Clinical cure of ventilator-associated pneumonia treated with piperacillin/tazobactam administered by continuous or intermittent infusion

Management of intra-abdominal infections: recommendations by the Italian council for the optimization of antimicrobial use

Intra-abdominal infections (IAIs) are common surgical emergencies and are an important cause of morbidity and mortality in hospital settings, particularly if poorly managed. The cornerstones of effective IAIs management include early diagnosis, adequate source control, appropriate antimicrobial therapy, and early physiologic stabilization using intravenous fluids and vasopressor agents in critically ill patients. Adequate empiric antimicrobial therapy in patients with IAIs is of paramount importance because inappropriate antimicrobial therapy is associated with poor outcomes. Optimizing antimicrobial prescriptions improves treatment effectiveness, increases patients' safety, and minimizes the risk of opportunistic infections (such as Clostridioides difficile) and antimicrobial resistance selection. The growing emergence of multi-drug resistant organisms has caused an impending crisis with alarming implications, especially regarding Gram-negative bacteria. The Multidisciplinary and Intersociety Italian Council for the Optimization of Antimicrobial Use promoted a consensus conference on the antimicrobial management of IAIs, including emergency medicine specialists, radiologists, surgeons, intensivists, infectious disease specialists, clinical pharmacologists, hospital pharmacists, microbiologists and public health specialists. Relevant clinical questions were constructed by the Organizational Committee in order to investigate the topic. The expert panel produced recommendation statements based on the best scientific evidence from PubMed and EMBASE Library and experts' opinions. The statements were planned and graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence. On November 10, 2023, the experts met in Mestre (Italy) to debate the statements. After the approval of the statements, the expert panel met via email and virtual meetings to prepare and revise the definitive document. This document represents the executive summary of the consensus conference and comprises three sections. The first section focuses on the general principles of diagnosis and treatment of IAIs. The second section provides twenty-three evidence-based recommendations for the antimicrobial therapy of IAIs. The third section presents eight clinical diagnostic-therapeutic pathways for the most common IAIs. The document has been endorsed by the Italian Society of Surgery.

Balancing the scales: achieving the optimal beta-lactam to beta-lactamase inhibitor ratio with continuous infusion piperacillin/tazobactam against extended spectrum beta-lactamase producing Enterobacterales

Piperacillin/tazobactam (TZP) is administered intravenously in a fixed ratio (8:1) with the potential for inadequate tazobactam exposure to ensure piperacillin activity against Enterobacterales. Adult patients receiving continuous infusion (CI) of TZP and therapeutic drug monitoring (TDM) of both agents were evaluated. Demographic variables and other pertinent laboratory data were collected retrospectively. A population pharmacokinetic approach was used to select the best kidney function model predictive of TZP clearance (CL). The probability of target attainment (PTA), cumulative fraction of response (CFR) and the ratio between piperacillin and tazobactam were computed to identify optimal dosage regimens by continuous infusion across kidney function. This study included 257 critically ill patients (79.3% male) with intra-abdominal, bloodstream, and hospital-acquired pneumonia infections in 89.5% as the primary indication. The median (min-max range) age, body weight, and estimated glomerular filtration rate (eGFR) were 66 (23-93) years, 75 (39-310) kg, and 79.2 (6.4-234) mL/min, respectively. Doses of up to 22.5 g/day were used to optimize TZP based on TDM. The 2021 chronic kidney disease epidemiology equation in mL/min best modeled TZP CL. The ratio of piperacillin:tazobactam increased from 6:1 to 10:1 between an eGFR of <20 mL/min and >120 mL/min. At conventional doses, the PTA is below 90% when eGFR is ≥100 mL/min. Daily doses of 18 g/day and 22.5 g/day by CI are expected to achieve a >80% CFR when eGFR is 100-120 mL/min and >120-160 mL/min, respectively. Inadequate piperacillin and tazobactam exposure is likely in patients with eGFR ≥ 100 mL/min. Dose regimen adjustments informed by TDM should be evaluated in this specific population.

Comparing prolonged infusion to intermittent infusion strategies for beta-lactam antibiotics in patients with gram-negative bacterial infections: a systematic review and meta-analysis

INTRODUCTION

Our objective is to determine whether prolonged infusion (PI) of beta-lactam antibiotics yields superior outcomes compared to intermittent infusion (II) in patients with Gram-Negative Bacterial (GNB) infections.

METHODS

We systematically searched papers from PubMed, the Cochrane Library, Embase, and Clinicaltrials.gov, targeting mortality as the primary outcome and looking at the clinical cure rate, hospital and intensive care unit (ICU) stay lengths, antibiotic treatment duration, and mechanical ventilation (MV) duration as secondary outcomes.

RESULTS

Our meta-analysis of 18 studies, including 5 randomized control trials and 13 observational studies, with a total of 3,035 patients-1,510 in the PI group and 1,525 in the II group, revealed significant findings. PI was associated with reduced mortality (RR, 0.67; 95% CI, 0.55-0.81; p = 0.001; I2 = 4.52%) and a shorter MV duration (SMD, -0.76; 95% CI, -1.37 to -0.16; p = 0.01; I2 = 87.81%) compared to II. However, no differences were found in clinical cure rates, antibiotic treatment duration, length of hospital stay, or length of ICU stay.

CONCLUSIONS

The PI approach for administering beta-lactam antibiotics in patients with suspected or confirmed GNB infections may be advantageous in reducing mortality rates and the duration of MV when compared to the II strategy.

International consensus recommendations for the use of prolonged-infusion beta-lactam antibiotics: Endorsed by the American College of Clinical Pharmacy, British Society for Antimicrobial Chemotherapy, Cystic Fibrosis Foundation, European Society of Clinical Microbiology and Infectious Diseases, Infectious Diseases Society of America, Society of Critical Care Medicine, and Society of Infectious Diseases Pharmacists

Intravenous β-lactam antibiotics remain a cornerstone in the management of bacterial infections due to their broad spectrum of activity and excellent tolerability. β-lactams are well established to display time-dependent bactericidal activity, where reductions in bacterial burden are directly associated with the time that free drug concentrations remain above the minimum inhibitory concentration (MIC) of the pathogen during the dosing interval. In an effort to take advantage of these bactericidal characteristics, prolonged (extended and continuous) infusions (PIs) can be applied during the administration of intravenous β-lactams to increase time above the MIC. PI dosing regimens have been implemented worldwide, but implementation is inconsistent. We report consensus therapeutic recommendations for the use of PI β-lactams developed by an expert international panel with representation from clinical pharmacy and medicine. This consensus guideline provides recommendations regarding pharmacokinetic and pharmacodynamic targets, therapeutic drug-monitoring considerations, and the use of PI β-lactam therapy in the following patient populations: severely ill and nonseverely ill adult patients, pediatric patients, and obese patients. These recommendations provide the first consensus guidance for the use of β-lactam therapy administered as PIs and have been reviewed and endorsed by the American College of Clinical Pharmacy (ACCP), the British Society for Antimicrobial Chemotherapy (BSAC), the Cystic Fibrosis Foundation (CFF), the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), the Infectious Diseases Society of America (IDSA), the Society of Critical Care Medicine (SCCM), and the Society of Infectious Diseases Pharmacists (SIDP).

