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

Provider perspectives on beta-lactam therapeutic drug monitoring programs in the critically ill: a protocol for a multicenter mixed-methods study

Background

Beta-lactams (i.e., penicillins, cephalosporins, carbapenems, monobactams) are the most widely used class of antibiotics in critically ill patients. There is substantial interpatient variability in beta-lactam pharmacokinetics which renders their effectiveness and safety largely unpredictable. One strategy to ensure achievement of therapeutic concentrations is drug level testing (“therapeutic drug monitoring”; TDM). While studies have suggested promise with beta-lactam TDM, it is not yet widely available or implemented. This protocol presents a mixed-methods study designed to examine healthcare practitioners’ perspectives on the use and implementation of beta-lactam TDM in the critically ill.

Methods

An explanatory sequential mixed-methods design will be used [QUANT → qual]. First, quantitative data will be collected through a web-based questionnaire directed at clinicians at three academic medical centers at different phases of beta-lactam TDM implementation (not yet implemented, partially implemented, fully implemented). The sampling frame will include providers from a variety of disciplines that interact with drug level testing and interpretation in the critical care environment including pharmacists, intensivists, infectious diseases experts, medical/surgical trainees, and advanced practice providers. Second, approximately 30 individuals will be purposively sampled from survey respondents to conduct in-depth qualitative interviews to explain and expand upon the results from the quantitative strand. Normalization Process Theory and the Consolidated Framework for Implementation Science will be used to guide data analysis.

Discussion

These data will be used to answer two specific questions: “What are ICU practitioners’ perspectives on implementing beta-lactam TDM?” and “What factors contribute to the success of beta-lactam TDM program implementation?” Results of this study will be used to design future implementation strategies for beta-lactam TDM programs in the critically ill.

Trial registration

NCT04755777.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43058-021-00134-9.

The effect of delays in second-dose antibiotics on patients with severe sepsis and septic shock

BACKGROUND

Early antibiotics are fundamental to sepsis management. Second-dose antibiotic delays were associated with increased mortality in a recent study. Study objectives include: 1) determine factors associated with delays in second-dose antibiotic administration; 2) evaluate if delays influence clinical outcomes.

METHODS

ED-treated adults (≥18 years; n = 1075) with severe sepsis or septic shock receiving ≥2 doses of intravenous antibiotics were assessed, retrospectively, for second-dose antibiotic delays (dose time > 25% of recommended interval). Predictors of delay and impact on outcomes were determined, controlling for MEDS score, 30 mL/kg fluids and antibiotics within three hours of sepsis onset, lactate, and renal failure, among others.

RESULTS

In total, 335 (31.2%) patients had delayed second-dose antibiotics. A total of 1864 second-dose antibiotics were included, with 354 (19.0%) delays identified by interval (delayed/total doses): 6-h (36/67) = 53.7%; 8-h (165/544) = 30.3%; 12-h (114/436) = 26.1%; 24-h (21/190) = 8.2%; 48-h (0/16) = 0%. In-hospital mortality in the timely group was 15.5% (shock-17.6%) and 13.7% in the delayed group (shock-16.9%). Increased odds of delay were observed for ED boarding (OR 2.54, 95% 1.81-3.55), shorter dosing intervals (6/8-h- OR 2.99, 95% CI 1.95-4.57; 12-h- OR 2.46, 95% CI 1.72-3.51), receiving 30 mL/kg fluids by three hours (OR 1.42, 95% CI 1.06-1.90), and renal failure (OR 2.57, 95% CI 1.50-4.39). Delays were not associated with increased mortality (OR 0.87, 95% CI 0.58-1.29) or other outcomes.

CONCLUSIONS

Factors associated with delayed second-dose antibiotics include ED boarding, antibiotics requiring more frequent dosing, receiving 30 mL/kg fluid, and renal failure. Delays in second-dose administration were not associated with mortality or other outcomes.

Pharmacokinetics and Pharmacodynamics of High-Dose Piperacillin-Tazobactam in Obese Patients

Background and Objective

Standard piperacillin–tazobactam (P-T) dosing may be suboptimal in obesity, but high-dose regimens have not been studied. We prospectively evaluated the pharmacokinetics and pharmacodynamics of standard- and high-dose P-T in obese adult inpatients.

Methods

Those receiving standard-dose P-T with BMI ≥ 30 kg/m² weighing 105–139 kg or ≥ 140 kg were given up to 6.75 g or 9 g every 6 h, respectively. Patients were monitored closely for safety. Elimination phase blood samples were drawn for 28 patients on standard and high doses to calculate the pharmacokinetic values using a one-compartment model. The likelihood of pharmacodynamic target attainment (100% fT > 16/4 mg/L) on various P-T regimens was calculated using each patient’s own pharmacokinetic values.

Results

Piperacillin and tazobactam half-lives ranged from 0.5–10.6 to 0.9–15.0 h, while volumes of distribution ranged from 13.6–54.8 to 11.5–60.1 L, respectively. Predicted dose requirements for target attainment ranged from 2.25 g every 6 h in hemodialysis patients to a 27 g/24-h continuous infusion in a patient with a short P-T half-life. An amount of 4.5 g every 6 h would have met the target for only 1/12 (8%) patients with creatinine clearance ≥ 80 mL/min and 13/28 (46%) for all enrolled patients. One patient (3%) experienced an adverse event deemed probably related to high-dose P-T.

Conclusion

Some patients required high P-T doses for target attainment, but dosing requirements were highly variable. Doses up to 6.75 g or 9 g every 6 h may be tolerable; however, studies are needed to see if high dosing, prolonged infusions, or real-time therapeutic drug monitoring improves outcomes in obese patients.

Clinical trial registration (clinicaltrials.gov)

NCT01923363.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13318-021-00677-1.

Poor Correlation between Meropenem and Piperacillin Plasma Concentrations and Delivered Dose of Continuous Renal Replacement Therapy

There is insufficient data on the relationship between antibiotic dosing and plasma concentrations in patients treated with continuous renal replacement therapy (CRRT). In this prospective observational study, we explored the variability in plasma concentrations of meropenem and piperacillin in critically ill patients treated with CRRT and the correlation between concentrations and CRRT intensity. Antibiotic concentrations were measured at the middle and end of the dosing interval and repeated after 2 to 3 days when feasible. Measured concentrations were compared to the clinical susceptible breakpoints for Pseudomonas aeruginosa, 16 and 2 mg/liter for piperacillin and meropenem, respectively. CRRT intensity was estimated by delivered, time-averaged, total effluent flow (Q _eff), corrected for predilution. Concentrations were also compared between patients with different residual diuresis. We included 140 meropenem concentrations from 98 patients and 47 piperacillin concentrations from 37 patients. Concentrations at the middle of the dosing interval were above target at all occasions for both antibiotics. For meropenem, 6.5% of trough concentrations were below target, and for piperacillin, 22%. Correlations between Q _eff and antibiotic concentrations or the concentration half-life (t _1/2) were either statistically not significant or weak. Meropenem concentrations and t _1/2 values differed between patients with different residual diuresis. Thus, when treating intensive care patients with CRRT and recommended doses of meropenem or piperacillin, both low, suboptimal plasma concentrations and unnecessarily high, potentially toxic, plasma concentrations are common. Plasma concentrations cannot be predicted from CRRT intensity. Residual diuresis is associated with lower meropenem concentrations, but the correlation is weak. Concentration measurement is probably the most useful approach to avoid suboptimal treatment.

Antibiotic dosing adjustments in hospitalized patients with chronic kidney disease: a retrospective chart review

BACKGROUND

Infections in patients with chronic kidney disease (CKD) are a major cause of hospitalization. The pharmacokinetics of renally eliminated antibiotics may lead to drug accumulation, resulting in potential toxicity. The renal dosing adjustment of antibiotics is crucial to avoid toxicity and decrease mortality. In Lebanon, limited data are available on antibiotic dose adequacy in CKD.

OBJECTIVES

To estimate the prevalence of inappropriately dosed antibiotics in non-dialysis CKD patients and to identify possible risk factors that may be associated with unadjusted renal dosing.

METHODS

A retrospective chart review was conducted at two tertiary-care hospitals in Lebanon. International Statistical Classification of Diseases (ICD-10) code for CKD was used to search the databases. Demographic and clinical data were collected for patients who received antibiotics that requires renal dosing adjustment. Lexi-Comp online Drug Information database was the guideline used to evaluate the appropriateness of dosing.

RESULTS

A total of 495 antibiotic orders were dispensed to 190 patients. 51.6% of patients received antibiotics without renal dose adjustments. The most inappropriately dosed class was penicillins (39.8%), while fluoroquinolones were the most adequately adjusted. Piperacillin/tazobactam was the most frequently prescribed drug (30.6%) without renal dose adjustment. Respiratory infections (OR 1.301, CI 95% 1.327-1.915) and multimorbidity (OR 1.183, CI 95% 1.358-2.081) were statistically highly significant associations for unadjusted antibiotic dosing from the fitted multivariable-adjusted logistic models.

