Antibiotic resistance--what's dosing got to do with it?

Pharmacovigilance Strategies to Address Resistance to Antibiotics and Inappropriate Use-A Narrative Review

The spread of antimicrobial resistance (AMR) is a global challenge. Close and continuous surveillance for quick detection of AMR can be difficult, especially in remote places. This narrative review focuses on the contributions of pharmacovigilance (PV) as an auxiliary tool for identifying and monitoring the ineffectiveness, resistance, and inappropriate use of antibiotics (ABs). The terms "drug ineffective", "therapeutic failure", "drug resistance", "pathogen resistance", and "multidrug resistance" were found in PV databases and dictionaries, denoting ineffectiveness. These terms cover a range of problems that should be better investigated because they are useful in warning about possible causes of AMR. "Medication errors", especially those related to dose and indication, and "Off-label use" are highlighted in the literature, suggesting inappropriate use of ABs. Hence, the included studies show that the terms of interest related to AMR and use are not only present but frequent in PV surveillance programs. This review illustrates the feasibility of using PV as a complementary tool for antimicrobial stewardship activities, especially in scenarios where other resources are scarce.

Formulation, pharmacokinetics, and antibacterial activity of florfenicol-loaded niosome

The growing interest in employing nano-sized pharmaceutical formulations in veterinary medicine has prompted the exploration of the novel nanocarriers' ability to augment the therapeutic outcome. In this study, we harnessed niosomes, spherical nanocarriers formed through non-ionic surfactant self-assembly, to enhance the therapeutic efficacy of the broad-spectrum antibiotic florfenicol. Pre-formulation studies were conducted to identify the optimal parameters for preparing florfenicol-loaded niosomes (FLNs). These studies revealed that the formulation that consisted of Span 60, cholesterol, and dihexadecyl phosphate (DDP) at a molar ratio of 1:1:0.1 exhibited the highest entrapment efficiency (%EE) and uniform size distribution. In vitro antibacterial testing demonstrated the niosomal capacity to significantly reduce florfenicol minimum inhibitory concentration (MIC) against E. coli and S. aureus. Pharmacokinetic profiles of free florfenicol and FLN were assessed following oral administration of 30 mg florfenicol/kg body weight to healthy or E. coli-infected chickens. FLN exhibited a substantially higher maximum plasma concentration (Cmax) of florfenicol compared to free florfenicol. Furthermore, FLN showed significantly higher area under the curve (AUC0-t) than free florfenicol as revealed from the relative bioavailability studies. Lethal dose (LD) 50 values for both free florfenicol and FLN exceeded 5 g/kg of body weight, indicating high safety profile. Assessment of mortality protection in mice against lethal E. coli infections showed the significantly higher capability of FLN to improve the survival rate (75%) than free florfenicol (25%). Collectively, these findings demonstrate the niosomal ability to improve the oral bioavailability as well as the antibacterial activity of the incorporated veterinary antibiotic florfenicol.

Impact of physical build on serum vancomycin concentrations of patients undergoing hemodialysis: A retrospective cohort study at an acute care hospital

INTRODUCTION

Estimating the serum vancomycin (VCM) concentrations of lean and patients with obesity is challenging. Additionally, VCM dosing for Japanese patients undergoing hemodialysis remains particularly unclear. This study aimed to determine the impact of the physical build on serum VCM concentrations of Japanese patients undergoing hemodialysis.

METHODS

This retrospective cohort study included hospitalized patients undergoing hemodialysis, who received treatment with VCM between May 1, 2019, and December 31, 2021, at Kansai Rosai Hospital, which is a 642-bed acute care hospital in Japan. Patients were divided into the following three groups based on their body mass index (BMI): lean group (≤18.5 kg/m2), normal group (18.5-25 kg/m2), and obese group (≥25 kg/m2). The VCM dose and predialysis serum VCM concentration (PVC) were compared.

