra-abdominal infections

Despite advances in diagnosis, surgery, and antimicrobial therapy, mortality rates associated with complicated intra-abdominal infections remain exceedingly high.The 2013 update of the World Society of Emergency Surgery (WSES) guidelines for the management of intra-abdominal infections contains evidence-based recommendations for management of patients with intra-abdominal infections.

Molecular Adsorbent Recirculating System (MARS(®)) removal of piperacillin/tazobactam in a patient with acetaminophen-induced acute liver failure

The objective of this study was to illustrate the pharmacokinetic removal of piperacillin/tazobactam in an anuric patient on Molecular Adsorbent Recirculating System (MARS(®)). The patient was a 32-year-old woman who presented to a medical intensive care unit with acute liver failure secondary to an acetaminophen overdose. While awaiting transplant, she was started on MARS therapy as a bridge to liver transplant and empirically started on piperacillin/tazobactam therapy. MARS is an extracorporeal hemofiltration device, which incorporates a continuous venovenous hemofiltration (CVVHD) machine linked to an albumin-enriched dialysate filter to normalize excess electrolytes, metabolic waste, and protein-bound toxins. In addition to protein-bound waste, MARS removes water-soluble, low molecular-weight molecules. The patient received piperacillin/tazobactam 4.5 g infused intravenously over 3 h. A steep decline in serum levels occurred between hours 4 and 6 while MARS continued and no antibiotic was infused. The elimination rate constant (k(e)) for the removal of piperacillin in this patent was 0.453 h(-1) and the half-life (λ) was 1.53 h. The k(e) was 2.9-fold higher than with CVVHD alone and the λ was 3.7-fold shorter. Low levels of piperacillin are achieved during MARS therapy, but in the treatment of more resistant organisms, such as Pseudomonas aeruginosa, these low levels may not be adequate to achieve bactericidal activity. Drug levels following a standard infusion of 30 min would likely be even lower. Formalized pharmacokinetic studies of piperacillin/tazobactam removal in patients on MARS therapy are necessary to make clear dosing recommendations.

Continuous infusion of piperacillin/tazobactam in septic critically ill patients--a multicenter propensity matched analysis

The clinical efficacy of continuous infusion of piperacillin/tazobactam in critically ill patients with microbiologically documented infections is currently unknown. We conducted a retrospective multicenter cohort study in 7 Portuguese intensive care units (ICU). We included 569 critically ill adult patients with a documented infection and treated with piperacillin/tazobactam admitted to one of the participating ICU between 2006 and 2010. We successfully matched 173 pairs of patients according to whether they received continuous or conventional intermittent dosing of piperacillin/tazobactam, using a propensity score to adjust for confounding variables. The majority of patients received 16g/day of piperacillin plus 2g/day of tazobactam. The 28-day mortality rate was 28.3% in both groups (p = 1.0). The ICU and in-hospital mortality were also similar either in those receiving continuous infusion or intermittent dosing (23.7% vs. 20.2%, p = 0.512 and 41.6% vs. 40.5%, p = 0.913, respectively). In the subgroup of patients with a Simplified Acute Physiology Score (SAPS) II>42, the 28-day mortality rate was lower in the continuous infusion group (31.4% vs. 35.2%) although not reaching significance (p = 0.66). We concluded that the clinical efficacy of piperacillin/tazobactam in this heterogeneous group of critically ill patients infected with susceptible bacteria was independent of its mode of administration, either continuous infusion or intermittent dosing.