CONCLUSION

Our study revealed a high frequency of guideline-discordant antibiotic dosing in patients with CKD. This dosing error is preventable by increasing awareness of prescribing physicians and collaborating with clinical pharmacists.

Optimizing Pharmacokinetics-Pharmacodynamics of Antimicrobial Management in Patients with Sepsis: A Review

Critically ill patients with sepsis or septic shock are at an increased risk of death. Early and aggressive interventions are essential for improving clinical outcomes. There are a number of therapeutic and practical challenges in the management of antimicrobials in patients with sepsis. These include the timely selection and administration of appropriate antimicrobials, significant physiological alterations that can influence antimicrobial pharmacokinetics, and significant interpatient variability of antimicrobial concentrations using standard dosing approaches. Understanding the impact of these factors on the probability of attaining pharmacokinetic-pharmacodynamic target goals is essential to guide optimal therapy. Using rapid diagnostic technology could facilitate timely selection of antimicrobials, and therapeutic drug monitoring would provide a more individualized dosing approach. Using an interdisciplinary sepsis team would also be beneficial in coordinating efforts to overcome the challenges encountered during this critical period to ensure optimal care.

Could simulation methods solve the curse of sparse data within clinical studies of antibiotic resistance?

Infectious disease (ID) physicians and ID pharmacists commonly confront therapeutic questions relating to antibiotic resistance. Randomized controlled trial data are few and meta-analytic-based approaches to develop the evidence-base from several small studies that might relate to an antibiotic resistance question are not simple. The overriding challenge is the sparsity of data which is problematic for traditional frequentist methods, being the paradigm underlying the derivation of ‘P value’ inferential statistics. In other sparse data contexts, simulation methods enable answers to key questions that are meaningful, quantitative and potentially relevant. How these simulation methods ‘work’ and how Bayesian-based methods, being not ‘P value based’, can facilitate simulation are reviewed. These methods are becoming increasingly accessible. This review highlights why sparse data is less of an issue within Bayesian versus frequentist paradigms. A fictional pharmacokinetic study with sparse data illustrates a simplistic application of Bayesian and simulation methods to antibiotic dosing. Whether within epidemiological projections or clinical studies, simulation methods are likely to play an increasing role in antimicrobial resistance research within both hospital and community studies of either rare infectious disease or infections within specific population groups.

Rationality of Time-Dependent Antimicrobial Use in Intensive Care Units in China: A Nationwide Cross-Sectional Survey

Background: Extended/continuous infusion and therapeutic drug monitoring (TDM) of time-dependent antimicrobials are recommended for optimizing drug exposure for patients in intensive care units (ICUs), although practical application of these measures remains uncertain. We surveyed current practices in infusion and monitoring of commonly prescribed time-dependent antimicrobials in ICUs across China.

Methods: From December 2019 to January 2020, we sent online questionnaires about various aspects of infusion and monitoring of time-dependent antimicrobials to intensivists across China. Responses from clinicians were matched with their professional titles using the Sankey diagram. Univariate and multivariate logistic regression analyses were performed to find factors associated with TDM.

Results: A total of 3,687 ICU specialists from 31 provincial administrative regions of China responded to our questionnaires. Antibiotic stewardship (ABS) teams were available in hospitals as reported by 3,243 (88.0%) intensivists, including 1,308 (35.5%) who were ABS team members. Although most intensivists (3,490, 94.7%) were acquainted with the concept of prolonged/continuous infusion, nearly half of them (1,634, 44.3%) commonly administered β-lactam antibiotics intermittently. Nearly two-thirds of the respondents reported that their hospitals could not perform TDM. Our multivariable logistic regression analysis revealed that at the hospital level, knowledge of drug sample timing and attitude toward monitoring treatment effects, and drug trough or peak concentration influenced the decision to conduct TDM.

Conclusions: We found great variability in prescribing practices, from drug administration to TDM, for several time-dependent antibiotics commonly used for patients with severe infections. Further studies are necessary to effectively evaluate strategies to promote consistent prescribing behavior.

A sensitive and high-throughput quantitative liquid chromatography high-resolution mass spectrometry method for therapeutic drug monitoring of 10 β-lactam antibiotics, linezolid and two β-lactamase inhibitors in human plasma

An ultra-high pressure liquid chromatography high-resolution mass spectrometric (UHPLC-HRMS) method was developed for the simultaneous and sensitive quantification of 10 β-lactam antibiotics (cefepime, meropenem, amoxicillin, cefazolin, benzylpenicillin, ceftazidime, piperacillin, flucloxacillin, cefuroxime and aztreonam), linezolid and β-lactamase inhibitors tazobactam and clavulanic acid in human plasma. Validation according to the EMA guidelines showed excellent within- and between-run accuracy and precision (i.e. between 1.1 and 8.5%) and high sensitivity (i.e. lower limit of quantification between 0.25 and 1 mg/L). The UHPLC-HRMS method enables a short turnaround time and high sensitivity and needs only a small amount of plasma, allowing appropriate routine therapeutic drug monitoring. The short turnaround time is obtained by speeding up the protocol on multiple levels, i.e. fast and workload-efficient sample preparation (i.e. protein precipitation and dilution), short (4 min) instrument run time, simultaneous measurement of all relevant β-lactam antibiotics used in the intensive care unit and the use of the same instrument, column and mobile phases as for the other routine methods in our laboratory.

Extended Infusion of Beta-Lactams Is Associated With Improved Outcomes in Pediatric Patients

OBJECTIVE

The pharmacokinetics of beta-lactam antibiotics favor administration via an extended infusion. Although literature supporting extended infusion beta-lactams exists in adults, few data are available to guide the practice in pediatrics. The purpose of this study was to compare clinical outcomes between extended and standard infusions in children.

METHODS

This retrospective chart analysis included hospitalized patients 0 to 18 years old who received at least 72 hours of cefepime, piperacillin-tazobactam, or meropenem between October 1, 2017, and March 31, 2019. Clinical outcomes of care included hospital length of stay, readmission within 30 days, and all-cause mortality.

RESULTS

A total of 551 patients (258 extended infusion, 293 standard infusion) met criteria for evaluation. Clinical outcomes among the entire population were similar. A subanalysis of select populations demonstrated decreased mortality in critical care patients (2.1% vs 19.6%, p = 0.006) and decreased 30-day readmission rates in bone marrow transplant patients (0% vs 50%, p = 0.012) who received the extended infusion compared with a standard infusion.

CONCLUSIONS

Outcomes were similar between extended and standard infusions in children. Subgroup analyses suggest a possible mortality benefit in the critically ill and decreased readmission rate in bone marrow transplant patients.

A guide to therapeutic drug monitoring of β-lactam antibiotics

Therapeutic drug monitoring (TDM) opens the door to personalized medicine, yet it is infrequently applied to β-lactam antibiotics, one of the most commonly prescribed drug classes in the hospital setting. As we continue to understand more about β-lactam pharmacodynamics (PD) and wide inter- and intra-patient variability in pharmacokinetics (PK), the utility of TDM has become increasingly apparent. For β-lactams, the time that free concentrations remain above the minimum inhibitory concentration (MIC) as a function of the dosing interval (%fT>MIC) has been shown to best predict antibacterial effect. Many studies have shown that β-lactam %fT>MIC exposures are often suboptimal across a wide variety of disease states and clinical settings. A limitation to implementing this practice is the general lack of understanding on how to best operationalize this intervention and interpret the results. The instrumentation and expertise needed to quantify β-lactams for TDM is rarely available locally, but certain laboratories advertise these services and perform them regularly. Familiarity with the modalities and nuances of antimicrobial susceptibility testing is crucial to establishing β-lactam concentration targets that meet the relevant exposure thresholds. Evaluation of these concentrations is best accomplished using population PK software and Bayesian modeling, for which a multitude of programs are available. While TDM of β-lactams has shown an ability to increase the rate of target attainment, there is currently limited evidence to suggest that it leads to improved clinical outcomes. Although consensus guidelines for β-lactam TDM do not exist in the United States, guidance would help to promote this important practice and better standardize the approach across institutions. Herein, we discuss the basis for β-lactam TDM, review supporting evidence, and provide guidance for implementation in specific patient populations.