RESULTS

This study included 191 patients. There were 50 patients in the lean group, 85 in the normal group, and 56 in the obese group. The median loading doses per body weight were 24.0, 22.1, and 21.2 mg/kg for the lean, normal, and obese groups, respectively. The VCM dose per body weight decreased significantly with increasing BMI. The median PVCs of the lean and normal groups were approximately 15 mg/L (not significantly different). However, the median PVC of the obese group was 18.3 mg/L, which was significantly higher (P < 0.001).

CONCLUSIONS

The VCM dose per body weight for Japanese patients undergoing hemodialysis should be adjusted based on the BMI.

Covariates in population pharmacokinetic studies of critically ill adults receiving β-lactam antimicrobials: a systematic review and narrative synthesis

Introduction

Population pharmacokinetic studies of β-lactam antimicrobials in critically ill patients derive models that inform their dosing. In non-linear mixed-effects modelling, covariates are often used to improve model fit and explain variability. We aimed to investigate which covariates are most commonly assessed and which are found to be significant, along with global patterns of publication.

Methods

We conducted a systematic review, searching MEDLINE, Embase, CENTRAL and Web of Science on 01 March 2023, including studies of critically ill adults receiving β-lactam antimicrobials who underwent blood sampling for population pharmacokinetic studies. We extracted and categorized all reported covariates and assessed reporting quality using the ClinPK checklist.

Results

Our search identified 151 studies with 6018 participants. Most studies reported observational cohorts (120 studies, 80%), with the majority conducted in high-income settings (136 studies, 90%). Of the 1083 identified covariate instances, 237 were unique; the most common categories were patient characteristics (n = 404), biomarkers (n = 206) and physiological parameters (n = 163). Only seven distinct commonly reported covariates (CLCR, weight, glomerular filtration rate, diuresis, need for renal replacement, serum albumin and C-reactive protein) were significant more than 20% of the time.

Conclusions

Covariates are most commonly chosen based on biological plausibility, with patient characteristics and biomarkers the most frequently investigated. We developed an openly accessible database of reported covariates to aid investigators with covariate selection when designing population pharmacokinetic studies. Novel covariates, such as sepsis subphenotypes, have not been explored yet, leaving a research gap for future work.

A rapid and simple HPLC-MS/MS method for the therapeutic drug monitoring of six special-grade antimicrobials in pediatric patients

Meropenem, linezolid, fluconazole, voriconazole, posaconazole, and vancomycin are six important antimicrobials used for severe infections in critically ill patients listed in special-grade antimicrobials in China. The six antimicrobials' highly variable pharmacodynamics and pharmacokinetics in critically ill pediatric patients present significant challenges to clinicians in ensuring optimal therapeutic targets. Therefore, therapeutic drug monitoring of these antimicrobials in human plasma is necessary to obtain their plasma concentration. A rapid, simple, and sample-saving high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed, which could simultaneously determine all six antimicrobials. It required only 10 μL of plasma and a one-step protein precipitation process. Chromatographic separation was achieved on a reversed-phase column (C18, 30 × 2.1 mm, 2.6 μm) via gradient elution using water and acetonitrile containing 0.1 % formic acid as mobile phase. The injection volume was 2 μL, and the total run time was only 2.5 min. Detection was done using a Triple Quad™ 4500MD tandem mass spectrometer coupled with an electrospray ionization (ESI) source in positive mode. The calibration curves ranged from 0.5 to 64 μg/mL for meropenem and fluconazole, 0.2-25.6 μg/mL for linezolid and voriconazole, 0.1-12.8 μg/mL for posaconazole and 1-128 μg/mL for vancomycin, with the coefficients of correlation all greater than 0.996. Furthermore, the method was validated rigorously according to the European Medicines Agency (EMA) guidelines, demonstrating excellent accuracy (from 93.0 % to 110.6 %) and precision (from 2.0 % to 12.8 %). Moreover, its applicability to various matrices (including serum, hemolytic plasma, and hyperlipidemic plasma) was evaluated. Thus, this method was successfully applied to routine therapeutic drug monitoring for critically ill pediatric patients and other patients in need.