Optimizing Betalactam Clinical Response by Using a Continuous Infusion: A Comprehensive Review

INTRODUCTION

Antimicrobial resistance is a major healthcare issue responsible for a large number of deaths. Many reviews identified that PKPD data are in favor of the use of continuous infusion, and we wanted to review clinical data results in order to optimize our clinical practice.

METHODOLOGY

We reviewed Medline for existing literature comparing continuous or extended infusion to intermittent infusion of betalactams.

RESULTS

In clinical studies, continuous infusion is as good as intermittent infusion. In the subset group of critically ill patients or those with an infection due to an organism with high MIC, a continuous infusion was associated with better clinical response.

CONCLUSIONS

Clinical data appear to confirm those of PK/PD to use a continuous infusion in severely ill patients or those infected by an organism with an elevated MIC, as it is associated with higher survival rates. In other cases, it may allow for a decrease in antibiotic daily dosage, thereby contributing to a decrease in overall costs.

Continuous infusion of beta-lactam antibiotics: narrative review of systematic reviews, and implications for outpatient parenteral antibiotic therapy

INTRODUCTION

Continuous infusion (CI) of beta-lactam antibiotics may be of benefit in some patients, particularly those with severe infections. However, most studies have been small and conflicting results have been reported. The best available evidence on clinical outcomes of beta-lactam CI comes from systematic reviews/meta-analyses that integrate the available data.

AREAS COVERED

A search of PubMed from inception to the end of February 2022 for systematic reviews of clinical outcomes with beta-lactam CI for any indication identified 12 reviews, all of which focused on hospitalized patients, most of whom were critically ill. A narrative overview of these systematic reviews/meta-analyses is provided. No systematic reviews evaluating the use of beta-lactam CI for outpatient parenteral antibiotic therapy (OPAT) were identified, as few studies have focused on this area. Relevant data are summarized, and consideration is given to issues that need to be addressed when using beta-lactam CI in the setting of OPAT.

EXPERT OPINION

Evidence from systematic reviews supports a role for beta-lactam CI in the treatment of hospitalized patients with severe/life-threatening infections. Beta-lactam CI can play a role in patients receiving OPAT for severe chronic/difficult-to-treat infections, but additional data are needed to clarify its optimal use.

Optimizing Clinical Outcomes Through Rational Dosing Strategies: Roles of Pharmacokinetic/Pharmacodynamic Modeling Tools

Significant progress in previous decades has led to several methodologies developed to facilitate the design of optimal antimicrobial dosing. In this review, we highlight common pharmacokinetic/pharmacodynamic (PKPD) modeling techniques and their roles in guiding rational dosing regimen design. In the early drug development phases, dose fractionation studies identify the PKPD index most closely associated with bacterial killing. Once discerned, this index is linked to clinical efficacy end points, and classification and regression tree analysis can be used to define the PKPD target goal. Monte Carlo simulations integrate PKPD and microbiological data to identify dosing strategies with a high probability of achieving the established PKPD target. Results then determine dosing regimens to investigate and/or validate the findings of randomized controlled trials. Further improvements in PKPD modeling could lead to an era of precision dosing and personalized therapeutics.

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

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

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

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

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

Population pharmacokinetics of polymyxin B: a systematic review

Background

Polymyxin B (PMB) is a basic cyclic polypeptide antibiotic produced by Bacillus polymyxa, and is one of the last options for treating multi-drug-resistant negative bacterial infections in clinical practice. In recent years, many population pharmacokinetic studies of PMB have been conducted. This paper sought to comprehensively summarize the characteristics of population pharmacokinetic models of PMB and provide a theoretical basis for the individualized use of PMB.

Methods

In this review, we systematically searched the PubMed and Embase databases to find articles on population pharmacokinetic models published from database establishment to August 2021.

Results

A total of 10 studies were included in this review, including studies on various types of severe infections caused by multi-drug-resistant bacteria, hospital-acquired infections with fibrosis and other male and female populations, and a study of 2 continuous renal replacement therapy (CRRT) patients, aged 16–94 years, who received PMB doses of 10–360 mg/day (0.13–3.45 mg/kg/day), at an administration time of 0.5–6 hours. First-order linear elimination was used in all the studies; a 1-compartment model was used in 5 studies, and a 2-compartment model was used in 5 studies. The most common covariates were creatinine clearance (CrCL) and body weight.

Discussion

Although these studies included several covariates and total clearance (CL) was close, but the external validation of some models was poorly correlated between the actual and predicted value. Novel or potential covariates represent important directions for further study.

Evaluation of Prolonged Versus Continuous Infusions of Piperacillin/Tazobactam During Shortages of Small Volume Parenteral Solutions

Background: In 2017, a national drug shortage of small volume solutions significantly affected the preparation of intravenous antibiotics. In response, a continuous infusion administration protocol for piperacillin/tazobactam (PIP/TAZ) was implemented. Objective: To compare the outcomes of continuous to prolonged infusions of PIP/TAZ in the setting of drug shortages. Methods: This study is a single-center, retrospective cohort study in a community hospital of patients 18 years and older who received intravenous PIP/TAZ through 2 different dosing strategies of intravenous antibiotics from December 2016 to January 2018. Data were collected for 2 months on patients receiving prolonged infusions of PIP/TAZ prior to November 2017 and for 2 months on patients receiving continuous infusions of PIP/TAZ after November 2017. Results: A total of 90 patients who received PIP/TAZ via either prolonged (n = 47) or continuous infusion (n = 43) were evaluated. There were no differences between the groups in mortality (3 vs 2 deaths, P = 1.00), length of therapy (6 ± 4 vs 6 ± 3 days, P = .86), or length of stay (9 ± 7 vs 8 ± 6 days, P = .47). Additionally, no differences were noted between incidences of thrombocytopenia (P = .41), Clostridioides difficile infection (P = .48), acute renal failure (P = 1.00), seizures (P = 1.0), or 30-day readmission rates (P = .27). Conclusions: Administration of continuous infusion PIP/TAZ appears to be a viable mitigation strategy during small volume fluid shortages. Future cost-effectiveness studies may provide information on the financial impact of continuous infusions during costly drug shortages.

