Comprehensive Guidance for Antibiotic Dosing in Obese Adults

Physiologically based pharmacokinetic modeling in obesity: applications and challenges

INTRODUCTION

Rising global obesity rates pose a threat to people's health. Obesity causes a series of pathophysiologic changes, making the response of patients with obesity to drugs different from that of nonobese, thus affecting the treatment efficacy and even leading to adverse events. Therefore, understanding obesity's effects on pharmacokinetics is essential for the rational use of drugs in patients with obesity.

AREAS COVERED

Articles related to physiologically based pharmacokinetic (PBPK) modeling in patients with obesity from inception to October 2023 were searched in PubMed, Embase, Web of Science and the Cochrane Library. This review outlines PBPK modeling applications in exploring factors influencing obesity's effects on pharmacokinetics, guiding clinical drug development and evaluating and optimizing clinical use of drugs in patients with obesity.

EXPERT OPINION

Obesity-induced pathophysiologic alterations impact drug pharmacokinetics and drug-drug interactions (DDIs), altering drug exposure. However, there is a lack of universal body size indices or quantitative pharmacology models to predict the optimal for the patients with obesity. Therefore, dosage regimens for patients with obesity must consider individual physiological and biochemical information, and clinically individualize therapeutic drug monitoring for highly variable drugs to ensure effective drug dosing and avoid adverse effects.

Impact of Obesity on Echinocandin Effectiveness in Treating Candida Infections: A Retrospective Observational Cohort Study

Introduction

Echinocandins are used to treat invasive candidiasis (IC), with FDA-approved doses indicated for both obese and non-obese patients. Pharmacokinetic (PK) studies have identified subtherapeutic exposure in obese patients receiving standard doses (SDs) of echinocandins. However, research on clinical outcome differences of echinocandins' SDs between obese and non-obese patients is lacking. Therefore, this study aimed to evaluate the effectiveness of echinocandins' SDs in obese compared to normal-weight patients with IC.

Patients and Methods

This retrospective cohort study was conducted at King Saud University Medical City (KSUMC) from Jan 2017 to Feb 2023. The study included adult patients diagnosed with Candida infections who received ≥ 4 doses of echinocandins. Patients with body mass index (BMI) less than 18 kg/m2 were excluded from the study. The primary and secondary outcomes included the total length of stay (LOS), IC duration, frequency of clinical resolution and all-cause mortality.

Results

This study included 132 patients (47 obese; 85 non-obese) with a median age of 61 years. The median BMI and weight were different between the obese (34.5 kg/m2, 88 kg) and non-obese (24 kg/m2, 65 kg) groups (P= 0.01). Micafungin and caspofungin were used in 63.6% and 36.4% of patients, respectively. The total LOS and length of IC infections were similar between both groups, with median values of 29.5 days (P= 0.896) and 18 days (P = 0.160), respectively. The clinical improvement percentages were 68.1% for obese and 65.9% for non-obese patients (P= 0.797), with all-cause mortality rates at 44.7% and 42.4%, respectively (P= 0.796).

Conclusion

The study found no clinical outcome differences between obese and non-obese patients, with Similar effectiveness of the echinocandins' SDs in both groups. Further research in multi-centre settings is recommended to detect any potential differences between the two groups.

Evaluation and implementation of optimized antimicrobial dosing strategies in obese and underweight patients

PURPOSE

We aimed to develop and implement dosing recommendations for antimicrobials in obese and underweight patients within an academic hospital, and assess their impact on antibiotic prescribing.

METHODS

A multi-step approach project was performed. First, obese and underweight patient prevalence and antimicrobial prescription frequency was determined in a point prevalence study. Second and third, a literature review and e-survey provided dosing evidence. Fourth, a consensus meeting was organized to formulate dosing recommendations. Fifth, these were implemented in our clinical validation service as six clinical rules continuously screening patients' records for potentially inappropriate prescriptions (PIPs). Uptake was evaluated by documenting the number of advices and acceptance rate. Last, an interrupted time series analysis (ITS) compared pre- and post-implementation periods to measure the impact of the intervention on residual PIPs/day. A residual PIP was defined as a PIP which persisted up to 48 h.

RESULTS

First, 41% of 15.896 hospitalized patients received antimicrobials over 20 days; of which 12% were obese and 9% underweight. Antibiotics were predominantly prescribed according to standard dosing regimens, adjusted to renal function. Next, six dosing recommendations, derived from literature, survey, and consensus, were implemented. In the fifth step, during an 18-week period, 219 advices were given, with 86% acceptance rate. Last, in the ITS analysis, at preintervention, a median of 75% residual PIPs/day existed, reduced to 0% postintervention. Use of clinical rules resulted in a significant immediate 84% relative reduction in residual PIPs (95% CI 0.55-0.94).

CONCLUSION

After conducting a literature review, e-survey, and seeking consensus from a panel of experts, dosing recommendations for antimicrobial treatment in both obese and underweight patients were developed. These recommendations have been successfully implemented into clinical practice, addressing the specific needs of these patient populations.

Updated antimicrobial dosing recommendations for obese patients

The prevalence of obesity has increased considerably in the last few decades. Pathophysiological changes in obese patients lead to pharmacokinetic (PK) and pharmacodynamic (PD) alterations that can condition the correct exposure to antimicrobials if standard dosages are used. Inadequate dosing in obese patients can lead to toxicity or therapeutic failure. In recent years, additional antimicrobial PK/PD data, extended infusion strategies, and studies in critically ill patients have made it possible to obtain data to provide a better dosage in obese patients. Despite this, it is usually difficult to find information on drug dosing in this population, which is sometimes contradictory. This is a comprehensive review of the dosing of different types of antimicrobials (antibiotics, antifungals, antivirals, and antituberculosis drugs) in obese patients, where the literature on PK and possible dosing strategies in obese adults was critically assessed.

A Quality Initiative to Improve Appropriate Medication Dosing in Pediatric Patients with Obesity

Introduction

Emerging evidence supports the use of alternative dosing weights for medications in patients with obesity. Pediatric obesity presents a particular challenge because most medications are dosed based on patient weight. Additionally, building system-wide pediatric obesity safeguards is difficult due to pediatric obesity definitions of body mass index-percentile-for-age via the Center for Disease Control growth charts. We describe a quality initiative to increase appropriate medication dosing in inpatients with obesity. The specific aim was to increase appropriate dosing for 7 high-risk medications in inpatients with obesity ≥2 years old from 37% to >74% and to sustain for 1 year.

Methods

The Institute for Healthcare Improvement model for improvement was used to plan interventions and track outcomes progress. Interventions included a literature review to establish internal dosing guidance, electronic health record (EHR) functionality to identify pediatric patients with obesity, a default selection for medication weight with an opt-out, and obtaining patient heights in the emergency department.

Results

Appropriate dosing weight use in medication ordered for patients with obesity increased from 37% to 83.4% and was sustained above the goal of 74% for 12 months.

Conclusions

Implementation of EHR-based clinical decision support has increased appropriate evidence-based dosing of medications in pediatric and adult inpatients with obesity. Future studies should investigate the clinical and safety implications of using alternative dosing weights in pediatric patients.

[An online tool to personalize the drug-doses for obese adults]

BACKGROUND

Between 1975 and 2014, the number of people suffering from obesity tripled, reaching 17% of the adult population in France and more than 35% in the United States. Obesity is defined by a Body Mass Index (BMI)>30kg/m2 and characterized by a significant accumulation of adipose tissue responsible for the increase in weight. This accumulation leads to physiological changes capable of modifying the pharmacokinetics of drugs, which can lead to the administration of inappropriate doses. For this reason, some significant dosage adjustments are necessary for obese patients. However, data on these adaptations are not easily accessible and sometimes complex to implement in practice.

AIM

To perform a new online tool allowing to calculate and propose an adjusted dose of a drug that should be administered to an obese patient.

METHOD

(i) carrying out an extensive bibliographic research according to the PRISMA methodology; and (ii) the development of a new website site proposing an adjusted dose for obese patients.

RESULTS

Firstly, 49 reviews concerning the dose adaptation have been evaluated and, secondly, 319 articles have been selected. Among them, 204 articles have been included in the database to justify the adjusted dose of 84 drugs and administration methods including antibiotics, antifungals, anticoagulants or even cancer drugs. This database is available online through a calculator on the website named Adapt'Obese. Thus, with the sex, height and weight of an obese patient, Adapt'Obese proposes a personalized and adjusted dose of the drug to administer.