Key Challenges in Providing Effective Antibiotic Therapy for Critically Ill Patients with Bacterial Sepsis and Septic Shock

Early initiation of effective antibiotic therapy is vitally important for saving the lives of critically ill patients with sepsis or septic shock. The susceptibility of the infecting pathogen and the ability of the selected dosage regimen to safely achieve the required antibiotic exposure need to be carefully considered to achieve a high probability of a successful outcome. Critically ill patients commonly experience substantial pathophysiological changes that impact the functions of various organs, including the kidneys. Many antibiotics are predominantly renally eliminated and thus renal function is a major determinant of the regimen needed to achieve the required antibiotic exposure. However, currently, there is a paucity of guidelines to inform antibiotic dosing in critically ill patients, including those with sepsis or septic shock. This paper briefly reviews methods that are commonly used in critically ill patients to provide a measure of renal function, and approaches that describe the relationship between the exposure to an antibiotic and its antibacterial effects. Two common conditions that very substantially complicate the use of antibiotics in critically ill patients with sepsis, unstable renal function, and augmented renal clearance, are considered in detail and their potential therapeutic implications are explored. Suggestions are provided on how treatment of bacterial infections in critically ill patients with sepsis might be improved. Of high potential are model-informed approaches that aim to individualize initial treatment regimens based on patient and bacterial characteristics, with refinement of regimens during treatment in response to monitoring antibiotic concentrations, responsive measures of renal function, and other important clinical data.

Carbapenem Therapeutic Drug Monitoring in Critically Ill Adult Patients and Clinical Outcomes: A Systematic Review with Meta-Analysis

Drug monitoring is one strategy of antibiotic stewardship to face antimicrobial resistance. This strategy could have a determinant role in critically ill patients treated with carbapenems to overcome pharmacokinetic variability, reduce the risk of subtherapeutic dosage or toxicity, and reduce the risks inherent to treatment. However, the effectiveness of therapeutic drug monitoring (TDM) is unknown. This paper aims to identify TDM effectiveness in critically ill patients treated with carbapenems. English and ClinicalTrials.gov databases were searched to identify relevant studies evaluating carbapenem TDM. Randomized controlled trials (RCTs) and comparative cohort studies were selected for inclusion if they compared carbapenem TDM to standard care in adult critically ill or sepsis/septic shock patients. The primary outcome was mortality. Secondary outcomes included morbidity, clinical cure, microbiological eradication, antimicrobial resistance, drug-related side effects, and achievement of target plasma concentrations. Overall, performing carbapenem TDM was not associated with a decrease in mortality. However, it could be evidence for a relationship with clinical cure as well as target attainment. Some studies found favorable outcomes related to clinical and microbiological responses, such as lower procalcitonin levels at the end of the monitored therapy compared to standard care. For the primary and secondary outcomes analyzed, strong evidence was not identified, which could be due to the size, risk of bias, and design of selected studies.

In-Water Antibiotic Dosing Practices on Pig Farms

Pigs reared on many farms are mass-medicated for short periods with antibiotics through their drinking water to control bacterial pathogen loads and, if a disease outbreak occurs, to treat pigs until clinical signs are eliminated. Farm managers are responsible for conducting in-water antibiotic dosing events, but little is known about their dosing practices. We surveyed managers of 25 medium to large single-site and multi-site pig farming enterprises across eastern and southern Australia, using a mixed methods approach (online questionnaire followed by a one-on-one semi-structured interview). We found wide variation in the antibiotics administered, the choice and use of dosing equipment, the methods for performing dosing calculations and preparing antibiotic stock solutions, the commencement time and duration of each daily dosing event, and the frequency of administration of metaphylaxis. Farm managers lacked data on pigs’ daily water usage patterns and wastage and the understanding of pharmacology and population pharmacometrics necessary to optimize in-water dosing calculations and regimens and control major sources of between-animal variability in systemic exposure of pigs to antibiotics. There is considerable scope to increase the effectiveness of in-water dosing and reduce antibiotic use (and cost) on pig farms by providing farm managers with measurement systems, technical guidelines, and training programs.

Meropenem use and therapeutic drug monitoring in clinical practice: a literature review

WHAT IS KNOWN AND OBJECTIVE

Meropenem, a carbapenem antibiotic, is widely prescribed for the treatment of life-threatening infections. The main parameter associated with its therapeutic success is the percentage of time that the levels remain above the minimum inhibitory concentration. Inadequate levels of meropenem can lead to therapeutic failure and increase the possibility of microbial resistance. The employment of strategies involving dose regimens and drug pharmacodynamics has become increasingly important to optimize therapies. In the present study, we conducted a review with the purpose of assembling information about the clinical use of meropenem and therapeutic drug monitoring.

METHODS

A literature review emphasizing the application of therapeutic drug monitoring (TDM) of meropenem in clinical practice has been done. To identify articles related to the topic, we performed a standardized search from January 21, 2020 to December 21, 2020, using specific descriptors in PubMed, Lilacs and Embase.

RESULTS AND DISCUSSION

In total, 35 studies were included in the review. The daily dose of meropenem commonly ranged from 3 to 6 g/day. Critically ill patients and those with impaired renal function appear to be the most suitable patients for the application of meropenem TDM, in order to guide therapy. We observed that most of the studies recommend TDM and that, in nine locations, the TDM of meropenem and of other beta-lactams is a routine practice. TDM data can help to maximize the clinical outcomes of the treatment with meropenem. It can also improve the patient care by providing suitable levels of meropenem, guiding the most appropriate dose regimens, which is the main parameter associated with therapeutic success.

WHAT IS NEW AND CONCLUSION

The findings from this review suggest that the therapeutic monitoring of meropenem can be beneficial, since it adjusts the treatment and aids clinical outcomes. It does so by indicating the appropriate dosage and preventing failure, toxicity and possible antimicrobial resistance. The multidisciplinary effort, basic knowledge and communication among the medical team are also essential.

An isotope-dilution LC-MS/MS method for the simultaneous quantification of meropenem and its open-ring metabolite in serum

BACKGROUND

Therapeutic drug monitoring (TDM) of beta-lactam antibiotics and, among them, especially meropenem gains importance in the field of laboratory medicine. Meropenem is known to be unstable, resulting in a degradation product with an open beta-lactam ring. For a more comprehensive TDM of meropenem, the aim was to develop a LC-MS/MS method for the simultaneous quantification of meropenem and its main degradation product, the open-ring metabolite (ORM).

METHODS

The method involves a protein precipitation followed by chromatographic separation using a formic acid-ammonium formate methanol gradient on a pentafluorophenyl column. Multiple reaction monitoring in the positive ion mode and stable isotope labeled internal standards were used for quantification. Validation was performed according to the European Medicines Agency guideline.

RESULTS

Validation was successful performed within the linear drug concentration range of 1.0-100.0 mg/l for meropenem and 0.62-62.30 mg/l for the ORM. Investigation of selectivity, accuracy and precision showed good results and potential matrix effects were successfully compensated by the internal standards. The suitability of the method was shown by the comparison of 35 anonymized leftover serum samples from intensive care patients with routine analyses.

CONCLUSION

For the first time, we herein describe a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of meropenem and its ORM in human serum. The ratio of active to inactive compound provides valuable pharmaceutical and pharmacokinetic information, which may contribute to therapeutic efficacy.

A narrative review of predictors for β-lactam antibiotic exposure during empirical treatment in critically ill patients

INTRODUCTION

: Emerging studies suggest that antibiotic pharmacokinetics (PK) are difficult to predict in critically ill patients. The high intra- and inter-patient PK variability makes it challenging to accurately predict the appropriate dosage required for a given patient. Identifying patients at risk could help clinicians to consider more individualized dosing regimens and perform therapeutic drug monitoring. We provide an overview of relevant predictors associated with target (non-)attainment of β-lactam antibiotics in critically ill patients.

AREAS COVERED

: This narrative review summarizes patient and clinical characteristics that can help to predict the attainment of target serum concentrations and to provide guidance on antimicrobial dose optimization. Literature was searched using Embase and Medline database, focusing on β-lactam antibiotics in critically ill patients.

EXPERT OPINION

: Adequate concentration attainment can be anticipated in critically ill patients prior to initiating empiric β-lactam antibiotic therapy based on readily available demographic and clinical factors. Male gender, younger age, and augmented renal clearance were the most significant predictors for target non-attainment and should be considered in further investigations to develop dosing algorithms for optimal β-lactam therapy.

Comparison of two empirical prolonged infusion dosing regimens for meropenem in patients with septic shock: A two-center pilot study

BACKGROUND

Due to high pharmacokinetic variability, standard doses of meropenem are frequently inadequate in septic patients. Therapeutic drug monitoring of meropenem is not widely available; therefore, improved empiric dosing recommendations are needed.

OBJECTIVES

This study aimed to compare the attainment of pharmacologic targets for two common empirical dosing regimens for meropenem in patients with septic shock.

METHODS

Two empiric dosing schemes for meropenem were compared using extended infusions (120 minutes) in 32 patients with septic shock in the intensive care units at two different hospitals. One regimen was 3 × 2 g meropenem/24 h for two days, followed by 3 × 1 g meropenem/24 h; the other regimen was 4 × 1 g meropenem/24 h. Serum meropenem concentrations were measured for the first 72 h of therapy, and pharmacokinetic modelling was performed to define the percentage of time the free drug concentration was above various target MICs for each regimen (%fT_>MIC).