Population pharmacokinetics of continuous infusion of piperacillin/tazobactam in very elderly hospitalized patients and considerations for target attainment against Enterobacterales and Pseudomonas aeruginosa

Continuous infusion (CI) piperacillin/tazobactam is frequently used to treat infections in very elderly patients. This study aimed to conduct a population pharmacokinetic analysis of CI piperacillin/tazobactam, and to identify optimal dosages for safe and effective probability of target attainment (PTA) against Enterobacterales and Pseudomonas aeruginosa. Non-linear mixed-effects modelling was performed with Pmetrics. Monte Carlo simulations assessed the steady-state concentration (Css) of increasing piperacillin/tazobactam regimens (from 2.25 to 18 g daily by continuous infusion). Permissible doses were defined as those associated with <10% probability of Css >157.2 mg/L. PTA at the pharmacodynamic targets of free plasma steady-state concentration (fCss)/minimum inhibitory concentration (MIC) ≥1 and ≥4 and cumulative fraction of response (CFR) against EUCAST MIC distribution were also calculated. A total of 141 patients (median age 85 years) provided 217 plasma piperacillin Css. Most patients (55.2%) had hospital-acquired pneumonia and intra-abdominal infections. A one-compartment pharmacokinetic model with parallel linear and Michaelis-Menten elimination best described piperacillin data. Creatinine clearance (CL_CR) was the covariate retained by the model. Pharmacokinetic estimates were 6.05 L/h for clearance and 3.39 mg/L for the Michaelis-Menten constant. Permissible doses were up to 4.5, 9, 11.25 and 13.5 g daily by continuous infusion for patients with CL_CR of 0-19, 20-39, 40-59 and 60-79 mL/min/1.73 m², respectively. At the clinical breakpoint of 8 mg/L, the permissible doses only achieved optimal PTA for fCss/MIC ≥1 in patients with CL_CR 20-79 mL/min/1.73 m². Optimal CFRs with the permissible doses were only attained against Escherichia coli and Proteus mirabilis. Permissible dosages and CL_CR should be considered for prescribing CI piperacillin/tazobactam in very elderly patients.

Prolonged infusion of beta-lactam antibiotics for Gram-negative infections: rationale and evidence base

PURPOSE OF REVIEW

The aim of this review is to discuss the rationale of and current evidence for prolonged beta-lactam infusion in the management of Gram-negative infections.

RECENT FINDINGS

Pharmacokinetic/pharmacodynamic (PK/PD) data from various in-vitro and in-vivo experimental studies conclusively support prolonged infusion over intermittent infusion in terms of achieving effective beta-lactam exposure for maximal bacterial killing. Superior PK/PD target attainment has been demonstrated with prolonged beta-lactam infusion in patient populations that are more likely to have less susceptible Gram-negative infections. These populations include critically ill patients, cystic fibrosis patients and patients with malignant diseases. The clinical impact of prolonged beta-lactam infusion is likely to be the greatest in these patient groups: critically ill patients with a high level of illness severity who are not receiving renal replacement therapy; patients with nonfermenting Gram-negative bacilli infection and patients with respiratory infection. Critically ill patients with augmented renal clearance may not achieve effective beta-lactam exposure even with the use of prolonged infusion. Maximizing the effectiveness of prolonged beta-lactam infusion via therapeutic drug monitoring is becoming a more common strategy in the management of critically ill patients with Gram-negative infection.

SUMMARY

Prolonged beta-lactam infusion may not benefit all patients but only for those who are critically ill and/or immunocompromised, who are also more likely to have less susceptible Gram-negative infections.

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.

[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.

Differential antibiotic dosing in critical care: survey on nurses' knowledge, perceptions and experience

Background

With the discovery of new antibiotics diminishing, optimizing the administration of existing antibiotics has become a necessity. Critical care nurses play a crucial role in combating antimicrobial resistance and are involved in preparing and administering antibiotics as well as monitoring their effects on patients. A dosing strategy proposed to reduce the development of ever-evolving antimicrobial resistance involves differential dosing regimens such as prolonged/continuous infusions.

Objectives

To assess critical care nurses’ knowledge, perceptions, comfort and experience in relation to prolonged/continuous infusion antibiotics.

Methods

A descriptive cross-sectional study was conducted using an investigator-developed, self-administered survey consisting of open- and closed-ended questions. Obtained data were computed using SPSS. Descriptive and inferential statistics were used to analyse the data.

Results

Fifty-two critical care nurses participated in the survey. Data revealed that nurses have adequate levels of knowledge and comfort relating to the use of prolonged/continuous infusion antibiotics along with the ability to communicate effectively on the topic. Results indicate there is a need for further learning, especially in terms of multiplicity of methods for preparing and administering prolonged/continuous infusions and dose calculations. Overall, results are promising as nurses support the wider implementation of prolonged/continuous infusion treatment regimens in critical care.

Conclusion

Although critical care nurses had a good understanding surrounding the use of prolonged/continuous infusion antibiotics, there is a need for further learning beyond information gained from nursing education courses. Findings from this study indicate that nurses are supportive of prolonged/continuous infusion antibiotics. However, further research is needed to determine the most effective mode of antibiotic administration.

Hospital preparedness and management of pediatric population during COVID-19 outbreak

With the recent pandemic of Coronavirus disease-2019 (COVID-19), there has been a higher number of reported cases in children more than to the prior Corona Virus-related diseases, namely, severe acute respiratory syndrome and the Middle East respiratory syndrome. The rate of COVID-19 in children is lower than adults; however, due to high transmission rate, the number of reported cases in children has been increasing. With the rising numbers among children, it is imperative to develop preparedness plans for the pediatric population at the hospital level, departmental level, and patient care areas. This paper summarizes important considerations for pediatric hospital preparedness at the hospital level that includes workforce, equipment, supply; capacity planning, and infection prevention strategies, it also span over the management of COVID-19 pediatric patients in high-risk areas such as critical care areas, Emergency Department and operative rooms.

Benefits of prolonged infusion of beta-lactam antibiotics in patients with sepsis: personal perspectives

INTRODUCTION

In the current era of relatively scarce antibiotic production and significant levels of antimicrobial resistance, optimization of pharmacokinetics and pharmacodynamics of antibiotic therapy is mandatory. Prolonged infusion of beta-lactam antibiotics in comparison to the intermittent infusion has the theoretical advantage of better patient outcomes. Apparently, conflicting data in the literature possibly underestimate the benefits of prolonged infusion of antibiotic treatment.

AREAS COVERED

We provide our perspective on the subject based on our experience and by critically evaluating literature data.

EXPERT OPINION COMMENTARY

In our opinion, the available data are suggestive of the beneficial role of prolonged infusion of beta-lactams in regard to piperacillin/tazobactam and carbapenems after administering a loading dose. While more data from randomized controlled trials are necessary to solidify or negate the evident benefits of prolonged infusion of the aforementioned antibiotics, clinicians should strongly consider this mode of administration of relevant antibiotics, especially in patients with severe infections.