PERSPECTIVES

Other drugs will be added soon, and functional improvements are planned, with the aim of adapting the dosages in obese patients, as for patients with renal insufficiency.

Optimizing Antibiotic Therapy for Intravenous Drug Users: A Narrative Review Unraveling Pharmacokinetics/Pharmacodynamics Challenges

Intravenous drug users (IVDUs) face heightened susceptibility to life-threatening gram-positive bacterial infections, particularly methicillin-resistant Staphylococcus aureus (MRSA). While the standard antibiotic dosing strategies for special patients, such as obese or critically ill individuals, are known to be inadequate, raising concerns about treatment efficacy, a similar sort of understanding has not been assessed for IVDUs yet. With this in mind, this review examines the pharmacokinetic/pharmacodynamic characteristics of antibiotics commonly used against gram-positive bacteria in IVDUs. Focusing on daptomycin, vancomycin, teicoplanin, aminoglycosides, and the novel lipoglycopeptide dalbavancin, the study reveals significant pharmacokinetic variations in IVDUs, suggesting the need for personalized dosing. Concomitant opioid substitution therapy and other factors, such as malnutrition, contribute to altered pharmacokinetics/pharmacodynamics, emphasizing the importance of targeted therapeutic drug monitoring. Overall, our study calls for increased awareness among clinicians regarding the unique pharmacokinetic/pharmacodynamic challenges in IVDUs and advocates for tailored antibiotic dosing strategies to enhance treatment outcomes in this marginalized population.

Which Are the Best Regimens of Broad-Spectrum Beta-Lactam Antibiotics in Burn Patients? A Systematic Review of Evidence from Pharmacology Studies

BACKGROUND

Burn injury causes profound pathophysiological changes in the pharmacokinetic/pharmacodynamic (PK/PD) properties of antibiotics. Infections are among the principal complications after burn injuries, and broad-spectrum beta-lactams are the cornerstone of treatment. The aim of this study was to review the evidence for the best regimens of these antibiotics in the burn patient population.

METHODS

We performed a systematic review of evidence available on MEDLINE (from its inception to 2023) of pharmacology studies that focused on the use of 13 broad-spectrum beta-lactams in burn patients. We extracted and synthetized data on drug regimens and their ability to attain adequate PK/PD targets.

RESULTS

We selected 35 studies for analysis. Overall, studies showed that both high doses and the continuous infusion (CI) of broad-spectrum beta-lactams were needed to achieve internationally-recognized PK/PD targets, ideally with therapeutic drug monitoring guidance. The most extensive evidence concerned meropenem, but similar conclusions could be drawn about piperacillin-tazobactam, ceftazidime, cefepime, imipenem-clinastatin and aztreonam. Insufficient data were available about new beta-lactam-beta-lactamase inhibitor combinations, ceftaroline, ceftobiprole and cefiderocol.

CONCLUSIONS

Both high doses and CI of broad-spectrum beta-lactams are needed when treating burn patients due to the peculiar changes in the PK/PD of antibiotics in this population. Further studies are needed, particularly about newer antibiotics.

Intramacrophage lipid accumulation compromises T cell responses and is associated with impaired drug therapy against visceral leishmaniasis

Under perturbing conditions such as infection with Leishmania, a protozoan parasite living within the phagosomes in mammalian macrophages, cellular and organellar structures, and metabolism are dynamically regulated for neutralizing the pressure of parasitism. However, how modulations of the host cell metabolic pathways support Leishmania infection remains unknown. Herein, we report that lipid accumulation heightens the susceptibility of mice to L. donovani infection and promotes resistance to first-line anti-leishmanial drugs. Despite being pro-inflammatory, the in vitro generated uninfected lipid-laden macrophages (LLMs) or adipose-tissue macrophages (ATMs) display lower levels of reactive oxygen and nitrogen species. Upon infection, LLMs secrete higher IL-10 and lower IL-12p70 cytokines, inhibiting CD4+ T cell activation and Th1 response suggesting a key modulatory role for intramacrophage lipid accumulation in anti-leishmanial host defence. We, therefore, examined this causal relationship between lipids and immunomodulation using an in vivo high-fat diet (HFD) mouse model. HFD increased the susceptibility to L. donovani infection accompanied by a defective CD4+ Th1 and CD8+ T cell response. The white adipose tissue of HFD mice displays increased susceptibility to L. donovani infection with the preferential infection of F4/80+ CD11b+ CD11c+ macrophages with higher levels of neutral lipids reserve. The HFD increased resistance to a first-line anti-leishmanial drug associated with a defective adaptive immune response. These data demonstrate that the accumulation of neutral lipids contributes to susceptibility to visceral leishmaniasis hindering host-protective immune response and reducing the efficacy of antiparasitic drug therapies.

Effect of Obesity on the Pharmacokinetics and Pharmacodynamics of Anticancer Agents

An objective of the Precision Medicine Initiative, launched in 2015 by the US Food and Drug Administration and National Institutes of Health, is to optimize and individualize dosing of drugs, especially anticancer agents, with high pharmacokinetic and pharmacodynamic variability. The American Society of Clinical Oncology recently reported that 40% of obese patients receive insufficient chemotherapy doses and exposures, which may lead to reduced efficacy, and recommended pharmacokinetic studies to guide appropriate dosing in these patients. These issues will only increase in importance as the incidence of obesity in the population increases. This publication reviews the effects of obesity on (1) tumor biology, development of cancer, and antitumor response; (2) pharmacokinetics and pharmacodynamics of small-molecule anticancer drugs; and (3) pharmacokinetics and pharmacodynamics of complex anticancer drugs, such as carrier-mediated agents and biologics. These topics are not only important from a scientific research perspective but also from a drug development and regulator perspective. Thus, it is important to evaluate the effects of obesity on the pharmacokinetics and pharmacodynamics of anticancer agents in all categories of body habitus and especially in patients who are obese and morbidly obese. As the effects of obesity on the pharmacokinetics and pharmacodynamics of anticancer agents may be highly variable across drug types, the optimal dosing metric and algorithm for difference classes of drugs may be widely different. Thus, studies are needed to evaluate current and novel metrics and methods for measuring body habitus as related to optimizing the dose and reducing pharmacokinetic and pharmacodynamic variability of anticancer agents in patients who are obese and morbidly obese.

Therapeutic Options for Adult Patients With Persistent Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Narrative Review

OBJECTIVE

To compare the efficacy of antimicrobial therapies used in the management of persistent methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.

DATA SOURCES

A literature search using the PubMed database (inception to December 2022) was conducted using the search terms "Staphylococcus aureus bacteremia," "methicillin-susceptible Staphylococcus aureus bacteremia," "persistent methicillin-susceptible Staphylococcus aureus bacteremia," and "refractory methicillin-susceptible Staphylococcus aureus bacteremia ." In addition, therapeutic agents which could be used as treatment for MSSA including "nafcillin," "oxacillin," "cefazolin," "ceftaroline," "gentamicin," "rifampin," and "daptomycin" were also combined with the aforementioned search terms to capture data using these agents.

STUDY SELECTION/DATA EXTRACTION

Clinical data were limited to those published in the English language. Articles and abstracts were considered for inclusion in addition to ongoing trials identified through ClinicalTrials.gov.

DATA SYNTHESIS

A total of 78 articles were reviewed including 17 in vitro or animal model studies and 39 studies including patient data. The remaining 22 articles included guidelines, review articles, and editorials. Recent data evaluating use of dual β-lactam regimens for persistent MSSA bacteremia were limited to 8 case reports or case series.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

At present, there is little guidance on how to best manage patients with persistent MSSA bacteremia. This narrative review collates the available data to assist clinicians in selecting the best possible antimicrobial regimen when facing this clinical conundrum.

CONCLUSIONS

Modification of antimicrobial therapy, in conjunction with source control and infectious diseases consultation, may all be necessary to sterilize blood cultures in patients with persistent MSSA bacteremia.

Pharmacokinetics of obese adults: Not only an increase in weight

Obesity is a pathophysiological state defined by a body mass index > 30 kg/m2 and characterized by an adipose tissue accumulation leading to an important weight increased. Several pathologies named comorbidities such as cardiovascular disease, type 2 diabetes and cancer make obesity the fifth cause of death in the world. Physiological changes impact the four main phases of pharmacokinetics of some drugs and leads to an inappropriate drug-dose. For absorption, the gastrointestinal transit is accelerated, and the gastric empty time is shortened, that can reduce the solubilization and absorption of some oral drugs. The drug distribution is probably the most impacted by the obesity-related changes because the fat mass (FM) increases at the expense of the lean body weight (LBW), leading to an important increase of the volume of distribution for lipophilic drugs and a low or moderately increase of this parameter for hydrophilic drugs. This modification of the distribution may require drug-dose adjustments. By various mechanisms, the metabolism and elimination of drugs are impacted by obesity and should be considered as similar or lower than that non-obese patients. To better understand the necessary drug-dose adjustments in obese patients, a narrative review of the literature was conducted to highlight the main elements to consider in the therapeutic management of adult obese patients.