RESULTS

Both regimens led to a sufficiently high %fT_>MIC for pathogens with target MICs < 4 mg/L. When higher MICs were targeted, the %fT_>MIC of 4 × 1 g meropenem decreased faster than that of 3 × 2 g meropenem. At high MICs of 32 mg/L, both dosing regimens failed to provide appropriate drug concentrations. Renal function was a significant covariate of target attainment.

CONCLUSIONS

The results of this study can guide clinicians in their choice of an empirical dosing regimen for meropenem. If pathogens with low MICs (< 4 mg/L) are targeted, both dosing regimens are adequate, whereas more resistant strains require higher doses.

Clinical and pharmacokinetic/dynamic outcomes of prolonged infusions of beta-lactam antimicrobials: An overview of systematic reviews

OBJECTIVE

This overview of reviews aims to map and compare of objectives, methods, and findings of existing systematic reviews to develop a greater understanding of the information available about prolonged beta-lactam infusions in hospitalized patients with infection.

DESIGN

Overview of systematic reviews.

DATA SOURCES

Medline, Embase, PROSPERO and the Cochrane Library were systematically searched from January, 1990 to June, 2019 using a peer reviewed search strategy. Grey literature was also searched for relevant reviews.

ELIGIBILITY CRITERIA FOR SELECTING REVIEWS

Systematic reviews were sought that compared two or more infusion strategies for intravenous beta-lactam antimicrobials and report clinical cure or mortality. Populations of included reviews were restricted to hospitalized patients with infection, without restrictions on age, infection type, or disease.

DATA EXTRACTION AND ANALYSIS

Abstract screening, data extraction, quality and risk of bias assessment were conducted by two independent reviewers. Overlap between reviews was assessed using a modified corrected covered area. Overview findings are reported in accordance with Cochrane's recommendation for overview conduct. Clinical outcomes extracted included survival, clinical cure, treatment failure, microbiological cure, length of stay, adverse events, cost, and emergence of resistance.

RESULTS

The search strategy identified 3327 unique citations from which 21 eligible reviews were included. Reviews varied by population, intervention and outcomes studied. Between reviews, overlap of primary studies was generally high, methodologic quality generally low and risk of bias variable. Nine of 14 reviews that quantitatively evaluated mortality and clinical cure identified a benefit with prolonged infusions of beta lactams when compared with intermittent infusions. Evidence of mortality and clinical cure benefit was greater among critically ill patients when compared to less sick patients and lower in randomized controlled trials when compared with observational studies.

CONCLUSIONS

Findings from our review demonstrate a consistent and reproducible lack of harm with prolonged infusions of beta-lactam antibiotics with variability in effect size and significance of benefits. Despite 21 systematic reviews addressing prolonged infusions of beta-lactams, this overview supports the continued need for a definitive systematic review given variability in populations, interventions and outcomes in the current systematic reviews. Subsequent systematic reviews should have more rigorous and transparent methods, only include RCTs and evaluate the proposed benefits found in various subgroup-analyses-i.e. high risk of mortality.

TRIAL REGISTRATION

Prospero registry, CRD42019117118.

Population Pharmacokinetics and Pharmacodynamics of Meropenem in Critically Ill Pediatric Patients

This study investigates the optimal meropenem (MEM) dosing regimen for critically ill pediatric patients, for which there is a lack of pharmacokinetic (PK) studies. We conducted a retrospective single-center PK and pharmacodynamic (PD) analysis of 34 pediatric intensive care unit patients who received MEM. Individual PK parameters were determined by a two-compartment analysis. The median (range) age and body weight were 1.4 (0.03 to 14.6) years and 8.9 (2.7 to 40.9) kg, respectively, and eight (23.5%) patients received continuous renal replacement therapy (CRRT), three of whom received extracorporeal membrane oxygenation. Renal function, the systemic inflammatory response syndrome (SIRS) score for the clearance (CL), and the use of CRRT for the central volume of distribution (V _c) were identified as significant covariates. The mean CL, V _c, and peripheral volume of distribution (V _p) were 0.45 liters/kg/h, 0.49 liters/kg, and 0.34 liters/kg, respectively. The mean population CL of MEM increased by 35% in patients with SIRS and V _c increased by 66% in patients on CRRT in the final model. Dosing simulations suggested that the standard dosing regimen provided insufficient PD exposures of a 100% free time above the MIC, and higher doses (40 to 80 mg/kg of body weight/dose every 8 h) with a prolonged 3-h infusion were required to ensure the appropriate PD exposures for patients with SIRS. Our PK model indicated that critically ill pediatric patients are at risk of subtherapeutic exposure under the standard dosing regimen of MEM. A larger, prospective investigation confirming the safety and efficacy of higher concentrations and prolonged infusion of MEM is necessary.

Safety considerations of current drug treatment strategies for nosocomial pneumonia

Introduction: Nosocomial pneumonia unfortunately remains a frequent event for which appropriate antibiotic treatment is central to improving outcomes. Physicians must choose an early and appropriate empirical treatment, basing their decision on the safety profile and possible side effects. Areas covered: In this review, we analyzed the safety profiles of the most common antimicrobials for treating nosocomial pneumonia. Beta-lactams are used most often for these infections, with a high percentage (6% to 25%) of patients reporting allergy or hypersensitivity reactions; however, exhaustive evaluation is key because it seems possible to de-label as many as 90% by proper assessment. Combinations including a beta-lactam are recommended in patients with risk factors for drug-resistant microorganisms and septic shock. Although aminoglycosides are safe for 3-5 days of therapy, renal function should be monitored. Fluoroquinolones must also be used with care given the risk of collagen degradation and cardiovascular events, mainly aneurysm or aortic dissection. Linezolid or vancomycin are both viable for the treatment of methicillin-resistant Staphylococcus aureus, but linezolid seems to be the superior option. Antibiotic stewardships programs must be developed for each center. Expert opinion: Choosing the most appropriate antimicrobial based on information from national and international guidelines, local microbiology data, and stewardship programs may reduce the use of broad-spectrum antibiotics. Daily assessment for the emergence of adverse events related to antimicrobial use is essential.

Clinical Effectiveness of a High Dose Versus the Standard Dose of Meropenem in Ventilator-associated Pneumonia Caused by Multidrugresistant Bacteria: A Randomized, Single-blind Clinical Trial

Meropenem standard doses are based on the minimum inhibitory concentration of sensitive pathogens and the pharmacokinetic parameter of not critically ill patients. We compared the efficacy of high versus standard dose of meropenem in ventilator-associated pneumonia (VAP). ; Methods: 24 out of 34 eligible patients were randomized to receive meropenem 3 g q8h (high dose group, 11 patients) or 2 g q8h (standard-dose group, 13 patients) as a 3h infusion. The primary outcome was considered as clinical success that was defined as stable hemodynamic, improved sequential organ failure assessment (SOFA) score, stable or improved PaO2/FiO2 after 7 days. Sputum culture was taken before the intervention. ; Results: Clinical success rate was not significantly different between the high and standard-dose group (54.5% vs. 38.5%, P= 0.431). There was a significant difference in the reduction of clinical pulmonary infection score (CPIS) compared to a high dose to the standard group (P=0.038). SOFA score declined significantly in the high dose group throughout the study (P=0.006). A shorter duration of VAP treatment was recorded in the high dose group (P=0.061). We did not observe any significant adverse event related to meropenem. Acinetobacter spp. (34.8%), Klebsiella spp. (32.6%) and Pseudomonas aeruginosa (19.5%) isolated more frequently from sputum cultures. ; Conclusion: Treatment with the high dose of meropenem seems to be safe. However, it did not provide a significantly higher clinical success rate in comparison with the standard dose, but could be considered as an appropriate empirical treatment in patients with severe infection due to reduction in SOFA and CPIS. ; The trial protocol was registered with IRCT.ir (registration number IRCT2010010700 3014N19 in April 2018).

Antimicrobial Stewardship in the Intensive Care Unit: The Role of Biomarkers, Pharmacokinetics, and Pharmacodynamics

The high prevalence of infectious diseases in the intensive care unit (ICU) and consequently elevated pressure for immediate and effective treatment have led to increased antimicrobial therapy consumption and misuse. Moreover, the emerging global threat of antimicrobial resistance and lack of novel antimicrobials justify the implementation of judicious antimicrobial stewardship programs (ASP) in the ICU. However, even though the importance of ASP is generally accepted, its implementation in the ICU is far from optimal and current evidence regarding strategies such as de-escalation remains controversial. The limitations of clinical guidance for antimicrobial therapy initiation and discontinuation have led to multiple studies for the evaluation of more objective tools, such as biomarkers as adjuncts for ASP. C-reactive protein and procalcitonin can be adequate for clinical use in acute infectious diseases, the latter being the most studied for ASP purposes. Although promising, current evidence highlights challenges in biomarker application and interpretation. Furthermore, the physiological alterations in the critically ill render pharmacokinetics and pharmacodynamics crucial parameters for adequate antimicrobial therapy use. Individual pharmacokinetic and pharmacodynamic targets can reduce antimicrobial therapy misuse and risk of antimicrobial resistance.