Evaluation of pharmacokinetic pharmacodynamic target attainment of meropenem in pediatric patients

BACKGROUND

Meropenem is a widely used carbapenem for treating severe pediatric infections. However, few studies have assessed its pharmacokinetics/pharmacodynamics (PK/PD) in pediatric patients. This study aimed to evaluate the proportion of Saudi pediatric patients achieving the PK/PD target of meropenem.

METHODS

A prospective observational study was conducted at King Saud University Medical City from July to September 2022. Pediatric patients receiving meropenem for suspected or proven infections were included in the study. The primary outcome was the percentage of patients achieving the recommended PK/PD target for critically ill or non-critically ill pediatric patients.

RESULTS

The study included 30 patients (nine neonates and 21 older pediatric patients). All neonates were critically ill. Among them, 55 % achieved the PK/PD target of 100 % free time above the MIC. In older ICU pediatric patients, only 11 % attained this target, whereas 58 % of older pediatrics in the general wards achieved the PK/PD target of 50 % free time above the MIC. Augmented renal clearance (ARC) was identified in 57 % of our pediatric patient population, none of whom achieved the recommended PK/PD targets. The median trough concentrations in patients with and without ARC were 0.75 and 1.3 μg/mL, respectively (P < 0.05).

CONCLUSIONS

The majority of patients in our cohort did not achieve the PK/PD target for meropenem. ARC emerged as a major risk factor for target attainment failure in both critically ill and non-critically ill pediatric patients.

Aminoglycoside uptake, stress, and potentiation in Gram-negative bacteria: new therapies with old molecules

SUMMARYAminoglycosides (AGs) are long-known molecules successfully used against Gram-negative pathogens. While their use declined with the discovery of new antibiotics, they are now classified as critically important molecules because of their effectiveness against multidrug-resistant bacteria. While they can efficiently cross the Gram-negative envelope, the mechanism of AG entry is still incompletely understood, although this comprehension is essential for the development of new therapies in the face of the alarming increase in antibiotic resistance. Increasing antibiotic uptake in bacteria is one strategy to enhance effective treatments. This review aims, first, to consolidate old and recent knowledge about AG uptake; second, to explore the connection between AG-dependent bacterial stress and drug uptake; and finally, to present new strategies of potentiation of AG uptake for more efficient antibiotic therapies. In particular, we emphasize on the connection between sugar transport and AG potentiation.

Ceftiofur use and antimicrobial stewardship in the horse

Equine practitioners require recommendations that support antimicrobial stewardship and avoid generating resistance to medically important antibiotics. This review examines current inadequacies in antimicrobial stewardship standards within the veterinary community, related to antimicrobial categorisation and prescribing practices. Resistance to cephalosporin antibiotics in horses is also described. Properties of cephalosporin antibiotics are outlined and equine-specific studies of ceftiofur, a third-generation cephalosporin antibiotic with medical importance, are detailed. Readers are provided with recommendations that encourage appropriate use of ceftiofur, citing the evidence available in horses.

Inhalable Excipient-Free Dry Powder of Tigecycline for the Treatment of Pulmonary Infections

Tigecycline (TIG) is a broad-spectrum antibiotic that has been approved for the treatment of a number of complicated infections, including community-acquired bacterial pneumonia. Currently it is available only as an intravenous injection that undergoes rapid chemical degradation and limits the use to in-patient scenarios. The use of TIG as an inhaled dry powder inhaler may offer a promising treatment option for patients with multidrug-resistant respiratory tract infections, such as Stenotrophomonas maltophilia (S. maltophilia). This study explores the feasibility of engineering an inhaled powder formulation of TIG that could administer relevant doses at a wide range of inhalation flow rates while maintaining stability of this labile drug. Using air-jet milling, micronized TIG had excellent aerosolization efficiency, with over 80% of the device emitted dose being within the respirable range. TIG was also readily dispersed using different inhaler devices even when tested at different pressure drops and flow rates. Additionally, micronized TIG was stable for 6 months at 25 °C/60% RH and 40 °C/75% RH. Micronized TIG maintained a low minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of 0.8 μM and >0.5 μM, respectively in S. maltophilia cultures in vitro. These results strongly suggest that the micronization of TIG results in a stable and respirable formulation that can be delivered via the pulmonary route for the treatment of lung infections.