Rationale and evidence for the use of new beta-lactam/beta-lactamase inhibitor combinations and cefiderocol in critically ill patients

BACKGROUND

Healthcare-associated infections involving Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) phenotype are associated with impaired patient-centered outcomes and poses daily therapeutic challenges in most of intensive care units worldwide. Over the recent years, four innovative β-lactam/β-lactamase inhibitor (BL/BLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of certain DTR-GNB infections. The literature addressing their microbiological spectrum, pharmacokinetics, clinical efficacy and safety was exhaustively audited by our group to support the recent guidelines of the French Intensive Care Society on their utilization in critically ill patients. This narrative review summarizes the available evidence and unanswered questions on these issues.

METHODS

A systematic search for English-language publications in PUBMED and the Cochrane Library database from inception to November 15, 2022.

RESULTS

These drugs have demonstrated relevant clinical success rates and a reduced renal risk in most of severe infections for whom polymyxin- and/or aminoglycoside-based regimen were historically used as last-resort strategies-namely, ceftazidime-avibactam for infections due to Klebsiella pneumoniae carbapenemase (KPC)- or OXA-48-like-producing Enterobacterales, meropenem-vaborbactam for KPC-producing Enterobacterales, ceftazidime-avibactam/aztreonam combination or cefiderocol for metallo-β-lactamase (MBL)-producing Enterobacterales, and ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam for non-MBL-producing DTR Pseudomonas aeruginosa. However, limited clinical evidence exists in critically ill patients. Extended-infusion scheme (except for imipenem-relebactam) may be indicated for DTR-GNB with high minimal inhibitory concentrations and/or in case of augmented renal clearance. The potential benefit of combining these agents with other antimicrobials remains under-investigated, notably for the most severe presentations. Other important knowledge gaps include pharmacokinetic information in particular situations (e.g., pneumonia, other deep-seated infections, and renal replacement therapy), the hazard of treatment-emergent resistance and possible preventive measures, the safety of high-dose regimen, the potential usefulness of rapid molecular diagnostic tools to rationalize their empirical utilization, and optimal treatment durations. Comparative clinical, ecological, and medico-economic data are needed for infections in whom two or more of these agents exhibit in vitro activity against the causative pathogen.

CONCLUSIONS

New BL/BLI combinations and cefiderocol represent long-awaited options for improving the management of DTR-GNB infections. Several research axes must be explored to better define the positioning and appropriate administration scheme of these drugs in critically ill patients.

The place of new antibiotics for Gram-negative bacterial infections in intensive care: report of a consensus conference

INTRODUCTION

New beta-lactams, associated or not with beta-lactamase inhibitors (NBs/BIs), can respond to the spread of carbapenemase-producing enterobacteriales and nonfermenting carbapenem-resistant bacteria. The risk of emergence of resistance to these NBs/BIs makes guidelines necessary. The SRLF organized a consensus conference in December 2022.

METHODS

An ad hoc committee without any conflict of interest (CoI) with the subject identified the molecules (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-cilastatin-relebactam, meropenem-vaborbactam and cefiderocol); defined 6 generic questions; drew up a list of subquestions according to the population, intervention, comparison and outcomes (PICO) model; and reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Seven experts in the field proposed their own answers to the questions in a public session and answered questions from the jury (a panel of 10 critical-care physicians without any CoI) and the public. The jury then met alone for 48 h to write its recommendations. Due to the frequent lack of powerful studies that have used clinically important criteria of judgment, the recommendations were formulated as expert opinions as often as necessary.

RESULTS

The jury provided 17 statements answering 6 questions: (1) Is there a place in the ICU for the probabilistic use of new NBs/IBs active against Gram-negative bacteria? (2) In the context of documented infections with sensitivity to several of these molecules, are there pharmacokinetic, pharmacodynamic, ecological or medico-economic elements for prioritization? (3) What are the possible combinations with these molecules and in what context? (4) Should we integrate these new molecules into a carbapenem-sparing strategy? (5) What pharmacokinetic and pharmacodynamic data are available to optimize their mode of administration in critically ill patients? (6) What are the dosage adaptations in cases of renal insufficiency, hepatocellular insufficiency or obesity?

CONCLUSION

These recommendations should optimize the use of NBs/BIs in ICU patients.

Optimizing the Use of Beta-Lactam Antibiotics in Clinical Practice: A Test of Time

Despite their limitations, the pharmacokinetics (PK) and pharmacodynamics (PD) indices form the basis for our current understanding regarding antibiotic development, selection, and dose optimization. Application of PK-PD in medicine has been associated with better clinical outcome, suppression of resistance, and optimization of antibiotic consumption. Beta-lactam antibiotics remain the cornerstone for empirical and directed therapy in many patients. The percentage of time of the dosing interval that the free (unbound) drug concentration remains above the minimal inhibitory concentration (MIC) (%fT > MIC) has been considered the PK-PD index that best predicts the relationship between antibiotic exposure and killing for the beta-lactam antibiotics. Time dependence of beta-lactam antibiotics has its origin in the acylation process of the serine active site of penicillin-binding proteins, which subsequently results in bacteriostatic and bactericidal effects during the dosing interval. To enhance the likelihood of target attainment, higher doses, and prolonged infusion strategies, with/or without loading doses, have been applied to compensate for subtherapeutic levels of antibiotics related to PK-PD changes, especially in the early phase of severe sepsis. To minimize resistance and maximize clinical outcome, empirical therapy with a meropenem loading dose followed by high-dose-prolonged infusion should be considered in patients with high inoculum infections presenting as severe (Gram negative) sepsis. Subsequent de-escalation and dosing of beta-lactam antibiotics should be considered as an individualized dynamic process that requires dose adjustments throughout the time course of the disease process mediated by clinical parameters that indirectly assess PK-PD alterations.

Therapeutic Drug Monitoring of Antimicrobials in Critically Ill Obese Patients

Obesity is a significant global public health concern that is associated with an elevated risk of comorbidities as well as severe postoperative and nosocomial infections. The treatment of infections in critically ill obese patients can be challenging because obesity affects the pharmacokinetics and pharmacodynamics of antibiotics, leading to an increased risk of antibiotic therapy failure and toxicity due to inappropriate dosages. Precision dosing of antibiotics using therapeutic drug monitoring may help to improve the management of this patient population. This narrative review outlines the pharmacokinetic and pharmacodynamic changes that result from obesity and provides a comprehensive critical review of the current available data on dosage adjustment of antibiotics in critically ill obese patients.

Trends and Prediction of Surgical Site Infection After Elective Spine Surgery: An Analysis of the American College of Surgeons National Surgical Quality Improvement Project Database

Background: Surgical site infection (SSI) is an infrequent but costly complication after elective spine surgery. Identification of important temporal changes and predictive factors may inform targeted prevention efforts. Patients and Methods: A retrospective study of elective spine surgery patients was performed using the National Surgical Quality Improvement Programs (NSQIP) database from 2011 and 2019. Temporal changes in SSI and related factors were examined descriptively. Recursive partitioning and bootstrap forest techniques were used to inform the development of predictive models for SSI. Results: A total of 6,038 (1.66%) of 363,754 patients had an SSI recorded. Peri-operative transfusion and preoperative anemia decreased over the nine-year period, however, obesity and diabetes mellitus increased, whereas the SSI rate remained essentially unchanged. A full model including 15 variables had an area under the curve (AUC) of 0.693 (95% confidence interval [CI], 0.686-0.700) whereas a reduced model with just nine variables had an AUC of 0.690 (95% CI, 0.683-0.697). Adjusted odd ratios (aOR) greater than two were noted for only three variables; a posterior approach (aOR, 2.32; 95% CI, 2.14-2.50), body mass index (BMI) >40 kg/m² (aOR, 2.63; 95% CI, 2.39-2.90), and surgical duration longer than 350 minutes (aOR, 2.39; 95% CI, 2.14-2.67). Remaining retained variables included albumin <3.5 g/dL, inpatient procedure, peri-operative transfusion, diabetes mellitus (both insulin/non-insulin), anemia, and smoking. Conclusions: Surgical site infection rate remained unchanged over a nine-year period despite the lower rates of allogeneic blood transfusion. Class 3 obesity, long operative times, and a posterior approach mainly for thoracic/lumbar spine procedures seemed more pragmatic, but their predictive performance was only modest in our prediction models for SSI.