[Pharmacokinetic modifications and pharmacokinetic/pharmacodynamic optimization of beta-lactams in ICU]

Pharmacokinetic modifications in critically ill patients and those induced by ICU therapeutics raise a lot of issues about antibiotic dose adaptation. Beta-lactams are anti-infectious widely used in ICU. Frequent beta-lactam underdoses induce a risk of therapeutic failure potentially lethal and of emergence of bacterial resistance. Overdoses expose to a neurotoxic and nephrotoxic risk. Therefore, an understanding of pharmacokinetics modifications appears to be essential. A global pharmacokinetic/pharmacodynamic approach is required, including use of prolonged or continued beta-lactam infusions to optimise probability of pharmacokinetic/pharmacodynamic target attainment. Beta-lactam therapeutic drug monitoring should also be considered. Experts agree to target a free plasma betalactam concentration above four times the MIC of the causative bacteria for 100 % of the dosing interval. Bayesian methods could permit individualized doses adaptations.

Strategies for implementation of a multidisciplinary approach to the treatment of nosocomial infections in critically ill patients

INTRODUCTION

Intensive Care Units (ICU) are among the hospital wards exhibiting the highest prevalence of antimicrobial resistance (AMR), and resulting impact on patient outcomes. Antimicrobial resistance surveillance and antimicrobial stewardship (AMS) programs play a pivotal role in promoting interventions tailored to optimize infection diagnosis and treatment in the final attempt to limit unnecessary antimicrobial use and development of resistance.

AREAS COVERED

A narrative review of the literature was carried out to summarize the available evidence and develop a set of actions that should be considered for integration into the ICU stewardship framework. Four questions were addressed: how AMR surveillance can inform antibiotic policy in ICU; whether pharmacokinetic and pharmacodynamic (PK/PD) principles and the use of procalcitonin should be incorporated as a standard practice in ICU AMS programs to optimize antibiotic treatment and to drive antibiotic discontinuation; which criteria should drive treatment duration of ICU-associated infections.

EXPERT OPINION

In this review we aim to highlight that the ICU must be considered in its own right. Each ICU has its own characteristics depending on the country, on the local antibiotic resistance profile, on the patients feature and the severity of infection.

Does dose reduction of renally cleared antibiotics in patients with impaired renal function lead to adequate drug exposure? A systematic review

BACKGROUND

There is inconsistency between many guidelines in the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function.

OBJECTIVES

This systematic review summarizes the available evidence on the adequacy of the recommended dose reduction in terms of achieving sufficient antibiotic drug exposure or pharmacokinetic/pharmacodynamic target attainment after treatment with these reduced doses.

DATA SOURCES

We systematically searched Ovid Medline and Embase from inception (respectively 1946 and 1947) through July 2019.

STUDY ELIGIBILITY CRITERIA

All studies reporting antibiotic drug exposure and/or pharmacokinetic/pharmacodynamic (PK/PD) target attainment after dose reduction of antibiotics in patients with impaired renal function.

PARTICIPANTS

Adult patients with or without infections.

INTERVENTIONS

Administration of reduced doses of antibiotics (orally, intravenously or intramuscularly).

METHODS

The reduced dose was considered adequate when the most relevant parameters of drug exposure or PK/PD target attainment in patients with impaired renal function were within a range of 80% to 125% of that patients with adequate renal function receiving a regular dose (reference) or when PK/PD target attainment was attained in at least 90% of the patients with impaired renal function, regardless of the lack of a reference group.

RESULTS

Twenty-seven of the 4202 identified studies were included. The quality of 15 of 27 studies was fair, and most studies were of β-lactams (12/27). Best evidence was available for meropenem: four studies were included, of which two studies were of good quality. Drug exposure for meropenem is 158% to 286% higher in patients with impaired renal function receiving reduced doses compared to patients with adequate renal function receiving regular doses. For all other antibiotics, a maximum of one good-quality study could be identified.

CONCLUSIONS

No good-quality evidence on the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function is present, with the exception of meropenem.

Infection, Sepsis and the Inflammatory Response: Mechanisms and Therapy

Sepsis secondary to bacterial infection remains a significant cause of morbidity and mortality globally. Recent decades have seen the evolution of international collaborations to improve care for these patients and identify areas for research. In this article we discuss the pathophysiology underlying the condition, review the current recommended management strategies, discuss areas of controversy, and highlight the need for ongoing research, particularly in diagnostics.

Personalized antibiotic therapy – a rapid high performance liquid chromatography–tandem mass spectrometry method for the quantitation of eight antibiotics and voriconazole for patients in the intensive care unit

Objectives

For a long time, the therapeutic drug monitoring of anti-infectives (ATDM) was recommended only to avoid the toxic side effects of overdosing. During the last decade, however, this attitude has undergone a significant change. Insufficient antibiotic therapy may promote the occurrence of drug resistance; therefore, the “one-dose-fits-all” principle can no longer be classified as up to date. Patients in intensive care units (ICU), in particular, can benefit from individualized antibiotic therapies.

Methods

Presented here is a rapid and sufficient LC-MS/MS based assay for the analysis of eight antibiotics (ampicillin, cefepime, cefotaxime, ceftazidime, cefuroxime, linezolid, meropenem, and piperacillin) applicated by continuous infusion and voriconazole. In addition a dose adjustment procedure for individualized antibiotic therapy has been established.

Results

The suggested dose adjustments following the initial dosing of 121 patient samples from ICUs, were evaluated over a period of three months. Only a minor percentage of the serum levels were found to be within the target range while overdosing was often observed for β-lactam antibiotics, and linezolid tended to be often underused. The results demonstrate an appreciable potential for β-lactam savings while enabling optimal therapy.

Conclusions

The presented monitoring method provides high specificity and is very robust against various interferences. A fast and straightforward method, the developed routine ensures rapid turnaround time. Its application has been well received by participating ICUs and has led to an expanding number of hospital wards participating in ATDM.

Antibiotic therapeutic drug monitoring in intensive care patients treated with different modalities of extracorporeal membrane oxygenation (ECMO) and renal replacement therapy: a prospective, observational single-center study

BACKGROUND

Effective antimicrobial treatment is key to reduce mortality associated with bacterial sepsis in patients on intensive care units (ICUs). Dose adjustments are often necessary to account for pathophysiological changes or renal replacement therapy. Extracorporeal membrane oxygenation (ECMO) is increasingly being used for the treatment of respiratory and/or cardiac failure. However, it remains unclear whether dose adjustments are necessary to avoid subtherapeutic drug levels in septic patients on ECMO support. Here, we aimed to evaluate and comparatively assess serum concentrations of continuously applied antibiotics in intensive care patients being treated with and without ECMO.

METHODS

Between October 2018 and December 2019, we prospectively enrolled patients on a pneumological ICU in southwest Germany who received antibiotic treatment with piperacillin/tazobactam, ceftazidime, meropenem, or linezolid. All antibiotics were applied using continuous infusion, and therapeutic drug monitoring of serum concentrations (expressed as mg/L) was carried out using high-performance liquid chromatography. Target concentrations were defined as fourfold above the minimal inhibitory concentration (MIC) of susceptible bacterial isolates, according to EUCAST breakpoints.

RESULTS

The final cohort comprised 105 ICU patients, of whom 30 were treated with ECMO. ECMO patients were significantly younger (mean age: 47.7 vs. 61.2 years; p < 0.001), required renal replacement therapy more frequently (53.3% vs. 32.0%; p = 0.048) and had an elevated ICU mortality (60.0% vs. 22.7%; p < 0.001). Data on antibiotic serum concentrations derived from 112 measurements among ECMO and 186 measurements from non-ECMO patients showed significantly lower median serum concentrations for piperacillin (32.3 vs. 52.9; p = 0.029) and standard-dose meropenem (15.0 vs. 17.8; p = 0.020) in the ECMO group. We found high rates of insufficient antibiotic serum concentrations below the pre-specified MIC target among ECMO patients (piperacillin: 48% vs. 13% in non-ECMO; linezolid: 35% vs. 15% in non-ECMO), whereas no such difference was observed for ceftazidime and meropenem.

CONCLUSIONS

ECMO treatment was associated with significantly reduced serum concentrations of specific antibiotics. Future studies are needed to assess the pharmacokinetic characteristics of antibiotics in ICU patients on ECMO support.

The higher the better? Defining the optimal beta-lactam target for critically ill patients to reach infection resolution and improve outcome

OBJECTIVES

Beta-lactam antibiotics are often subject to therapeutic drug monitoring, but breakpoints of target attainment are mostly based on expert opinions. Studies that show a correlation between target attainment and infection resolution are missing. This analysis investigated whether there is a difference in infection resolution based on two breakpoints of target attainment.