Drug Utilization Evaluation and Impact of Pharmacist Interventions on Optimization of Piperacillin/Tazobactam Use: A Retrospective Analysis and Prospective Audit

(1) Background: Piperacillin/tazobactam is a broad-spectrum antimicrobial encompassing most Gram-positive and Gram-negative aerobic and anaerobic bacteria. The inappropriate use of such broad-spectrum antibiotics is an important contributor to the rising rates of antimicrobial drug resistance worldwide. Drug utilization evaluation studies and pharmacists' interventions are vital to assess, develop, and promote the rational use of antibiotics. This drug utilization study aimed to evaluate the current utilization practice of piperacillin/tazobactam in a hospital setting and assess the impact of pharmacist intervention in improving its appropriate use. (2) Methodology: In this study, we used a retrospective cohort and a prospective cohort, a cross-sectional, observational method. It included a retrospective (Cycle A/pre-intervention-CycA) phase followed by an educational interventional phase conducted by the pharmacists. During the 2 months of educational intervention, pharmacists used several methods, including workshops, lectures, oral presentations, and the development and reinforcement of clinical pathways to promote the judicious use of piperacillin/tazobactam. This was followed by a prospective (Cycle B/post-intervention-CycB) phase to improve piperacillin/tazobactam usage appropriateness. The appropriateness criteria for this drug utilization evaluation were established based on antimicrobial guidelines, the published literature, the institutional antibiogram, consultation from the antimicrobial stewardship committee, and the product monograph (Tazocin). The appropriateness of CycA and CycB patients was compared using the measurable elements, including indication and dose based on renal function, timely order for cultures, de-escalation, and use of extended infusion protocol. (3) Results: The study population comprised 100 patients in both CycA and CycB. The mean age of the patients was 66.28 ± 16.15 and 67.35 ± 17.98, and the ratios of men to women were found to be 49:51 and 61:39 in CycA and CycB, respectively. It was observed that inappropriate usage was high in CycA patients, and the appropriateness was improved in CycB patients. A total of 31% of inappropriate empirical broad-spectrum use was found in CycA, and it was reduced to 12% in CycB patients. The transition of appropriateness was observed in all measurable criteria, which includes the optimized dose according to the renal function (CycA = 49% to CycB = 94%), timely bacterial culture orders (CycA = 47% to CycB = 74%), prompt de-escalation (CycA = 31% to CycB = 53%), and adherence to extended infusion institutional guidelines (CycA = 34% to CycB = 86%). (4) Conclusions: The study highlighted important aspects of inappropriate piperacillin/tazobactam use. This can be considerably improved by proper education and timely interventions based on the pharmacists' vigilant approach. The study results emphasized the need for surveillance of piperacillin/tazobactam usage by conducting similar drug utilization evaluations and practice to improve quality and safety in healthcare organizations globally.

Extended and Continuous Infusion of Novel Protected β-Lactam Antibiotics: A Narrative Review

Consolidated data from pharmacokinetic and pharmacodynamic studies support the administration of β-lactam antibiotics in prolonged infusion (i.e., extended or continuous) to optimize therapeutic efficacy by increasing the probability of attaining maximal bactericidal activity. This is the longest possible time during which the free drug concentrations are approximately four-fold the minimum inhibitory concentration between dosing intervals. In the context of antimicrobial stewardship strategies, achieving aggressive pharmacokinetic and pharmacodynamic targets is an important tool in the management of multi-drug resistant (MDR) bacterial infections and in the attainment of mutant preventing concentrations. However, prolonged infusion remains an unexploited resource. Novel β-lactam/β-lactamase inhibitor (βL/βLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-cilastatin-relebactam) have been released in recent years to face the emerging challenge of MDR Gram-negative bacteria. Pre-clinical and real-life evidence has confirmed the promising role of prolonged infusion of these molecules in specific settings and clinical populations. In this narrative review we have summarized available pharmacological and clinical data, future perspectives, and current limitations of prolonged infusion of the novel protected β-lactams, their application in hospital settings and in the context of outpatient parenteral antimicrobial therapy.