Pharmacokinetics of Antibacterial Agents in the Elderly: The Body of Evidence

Infections are important factors contributing to the morbidity and mortality among elderly patients. High rates of consumption of antimicrobial agents by the elderly may result in increased risk of toxic reactions, deteriorating functions of various organs and systems and leading to the prolongation of hospital stay, admission to the intensive care unit, disability, and lethal outcome. Both safety and efficacy of antibiotics are determined by the values of their plasma concentrations, widely affected by physiologic and pathologic age-related changes specific for the elderly population. Drug absorption, distribution, metabolism, and excretion are altered in different extents depending on functional and morphological changes in the cardiovascular system, gastrointestinal tract, liver, and kidneys. Water and fat content, skeletal muscle mass, nutritional status, use of concomitant drugs are other determinants of pharmacokinetics changes observed in the elderly. The choice of a proper dosing regimen is essential to provide effective and safe antibiotic therapy in terms of attainment of certain pharmacodynamic targets. The objective of this review is to perform a structure of evidence on the age-related changes contributing to the alteration of pharmacokinetic parameters in the elderly.

Aminoglycosides for the Treatment of Severe Infection Due to Resistant Gram-Negative Pathogens

Aminoglycosides are a family of rapidly bactericidal antibiotics that often remain active against resistant Gram-negative bacterial infections. Over the past decade, their use in critically ill patients has been refined; however, due to their renal and cochleovestibular toxicity, their indications in the treatment of sepsis and septic shock have been gradually reduced. This article reviews the spectrum of activity, mode of action, and methods for optimizing the efficacy of aminoglycosides. We discuss the current indications for aminoglycosides, with an emphasis on multidrug-resistant Gram-negative bacteria, such as extended-spectrum β-lactamase-producing Enterobacterales, carbapenemase-producing Enterobacterales, multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii. Additionally, we review the evidence for the use of nebulized aminoglycosides.

The Current Status and Future Perspectives of Beta-Lactam Therapeutic Drug Monitoring in Critically Ill Patients

Beta-lactams (BL) are the first line agents for the antibiotic management of critically ill patients with sepsis or septic shock. BL are hydrophilic antibiotics particularly subject to unpredictable concentrations in the context of critical illness because of pharmacokinetic (PK) and pharmacodynamics (PD) alterations. Thus, during the last decade, the literature focusing on the interest of BL therapeutic drug monitoring (TDM) in the intensive care unit (ICU) setting has been exponential. Moreover, recent guidelines strongly encourage to optimize BL therapy using a PK/PD approach with TDM. Unfortunately, several barriers exist regarding TDM access and interpretation. Consequently, adherence to routine TDM in ICU remains quite low. Lastly, recent clinical studies failed to demonstrate any improvement in mortality with the use of TDM in ICU patients. This review will first aim at explaining the value and complexity of the TDM process when translating it to critically ill patient bedside management, interpretating the results of clinical studies and discussion of the points which need to be addressed before conducting further TDM studies on clinical outcomes. In a second time, this review will focus on the future aspects of TDM integrating toxicodynamics, model informed precision dosing (MIPD) and “at risk” ICU populations that deserve further investigations to demonstrate positive clinical outcomes.

Piperacillin/Tazobactam in critically ill morbidly obese patients: A case series: The first One-Centre experience with TDM

The aim of this article is to demonstrate extreme interindividual variability of piperacilin/tazobactam (PIP/TAZO) pharmacokinetics in critically ill morbidly obese patients and to emphasize the need for the practice of routine PIP/TAZO plasma concentrations measurement in order to ensure optimal efficacy and safety of antibiotic therapy.

Comprehensive guidance for antibiotic dosing in obese adults: 2022 update

Drug dosing in obese patients continues to be challenging due to a lack of high-quality evidence to guide dosing recommendations. We first published guidance for antibiotic dosing in obese adults in 2017, in which we critically reviewed articles identified from a broad search strategy to develop dosing recommendations for 35 antimicrobials. In this updated narrative review, we searched Pubmed, Web of Science, and the Cochrane Library using Medical Subject Headings including anti-infectives, specific generic antimicrobial names, obese, pharmacokinetics, and others. We reviewed 393 articles, cross-referenced select cited references, and when applicable, referenced drug databases, package inserts, and clinical trial data to update dosing recommendations for 41 antimicrobials. Most included articles were pharmacokinetic studies, other less frequently included articles were clinical studies (mostly small, retrospective), case reports, and very rarely, guidelines. Pharmacokinetic changes are frequently reported, can be variable, and sometimes conflicting in this population, and do not always translate to a documented difference in clinical outcomes, yet are used to inform dosing strategies. Extended infusions, high doses, and therapeutic drug monitoring remain important strategies to optimize dosing in this population. Additional studies are needed to clinically validate proposed dosing strategies, clarify optimal body size descriptors, dosing weight scalars, and estimation method of renal function in obese patients.

Adherence to Sedation Targets With Weight-Based Propofol and Dexmedetomidine in Patients With Morbid Obesity

BACKGROUND

Propofol and dexmedetomidine are routinely used in intensive care units (ICUs). Both are lipophilic, potentially leading to accumulation in adipose tissue. Limited evidence exists on what body weight to utilize in patients with morbid obesity.

OBJECTIVE

The purpose of this research was to evaluate the safety and efficacy of weight-based sedation with propofol and dexmedetomidine in ICU patients with morbid obesity.

METHODS

Retrospective review of ICU patients admitted from January 2018 to January 2020 who were sedated for ≥48 hours was performed. The primary outcome was the percentage of time within target sedation during the first 48 hours, stratified by body mass index (BMI) <40 or ≥40 kg/m². Additional outcomes included adverse events and the infusion rate to achieve target sedation. Data were evaluated using descriptive statistics.

RESULTS

A total of 80 patients were analyzed. Patients on propofol with a BMI <40 kg/m² were in their target Richmond Agitation-Sedation Scale (RASS) 11.7% versus 16.1% with a BMI ≥40 kg/m² (P = .580). Patients with a BMI <40 kg/m² on dexmedetomidine were in their target RASS 27.6% versus 10.7% with a BMI ≥40 kg/m² (P = .053).

CONCLUSION AND RELEVANCE

Body mass index did not significantly alter propofol target sedation attainment. However, patients with morbid obesity on dexmedetomidine demonstrated significantly less time in target sedation. An actual body weight dosing strategy of these drugs did not achieve desired target sedation for those with a BMI ≥40 versus BMI <40 kg/m². These findings support future research on the optimal sedation dosing strategy in this patient population.

Population pharmacokinetics and pharmacodynamics of cefazolin using total and unbound serum concentrations in patients with high body weight

The objective of this study was to evaluate the steady state pharmacokinetics and pharmacodynamics of cefazolin in patients with a high body weight. Cefazolin was administered by 0.5-h infusions to 11 patients with total body weight (TBW) ≥120 kg receiving 3 g q8h, and 12 patients with TBW <120 kg receiving 2 g q8h. Total and unbound serum concentration-time data obtained from serial blood samples were analysed simultaneously by population pharmacokinetic modelling using NONMEM. Probability of target attainment (PTA) was calculated for various dosing regimens through Monte Carlo simulations based on the cumulative percentage of the dosing interval that the unbound concentration exceeds the minimum inhibitory concentration (MIC) value for the pathogen at steady state (fT_MIC) ≥40%, ≥60% and 100%. A two-compartment model with non-linear protein binding and allometric scaling of the central volume of distribution using TBW best characterized both total and unbound concentration-time data. Unbound clearance was significantly associated with creatinine clearance, and maximum protein binding constant was significantly associated with serum albumin concentration and body mass index (P <0.05). Based on unbound concentration-time profiles, all simulated regimens achieved PTA >90% at MIC values ≤2 mg/L using fT_MIC ≥40%, at MIC values ≤1 mg/L using fT_MIC ≥60%, and at MIC values ≤0.5 mg/L using fT_MIC of 100%. At fT_MIC ≥60%, 0.5-h infusion of cefazolin 1 g q8h achieved PTA <90% at MIC values ≥2 mg/L in patients with TBW≥120 kg; however, prolonged-infusion and higher-dose regimens improved PTA to >90%. Overall, cefazolin pharmacokinetics are altered considerably in obese patients. Higher-dose and/or prolonged-infusion cefazolin regimens should be considered in patients with TBW ≥120 kg, particularly those with less-susceptible Gram-negative infections.