METHODS

An outcome group out of 1392 critically ill patients treated with meropenem or piperacillin-tazobactam was formed due to different selection criteria. Afterwards, three groups were created: group 1=free drug concentration (f) was < 100% of the time (T) above the minimal inhibitory concentration (MIC) (< 100% fT > MIC), group 2=100% fT > MIC < 4xMIC, and group 3=100% fT > 4xMIC. Parameters for infection control, renal and liver function, and estimated and observed in-hospital mortality were compared between those groups. Statistical analysis was performed with one-way analysis of variance, Tukey post hoc test, U test, and bivariate logistic regression.

RESULTS

The outcome group consisted of 55 patients (groups 1-3, 17, 24, and 14 patients, respectively). Patients allocated to group 2 or 3 had a significantly faster reduction of the C-reactive protein in contrast to patients allocated to group 1 (p = 0.033 and p = 0.026). Patients allocated to group 3 had a worse renal function, a higher Acute Physiology and Chronic Health Evaluation (APACHE II) score, were older, and had a significantly higher in-hospital mortality compared to group 1 (p = 0.017) and group 2 (p = 0.001). The higher mortality was significantly influenced by worse liver function, higher APACHE II, and higher Sequential Organ Failure Assessment (SOFA) score and norepinephrine therapy.

CONCLUSION

Achieving the target 100% fT > MIC leads to faster infection resolution in the critically ill. However, there was no benefit for patients who reached the highest target of 100% fT > 4xMIC, although the mortality rate was higher possibly due to confounding effects. In conclusion, we recommend the target 100% fT > MIC < 4xMIC for critically ill patients.

TRIAL REGISTRATION

NCT03985605.

Population pharmacokinetic evaluation of cefuroxime in perioperative antibiotic prophylaxis during and after cardiopulmonary bypass

AIMS

The purpose of this study was to explore pharmacokinetic and pharmacodynamic aspects of a contemporary dosing scheme of cefuroxime as perioperative prophylaxis in cardiac surgery using cardiopulmonary bypass (CPB).

METHODS

Cefuroxime plasma concentrations were measured in 23 patients. A 1.5-g dose of cefuroxime was administered at start of surgery and CPB, followed by 3 additional doses every 6 hours postoperative. Drug levels were used to build a population pharmacokinetic model. Target attainment for Staphylococcus aureus (2-8 mg/L) and Escherichia coli (8-32 mg/L) were evaluated and dosing strategies for optimization were investigated.

RESULTS

A dosing scheme of 1.5 g cefuroxime preoperatively with a repetition at start of CPB achieves plasma unbound concentrations of 8 mg/L in almost all patients during surgery. The second administration is critical to provide this level of coverage. Simulations indicate that higher unbound concentrations up to 32 mg/L are reached by a continuous infusion rate of 1 g/h after a bolus of 1 g. In the postoperative phase, most patients do not reach unbound concentrations above 2 mg/L. To improve target attainment up to 8 mg/L, the continuous application of cefuroxime with infusion rates of 0.125-0.25 g/h is simulated and shown to be an alternative to bolus dosing.

CONCLUSION

Dosing recommendations for cefuroxime as perioperative antibiotic prophylaxis in cardiac surgery are sufficient to reach plasma unbound concentration to cover S. aureus during the operation. Target attainment is not achieved in the postoperative period. Continuous infusion of cefuroxime may optimize target attainment.

Pharmacokinetic Model for Cefuroxime Dosing during Cardiac Surgery under Cardiopulmonary Bypass

Cefuroxime (CXM) is an antibiotic recommended for surgical site infection prevention in cardiac surgery. However, the dosing regimens commonly used do not sustain therapeutic concentrations throughout surgery. The aim of this study was to conduct a population analysis of CXM pharmacokinetics (PK), and to propose an optimized dosing regimen. Adult patients undergoing cardiac surgery under cardiopulmonary bypass (CPB) received a 1,500 mg CXM intravenous bolus followed by a 750 mg bolus at CPB priming, then every 2 h thereafter. Model-based PK simulations were used to develop an optimized dosing regimen and evaluate its efficacy in attaining various concentration thresholds, including those recommended in US and European guidelines. In total, 447 CXM measurements were acquired in 50 patients. A two-compartment model best fit the data, with total body weight and creatinine clearance determining interpatient variability in the central and peripheral volumes of distribution, and in elimination clearance, respectively. Using our optimized dosing regimen, different dosing schemes adapted to body weight and renal function were calculated to attain total concentration thresholds ranging from 12 to 96 mg/liter. Our simulations showed that the dosing regimens recommended in US and European guidelines failed to maintain concentrations above 48 mg/liter. Our individualized dosing strategy was capable of ensuring therapeutic CXM concentrations conforming to each target threshold. Our model yielded an optimized CXM dosing regimen adapted to body weight and renal function, and sustaining therapeutic concentrations consistent with each desired threshold. The optimal target concentration and necessary duration of its maintenance in cardiac surgery still remain unclear.

<p>Optimal Empiric Treatment for <em>Klebsiella pneumoniae</em> Infections in Short-Stay ICU Patients During Continuous Renal Replacement Therapy: Results from a Population Pharmacokinetic/Pharmacodynamic Analysis</p>

Objective

There is a paucity of published data to evaluate the efficacy and safety of imipenem (IPM) and piperacillin-tazobactam (PT) dosing regimens in the treatment of septic patients acquiring continuous renal replacement therapy (CRRT).

Methods and Materials

Critically-ill patients were grouped into short-stay and long-stay intensive care unit (ICU) patients. Pathogens were isolated from bloodstream infections in these patients. Minimum inhibitory concentration (MIC) value was determined by agar dilution method. Population PK models were introduced in this study, and differences in the likelihood of achieving efficacious and toxic exposures of IPM and PT for critically-ill patients were assessed.

Results

A total of 86 K. pneumoniae bloodstream infection associated isolates were collected, and the MIC₅₀ and MIC₉₀ for short-stay ICU patients were 0.5/4 mg/L and 32/128 mg/L, respectively. IMP 0.5g q8h reached 90% probability of target attainment (PTA) against isolates with MICs ≤2 mg/L and was recommended to empirically treat short-stay ICU patients during CRRT based on the target of 40% ƒT>MIC. However, based on a more aggressive target of 100% ƒT>MIC, all the simulated IMP regimens except for IMP 1g q6h failed to achieve >80% cumulative fraction of response (CFR) in such patients. Unfortunately, the risk of drug-related toxicity for IMP 1g q6h was relatively high (50–85%). For PT, even the regimen of 4/0.5g q6h failed to provide sufficient antimicrobial exposure in short-stay ICU patients acquiring CRRT.

Conclusion

No dose adjustment was required for the conventional IMP and PT regimens in the critically-ill population acquiring CRRT. Empirical treatment of IMP 0.5g q8h/q6h, not for PT, may provide sufficient antimicrobial exposure for short-stay ICU patients during CRRT. PT should be used in the knowledge of MIC results.

Prolonged Versus Intermittent Infusion of β-Lactam Antibiotics: A Systematic Review and Meta-Regression of Bacterial Killing in Preclinical Infection Models

BACKGROUND

Administering β-lactam antibiotics via prolonged infusions for critically ill patients is mainly based on preclinical evidence. Preclinical data on this topic have not been systematically reviewed before.

OBJECTIVES

The aim of this study was to describe the pharmacokinetic/pharmacodynamic (PK/PD) indices and targets reported in preclinical models and to compare the bactericidal efficacy of intermittent and prolonged infusions of β-lactam antibiotics.

METHODS

The MEDLINE and EMBASE databases were searched. To compare the bactericidal action of β-lactam antibiotics across different modes of infusion, the reported PK/PD outcomes, expressed as the percentage of time (T) that free (f) β-lactam antibiotic concentrations remain above the minimal inhibitory concentration (MIC) (%fT>MIC) or trough concentration (Cmin)/MIC of individual studies, were recomputed relative to the area under the curve of free drug to MIC ratio (fAUC24/MIC). A linear mixed-effects meta-regression was performed to evaluate the impact of the β-lactam class, initial inoculum, Gram stain, in vivo or in vitro experiment and mode of infusion on the reduction of bacterial cells (in colony-forming units/mL).

RESULTS

Overall, 33 articles were included for review, 11 of which were eligible for meta-regression. For maximal bactericidal activity, intermittent experiments reported a PK/PD target of 40-70% fT>MIC, while continuous experiments reported a steady-state concentration to MIC ratio of 4-8. The adjusted effect of a prolonged as opposed to intermittent infusion on bacterial killing was small (coefficient 0.66, 95% confidence interval - 0.78 to 2.11).

CONCLUSIONS

Intermittent and prolonged infusions of β-lactam antibiotics require different PK/PD targets to obtain the same level of bacterial cell kill. The additional effect of a prolonged infusion for enhancing bacterial killing could not be demonstrated.