Prevalence of Augmented Renal Clearance (ARC), Utility of Augmented Renal Clearance Scoring System (ARC score) and Augmented Renal Clearance in Trauma Intensive Care Scoring System (ARCTIC score) in Predicting ARC in the Intensive Care Unit: Proactive Study

Objectives

We aimed to study the prevalence of augmented renal clearance (ARC) and validate the utility of ARC and ARCTIC scores. We also aimed to assess the correlation and agreement between estimated GFR (eGFR-EPI) and 8-hour measured creatinine clearance (8 hr-mCL_cr).

Study design and methodology

This was a prospective, observational study done in the mixed medical-surgical intensive care unit (ICU) and 90 patients were recruited. 8 hr-mCL_cr, ARC, and ARCTIC scores and eGFR-EPI were calculated for all patients. ARC was said to be present if 8 hr-mCLcr was ≥ 130 mL/min.

Results

Four patients were excluded from the analysis. The prevalence of ARC was 31.4%. The sensitivity, specificity, and positive and negative predictive values of ARC and ARCTIC scores were found to be 55.6, 84.7, 62.5, 80.6, and 85.2, 67.8, 54.8, and 90.9 respectively. AUROC for ARC and ARCTIC scores were 0.802 and 0.765 respectively. A strong positive correlation and poor agreement were observed between eGFR-EPI and 8 hr-mCL_cr.

Conclusion

The prevalence of ARC was significant and the ARCTIC score showed good potential as a screening tool to predict ARC. Lowering the cut-off of ARC score to ≥5 improved its utility in predicting ARC. Despite its poor agreement with 8 hr-mCL_cr, eGFR-EPI with a cut-off ≥114 mL/min showed utility in predicting ARC.

How to cite this article

Kanna G, Patodia S, Annigeri RA, Ramakrishnan N, Venkataraman R. Prevalence of Augmented Renal Clearance (ARC), Utility of Augmented Renal Clearance Scoring System (ARC score) and Augmented Renal Clearance in Trauma Intensive Care Scoring System (ARCTIC score) in Predicting ARC in the Intensive Care Unit: Proactive Study. Indian J Crit Care Med 2023;27(6):433-443.

Adverse Drug Reactions Relevant to Drug Resistance and Ineffectiveness Associated with Meropenem, Linezolid, and Colistin: An Analysis Based on Spontaneous Reports from the European Pharmacovigilance Database

Antimicrobial resistance is considered one of the major threats to public health and is an important factor that influences the patient's outcome in the intensive care unit. Pharmacovigilance can help raise awareness of potential drug resistance (DR) or ineffectiveness (DI) through adverse drug reaction reports that are submitted to different spontaneous reporting systems. Based on spontaneous Individual Case Safety Reports from EudraVigilance, we conducted a descriptive analysis of adverse drug reactions associated with meropenem, colistin, and linezolid, with a focus on DR and DI. Of the total adverse drug reactions (ADRs) reported for each analyzed antibiotic by 31 December 2022, between 2.38-8.42% and 4.15-10.14% of the reports were related to DR and DI, respectively. A disproportionality analysis was conducted to evaluate the frequency of reporting adverse drug reactions relevant to the DR and DI of the analyzed antibiotics compared to other antimicrobials. Based on the analysis of the collected data, this study underlines the importance of post-marketing drug safety monitoring in raising a warning signal regarding antimicrobial resistance, thereby potentially contributing to the reduction in antibiotic treatment failure in an intensive care setting.