Characterization of plasma daptomycin in patients with serum highly glycated albumin and obesity

PURPOSE

Plasma daptomycin has not been fully characterized in diabetic and obese patients. This study aimed to evaluate the associations of plasma daptomycin with glycation of serum albumin and obesity.

METHODS

Infectious patients (n = 70) receiving intravenous daptomycin were enrolled. The plasma concentration of total and free daptomycin were determined using liquid chromatograph-tandem mass spectrometer. The associations of the plasma concentrations of daptomycin with clinical factors including serum albumin fractionations and physical status (obese including overweight, body mass index ≥ 25.0) were investigated. Daptomycin doses were adjusted using total body-weight.

RESULTS

The serum albumin level was positively and negatively correlated with the plasma concentration of total daptomycin and its free fraction proportion, respectively. The serum non-glycated albumin was negatively correlated with the free fraction proportion. The dose-normalized plasma concentration of total daptomycin was higher in the obese patients than in non-obese patients when the body-weight was corrected with total and adjusted values. For the dose adjustment with lean body-weight, no difference was observed in the dose-normalized plasma concentration of total daptomycin between the physical statuses. For each body-weight correction method, physical status did not affect the dose-normalized plasma concentration of free daptomycin.

CONCLUSION

The glycation of serum albumin and obesity did not associate with dose-normalized plasma free daptomycin. In obese patients, daptomycin dosage adjustment with total body-weight and adjusted body-weight may lead to an apparent excessive exposure resulting in overdosage compared to lean body-weight.

Chemotherapy and Anticancer Drugs Adjustment in Obesity: A Narrative Review

BACKGROUND

Obese individuals have higher rates of cancer incidence and cancer- related mortality. The worse chemotherapy outcomes observed in this subset of patients are multifactorial, including the altered physiology in obesity and its impact on pharmacokinetics, the possible increased risk of underdosing, and treatment-related toxicity.

AIMS

The present review aimed to discuss recent data on physiology, providing just an overall perspective and pharmacokinetic alterations in obesity concerning chemotherapy. We also reviewed the controversies of dosing adjustment strategies in adult and pediatric patients, mainly addressing the use of actual total body weight and ideal body weight.

METHODS

This narrative review tried to provide the best evidence to support antineoplastic drug dosing strategies in children, adolescents, and adults.

RESULTS

Cardiovascular, hepatic, and renal alterations of obesity can affect the distribution, metabolism, and clearance of drugs. Anticancer drugs have a narrow therapeutic range, and variations in dosing may result in either toxicity or underdosing. Obese patients are underrepresented in clinical trials that focus on determining recommendations for chemotherapy dosing and administration in clinical practice. After considering associated comorbidities, the guidelines recommend that chemotherapy should be dosed according to body surface area (BSA) calculated with actual total body weight, not an estimate or ideal weight, especially when the intention of therapy is the cure.

CONCLUSION

The actual total body weight dosing appears to be a better approach to dosing anticancer drugs in both adults and children when aiming for curative results, showing no difference in toxicity and no limitation in treatment outcomes compared to adjusted doses.

Outcomes of Beta-Lactam Allergic and Non-Beta-Lactam Allergic Patients with Intra-Abdominal Infection: A Case-Control Study

Background: In the case of intra-abdominal infections (IAI) in beta-lactam (BL) allergic patients, empiric antimicrobial therapy without BL is recommended; however, data regarding the outcome with alternative regimens are scarce. This study aimed to compare the outcomes of BL allergic (BLA) patients with IAI to those who were non-BLA (NBLA). Method: We conducted a case−control study in a French teaching hospital, between 1 January 2016 and 31 August 2021. BLA patients with IAI treated with fluoroquinolone or aztreonam and metronidazole were matched with controls treated with BL, on age, sex, disease severity, IAI localization, and healthcare-associated infection (HAI) status. We compared rates of therapeutic failures, adverse events, and HAI, and then assessed factors associated with therapeutic failure using a logistic regression model. Results: The therapeutic failure rate was 14% (p > 0.99) in both groups of 43 patients, and there was no significant difference in the adverse events rate (p > 0.99) and HAI rate (p = 0.154). Factors independently associated with therapeutic failure were higher BMI (OR 1.16; 95%CI [1.00−1.36]; p = 0.041), longer hospital length of stay (OR 1,20; 95%CI [1.08−1.41]; p = 0.006), and inadequate empiric antimicrobial therapy (OR 11.71; 95%CI [1.43−132.46]; p = 0.025). Conclusion: The outcomes of BLA patients with IAI treated without BL were the same as those for NBLA patients treated with BL.

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

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION AND DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSION

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

Readiness to Accept Genetic Testing for Personalized Medicine: Survey Findings on the Role of Socio-Demographic Characteristics, Health Vulnerabilities, Perceived Genetic Risk and Personality Factors

Studies from various countries have shown that majorities would accept genetic testing for personalization of treatment, but little is known about differences among population subgroups. The present study investigated whether readiness to accept a hypothetical cost-free offer of genetic testing to personalize treatment depends on socio-demographic characteristics, health-related vulnerabilities, personal dispositions, and prior awareness about personalized medicine. The study was based on a cross-sectional survey design. Out of a representative initial sample of 50-80-year-old Danish citizens (n = 15,072), n = 6807 returned a fully answered web-based questionnaire. Socio-demographic data were added from a national registry. Data were analyzed by multivariable logistic regression. A large majority of respondents (78.3%) expressed their readiness to be tested. Rates were higher in men, younger persons, and those with higher income. Additionally, ex-smokers and obese persons as well as those less satisfied with their health and respondents who perceived a personal genetic risk were more interested, as were those with higher internal health control, higher extraversion, higher emotional stability, and those who had not heard about this option before. Further research should investigate the specific concerns among population subgroups which need being addressed by systematic communication efforts in a clinical but also a broader public health context.

Obesity Worsens Local and Systemic Complications of Necrotizing Pancreatitis and Prolongs Disease Course

BACKGROUND

Obesity is epidemic in the USA. Limited data exist examining obesity's influence on necrotizing pancreatitis (NP) disease course.

METHODS

Retrospective review of prospectively maintained database of 571 adult necrotizing pancreatitis patients treated between 2007 and 2018. Patients were grouped according to body mass index (BMI) at disease onset. Patient characteristics, necrotizing pancreatitis course, and outcomes were compared between non-obese (BMI < 30) and obese (BMI > 30) patients.

RESULTS

Among 536 patients with BMI data available, 304 (57%) were obese (BMI > 30), and 232 (43%) were non-obese (BMI < 30). NP etiology in the obese group was more commonly biliary (55% versus 46%, p = 0.04) or secondary to hypertriglyceridemia (10% versus 2%, p < 0.001) and less commonly alcohol (17% versus 26%, p = 0.01). Obese patients had a higher incidence of baseline comorbid disease. The CT severity index was similar between groups though obese patients had a higher rate of > 50% pancreatic gland necrosis (27% versus 19%, p = 0.02). The rates of infected necrosis and organ failure were higher among obese patients. Percutaneous drainage was more common in obese patients. Time to first necrosis intervention was earlier with increasing BMI. NP disease duration was longer in obese patients. The overall mortality rate of non-obese and obese patients did not differ. However, mortality rate increased with increasing BMI.

CONCLUSION

Necrotizing pancreatitis in obese patients is characterized by a prolonged disease course, a higher risk of organ failure, infected necrosis, and the need for early necrosis-related intervention. Mortality increases with increasing BMI.

Impact of therapeutic drug monitoring of antibiotics in the management of infective endocarditis

Treatment of infective endocarditis (IE) is based on high doses of antibiotics with a prolonged duration. Therapeutic drug monitoring (TDM) allows antibiotic prescription optimization and leads to a personalized medicine, but no study evaluates its interest in the management of IE. We conducted a retrospective, bicentric, descriptive study, from January 2007 to December 2019. We included patients cared for IE, defined according to Duke's criteria, for whom a TDM was requested. Clinical and microbiological data were collected after patients' charts review. We considered a trough or steady-state concentration target of 20 to 50 mg/L. We included 322 IE episodes, corresponding to 306 patients, with 78.6% (253/326) were considered definite according to Duke's criteria. Native valves were involved in 60.5% (185/306) with aortic valve in 46.6% (150/322) and mitral in 36.3% (117/322). Echocardiography was positive in 76.7% (247/322) of cases. After TDM, a dosage modification was performed in 51.5% (166/322) (decrease in 84.3% (140/166)). After initial dosage, 46.3% (82/177) and 92.8% (52/56) were considered overdosed, when amoxicillin and cloxacillin were used, respectively. The length of hospital stay was higher for patient overdosed (25 days versus 20 days (p = 0.04)), and altered creatinine clearance was associated with overdosage (p = 0.01). Our study suggests that the use of current guidelines probably leads to unnecessarily high concentrations in most patients. TDM benefits predominate in patients with altered renal function, but probably limit adverse effects related to overdosing in most patients.