Case-control study of drug monitoring of β-lactams in obese critically ill patients

Severe sepsis and septic shock can alter the pharmacokinetics of broad-spectrum β-lactams (meropenem, ceftazidime/cefepime, and piperacillin-tazobactam), resulting in inappropriate serum concentrations. Obesity may further modify the pharmacokinetics of these agents. We reviewed our data on critically ill obese patients (body mass index of ≥ 30 kg/m(2)) treated with a broad-spectrum β-lactam in whom therapeutic drug monitoring was performed and compared the data to those obtained in critically nonobese patients (body mass index of <25 kg/m(2)) to assess whether there were differences in reaching optimal drug concentrations for the treatment of nosocomial infections. Sixty-eight serum levels were obtained from 49 obese patients. There was considerable variability in β-lactam serum concentrations (coefficient of variation of 50% to 92% for the three drugs). Standard drug regimens of β-lactams resulted in insufficient serum concentrations in 32% of the patients and overdosed concentrations in 25%. Continuous renal replacement therapy was identified by multivariable analysis as a risk factor for overdosage and a protective factor for insufficient β-lactam serum concentrations. The serum drug levels from the obese cohort were well matched for age, gender, renal function, and sequential organ failure assessment (SOFA) score to 68 serum levels measured in 59 nonobese patients. The only difference observed between the two cohorts was in the subgroup of patients treated with meropenem and who were not receiving continuous renal replacement therapy: serum concentrations were lower in the obese cohort. No differences were observed in pharmacokinetic variables between the two groups. Routine therapeutic drug monitoring of β-lactams should be continued in obese critically ill patients.

Pharmacodynamics of doripenem in critically ill patients with ventilator-associated Gram-negative bacilli pneumonia

Several pathophysiological changes in critically ill patients are important in determining the therapeutic success of β-lactam antibiotics. The aim of this study was to assess the population pharmacokinetics and probabilities of target attainment (PTAs) of doripenem in patients with ventilator-associated pneumonia, comparing administration by 1-h and 4-h infusion. Patients were randomised into two groups: Group I received a 1-h infusion of 0.5 g every 8 h (q8h) for seven doses; and Group II received a 4-h infusion of 0.5 g q8h for seven doses. A Monte Carlo simulation was performed to determine the PTAs. PTAs of achieving 40% T(>MIC) [exposure time during which the free drug concentration remains above the minimum inhibitory concentration (MIC)] and 75% T(>MIC) are required for effective bactericidal activity of this agent in immunocompetent and immunocompromised hosts, respectively. Values of volume of distribution and total clearance of doripenem in these patients were 17.26±1.83 L and 24.89±1.63 L/h, respectively. For pathogens with a MIC of 1 μg/mL, the PTAs of achieving 40% T(>MIC) following administration of doripenem by a 1-h and 4-h infusion of 0.5 g q8h were 92.95% and 98.32%, respectively. For pathogens with a MIC of 2 μg/mL in immunocompromised hosts, the PTAs of achieving 80% T(>MIC) following administration of doripenem by 1-h and 4-h infusion of 2 g q8h were 56.57% and 91.21%, respectively. In conclusion, these findings indicated that higher than recommended doses in this patient population, particularly neutropenic patients, would be necessary to optimise the pharmacokinetics of doripenem.

Quantification of seven β-lactam antibiotics and two β-lactamase inhibitors in human plasma using a validated UPLC-MS/MS method

There is an increasing interest in monitoring plasma concentrations of β-lactam antibiotics. The objective of this work was to develop and validate a rapid ultra-performance liquid chromatographic method with tandem mass spectrometric detection (UPLC-MS/MS) for simultaneous quantification of amoxicillin, ampicillin, cefuroxime, cefazolin, ceftazidime, meropenem, piperacillin, clavulanic acid and tazobactam. Sample clean-up included protein precipitation with acetonitrile and back-extraction of acetonitrile with dichloromethane. Six deuterated β-lactam antibiotics were used as internal standards. Chromatographic separation was performed on a Waters ACQUITY UPLC system using a BEH C(18) column (1.7 μm, 100 mm×2.1 mm) applying a binary gradient elution of water and acetonitrile both containing 0.1% formic acid. The total run time was 5.5 min. The developed method was validated in terms of precision, accuracy, linearity, matrix effect and recovery. The assay has now been successfully used to determine concentrations of amoxicillin/clavulanic acid, cefuroxime and meropenem in plasma samples from intensive care patients.