Antibiotic stewardship in the ICU: time to shift into overdrive

Antibiotic resistance is a major health problem and will be probably one of the leading causes of deaths in the coming years. One of the most effective ways to fight against resistance is to decrease antibiotic consumption. Intensive care units (ICUs) are places where antibiotics are widely prescribed, and where multidrug-resistant pathogens are frequently encountered. However, ICU physicians may have opportunities to decrease antibiotics consumption and to apply antimicrobial stewardship programs. The main measures that may be implemented include refraining from immediate prescription of antibiotics when infection is suspected (except in patients with shock, where immediate administration of antibiotics is essential); limiting empiric broad-spectrum antibiotics (including anti-MRSA antibiotics) in patients without risk factors for multidrug-resistant pathogens; switching to monotherapy instead of combination therapy and narrowing spectrum when culture and susceptibility tests results are available; limiting the use of carbapenems to extended-spectrum beta-lactamase-producing Enterobacteriaceae, and new beta-lactams to difficult-to-treat pathogen (when these news beta-lactams are the only available option); and shortening the duration of antimicrobial treatment, the use of procalcitonin being one tool to attain this goal. Antimicrobial stewardship programs should combine these measures rather than applying a single one. ICUs and ICU physicians should be at the frontline for developing antimicrobial stewardship programs.

Colistin- and amikacin-loaded lipid-based drug delivery systems for resistant gram-negative lung and wound bacterial infections

Antimicrobial resistance (AMR) is a global health issue, which needs to be tackled without further delay. The World Health Organization(WHO) has classified three gram-negative bacteria, Pseudomonas aeruginosa, Klebsiella pneumonia and Acinetobacter baumannii, as the principal responsible for AMR, mainly causing difficult to treat nosocomial lung and wound infections. In this regard, the need for colistin and amikacin, the re-emerged antibiotics of choice for resistant gram-negative infections, will be examined as well as their associated toxicity. Thus, current but ineffective clinical strategies designed to prevent toxicity related to colistin and amikacin will be reported, highlighting the importance of lipid-based drug delivery systems (LBDDSs), such as liposomes, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), as efficient delivery strategies for reducing antibiotic toxicity. This review reveals that colistin- and amikacin-NLCs are promising carriers with greater potential than liposomes and SLNs to safely tackle AMR, especially for lung and wound infections.

Electrospun sandwich-structured of polycaprolactone/gelatin-based nanofibers with controlled release of ceftazidime for wound dressing

In the present work, sandwich-like polycaprolactone/gelatin/polycaprolactone electrospun multilayered mats were implemented to control the release of ceftazidime (CTZ). The outer layers were made from polycaprolactone nanofibers (NFs), and CTZ-loaded gelatin provided an internal layer. The release profile of CTZ from mats was compared with monolayer gelatin mats and chemically cross-linked GEL mats. All the constructs were characterized using scanning electron microscopy (SEM), mechanical properties, viscosity, electrical conductivity, X-ray diffraction (XRD), and Fourier transform-infrared spectroscopy (FT-IR). In vitro cytotoxicity against normal fibroblasts as well as antibacterial activity of CTZ-loaded sandwich-like NFs were investigated by the MTT assay. The results showed that the drug release rate from the polycaprolactone/gelatin/polycaprolactone mat was slower than that of gelatin monolayer NFs, and the rate of release can be adjusted by changing the thickness of hydrophobic layers. The NFs exhibited high activity against Pseudomonas aeruginosa and Staphylococcus aureus, while no significant cytotoxicity was observed against human normal cells. Altogether, the final mat as a predominant antibacterial scaffold can be used for controlled drug release of antibacterial drugs as the wound healing dressings in tissue engineering.

Antimicrobial Exposure in Critically Ill Patients with Sepsis-Associated Multi-Organ Dysfunction Requiring Extracorporeal Organ Support: A Narrative Review

Sepsis is a leading cause of disability and mortality worldwide. The pathophysiology of sepsis relies on the maladaptive host response to pathogens that fosters unbalanced organ crosstalk and induces multi-organ dysfunction, whose severity was directly associated with mortality. In septic patients, etiologic interventions aiming to reduce the pathogen load via appropriate antimicrobial therapy and the effective control of the source infection were demonstrated to improve clinical outcomes. Nonetheless, extracorporeal organ support represents a complementary intervention that may play a role in mitigating life-threatening complications caused by sepsis-associated multi-organ dysfunction. In this setting, an increasing amount of research raised concerns about the risk of suboptimal antimicrobial exposure in critically ill patients with sepsis, which may be worsened by the concomitant delivery of extracorporeal organ support. Accordingly, several strategies have been implemented to overcome this issue. In this narrative review, we discussed the pharmacokinetic features of antimicrobials and mechanisms that may favor drug removal during renal replacement therapy, coupled plasma filtration and absorption, therapeutic plasma exchange, hemoperfusion, extracorporeal CO₂ removal and extracorporeal membrane oxygenation. We also provided an overview of evidence-based strategies that may help the physician to safely prescribe effective antimicrobial doses in critically ill patients with sepsis-associated multi-organ dysfunction who receive extracorporeal organ support.