Low-dose trimethoprim-sulfamethoxazole for the treatment of Pneumocystis jirovecii pneumonia (LOW-TMP): protocol for a phase III randomised, placebo-controlled, dose-comparison trial

INTRODUCTION

Pneumocystis jirovecii pneumonia (PJP) is an opportunistic infection of immunocompromised hosts with significant morbidity and mortality. The current standard of care, trimethoprim-sulfamethoxazole (TMP-SMX) at a dose of 15-20 mg/kg/day, is associated with serious adverse drug events (ADE) in 20%-60% of patients. ADEs include hypersensitivity reactions, drug-induced liver injury, cytopenias and renal failure, all of which can be treatment limiting. In a recent meta-analysis of observational studies, reduced dose TMP-SMX for the treatment of PJP was associated with fewer ADEs, without increased mortality.

METHODS AND ANALYSIS

A phase III randomised, placebo-controlled, trial to directly compare the efficacy and safety of low-dose TMP-SMX (10 mg/kg/day of TMP) with the standard of care (15 mg/kg/day of TMP) among patients with PJP, for a composite primary outcome of change of treatment, new mechanical ventilation, or death. The trial will be undertaken at 16 Canadian hospitals. Data will be analysed as intention to treat. Primary and secondary outcomes will be compared using logistic regression adjusting for stratification and presented with 95% CI.

ETHICS AND DISSEMINATION

This study has been conditionally approved by the McGill University Health Centre; Ethics approval will be obtained from all participating centres. Results will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04851015.

Review and evaluation of vancomycin dosing guidelines for obese individuals

INTRODUCTION

Vancomycin dosing decisions are informed by factors such as body weight and renal function. It is important to understand the impact of obesity on vancomycin pharmacokinetics and how this may influence dosing decisions. Vancomycin dosing guidelines use varied descriptors of body weight and renal function. There is uncertainty whether current dosing guidelines result in attainment of therapeutic targets in obese individuals.

AREAS COVERED

Literature was explored using PubMed, Embase and Google Scholar for articles from January 1980 to July 2021 regarding obesity-driven physiological changes, their influence on vancomycin pharmacokinetics and body size descriptors and renal function calculations in vancomycin dosing. Pharmacokinetic simulations reflective of international vancomycin dosing guidelines were conducted to evaluate the ability of using total, ideal and adjusted body weight, as well as Cockcroft-Gault and CKD-EPI equations to attain an area-under-the-curve to minimum inhibitory concentration ratio (AUC₂₄/MIC) target (400-650) in obese individuals.

EXPERT OPINION

Vancomycin pharmacokinetics in obese individuals remains debated. Guidelines that determine loading doses using total body weight, and maintenance doses adjusted based on renal function and adjusted body weight, may be most appropriate for obese individuals. Use of ideal body weight leads to subtherapeutic vancomycin exposure and underestimation of renal function.

Pitfalls and pearls with drug dosing in the critically ill obese patient: 10 statements to guide ICU practitioners

Obesity is highly prevalent in ICU patients presenting a number of challenges, one of which is drug dosing. There are limited high-quality data describing drug dosing in obesity, which can lead to dosing strategies that are suboptimal. For example, inappropriately using the wrong weight for weight-based dosing can lead to supratherapeutic drug concentrations and an adverse drug event or subtherapeutic drug concentrations and treatment failure. A generalized framework for decision making specific for obese patients is available that describes a step-by-step approach for constructing dosing regimens. This manuscript will build on that framework by providing pitfalls and pearls for clinicians to consider when making dosing decisions in critically ill patients with severe obesity.

Vancomycin dosing in an obese patient with acute renal failure: A case report and review of literature

BACKGROUND

Vancomycin is the most commonly used drug for methicillin-resistant Staphylococcus aureus. The empirical clinical doses of vancomycin based on non-obese patients may not be optimal for obese ones.

CASE SUMMARY

This study reports a case of vancomycin dosing adjustment in an obese patient (body mass index 78.4 kg/m²) with necrotizing fasciitis of the scrotum and left lower extremity accompanied with acute renal failure. Dosing adjustment was performed based on literature review and factors that influence pharmacokinetic parameters are analyzed. The results of the blood drug concentration monitoring confirmed the successful application of our dosing adjustment strategy in this obese patient. Total body weight is an important consideration for vancomycin administration in obese patients, which affects the volume of distribution and clearance of vancomycin. The alterations of pharmacokinetic parameters dictate that vancomycin should be dose-adjusted when applied to obese patients. At the same time, the pathophysiological status of patients, such as renal function, which also affects the dose adjustment of the patient, should be considered.

CONCLUSION

Monitoring vancomycin blood levels in obese patients is critical to help adjust the dosing regimen to ensure that vancomycin concentrations are within the effective therapeutic range and to reduce the incidence of renal injury.

High-Dosage Fosfomycin Results in Adequate Plasma and Target-Site Exposure in Morbidly Obese and Nonobese Nonhyperfiltration Patients

The objectives of this study were the identification in (morbidly) obese and nonobese patients of (i) the most appropriate body size descriptor for fosfomycin dose adjustments and (ii) adequacy of the currently employed dosing regimens. Plasma and target site (interstitial fluid of subcutaneous adipose tissue) concentrations after fosfomycin administration (8 g) to 30 surgery patients (15 obese/15 nonobese) were obtained from a prospective clinical trial. After characterization of plasma and microdialysis-derived target site pharmacokinetics via population analysis, short-term infusions of fosfomycin 3 to 4 times daily were simulated. The adequacy of therapy was assessed by probability of pharmacokinetic/pharmacodynamic target attainment (PTA) analysis based on the unbound drug-related targets of an %fT_>MIC (the fraction of time that unbound fosfomycin concentrations exceed the MIC during 24 h) of 70 and an fAUC_0-24h/MIC (the area under the concentration-time curve from 0 to 24 h for the unbound fraction of fosfomycin relative to the MIC) of 40.8 to 83.3. Lean body weight, fat mass, and creatinine clearance calculated via adjusted body weight (ABW) (CLCR_{CG_ABW}) of all patients (body mass index [BMI] = 20.1 to 52.0 kg/m²) explained a considerable proportion of between-patient pharmacokinetic variability (up to 31.0% relative reduction). The steady-state unbound target site/plasma concentration ratio was 26.3% lower in (morbidly) obese than nonobese patients. For infections with fosfomycin-susceptible pathogens (MIC ≤ 16 mg/L), intermittent "high-dosage" intravenous (i.v.) fosfomycin (8 g, three times daily) was sufficient to treat patients with a CLCR_{CG_ABW} of <130 mL/min, irrespective of the pharmacokinetic/pharmacodynamic indices considered. For infections by Pseudomonas aeruginosa with a MIC of 32 mg/L, when the index fAUC_0-24h/MIC is applied, fosfomycin might represent a promising treatment option in obese and nonobese patients, especially in combination therapy to complement β-lactams, in which carbapenem-resistant P. aeruginosa is critical. In conclusion, fosfomycin showed excellent target site penetration in obese and nonobese patients. Dosing should be guided by renal function rather than obesity status. (This study has been registered in the EU Clinical Trials Register under EudraCT no. 2012-004383-22.).

Preoperative and perioperative risk factors, and risk score development for prosthetic joint infection due to Staphylococcus aureus: A multinational matched case-control study

OBJECTIVES

We aim to identify the preoperative and perioperative risk factors associated with post-surgical Staphylococcus aureus prosthetic joint infections (PJI), and to develop and validate risk-scoring systems, to allow a better identification of high-risk patients for more efficient targeted interventions.

METHODS

We performed a multicenter matched case-control study of patients who underwent a primary hip and knee arthroplasty from 2014 to 2016. Two multivariable models by logistic regression were performed, one for the preoperative and one for perioperative variables; also, predictive scores were developed and validated in an external cohort.