Comparing clinical outcomes of piperacillin-tazobactam administration and dosage strategies in critically ill adult patients: a systematic review and meta-analysis

Background

Recently, continuous administration of piperacillin-tazobactam has been proposed as a valuable alternative to traditional intermittent administration especially in critically ill patients. However, antibiotic dosing remains a challenge for clinicians as antibiotic dosing regimens are usually determined in non-critically ill hospitalized adult patients. The aim was to conduct a systematic review to identify and highlight studies comparing clinical outcomes of piperacillin tazobactam dosing regimens, continuous/prolonged infusion vs intermittent infusion in critically ill patients. Meta-analyses were performed to assess the overall effect of dosing regimen on clinical efficacy.

Methods

Studies were identified systematically through searches of PubMed and Science Direct, in compliance with PRISMA guidelines. Following the systematic literature review, meta-analyses were performed using Review Manager.

Results

Twenty-three studies were included in the analysis involving 3828 critically ill adult participants in total (continuous/prolonged infusion = 2197 and intermittent infusion = 1631) from geographically diverse regions. Continuous/prolonged resulted in significantly: higher clinical cure rates (Odds Ratio 1.56, 95% Confidence Interval 1.28–1.90, P = 0 .0001), lower mortality rates (Odds Ratio 0.68, 95% Confidence Interval 0.55–0.84, P = 0 .0003), higher microbiological success rates (Odds Ratio 1.52, 95% Confidence Interval 1.10–2.11, P = 0.01) and decreasing the length of hospital stay (Mean Difference − 1.27, 95% Confidence Interval − 2.45—0.08, P = 0.04) in critically ill patients.

Conclusion

Results from this study show that there is a significant level of evidence that clinical outcome in critically ill patients is improved in patients receiving piperacillin-tazobactam via continuous/prolonged infusion. However, more rigorous scientific studies in critically ill patients are warranted to reach a sufficient level of evidence and promote further implementation of C/PI as a dosing strategy.

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

BACKGROUND

Beta-lactam antibiotics (βLA) are the most commonly used antibiotics in the intensive care unit (ICU). ICU patients present many pathophysiological features that cause pharmacokinetic (PK) and pharmacodynamic (PD) specificities, leading to the risk of underdosage. The French Society of Pharmacology and Therapeutics (SFPT) and the French Society of Anaesthesia and Intensive Care Medicine (SFAR) have joined forces to provide guidelines on the optimization of beta-lactam treatment in ICU patients.

METHODS

A consensus committee of 18 experts from the two societies had the mission of producing these guidelines. The entire process was conducted independently of any industry funding. A list of questions formulated according to the PICO model (Population, Intervention, Comparison, and Outcomes) was drawn-up by the experts. Then, two bibliographic experts analysed the literature published since January 2000 using predefined keywords according to PRISMA recommendations. The quality of the data identified from the literature was assessed using the GRADE® methodology. Due to the lack of powerful studies having used mortality as main judgement criteria, it was decided, before drafting the recommendations, to formulate only "optional" recommendations.

RESULTS

After two rounds of rating and one amendment, a strong agreement was reached by the SFPT-SFAR guideline panel for 21 optional recommendations and a recapitulative algorithm for care covering four areas: (i) pharmacokinetic variability, (ii) PK-PD relationship, (iii) administration modalities, and (iv) therapeutic drug monitoring (TDM). The most important recommendations regarding βLA administration in ICU patients concerned (i) the consideration of the many sources of PK variability in this population; (ii) the definition of free plasma concentration between four and eight times the Minimal Inhibitory Concentration (MIC) of the causative bacteria for 100% of the dosing interval as PK-PD target to maximize bacteriological and clinical responses; (iii) the use of continuous or prolonged administration of βLA in the most severe patients, in case of high MIC bacteria and in case of lower respiratory tract infection to improve clinical cure; and (iv) the use of TDM to improve PK-PD target achievement.

CONCLUSIONS

The experts strongly suggest the use of personalized dosing, continuous or prolonged infusion and therapeutic drug monitoring when administering βLA in critically ill patients.

Continuous versus intermittent infusions of antibiotics for the treatment of infectious diseases: Meta-analysis and systematic review

BACKGROUND

Severe sepsis and pneumonia are common problems in the intensive care units (ICUs) and cause high morbidity and mortality. Optimal doses and appropriate routes of antibiotics are critical to improve their efficacy, but their appropriate routes remain controversial.

OBJECTIVE

The efficacy of antibiotic administration among critically ill patient populations remains controversial. Therefore, the present meta-analysis aimed to investigate the effectiveness of antibiotic administration in patients with infection and to assess whether the effect differs between the two antibiotic administration types.

METHODS

A systematic search of studies on continuous infusions of intravenous antibiotics and traditional intermittent infusions of antibiotics for patients with infection was performed mainly in PubMed. The odds ratios (ORs) of the microbiological results as primary outcome and mortality rate, length of stay, and duration of antibiotic treatment as secondary outcomes were evaluated.

RESULTS

The meta-analysis comprised 9 randomized controlled trials (RCTs) and 4 retrospective studies comprising 1957 participants. Current analysis showed that the overall OR of clinical success between the continuous and intermittent groups was 0.675 (95% confidence interval [CI]: 0.523-0.870). Comparing continuous and intermittent groups, the subgroup analysis showed a lower ICU stay (OR 0.834, 95% CI: 0.542-1.282), a higher mortality (OR 1.433, 95% CI: 1.139-1.801), and a longer antibiotic duration (OR 1.055, 95% CI: 0.659-1.689), but the results of present meta-analysis were not significant because of the limited number of enrolled trials.

LIMITATIONS

Heterogeneity of included trials and studies.

CONCLUSIONS

The results of present meta-analysis were insufficient to recommend continuous infusion of intravenous antibiotics better than traditional intermittent infusions of antibiotics at routine clinical care. Hope large-scale RCT to provide more rebuts evidence for making recommendations to warrant continuous infusions of intravenous antibiotics at clinical practice.

Population Pharmacokinetics of Piperacillin in Sepsis Patients: Should Alternative Dosing Strategies Be Considered?

Sufficient antibiotic dosing in septic patients is essential for reducing mortality. Piperacillin-tazobactam is often used for empirical treatment, but due to the pharmacokinetic (PK) variability seen in septic patients, optimal dosing may be a challenge. We determined the PK profile for piperacillin given at 4 g every 8 h in 22 septic patients admitted to a medical ward. Piperacillin concentrations were compared to the clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/liter), and the following PK/pharmacodynamic (PD) targets were evaluated: the percentage of the dosing interval that the free drug concentration is maintained above the MIC (fTMIC) of 50% and 100%. A two-compartment population PK model described the data well, with clearance being divided into renal and nonrenal components. The renal component was proportional to the estimated creatinine clearance (eCLCR) and constituted 74% of the total clearance in a typical individual (eCLCR, 83.9 ml/min). Patients with a high eCLCR (>130 ml/min) were at risk of subtherapeutic concentrations for the current regimen, with a 90% probability of target attainment being reached at MICs of 2.0 (50% fTMIC) and 0.125 mg/liter (100% fTMIC). Simulations of alternative dosing regimens and modes of administration showed that dose increment and prolonged infusion increased the chance of achieving predefined PK/PD targets. Alternative dosing strategies may therefore be needed to optimize piperacillin exposure in septic patients. (This study has been registered at ClinicalTrials.gov under identifier NCT02569086.).