β-Lactam antimicrobial pharmacokinetics and target attainment in critically ill patients aged 1 day to 90 years: the ABDose study

Background

The pharmacokinetics of β-lactam antibiotics in critical illness remain poorly characterized, particularly in neonates, children and the elderly. We undertook a pharmacokinetic study of commonly used β-lactam antibiotics in critically ill patients of all ages. The aims were to produce a whole-life β-lactam pharmacokinetic model and describe the extent to which standard doses achieve pharmacokinetic/pharmacodynamic targets associated with clinical cure.

Patients and methods

A total of 212 critically ill participants with an age range from 1 day (gestational age 24 weeks) to 90 years were recruited from a UK hospital, providing 1339 pharmacokinetic samples. Population pharmacokinetic analysis was undertaken using non-linear mixed-effects modelling (NONMEM) for each drug. Pooled data were used to estimate maturation and decline of β-lactam pharmacokinetics throughout life.

Results

Pharmacokinetic models for eight drugs were described, including what is thought to be the first benzylpenicillin model in critically ill adults. We estimate that 50% of adult β-lactam clearance is achieved by 43 weeks post-menstrual age (chronological plus gestational age). Fifty percent of decline from peak adult clearance occurs by 71 years. Paediatric participants were significantly less likely than adults to achieve pharmacokinetic/pharmacodynamic targets with standard antibiotic doses (P &lt; 0.01).

Conclusions

We believe this to be the first prospective whole-life antibiotic pharmacokinetic study in the critically ill. The study provides further evidence that standard antibiotic doses fail to achieve pharmacokinetic/pharmacodynamic targets associated with clinical success in adults, children and neonates. Maturation and decline parameters estimated from this study could be adopted as a standard for future prospective studies.

Antimicrobial resistance: more than 70 years of war between humans and bacteria

Development of antibiotic resistance in bacteria is one of the major issues in the present world and one of the greatest threats faced by mankind. Resistance is spread through both vertical gene transfer (parent to offspring) as well as by horizontal gene transfer like transformation, transduction and conjugation. The main mechanisms of resistance are limiting uptake of a drug, modification of a drug target, inactivation of a drug, and active efflux of a drug. The highest quantities of antibiotic concentrations are usually found in areas with strong anthropogenic pressures, for example medical source (e.g., hospitals) effluents, pharmaceutical industries, wastewater influents, soils treated with manure, animal husbandry and aquaculture (where antibiotics are generally used as in-feed preparations). Hence, the strong selective pressure applied by antimicrobial use has forced microorganisms to evolve for survival. The guts of animals and humans, wastewater treatment plants, hospital and community effluents, animal husbandry and aquaculture runoffs have been designated as "hotspots for AMR genes" because the high density of bacteria, phages, and plasmids in these settings allows significant genetic exchange and recombination. Evidence from the literature suggests that the knowledge of antibiotic resistance in the population is still scarce. Tackling antimicrobial resistance requires a wide range of strategies, for example, more research in antibiotic production, the need of educating patients and the general public, as well as developing alternatives to antibiotics (briefly discussed in the conclusions of this article).

Failure of target attainment of beta-lactam antibiotics in critically ill patients and associated risk factors: a two-center prospective study (EXPAT)

Background

Early and appropriate antibiotic dosing is associated with improved clinical outcomes in critically ill patients, yet target attainment remains a challenge. Traditional antibiotic dosing is not suitable in critically ill patients, since these patients undergo physiological alterations that strongly affect antibiotic exposure. For beta-lactam antibiotics, the unbound plasma concentrations above at least one to four times the minimal inhibitory concentration (MIC) for 100% of the dosing interval (100%ƒT > 1–4×MIC) have been proposed as pharmacodynamic targets (PDTs) to maximize bacteriological and clinical responses. The objectives of this study are to describe the PDT attainment in critically ill patients and to identify risk factors for target non-attainment.

Methods

This prospective observational study was performed in two ICUs in the Netherlands. We enrolled adult patients treated with the following beta-lactam antibiotics: amoxicillin (with or without clavulanic acid), cefotaxime, ceftazidime, ceftriaxone, cefuroxime, and meropenem. Based on five samples within a dosing interval at day 2 of therapy, the time unbound concentrations above the epidemiological cut-off (ƒT > MIC_ECOFF and ƒT > 4×MIC_ECOFF) were determined. Secondary endpoints were estimated multivariate binomial and binary logistic regression models, for examining the association of PDT attainment with patient characteristics and clinical outcomes.

Results

A total of 147 patients were included, of whom 63.3% achieved PDT of 100%ƒT > MIC_ECOFF and 36.7% achieved 100%ƒT > 4×MIC_ECOFF. Regression analysis identified male gender, estimated glomerular filtration rate (eGFR) ≥ 90 mL/min/1.73 m², and high body mass index (BMI) as risk factors for target non-attainment. Use of continuous renal replacement therapy (CRRT) and high serum urea significantly increased the probability of target attainment. In addition, we found a significant association between the 100%ƒT > MIC_ECOFF target attainment and ICU length of stay (LOS), but no significant correlation was found for the 30-day survival.

Conclusions

Traditional beta-lactam dosing results in low target attainment in the majority of critically ill patients. Male gender, high BMI, and high eGFR were significant risk factors for target non-attainment. These predictors, together with therapeutic drug monitoring, may help ICU clinicians in optimizing beta-lactam dosing in critically ill patients.

Trial registration

Netherlands Trial Registry (EXPAT trial), NTR 5632. Registered on 7 December 2015.

The role of antibiotic pharmacokinetic studies performed post-licensing

Post-licensing pharmacometric studies can provide a better understanding of the pharmacokinetic (PK) alterations in special patient populations and may lead to better clinical outcomes. Some patient populations exhibit markedly different pathophysiology to general ward patients or healthy individuals. This may be developmental (paediatric patients), a manifestation of an underlying disease pathology (patients with obesity or haematological malignancies) or due to medical interventions (critically ill patients receiving extracorporeal therapies). This paper outlines the factors that affect the PK of special patient populations and describes some novel methods of antimicrobial administration that may increase antimicrobial concentrations at the site of infection and improve treatment of severe infection.

Pharmacists' Knowledge About the Impact of Augmented Renal Clearance on Antimicrobial Dosing in Critically Ill Patients: A Cross-Sectional Study

BACKGROUND

Broad-spectrum antibiotics are commonly prescribed in critically ill patients. While it is commonly believed that only patients with impaired renal function need dose adjustment, augmented renal clearance (ARC) is a phenomenon that warrants dose adjustment as well. In critically ill patients ARC is often undetectable because it is associated with a normal or decreased serum creatinine concentration (SCr). This study's objective was to assess pharmacists' knowledge about ARC identification, risk factors, affected antimicrobials, and dosing of antibiotics in patients with ARC.

METHODS

In January 2020, we carried out a cross-sectional study by sending out an online survey to the Saudi Pharmaceutical Society, Kuwait Pharmaceutical Association, and Oman Pharmaceutical Society. Due to the expected low response rate, we administered an electronic questionnaire to pharmacists attending Dubai International Pharmaceuticals and Technologies Conference and Exhibition 2020 (DUPHAT).

RESULTS

Data were collected from 288 respondents. However, only 134 were included in the final analysis following the exclusion of incomplete responses, no experience working in in-patient settings, and respondents who chose "no" universal ARC definition. Those who chose "yes" or "I do not know" regarding the universal definition of ARC were asked about SCr status in ARC. Elevation in SCr was chosen by 67/134 (50%) compared to those who chose decreased or normal (48/134, 35.8%). Regarding risk factors, only 1/134 (0.7%) respondent selected all risk factors. Two/134 (1.4%) respondents chose all hydrophilic antibiotics that are likely to be affected by ARC. Concerning the appropriate dose and frequency of piperacillin-tazobactam and meropenem, they were selected by 60.4% and 30.5%, respectively.

CONCLUSION

Pharmacists' knowledge about ARC was limited. Implementation of educational programs targeting hospital pharmacists, especially those practicing in critical care settings, and developing antimicrobial institutional guidelines are important.

Non-invasive Drug Monitoring of β-Lactam Antibiotics Using Sweat Analysis-A Pilot Study

Background: Antimicrobial resistance is a major challenge in treating infectious diseases. Therapeutic drug monitoring (TDM) can optimize and personalize antibiotic treatment. Previously, antibiotic concentrations in tissues were extrapolated from skin blister studies, but sweat analyses for TDM have not been conducted. Objective: To investigate the potential of sweat analysis as a non-invasive, rapid, and potential bedside TDM method. Methods: We analyzed sweat and blood samples from 13 in-house patients treated with intravenous cefepime, imipenem, or flucloxacillin. For cefepime treatment, full pharmacokinetic sampling was performed (five subsequent sweat samples every 2 h) using ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. The ClinicalTrials.gov registration number is NCT03678142. Results: In this study, we demonstrated for the first time that flucloxacillin, imipenem, and cefepime are detectable in sweat. Antibiotic concentration changes over time demonstrated comparable (age-adjusted) dynamics in the blood and sweat of patients treated with cefepime. Patients treated with standard flucloxacillin dosage showed the highest mean antibiotic concentration in sweat. Conclusions: Our results provide a proof-of-concept that sweat analysis could potentially serve as a non-invasive, rapid, and reliable method to measure antibiotic concentration and as a surrogate marker for tissue penetration. If combined with smart biosensors, sweat analysis may potentially serve as the first lab-independent, non-invasive antibiotic TDM method.