RESULTS

In total, 130 cases and 386 controls were included. The variables independently associated with S. aureus-PJI in the preoperative period were (adjusted OR; 95% CI): BMI >30 kg/m² (3.0; 1.9-4.8), resident in a long-term care facility (2.8; 1.05-7.5), fracture as reason for arthroplasty (2.7; 1.4-5.03), skin disorders (2.5; 0.9-7.04), previous surgery in the index joint (2.4; 1.3-4.4), male sex (1.9; 1.2-2.9) and ASA score 3-4 (1.8; 1.2-2.9). The AUROC curve was 0.73 (95% CI 0.68-0.78). In perioperative model, the risk factors were the previous ones plus surgical antibiotic prophylaxis administered out of the first 60 minutes before incision (5.9; 2.1-16.2), wound drainage for >72h after arthroplasty (4.5; 1.9-19.4) and use of metal bearing material vs. ceramic (1.9; 1.1-3.3). The AUROC curve was 0.78 (95% CI 0.72-0.83). The predictive scores developed were validated in the external cohort.

CONCLUSIONS

Predictive scores for S. aureus-PJI were developed and validated; this information would be useful for implementation of specific preventive measures.

Antibiotics and ECMO in the Adult Population—Persistent Challenges and Practical Guides

Extracorporeal membrane oxygenation (ECMO) is an emerging treatment modality associated with a high frequency of antibiotic use. However, several covariables emerge during ECMO implementation, potentially jeopardizing the success of antimicrobial therapy. These variables include but are not limited to: the increased volume of distribution, altered clearance, and adsorption into circuit components, in addition to complex interactions of antibiotics in critical care illness. Furthermore, ECMO complicates the assessment of antibiotic effectiveness as fever, or other signs may not be easily detected, the immunogenicity of the circuit affects procalcitonin levels and other inflammatory markers while disrupting the immune system. We provided a review of pharmacokinetics and pharmacodynamics during ECMO, emphasizing practical application and review of patient-, illness-, and ECMO hardware-related factors.

Therapeutic Drug Monitoring of Antibiotics: Defining the Therapeutic Range

PURPOSE

In the present narrative review, the authors aimed to discuss the relationship between the pharmacokinetic/pharmacodynamic (PK/PD) of antibiotics and clinical response (including efficacy and toxicity). In addition, this review describes how this relationship can be applied to define the therapeutic range of a particular antibiotic (or antibiotic class) for therapeutic drug monitoring (TDM).

METHODS

Relevant clinical studies that examined the relationship between PK/PD of antibiotics and clinical response (efficacy and response) were reviewed. The review (performed for studies published in English up to September 2021) assessed only commonly used antibiotics (or antibiotic classes), including aminoglycosides, beta-lactam antibiotics, daptomycin, fluoroquinolones, glycopeptides (teicoplanin and vancomycin), and linezolid. The best currently available evidence was used to define the therapeutic range for these antibiotics.

RESULTS

The therapeutic range associated with maximal clinical efficacy and minimal toxicity is available for commonly used antibiotics, and these values can be implemented when TDM for antibiotics is performed. Additional data are needed to clarify the relationship between PK/PD indices and the development of antibiotic resistance.

CONCLUSIONS

TDM should only be regarded as a means to achieve the main goal of providing safe and effective antibiotic therapy for all patients. The next critical step is to define exposures that can prevent the development of antibiotic resistance and include these exposures as therapeutic drug monitoring targets.

Clinical Outcomes with Ertapenem for Pneumonia in Obese versus Nonobese Patients

The objective of this study was to compare the rate of pneumonia resolution in obese (body mass index [BMI], ≥30 kg/m2) and nonobese (BMI, <30 kg/m2) patients treated with 1 gram ertapenem daily. In this retrospective cohort study, we evaluated patients treated at The Ohio State University Wexner Medical Center between 1 January 2015 and 31 August 2020. Patients were included if they were between 18 and 89 years old and received ertapenem for at least 48 hours for pneumonia treatment. Patients were excluded if they were pregnant, were incarcerated, had renal impairment, received antibiotics with Gram-negative activity for a significant period prior to or in addition to ertapenem, and had other concomitant deep-seated infections. The primary outcome of clinical resolution was defined as meeting any of the following three criteria in order of evaluations: discontinuation of antibiotics by day 8 of therapy, afebrile while on ertapenem in addition to a decrease in white blood cell count, or improvement on chest radiograph at day 7 of therapy. A multivariable logistic regression analysis was performed to examine the association between obesity and clinical resolution, while adjusting for proven confounders. There were 76 nonobese and 65 obese patients included. The median patient BMI was 23.7 kg/m2 (21.0 to 26.9) and 35.0 kg/m2 (32.8 to 39.8) for the nonobese and obese cohorts, respectively. Clinical resolution was achieved in 78% (59/76) of nonobese and 75% (49/65) of obese patients (P = 0.75) without an observed difference in the regression model. Outcomes were similar in obese and nonobese patients treated with 1 gram of ertapenem daily for pneumonia.

The Interplay between Host Defense, Infection, and Clinical Status in Septic Patients: A Narrative Review

Sepsis is a life-threatening condition that arises when the body's response to an infection injures its own tissues and organs. Despite significant morbidity and mortality throughout the world, its pathogenesis and mechanisms are not clearly understood. In this narrative review, we aimed to summarize the recent developments in our understanding of the hallmarks of sepsis pathogenesis (immune and adaptive immune response, the complement system, the endothelial disfunction, and autophagy) and highlight novel laboratory diagnostic approaches. Clinical management is also discussed with pivotal consideration for antimicrobic therapy management in particular settings, such as intensive care unit, altered renal function, obesity, and burn patients.

Systematic review and meta-analysis of risk factors for Mesh infection following Abdominal Wall Hernia Repair Surgery

BACKGROUND

Surgical Mesh Infection (SMI) after Abdominal Wall Hernia Repair (AWHR) represents a catastrophic complication. We performed a systematic review and meta-analysis to analyze the risk factors for SMI in the context of AWHR.

METHODS

PubMed, Embase, Scielo, and LILACS were searched without language or time restrictions from inception until June 2021. Articles evaluating the association between demographic, clinical, laboratory and surgical characteristics with SMI in AWHR were included.

RESULTS

23 studies were evaluated, comprising a total of 118,790 patients (98% males; mean age 56.5 years) with a mesh infection pooled prevalence of 4%. Significant risk factors for SMI were type 2 diabetes mellitus, obesity, smoking history, steroids use, ASA III/IV, laparotomy vs laparoscopy, emergency surgery, duration of surgery and onlay mesh position vs sublay. The quality of evidence was regarded as very low-moderate.

CONCLUSION

Several factors, highlighting sociodemographic characteristics, comorbidities, and the clinical scenario, may increase the risk of developing mesh infections in AWHR. The recognition and mitigation of these may significantly reduce mesh infection rates in this context.

Surgical Antibiotic Prophylaxis in an Era of Antibiotic Resistance: Common Resistant Bacteria and Wider Considerations for Practice

The increasing incidence of antimicrobial resistance (AMR) presents a global crisis to healthcare, with longstanding antimicrobial agents becoming less effective at treating and preventing infection. In the surgical setting, antibiotic prophylaxis has long been established as routine standard of care to prevent surgical site infection (SSI), which remains one of the most common hospital-acquired infections. The growing incidence of AMR increases the risk of SSI complicated with resistant bacteria, resulting in poorer surgical outcomes (prolonged hospitalisation, extended durations of antibiotic therapy, higher rates of surgical revision and mortality). Despite these increasing challenges, more data are required on approaches at the institutional and patient level to optimise surgical antibiotic prophylaxis in the era of antibiotic resistance (AR). This review provides an overview of the common resistant bacteria encountered in the surgical setting and covers wider considerations for practice to optimise surgical antibiotic prophylaxis in the perioperative setting.

Comparative Plasma and Interstitial Tissue Fluid Pharmacokinetics of Meropenem Demonstrate the Need for Increasing Dose and Infusion Duration in Obese and Non-obese Patients

BACKGROUND AND OBJECTIVES

A quantitative evaluation of the PK of meropenem, a broad-spectrum β-lactam antibiotic, in plasma and interstitial space fluid (ISF) of subcutaneous adipose tissue of obese patients is lacking as of date. The objective of this study was the characterisation of meropenem population pharmacokinetics in plasma and ISF in obese and non-obese patients for identification of adequate dosing regimens via Monte-Carlo simulations.