Resistance Trends and Treatment Options in Gram-Negative Ventilator-Associated Pneumonia

PURPOSE OF REVIEW

Hospital-acquired and ventilator-associated pneumonia (VAP) are frequent causes of infection among critically ill patients. VAP is the most common hospital-acquired bacterial infection among mechanically ventilated patients. Unfortunately, many of the nosocomial Gram-negative bacteria that cause VAP are increasingly difficult to treat. Additionally, the evolution and dissemination of multi- and pan-drug resistant strains leave clinicians with few treatment options. VAP patients represent a dynamic population at risk for antibiotic failure and under-dosing due to altered antibiotic pharmacokinetic parameters. Since few antibiotic agents have been approved within the last 15 years, and no new agents specifically targeting VAP have been approved to date, it is anticipated that this problem will worsen. Given the public health crisis posed by resistant Gram-negative bacteria, it is essential to establish a firm understanding of the current epidemiology of VAP, the changing trends in Gram-negative resistance in VAP, and the current issues in drug development for Gram-negative bacteria that cause VAP.

RECENT FINDINGS

Rapid identification technologies and phenotypic methods, new therapeutic strategies, and novel treatment paradigms have evolved in an attempt to improve treatment outcomes for VAP; however, clinical data supporting alternative treatment strategies and adjunctive therapies remain sparse. Importantly, new classes of antimicrobials, novel virulence factor inhibitors, and beta-lactam/beta-lactamase inhibitor combinations are currently in development. Conscientious stewardship of new and emerging therapeutic agents will be needed to ensure they remain effective well into the future.

Pharmacokinetic and Pharmacodynamic Efficacies of Continuous versus Intermittent Administration of Meropenem in Patients with Severe Sepsis and Septic Shock: A Prospective Randomized Pilot Study

Background:

The antibiotic meropenem is commonly administered in patients with severe sepsis and septic shock. We compared the pharmacokinetic, clinical, and bacteriological efficacies of continuous infusion of meropenem versus intermittent administration in such patients.

Methods:

Patients admitted to the Intensive Care Unit (ICU) with severe sepsis or septic shock who received meropenem were randomly assigned to either the continuous (n = 25) or intermittent groups (n = 25). The continuous group received a loading dose of 0.5 g of meropenem followed by a continuous infusion of 3 g/day; the intermittent group received an initial dose of 1.5 g followed by 1 g for every 8 h. Clinical success, microbiological eradication, superinfection, ICU mortality, length of ICU stay, and duration of meropenem treatment were assessed. Serial plasma meropenem concentrations for the first and third dosing periods (steady state) were also measured.

Results:

Clinical success was similar in both the continuous (64%) and intermittent (56%) groups (P = 0.564); the rates of microbiological eradication and superinfection (81.8% vs. 66.7% [P = 0.255] and 4% vs. 16% [P = 0.157], respectively) showed improvement in the continuous group. The duration of meropenem treatment was significantly shorter in the continuous group (7.6 vs. 9.4 days; P = 0.035), where a better steady-state concentration was also achieved. Peak and trough concentrations were significantly different between the continuous and intermittent groups both in the first (Cmax: 19.8 mg/L vs. 51.8 mg/L, P = 0.000; Cmin: 11.2 mg/L vs. 0.5 mg/L, P = 0.000) and third dosing periods (Cmax: 12.5 mg/L vs. 46.4 mg/L, P = 0.000; Cmin: 11.4 mg/L vs. 0.6 mg/L, P = 0.000). For medium-susceptibility pathogens, continuous infusion concentrations above the minimal inhibitory concentration were 100%, which was better than that in the intermittent group.

Conclusions:

Continuous infusion of meropenem provides significantly shorter treatment duration and a tendency for superior bacteriological efficacy than intermittent administration. Continuous infusion may be more optimal against intermediate-susceptibility pathogens.

Determining β-lactam exposure threshold to suppress resistance development in Gram-negative bacteria

Objectives

β-Lactams are commonly used for nosocomial infections and resistance to these agents among Gram-negative bacteria is increasing rapidly. Optimized dosing is expected to reduce the likelihood of resistance development during antimicrobial therapy, but the target for clinical dose adjustment is not well established. We examined the likelihood that various dosing exposures would suppress resistance development in an in vitro hollow-fibre infection model.

Methods

Two strains of Klebsiella pneumoniae and two strains of Pseudomonas aeruginosa (baseline inocula of ∼10 8  cfu/mL) were examined. Various dosing exposures of cefepime, ceftazidime and meropenem were simulated in the hollow-fibre infection model. Serial samples were obtained to ascertain the pharmacokinetic simulations and viable bacterial burden for up to 120 h. Drug concentrations were determined by a validated LC-MS/MS assay and the simulated exposures were expressed as C min /MIC ratios. Resistance development was detected by quantitative culture on drug-supplemented media plates (at 3× the corresponding baseline MIC). The C min /MIC breakpoint threshold to prevent bacterial regrowth was identified by classification and regression tree (CART) analysis.

Results

For all strains, the bacterial burden declined initially with the simulated exposures, but regrowth was observed in 9 out of 31 experiments. CART analysis revealed that a C min /MIC ratio ≥3.8 was significantly associated with regrowth prevention (100% versus 44%, P  = 0.001).

Conclusions

The development of β-lactam resistance during therapy could be suppressed by an optimized dosing exposure. Validation of the proposed target in a well-designed clinical study is warranted.

Hospital Length of Stay Among Patients Receiving Intermittent Versus Prolonged Piperacillin/Tazobactam Infusion in the Intensive Care Units

OBJECTIVES

We sought to evaluate clinical outcomes of intensive care unit (ICU) patients following a hospital-wide initiative of prolonged piperacillin/tazobactam (PIP/TAZ) infusion.

METHODS

Retrospective observational study of patients >18 years old who was hospitalized in the ICU receiving PIP/TAZ for >72 hours during the preimplementation (June 1, 2010 to May 31, 2011) and postimplementation (July 7, 2011 to June 30, 2014) periods.

