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

Biomarkers: Are They Useful in Severe Community-Acquired Pneumonia?

Community acquired pneumonia (CAP) is a prevalent infectious disease often requiring hospitalization, although its diagnosis remains challenging as there is no gold standard test. In severe CAP, clinical and radiologic criteria have poor sensitivity and specificity, and microbiologic documentation is usually delayed and obtained in less than half of sCAP patients. Biomarkers could be an alternative for diagnosis, treatment monitoring and establish resolution. Beyond the existing evidence about biomarkers as an adjunct diagnostic tool, most evidence comes from studies including CAP patients in primary care or emergency departments, and not only sCAP patients. Ideally, biomarkers used in combination with signs, symptoms, and radiological findings can improve clinical judgment to confirm or rule out CAP diagnosis, and may be valuable adjunctive tools for risk stratification, differentiate viral pneumonia and monitoring the course of CAP. While no single biomarker has emerged as an ideal one, CRP and PCT have gathered the most evidence. Overall, biomarkers offer valuable information and can enhance clinical decision-making in the management of CAP, but further research and validation are needed to establish their optimal use and clinical utility.

The budget impact of procalcitonin-guided antibiotic stewardship compared to standard of care for patients with suspected sepsis admitted to the intensive care unit in Belgium

In Belgium, antibiotic resistance leads to approximately 530 deaths with a €24 million financial burden annually. This study estimated the impact of procalcitonin-guided antibiotic stewardship programs to reduce antibiotic consumption versus standard of care in patients with suspected sepsis. A decision analytic tree modelled health and budget outcomes of procalcitonin-guided antibiotic stewardship programs for patients admitted to the intensive care unit (ICU). A literature search, a survey with local clinical experts, and national database searches were conducted to obtain model input parameters. The main outcomes were total budget impact per patient, reduction in number of antibiotic resistance cases, and cost per antibiotic day avoided. To evaluate the impact of parameter uncertainty on the source data, a deterministic sensitivity analysis was performed. A scenario analysis was conducted to investigate budget impact when including parameters for reduction in length of ICU stay and mechanical ventilation duration, in addition to base-case parameters. Based on model predictions, procalcitonin-guided antibiotic stewardship programs could reduce the number of antibiotic days by 66,868, resulting in €1.98 million savings towards antibiotic treatment in current clinical practice. Antibiotic resistance cases could decrease by 7.7% (6.1% vs 9.2%) in the procalcitonin-guided setting compared with standard of care. The base-case budget impact suggests an investment of €1.90 per patient. The sensitivity analysis showed uncertainty, as the main drivers can alter potential cost savings. The scenario analysis indicated a saving of €1,405 per patient, with a reduction of 1.5 days in the ICU (14.8 days vs 12.8 days), and a reduction of 22.7% (18.1-27.2%) in mechanical ventilation duration. The associated sensitivity analysis was shown to be robust in all parameters. Procalcitonin-guided antibiotic stewardship programs are associated with clinical benefits that positively influence antimicrobial resistance in Belgium. A small investment per patient to implement procalcitonin testing may lead to considerable cost savings.

Case - Control study: Evaluation of plasma procalcitonin concentration as an indicator of inflammation in healthy and sick cows

This case - control study aims to evaluate Procalcitonin (PCT) plasma concentrations in healthy and hospitalized cows with a conclusive diagnosis of inflammation due to bacterial infection. Thirty-four healthy and 131 sick cows were included. Procalcitonin concentrations were assessed using an ELISA kit for cattle. Depending on whether sick cows received antimicrobial treatments prior to admission or not, they were divided in treated (TP) or not treated (NTP) subgroups. Mann-Whitney U tests were performed to determine differences between healthy vs sick cows, while Kruskal-Wallis with Dunn's multiple comparison test were applied for healthy vs sick subgroups. Receiver operating characteristic (ROC) analysis was performed to assess the optimal cut-off value. Kaplan-Meier survival curves were determined for cows belonging to the groups with PCT values below and above ROC cut-offs. Plasma PCT concentration was 200.1 (147.8-324.1) pg/mL and 361.6 (239.7-947.1) pg/mL in the healthy control and in the sick group, respectively (P < 0.001). The optimal cut-off value of plasma PCT concentration was 244.4 pg/mL (sensitivity 73.6%, specificity 60.0%). The plasma PCT concentration was 267.5 (210.3-771.2) pg/mL in the TP subgroup and 425.6 (253.1-1242) pg/mL in the NTP subgroup (P = 0.03). Cows with PCT above the ROC cut-off value had a reduced survival percentage and a higher mortality risk (P < 0.05). Procalcitonin showed the ability of differentiate healthy cows from hospitalized cows with a conclusive diagnosis of inflammation due to bacterial infection. Moreover, PCT was a good predictor of negative prognostic outcome.