METHODS

We obtained plasma and microdialysate concentrations after administration of meropenem 1000 mg to 15 obese and 15 non-obese surgery patients from a prospective clinical trial. After characterizing plasma- and microdialysis-derived ISF pharmacokinetics via population pharmacokinetic analysis, we simulated thrice-daily (TID) meropenem short-term (0.5 h), prolonged (3.0 h), and continuous infusions. Adequacy of therapy was assessed by the probability of pharmacokinetic/pharmacodynamic (PK/PD) target attainment (PTA) analysis based on time unbound concentrations exceeded minimum inhibitory concentrations (MIC) on treatment day 1 (%fT _{> MIC}) and the sum of PTA weighted by relative frequency of MIC values for infections by pathogens commonly treated with meropenem. To avoid interstitial tissue fluid concentrations below MIC for the entire dosing interval during continuous infusions, a more conservative PK/PD index was selected (%fT _{> 4 × MIC}).

RESULTS

Adjusted body weight (ABW) and calculated creatinine clearance (CLCR_{CG_ABW}) of all patients (body mass index [BMI] = 20.5-81.5 kg/m²) explained a considerable proportion of the between-patient pharmacokinetic variability (15.1-31.0% relative reduction). The ISF:plasma ratio of %fT _{> MIC} was relatively similar for MIC ≤ 2 mg/L but decreased for MIC = 8 mg/L over ABW = 60-120 kg (0.50-0.20). Steady-state concentrations were 2.68 times (95% confidence interval [CI] = 2.11-3.37) higher in plasma than in ISF, supporting PK/PD targets related to four times the MIC during continuous infusions to avoid suspected ISF concentrations constantly below the MIC. A 3000 mg/24 h continuous infusion was sufficient at MIC = 2 mg/L for patients with CLCR_{CG_ABW} ≤ 100 mL/min and ABW < 90 kg, whereas 2000 mg TID prolonged infusions were adequate for those with CLCR_{CG_ABW} ≤ 100 mL/min and ABW > 90 kg. For MIC = 2 mg/L and %fT_{> MIC} = 95, PTA was adequate in patients over the entire investigated range of body mass and renal function using a 6000 mg continuous infusion. A prolonged infusion of meropenem 2000 mg TID was sufficient for MIC ≤ 8 mg/L and all investigated ABW and CLCR_{CG_ABW} when employing the PK/PD target %fT _{> MIC} = 40. Short-term infusions of 1000 mg TID were sufficient for CLCR_{CG_ABW} ≤ 130 mL/min and distributions of MIC values for Escherichia coli, Citrobacter freundii, and Klebsiella pneumoniae but not for Pseudomonas aeruginosa.

CONCLUSIONS

This analysis indicated a need for higher doses (≥ 2000 mg) and prolonged infusions (≥ 3 h) for obese and non-obese patients at MIC ≥ 2 mg/L. Higher PTA was achieved with prolonged infusions in obese patients and with continuous infusions in non-obese patients.

TRIAL REGISTRATION

EudraCT: 2012-004383-22.

Population Pharmacokinetics of Polymyxin B in Obese Patients for Resistant Gram-Negative Infections

Polymyxin B is an effective but potentially nephrotoxic antibiotic that is commonly used to treat resistant Gram-negative infections. As a weight-based dosing drug, obese patients may be at a high risk of nephrotoxicity. However, the pharmacokinetics and dosing recommendations for this population are currently lacking. This study aimed to describe the polymyxin B population pharmacokinetics and to evaluate pharmacokinetic/pharmacodynamics (PK/PD) target attainment for obese patients. This study included 26 patients (body mass index, BMI >30) who received polymyxin B for ≥3 days. The total body weight (TBW) ranged from 75 to 125 kg, and the BMI ranged from 30.04 to 40.35. A two-compartment model adequately described the data using Phoenix NLME software. Monte Carlo simulation was used to assess polymyxin B exposure and the probability of target attainment (PTA). As a result, body weight had no significant effect on polymyxin B pharmacokinetics. According to model-based simulation, adjusted body weight (ABW)-based regimens had a high probability of achieving optimal exposure with minimal toxicity risk by comparing TBW and ideal body weight (IBW)-based regimens. The fixed dose of 125 mg or 150 mg q12h had a high toxicity risk. PTA results showed that TBW, IBW, and ABW-based regimens had similar PTA values. Therefore, for obese patients, ABW-based regimens but with a daily dose <250 mg have a high likelihood of achieving an AUC_ss,24h of 50-100 mg h/L and attaining PK/PD targets with the MIC ≤0.5 mg/L.

A rare case of Campylobacter rectus pyogenic extensor tenosynovitis

INTRODUCTION

Pyogenic extensor tenosynovitis is a severe inflammatory process of the extensor compartment of the hand. Common pathogens involved in this condition are Streptococcus and Staphylococcus; however, in immunocompromised patients, rare pathogens can be implicated.

CASE REPORT

Herein a rare case of a 61-year-old female who developed severe extensor tenosynovitis from Campylobacter rectus after a dog bite is presented. The patient required surgical debridement, four weeks of doxycycline and amoxicillin-clavulanate antibiotic therapy and physical therapy to successfully cure her C. rectus infection and preserve functionality.

CONCLUSIONS

This case reinforces the virulence of microaerophilic pathogens, the need for multidisciplinary management in complex cases and alternative treatments with morbid obesity. As well, this case adds to the paucity of data with respect to this pathogen causing infections outside periodontal disease.

Emergencies in obese patients: a narrative review

Obesity is associated to an increased risk of morbidity and mortality due to respiratory, cardiovascular, metabolic, and neoplastic diseases. The aim of this narrative review is to assess the physio-pathological characteristics of obese patients and how they influence the clinical approach during different emergency settings, including cardiopulmonary resuscitation. A literature search for published manuscripts regarding emergency and obesity across MEDLINE, EMBASE, and Cochrane Central was performed including records till January 1, 2021. Increasing incidence of obesity causes growth in emergency maneuvers dealing with airway management, vascular accesses, and drug treatment due to both pharmacokinetic and pharmacodynamic alterations. Furthermore, instrumental diagnostics and in/out-hospital transport may represent further pitfalls. Therefore, people with severe obesity may be seriously disadvantaged in emergency health care settings, and this condition is enhanced during the COVID-19 pandemic, when obesity was stated as one of the most frequent comorbidity. Emergency in critical obese patients turns out to be an intellectual, procedural, and technical challenge. Organization and anticipation based on the understanding of the physiopathology related to obesity are very important for the physician to be mentally and physically ready to face the associated issues.

Optimizing antimicrobial use: challenges, advances and opportunities

An optimal antimicrobial dose provides enough drug to achieve a clinical response while minimizing toxicity and development of drug resistance. There can be considerable variability in pharmacokinetics, for example, owing to comorbidities or other medications, which affects antimicrobial pharmacodynamics and, thus, treatment success. Although current approaches to antimicrobial dose optimization address fixed variability, better methods to monitor and rapidly adjust antimicrobial dosing are required to understand and react to residual variability that occurs within and between individuals. We review current challenges to the wider implementation of antimicrobial dose optimization and highlight novel solutions, including biosensor-based, real-time therapeutic drug monitoring and computer-controlled, closed-loop control systems. Precision antimicrobial dosing promises to improve patient outcome and is important for antimicrobial stewardship and the prevention of antimicrobial resistance.

COVID-19 Pandemic as Risk Factors for Excessive Weight Gain in Pediatrics: The Role of Changes in Nutrition Behavior. A Narrative Review

During the coronavirus disease 2019 (COVID-19) pandemic, social isolation, semi-lockdown, and "stay at home" orders were imposed upon the population in the interest of infection control. This dramatically changes the daily routine of children and adolescents, with a large impact on lifestyle and wellbeing. Children with obesity have been shown to be at a higher risk of negative lifestyle changes and weight gain during lockdown. Obesity and COVID-19 negatively affect children and adolescents' wellbeing, with adverse effects on psychophysical health, due in large part to food choices, snacking between meals, and comfort eating. Moreover, a markable decrease in physical activity levels and an increase in sedentary behavior is associated with weight gain, especially in children with excessive weight. In addition, obesity is the most common comorbidity in severe cases of COVID-19, suggesting that immune dysregulation, metabolic unbalance, inadequate nutritional status, and dysbiosis are key factors in the complex mechanistic and clinical interplay between obesity and COVID-19. This narrative review aims to describe the most up-to-date evidence on the clinical characteristics of COVID-19 in children and adolescents, focusing on the role of excessive weight and weight gain in pediatrics. The COVID-19 pandemic has taught us that nutrition education interventions, access to healthy food, as well as family nutrition counselling should be covered by pediatric services to prevent obesity, which worsens disease outcomes related to COVID-19 infection.