RESULTS

There were 124 and 429 patients who met inclusion criteria with average age of 54.3 and 56.9 years, and average duration of PIP/TAZ therapy was 6.1 ± 2.8 days and 5.9 ± 3.4 days in the pre- and postimplementation period, respectively. Intensive care unit and hospital length of stay (LOS) following initiation of PIP/TAZ were 8.0 ± 8.4 days versus 6.4 ± 6.8 days and 26.3 ± 22.8 days versus 20.4 ± 16.1 days among patients in the pre- and postimplementation periods, respectively. Compared to patients who received intermittent PIP/TAZ infusion, the adjusted difference in ICU and hospital LOS was 0.6 ± 0.8 days (95% confidence interval [CI]: -0.9 to 2.1 days) and 5.6 ± 2.1 days (95% CI: 1.4 - 9.7 days) shorter among patients who received prolonged PIP/TAZ infusion. At hospital discharge, 19 (15.3%) intermittent infusion and 74 (17.2%) prolonged infusion recipients had died. In comparison to intermittent infusion recipients, the adjusted odds ratio for mortality was 1.17 (95% CI: 0.65-2.1) with prolonged infusion.

CONCLUSION

Our study demonstrated a reduction in hospital LOS with prolonged PIP/TAZ infusion among critically ill patients. Randomized trials are needed to further validate these findings.

Target attainment with continuous dosing of piperacillin/tazobactam in critical illness: a prospective observational study

Optimal dosing of β-lactam antibiotics in critically ill patients is a challenge given the unpredictable pharmacokinetic profile of this patient population. Several studies have shown intermittent dosing to often yield inadequate drug concentrations. Continuous dosing is an attractive alternative from a pharmacodynamic point of view. This study evaluated whether, during continuous dosing, piperacillin concentrations reached and maintained a pre-defined target in critically ill patients. Adult patients treated with piperacillin by continuous dosing in the intensive care unit of a university medical centre in The Netherlands were prospectively studied. Total and unbound piperacillin concentrations drawn at fixed time points throughout the entire treatment course were determined by liquid chromatography-tandem mass spectrometry. A pharmacokinetic combined target of a piperacillin concentration ≥80 mg/L, reached within 1 h of starting study treatment and maintained throughout the treatment course, was set. Eighteen patients were analysed. The median duration of monitored piperacillin treatment was 60 h (interquartile range, 33-96 h). Of the 18 patients, 5 (27.8%) reached the combined target; 15 (83.3%) reached and maintained a less strict target of >16 mg/L. In this patient cohort, this dosing schedule was insufficient to reach the pre-defined target. Depending on which target is to be met, a larger initial cumulative dose is desirable, combined with therapeutic drug monitoring.

Management of intra-abdominal infections: recommendations by the WSES 2016 consensus conference

This paper reports on the consensus conference on the management of intra-abdominal infections (IAIs) which was held on July 23, 2016, in Dublin, Ireland, as a part of the annual World Society of Emergency Surgery (WSES) meeting. This document covers all aspects of the management of IAIs. The Grading of Recommendations Assessment, Development and Evaluation recommendation is used, and this document represents the executive summary of the consensus conference findings.

Continuous and Prolonged Intravenous β-Lactam Dosing: Implications for the Clinical Laboratory

Beta-lactam antibiotics serve as a cornerstone in the management of bacterial infections because of their wide spectrum of activity and low toxicity. Since resistance rates among bacteria are continuously on the rise and the pipeline for new antibiotics does not meet this trend, an optimization of current beta-lactam treatment is needed. This review provides an overview of optimization through use of prolonged- and continuous-infusion dosing strategies compared with more traditional intermittent infusions. Included is an overview of the scientific basis for using these nontraditional prolonged- and continuous-infusion-based regimens, with a focus on major areas in which the clinical laboratory can support the clinical use of these regimens.

Standard dosing of piperacillin and meropenem fail to achieve adequate plasma concentrations in ICU patients

BACKGROUND

Controversies remain regarding optimal dosing and the need for plasma concentration measurements when treating intensive care patients with beta-lactam antibiotics.

METHODS

We studied ICU patients treated with either antibiotic, excluding patients on renal replacement therapy. Antibiotic concentrations were measured at the mid and end of the dosing interval, and repeated after 2-3 days when feasible. Glomerular filtration rate (GFR) was estimated from plasma creatinine and cystatin C, GFR calculated from cystatin C (eGFR) and measured creatinine clearance (CrCl). Measured concentrations were compared to the clinical susceptible breakpoints for Pseudomonas aeruginosa, 16 and 2 mg/l for piperacillin and meropenem respectively.

RESULTS

We analysed 33 and 31 paired samples from 20 and 19 patients treated with piperacillin-tazobactam and meropenem respectively. Antibiotic concentrations at the mid and end of the dosing interval were for piperacillin, 27.0 (14.7-52.9) and 8.6 (2.7-30.3); and for meropenem, 7.5 (4.7-10.2) and 2.4 (1.0-3.5). All values median (interquartile range) and concentrations in mg/l. The percentage of measured concentrations below the breakpoint at the mid and end of the dosing interval were for piperacillin, 27% and 61%; and for meropenem, 6% and 48%. Lower estimates of GFR were associated with higher concentrations but concentrations varied greatly between patients with similar GFR. The correlation with terminal concentration half-life was similar for eGFR and CrCl.

CONCLUSIONS

With standard doses of meropenem and piperacillin-tazobactam, plasma concentrations in ICU patients vary > 10-fold and are suboptimal in a significant percentage of patients. The variation is large also between patients with similar renal function.

Clinical outcomes of extended versus intermittent administration of piperacillin/tazobactam for the treatment of hospital-acquired pneumonia: a randomized controlled trial

The purpose of this study was to assess the pharmacokinetic (PK) characteristics, clinical efficiency, and pharmacoeconomic parameters of piperacillin/tazobactam administered by extended infusion (EI) or intermittent infusion (II) in the treatment of hospital-acquired pneumonia (HAP) in critically ill patients with low illness severity in China. Fifty patients completed the study, with 25 patients receiving 4/0.5 g piperacillin/tazobactam over 30 min as the II group and 25 patients receiving 4/0.5 g piperacillin/tazobactam over 3 h every 6 h as the EI group. Drug assay was performed using high-performance liquid chromatography (HPLC). The percentage of the dosing interval for which the free piperacillin concentration (%fT) exceeds the minimum inhibitory concentration (MIC) was calculated. The patients' therapy cost, clinical efficiency, and adverse effects were also recorded. %fT>MIC was about 100, 98.73, and 93.04 % in the EI arm versus 81.48, 53.29, and 42.15 % in the II arm, respectively, when the microorganism responsible for HAP had an MIC of 4, 8, and 16 mg/L. The therapy cost in the EI group was lower than that of the II group ($1351.72 ± 120.39 vs. $1782.04 ± 164.51, p = 0.001). However, the clinical success rate, clinical failure rate, and drug-related adverse events did not significantly differ between groups. EI treatment with piperacillin/tazobactam was a cost-effective approach to the management of HAP, being equally clinically effective to conventional II.