Does Beta-lactam Pharmacokinetic Variability in Critically Ill Patients Justify Therapeutic Drug Monitoring? A Systematic Review

The pharmacokinetics of beta-lactam antibiotics in intensive care patients may be profoundly altered due to the dynamic, unpredictable pathophysiological changes that occur in critical illness. For many drugs, significant increases in the volume of distribution and/or variability in drug clearance are common. When “standard” beta-lactam doses are used, such pharmacokinetic changes can result in subtherapeutic plasma concentrations, treatment failure, and the development of antibiotic resistance. Emerging data support the use of beta-lactam therapeutic drug monitoring (TDM) and individualized dosing to ensure the achievement of pharmacodynamic targets associated with rapid bacterial killing and optimal clinical outcomes. The purpose of this work was to describe the pharmacokinetic variability of beta-lactams in the critically ill and to discuss the potential utility of TDM to optimize antibiotic therapy through a structured literature review of all relevant publications between 1946 and October 2011. Only a few studies have reported the utility of TDM as a tool to improve beta-lactam dosing in critically ill patients. Moreover, there is little agreement between studies on the pharmacodynamic targets required to optimize antibiotic therapy. The impact of TDM on important clinical outcomes also remains to be established. Whereas TDM may be theoretically rational, clinical studies to assess utility in the clinical setting are urgently required.

Swedish guidelines on the management of community-acquired pneumonia in immunocompetent adults--Swedish Society of Infectious Diseases 2012

This document presents the 2012 evidence based guidelines of the Swedish Society of Infectious Diseases for the in- hospital management of adult immunocompetent patients with community-acquired pneumonia (CAP). The prognostic score 'CRB-65' is recommended for the initial assessment of all CAP patients, and should be regarded as an aid for decision-making concerning the level of care required, microbiological investigation, and antibiotic treatment. Due to the favourable antibiotic resistance situation in Sweden, an initial narrow-spectrum antibiotic treatment primarily directed at Streptococcus pneumoniae is recommended in most situations. The recommended treatment for patients with severe CAP (CRB-65 score 2) is penicillin G in most situations. In critically ill patients (CRB-65 score 3-4), combination therapy with cefotaxime/macrolide or penicillin G/fluoroquinolone is recommended. A thorough microbiological investigation should be undertaken in all patients, including blood cultures, respiratory tract sampling, and urine antigens, with the addition of extensive sampling for more uncommon respiratory pathogens in the case of severe disease. Recommended measures for the prevention of CAP include vaccination for influenza and pneumococci, as well as smoking cessation.

DALI: Defining Antibiotic Levels in Intensive care unit patients: a multi-centre point of prevalence study to determine whether contemporary antibiotic dosing for critically ill patients is therapeutic

Background

The clinical effects of varying pharmacokinetic exposures of antibiotics (antibacterials and antifungals) on outcome in infected critically ill patients are poorly described. A large-scale multi-centre study (DALI Study) is currently underway describing the clinical outcomes of patients achieving pre-defined antibiotic exposures. This report describes the protocol.

Methods

DALI will recruit over 500 patients administered a wide range of either beta-lactam or glycopeptide antibiotics or triazole or echinocandin antifungals in a pharmacokinetic point-prevalence study. It is anticipated that over 60 European intensive care units (ICUs) will participate. The primary aim will be to determine whether contemporary antibiotic dosing for critically ill patients achieves plasma concentrations associated with maximal activity. Secondary aims will compare antibiotic pharmacokinetic exposures with patient outcome and will describe the population pharmacokinetics of the antibiotics included. Various subgroup analyses will be conducted to determine patient groups that may be at risk of very low or very high concentrations of antibiotics.

Discussion

The DALI study should inform clinicians of the potential clinical advantages of achieving certain antibiotic pharmacokinetic exposures in infected critically ill patients.