Antimicrobial Stewardship in the ICU

Increasing rates of infection and multidrug-resistant pathogens, along with a high use of antimicrobial therapy, make the intensive care unit (ICU) an ideal setting for implementing and supporting antimicrobial stewardship efforts. Overuse of antimicrobial agents is common in the ICU, as practitioners are challenged daily with achieving early, appropriate empiric antimicrobial therapy to improve patient outcomes. While early antimicrobial stewardship programs focused on the financial implications of antimicrobial overuse, current goals of stewardship programs align closely with those of critical care providers-to optimize patient outcomes, reduce development of resistance, and minimize adverse outcomes associated with antibiotic overuse and misuse such as acute kidney injury and Clostridioides difficile-associated disease. Significant opportunities exist in the ICU for critical care clinicians to support stewardship practices at the bedside, including thoughtful and restrained initiation of antimicrobial therapy, use of biomarkers in addition to rapid diagnostics, Staphylococcus aureus screening, and traditional microbiologic culture and susceptibilities to guide antibiotic de-escalation, and use of the shortest duration of therapy that is clinically appropriate. Integration of critical care practitioners into the initiatives of antimicrobial stewardship programs is key to their success. This review summarizes key components of antimicrobial stewardship programs and mechanisms for critical care practitioners to share the responsibility for antimicrobial stewardship.

Place in Therapy of the Newly Available Armamentarium for Multi-Drug-Resistant Gram-Negative Pathogens: Proposal of a Prescription Algorithm

The worldwide propagation of antimicrobial resistance represents one of the biggest threats to global health and development. Multi-drug-resistant organisms (MDROs), including carbapenem-resistant non-fermenting Gram-negatives and Enterobacterales, present a heterogeneous and mutating spread. Infections by MDRO are often associated with an unfavorable outcome, especially among critically ill populations. The polymyxins represented the backbone of antibiotic regimens for Gram-negative MDROs in recent decades, but their use presents multiple pitfalls. Luckily, new agents with potent activity against MDROs have become available in recent times and more are yet to come. Now, we have the duty to make the best use of these new therapeutic tools in order not to prematurely compromise their effectiveness and at the same time improve patients’ outcomes. We reviewed the current literature on ceftazidime/avibactam, meropenem/vaborbactam and cefiderocol, focusing on antimicrobial spectrum, on the prevalence and mechanisms of resistance development and on the main in vitro and clinical experiences available so far. Subsequently, we performed a step-by-step construction of a speculative algorithm for a reasoned prescription of these new antibiotics, contemplating both empirical and targeted use. Attention was specifically posed on patients with life-risk conditions and in settings with elevated prevalence of MDRO.

Optimizing Antimicrobial Drug Dosing in Critically Ill Patients

A fundamental step in the successful management of sepsis and septic shock is early empiric antimicrobial therapy. However, for this to be effective, several decisions must be addressed simultaneously: (1) antimicrobial choices should be adequate, covering the most probable pathogens; (2) they should be administered in the appropriate dose, (3) by the correct route, and (4) using the correct mode of administration to achieve successful concentration at the infection site. In critically ill patients, antimicrobial dosing is a common challenge and a frequent source of errors, since these patients present deranged pharmacokinetics, namely increased volume of distribution and altered drug clearance, which either increased or decreased. Moreover, the clinical condition of these patients changes markedly over time, either improving or deteriorating. The consequent impact on drug pharmacokinetics further complicates the selection of correct drug schedules and dosing during the course of therapy. In recent years, the knowledge of pharmacokinetics and pharmacodynamics, drug dosing, therapeutic drug monitoring, and antimicrobial resistance in the critically ill patients has greatly improved, fostering strategies to optimize therapeutic efficacy and to reduce toxicity and adverse events. Nonetheless, delivering adequate and appropriate antimicrobial therapy is still a challenge, since pathogen resistance continues to rise, and new therapeutic agents remain scarce. We aim to review the available literature to assess the challenges, impact, and tools to optimize individualization of antimicrobial dosing to maximize exposure and effectiveness in critically ill patients.