Sepsis and Septic Shock in the Equine Neonate

Sepsis and septic shock represent a major cause of morbidity and mortality in equine neonates and in all species. Early recognition of the condition is important, but definitive examination and laboratory variables to predict equine neonatal sepsis are lacking. Early and aggressive treatment should include broad-spectrum antimicrobial coverage, source control, and hemodynamic support. Field practitioners and intensive care clinicians work together in the management of this condition because the recognition and initial treatment should begin as early as possible.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

Prolonged versus Intermittent Infusion of β-Lactams for the Treatment of Nosocomial Pneumonia: A Meta-Analysis

BACKGROUND

The primary objective of this meta-analysis is aimed at determining whether β-lactams prolonged infusion in patients with nosocomial pneumonia (NP) results in higher cure rate and improved mortality compared to intermittent infusion.

MATERIALS AND METHODS

Relevant studies were identified from searches of MEDLINE, EMBASE, and CENTRAL from inception to September 1st, 2015. All published articles which evaluated the outcome of extended/continuous infusion of antimicrobial therapy versus intermittent infusion therapy in the treatment of NP were reviewed.

RESULTS

A total of ten studies were included in the analysis involving 1,051 cases of NP. Prolonged infusion of β-lactams was associated with higher clinical cure rate (OR 2.45, 95% CI, 1.12, 5.37) compared to intermittent infusion. However, there was no significant difference in mortality (OR 0.85, 95% CI 0.63-1.15) between the two groups. Subgroup analysis for β-lactam subclasses and for severity of illness showed comparable outcomes.

CONCLUSION

The limited data available suggest that reduced clinical failure rates when using prolonged infusions of β-lactam antibiotics in critically ill patients with NP. More detailed studies are needed to determine the impact of such strategy on mortality in this patient population.

A Multicenter Randomized Trial of Continuous versus Intermittent β-Lactam Infusion in Severe Sepsis

RATIONALE

Continuous infusion of β-lactam antibiotics may improve outcomes because of time-dependent antibacterial activity compared with intermittent dosing.

OBJECTIVES

To evaluate the efficacy of continuous versus intermittent infusion in patients with severe sepsis.

METHODS

We conducted a randomized controlled trial in 25 intensive care units (ICUs). Participants commenced on piperacillin-tazobactam, ticarcillin-clavulanate, or meropenem were randomized to receive the prescribed antibiotic via continuous or 30-minute intermittent infusion for the remainder of the treatment course or until ICU discharge. The primary outcome was the number of alive ICU-free days at Day 28. Secondary outcomes were 90-day survival, clinical cure 14 days post antibiotic cessation, alive organ failure-free days at Day 14, and duration of bacteremia.

MEASUREMENTS AND MAIN RESULTS

We enrolled 432 eligible participants with a median age of 64 years and an Acute Physiology and Chronic Health Evaluation II score of 20. There was no difference in ICU-free days: 18 days (interquartile range, 2-24) and 20 days (interquartile range, 3-24) in the continuous and intermittent groups (P = 0.38). There was no difference in 90-day survival: 74.3% (156 of 210) and 72.5% (158 of 218); hazard ratio, 0.91 (95% confidence interval, 0.63-1.31; P = 0.61). Clinical cure was 52.4% (111 of 212) and 49.5% (109 of 220); odds ratio, 1.12 (95% confidence interval, 0.77-1.63; P = 0.56). There was no difference in organ failure-free days (6 d; P = 0.27) and duration of bacteremia (0 d; P = 0.24).

CONCLUSIONS

In critically ill patients with severe sepsis, there was no difference in outcomes between β-lactam antibiotic administration by continuous and intermittent infusion. Australian New Zealand Clinical Trials Registry number (ACT RN12612000138886).

Bloodstream infections in the Intensive Care Unit

Bloodstream infections (BSIs) represent a common complication among critically ill patients and a leading cause of morbidity and mortality. The prompt initiation of an effective antibiotic therapy is necessary in order to reduce mortality and to improve clinical outcomes. However, the choice of the empiric antibiotic regimen is often challenging, due to the worldwide spread of multi-drug resistant (MDR) organisms with reduced susceptibility to the available broad-spectrum antimicrobials. New therapeutic strategies are 5 to improve the effectiveness of antibiotic treatment while minimizing the risk of resistance selection.

Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs.

Interethnic differences in pharmacokinetics of antibacterials

BACKGROUND

Optimal antibacterial dosing is imperative for maximising clinical outcome. Many factors can contribute to changes in the pharmacokinetics of antibacterials to the extent where dose adjustment may be needed. In acute illness, substantial changes in important pharmacokinetic parameters such as volume of distribution and clearance can occur for certain antibacterials. The possibility of interethnic pharmacokinetic differences can further complicate attempts to design an appropriate dosing regimen. Factors of ethnicity, such as genetics, body size and fat distribution, contribute to differences in absorption, distribution, metabolism and elimination of drugs. Despite extensive previous work on the altered pharmacokinetics of antibacterials in some patient groups such as the critically ill, knowledge of interethnic pharmacokinetic differences for antibacterials is limited.

OBJECTIVES

This systematic review aims to describe any pharmacokinetic differences in antibacterials between different ethnic groups, and discuss their probable mechanisms as well as any clinical implications.

METHODS

We performed a structured literature review to identify and describe available data of the interethnic differences in the pharmacokinetics of antibacterials.

RESULTS

We found 50 articles that met our inclusion criteria and only six of these compared antibacterial pharmacokinetics between different ethnicities within the same study. Overall, there was limited evidence available. We found that interethnic pharmacokinetic differences are negligible for carbapenems, most β-lactams, aminoglycosides, glycopeptides, most fluoroquinolones, linezolid and daptomycin, whereas significant difference is likely for ciprofloxacin, macrolides, clindamycin, tinidazole and some cephalosporins. In general, subjects of Asian ethnicity achieve drug exposures up to two to threefold greater than Caucasian counterparts for these antibacterials. This difference is caused by a comparatively lower volume of distribution and/or drug clearance.

CONCLUSION

Interethnic pharmacokinetic differences of antibacterials are likely; however, the clinical relevance of these differences is unknown and warrants further research.

Population pharmacokinetics of piperacillin in the early phase of septic shock: does standard dosing result in therapeutic plasma concentrations?