Optimized meropenem dosage regimens using a pharmacokinetic/pharmacodynamic population approach in patients undergoing continuous venovenous haemodiafiltration with high-adsorbent membrane

BACKGROUND

The pharmacokinetics (PK) of antibiotics change during sepsis and continuous renal replacement therapies in critically ill patients. Limited evidence exists on the use of the oXiris® high-adsorbent membrane.

OBJECTIVES

To develop a PK/pharmacodynamic (PD) model for meropenem in critically ill sepsis patients undergoing continuous venovenous haemodiafiltration (CVVHDF) with the oXiris® membrane, and to design an optimal dosing regimen assessed according to the PTA.

METHODS

A prospective, open-label, observational PK trial was performed (EUDRACT 2011-005902-30). We conducted PK studies (plasma and ultrafiltrate) for at least 24 h after concomitant administration of CVVHDF and meropenem 1 g q8h. We constructed a PK model using the non-linear mixed-effects approach (NONMEM 7.3). We evaluated the suitability of different dosage regimens using Monte Carlo simulations and calculated the PTA as the percentage of subjects achieving a given percentage of time above the MIC (fT>MIC).

RESULTS

The PK of meropenem was best captured by a two-open-compartment model with zero-order input kinetics and first-order elimination. Extracorporeal CL was 7.78 L/h [relative standard error (RSE) 16.45 L/h] and central compartment V (Vc) was 24.9 L (RSE 13.73 L). Simulations showed that, for susceptible Pseudomonas aeruginosa isolates (EUCAST MIC ≤2 mg/L) and attainment of 100%fT>MIC, 500 mg q8h given as extended (EI) or continuous infusion (CI) would be sufficient. For a target of 100%fT>4×MIC, CI of 3000 mg q24h or 2000 mg q8h administered as EI or CI would be required.

CONCLUSIONS

We have constructed a PK model of meropenem in sepsis patients undergoing CVVHDF using the oXiris® membrane. This tool will support physicians when calculating the optimal initial dose.

Antimicrobial Therapy in Septic Shock Is Conservative During Resuscitation and Maintenance Phases

Background: Maximal dosing of early antimicrobials with high loading and maintenance doses may optimize pharmacokinetic parameters to achieve and maintain therapeutic concentrations at the site of infection in septic shock. Little is known about the current practice of early antimicrobial dosing in septic shock. Objective: To characterize early antimicrobial dosing in patients in the resuscitation phase of septic shock. Methods: This retrospective cohort study included patients admitted to the medical intensive care unit (ICU) with septic shock. The primary outcome was the percentage of early antibiotic orders that were maximal or conservative during the resuscitation (0 to 48 hours) phase based on predefined dosing criteria. The secondary outcomes were the correlations of different dosing strategies on hospital length of stay (LOS), ICU LOS, and hospital mortality. Results: This study evaluated 161 patients and 692 antibiotic orders; 504 (72.8%) of the orders during the resuscitation phase were conservative. There were no differences in mortality (odds ratio = 0.66; 95% confidence interval = 0.35-1.25; P = .20), hospital LOS (median = 20 [interquartile range (IQR) = 10-34] vs 19 [IQR = 11-32] days; P = .93), or ICU LOS (median = 8 [IQR = 5-16] vs 9 [IQR = 5-15] days; P = .63) between maximal and conservative dosing groups, respectively, in the resuscitation phase. Limitations of this study included the use of institution-specific antimicrobial dosing guidelines and its retrospective nature. Conclusions: Early antibiotic dosing is conservative for a majority of patients in septic shock. Future studies are needed to evaluate the impact of dosing strategy on patient-centered outcomes in septic shock.

Aminoglycosides in critically ill patients: which dosing regimens for which pathogens?

Modifications of antibiotic pharmacokinetic parameters have been reported in critically ill patients, resulting in a risk of treatment failure. We aimed to determine optimised amikacin (AMK), gentamicin (GEN) and tobramycin (TOB) intravenous dosing regimens in this patient population. Patients admitted to the medical ICU and treated with AMK, GEN or TOB were included. Analyses were performed using a parametric population approach. Monte Carlo simulations were performed and the probability of target attainment (PTA) was calculated using C_max/MIC ≥ 8 and trough concentrations as targets. A total of 117 critically ill hospitalised patients were studied. Median values (interindividual variability, ɷ²) of clearance were 3.51 (0.539), 3.53 (0.297), 2.70 (0.339) and 5.07 (0.339) L/h for AMK, GEN, TOB, and TOB in cystic fibrosis (CF), respectively. Median values (ɷ²) of central volume of distribution were 30.2 (0.215), 20.0 (0.109) and 25.6 (0.177) L for AMK, GEN and TOB, respectively. Simulations showed that doses should be adjusted to actual body weight and creatinine clearance (CLCR) for AMK and GEN, and according to CLCR and presence of CF for TOB. In conclusion, our recommendations for treating Pseudomonas aeruginosa infections in this population include using initial doses of 35 mg/kg for AMK or 10 mg/kg for TOB (CF and non-CF patients). GEN demonstrated the best rates of target attainment against Staphylococcus aureus infections with a dose of 5 mg/kg. As high aminoglycoside doses are required in this population, efficacy and safety targets are conflicting and therapeutic drug monitoring remains an important tool to manage this issue.

Time above the MIC of Piperacillin-Tazobactam as a Predictor of Outcome in Pseudomonas aeruginosa Bacteremia

Pseudomonas aeruginosa bacteremia is an infection associated with a high mortality rate. Piperacillin-tazobactam is a β-lactam-β-lactamase inhibitor combination that is frequently used for the management of Pseudomonas aeruginosa infections. The pharmacokinetic-pharmacodynamic index associated with in vitro maximal bacterial killing for piperacillin-tazobactam is the percentage of the time between doses at which the free fraction concentration remains above the MIC (%fT _>MIC). However, the precise %fT _>MIC target associated with improved clinical outcomes is unknown. The aim of this study was to investigate the correlation between the survival of patients with Pseudomonas aeruginosa bacteremia and the threshold of the piperacillin-tazobactam %fT _>MIC This retrospective study included all adult patients hospitalized over an 82-month period with Pseudomonas aeruginosa bacteremia and treated with piperacillin-tazobactam. Patients with a polymicrobial infection or those who died within 72 h of the time of collection of a sample for culture were excluded. The %fT _>MIC of piperacillin-tazobactam associated with in-hospital survival was derived using classification and regression tree analysis. After screening 270 patients, 78 were eligible for inclusion in the study; 18% died during hospitalization. Classification and regression tree analysis identified a %fT _>MIC of >60.68% to be associated with improved survival, and this remained statistically significant after controlling for clinical covariates (odds ratio = 7.74, 95% confidence interval = 1.32 to 45.2). In conclusion, the findings recommend dosing of piperacillin-tazobactam with the aim of achieving a pharmacodynamic target %fT _>MIC of at least 60% in these patients.

Antibiotic treatment in patients with sepsis: a narrative review

Sepsis is a medical emergency and life-threatening condition due to a dysregulated host response to infection, with unacceptably high morbidity and mortality. Similar to acute myocardial infarction or cerebral vascular accident, sepsis is a severe and continuous time-dependent condition. Thus, in the case of sepsis, early and adequate administration of antimicrobials must be a priority, ideally within the first hour of diagnosis, simultaneously with organ support.As a consequence of the emergence of multidrug-resistant pathogens, the choice of antimicrobials should be performed according to the local pathogen patterns of resistance. Individual antimicrobial optimization is essential to achieve adequate concentrations of antimicrobials, to reduce adverse effects, and to ensure successful outcomes, as well as preventing the emergence of multidrug-resistant pathogens. The loading dose is the administration of an initial higher dose of antimicrobials, regardless of the presence of organ dysfunction. Further doses should be implemented according to pharmacokinetics/pharmacodynamics of antimicrobials and should be adjusted according to the presence of renal or liver dysfunction. Extended or continuous infusion of beta-lactams and therapeutic drug monitoring can help to achieve therapeutic levels of antimicrobials. Duration and adequacy of treatment must be reviewed at regular intervals to allow effective de-escalation and administration of short courses of antimicrobials for most patients. Antimicrobial stewardship frameworks, leadership, focus on the optimal duration of treatments, de-escalation, and novel diagnostic stewardship approaches will help us to improve patients the process of care and overall quality of care.