Antibiotic dosing in septic shock patients poses a challenge for clinicians due to the pharmacokinetic (PK) variability seen in this patient population. Piperacillin-tazobactam is often used for empirical treatment, and initial appropriate dosing is crucial for reducing mortality. Accordingly, we determined the pharmacokinetic profile of piperacillin (4 g) every 8 h, during the third consecutive dosing interval, in 15 patients treated empirically for septic shock. We developed a population pharmacokinetic model to assess empirical dosing and to simulate alternative dosing regimens and modes of administration. Time above the MIC (T>MIC) predicted for each patient was evaluated against clinical breakpoint MIC for Pseudomonas aeruginosa (16 mg/liter). Pharmacokinetic-pharmacodynamic (PK/PD) targets evaluated were 50% fT>4×MIC and 100% fT>MIC. A population PK model was developed using NONMEM, and data were best described by a two-compartment model. Central and intercompartmental clearances were 3.6 liters/h (relative standard error [RSE], 15.7%) and 6.58 liters/h (RSE, 16.4%), respectively, and central and peripheral volumes were 7.3 liters (RSE, 11.8%) and 3.9 liters (RSE, 9.7%), respectively. Piperacillin plasma concentrations varied considerably between patients and were associated with levels of plasma creatinine. Patients with impaired renal function were more likely to achieve predefined PK/PD targets than were patients with preserved or augmented renal function. Simulations of alternative dosing regimens showed that frequent intermittent bolus dosing as well as dosing by extended and continuous infusion increases the probability of attaining therapeutic plasma concentrations. For septic shock patients with preserved or augmented renal function, dose increment or prolonged infusion of the drug needs to be considered. (This study has been registered at ClinicalTrials.gov under registration no. NCT02306928.).

Pharmacokinetic and pharmacodynamic considerations of antimicrobial drug therapy in cancer patients with kidney dysfunction

Patients with cancer have a high inherent risk of infectious complications. In addition, the incidence of acute and chronic kidney dysfunction rises in this population. Anti-infective drugs often require dosing modifications based on an estimate of kidney function, usually the glomerular filtration rate (GFR). However, there is still no preferential GFR formula to be used, and in acute kidney injury there is always a considerable time delay between true kidney function and estimated GFR. In most cases, the anti-infective therapy should start with an immediate and high loading dose. Pharmacokinetic as well as pharmacodynamic principles must be applied for further dose adjustment. Anti-infective drugs with time-dependent action should be given with the target of high trough concentrations (e.g., beta lactam antibiotics, penems, vancomycin, antiviral drugs). Anti-infective drugs with concentration-dependent action should be given with the target of high peak concentrations (e.g., aminoglycosides, daptomycin, colistin, quinolones). Our group created a pharmacokinetic database, called NEPharm, hat serves as a reference to obtain reliable dosing regimens of anti-infective drugs in kidney dysfunction as well as renal replacement therapy. To avoid the risk of either too low or too infrequent peak concentrations, we prefer the eliminated fraction rule for dose adjustment calculations.

[Pharmacokinetics and pharmacodynamics of antibiotic therapy]

Antibiotic agents are crucial pillars in intensive care medicine and must be used rationally and sensibly. In the case of critically ill patients optimal dosing with respect to pharmacokinetic and pharmacodynamic principles (PK/PD) can be vital. Preclinical results demonstrated important differences between antibiotic classes and gave rise to differing clinical dosing strategies, e.g. high dose once daily regimens for aminoglycosides or extended/continuous infusion of betalactams. Critically ill patients with altered pharmacokinetic parameters and infections by pathogens with low susceptibility are most likely to benefit from PK/PD-guided therapy.

Clinical and Economic Impact of Empirical Extended-Infusion Piperacillin-Tazobactam in a Community Medical Center

BACKGROUND

Current medical center practice allows for the automatic conversion of all piperacillin/tazobactam orders from intermittent to extended infusion (EI).

OBJECTIVE

To compare the clinical and cost impact of empirical extended-infusion piperacillin/tazobactam.

METHODS

All consecutive patients treated with piperacillin/tazobactam for >48 hours were reviewed for inclusion. Patients were stratified into 2 groups: (1) traditional infusion (TI), preprotocol implementation, and (2) EI, postprotocol implementation. Patient demographics and primary and secondary diagnoses were extracted from the hospital discharge database. All patients were assessed for the primary end point of all cause 14-day in-hospital mortality. Secondary outcomes included length of hospital stay, duration of antibiotic therapy, cost per treatment course, and occurrence of Clostridium difficile infection.

RESULTS

A total of 2150 patients were included (EI = 632; TI = 1518). After adjusting for comorbidity, length of stay, and age, 14-day in-hospital mortality was similar between groups (odds ratio = 1.16; 95% CI = 0.85-1.58; P = 0.37). Length of stay was similar between the EI group versus TI (mean ± SD: 12.5 ± 9.58 days vs 11.8 ± 9.58 days, respectively; P = 0.10) after adjusting for age and Chalson-Deyo comorbidity index. Total cost per treatment course was reduced in the EI group by 13% compared with the TI group ($565.90 ± $257.70 vs $648.30 ± $349.20, respectively; P < 0.0001).

CONCLUSION

Automatic substitution of EI for TI piperacillin/tazobactam is safe and associated with significant cost savings. EI piperacillin/tazobactam was not associated with a reduction in mortality or length of stay.

Augmented renal clearance and therapeutic monitoring of β-lactams

Successful application of antibacterial therapy in the critically ill requires an appreciation of the complex interaction between the host, the causative pathogen and the chosen pharmaceutical. A pathophysiological change in the intensive care unit (ICU) patient challenging the 'one dose fits all' concept includes augmented renal clearance (ARC), defined as a creatinine clearance (CL(Cr)) of ≥130 mL/min. Ideally, CL(Cr) values should be obtained by a timed measured collection of urine, with plasma and urine creatinine levels. Increased renal clearance of antibiotics also occurs in the ICU patient and therefore β-lactam antibiotic exposure in the critically ill could easily lead to trough drug concentrations below therapeutic ranges. One way to document and alter drug levels is via therapeutic drug monitoring (TDM). The interactions of ARC and β-lactam TDM are further explored in this article in specific reference to a concomitant article in this issue of the journal.

Pharmacokinetic considerations and dosing strategies of antibiotics in the critically ill patient

The treatment of sepsis remains a significant challenge and is the cause of high mortality and morbidity. The pathophysiological alterations that are associated with sepsis can complicate drug dosing. Critical care patients often have capillary leak, increased cardiac output and altered protein levels which can have profound effects on the volume of distribution (Vd) and clearance (Cl) of antibacterial agents, both of which may affect the pharmacokinetics (PK) / pharmacodynamics (PD) of the drug. Along with antibacterial factors such as the hydrophilicity and its kill characteristics and the susceptibility and site of action of the microorganism, different dosing and administration strategies may be needed for the different drug classes. In conclusion, developing dosing and administration regimes of antibacterials that adhere to PK/PD principles increase antibacterial exposure. Tailoring therapy to the individual patient combined with TDM may contribute to improved clinical efficacy and contain the spread of resistance.