Antimicrobial residual drug error in the intensive care unit; a single blinded prospective observational study

OBJECTIVE

To determine the percentage of drug remaining in discarded antibiotic vials after use.

DESIGN

Blinded prospective observational trial.

SETTING

26-bed Australian metropolitan tertiary referral intensive care unit.

MAIN OUTCOME MEASURES

Percentage of labelled dose remaining in the vial after discard.

METHOD

Discarded antibiotic vials collected over a 7-day period in an adult intensive care unit were analysed. Each collected vial had any drug remnant washed out and made up to a known volume. A 1 ml aliquot of each vials washings was analysed using high performance liquid chromatography. From this concentration, the percentage of the drug remaining in the vial after discard was calculated. Additionally, each vial was weighed before and after washing to determine the weight of the remnant in each vial.

RESULTS

A total of 311 vials comprising of 11 different drugs and 14 individual vial types were collected. The median residual drug error across all vials was 3.7 %. The drug with the highest median was piperacillin at 6.1 % (IQR 4.3) and the lowest was amoxicillin 0.2 % (IQR 0.1). The single highest value for a given vial was vancomycin (500 mg) with 33.2 % and the lowest for a given vial was 0.1 % amoxicillin (1 g). These two drugs also exhibited the greatest range between the maximum and minimum value for any drug being 32 % and 0.9 % respectively.

CONCLUSIONS

Our study shows that up to a third of the intended dose may fail to reach the patient, highlighting a significant factor in the administration of antibiotics to the critically ill population.

IMPLICATIONS FOR CLINICAL PRACTICE

Residual drug often remains in antibiotic vials meaning that drug is not reaching the patient. There is considerable variation in the method by which medications are reconstituted in clinical settings. Two person checks should be completed after reconstitution in order to ensure that the medication is fully reconstituted and extracted from the vial.

The Effect of Clinical Pharmacist Intervention on Renal Function Impairment in Patients with Antimicrobial-Induced Acute Kidney Injury in ICU

OBJECTIVE

The purpose of this study was to analyze the improvement effect of clinical pharmacist intervention on renal function impairment in patients with antimicrobial-induced acute kidney injury (AKI).

METHODS

A total of 145 patients with AKI caused by antibiotics admitted to the ICU department were selected as the research subjects. The patients were divided into the control group (n=57) and the intervention group (n=88) according to whether there were ICU specialist clinical pharmacists involved in clinical treatment. The renal function outcome and infection control were evaluated in the two groups.

RESULTS

The proportion of renal function outcome in the intervention group was 88.6%, which was significantly higher than that in the control group. However, there was no statistically significant difference in infection control between the two groups. For the intervention group, the clinical pharmacists adopted three intervention methods: dose adjustment, drug replacement and CRRT treatment, respectively, according to the disease conditions of AKI patients. Among them, dose adjustment and drug replacement were the most frequently used intervention methods. In addition, the proportion of renal function outcome was higher in the group of patients who changed antibiotics and underwent CRRT, which were 93.1% and 100%, respectively. The adjusted-dose group had the highest infection control rate at 82.1%. However, there were no statistically significant differences in renal function outcomes and infection control among the three interventions.

CONCLUSION

Clinical pharmacists participating in the clinical treatment of patients with antimicrobial-induced AKI in ICU can effectively improve the renal function of patients.

Sequestration of Antimicrobial Agents in Xcoating and Heparin-Coated Extracorporeal Membrane Oxygenation Circuits: An In Vitro Study

Limited data exist to guide antimicrobial therapy commonly prescribed to patients undergoing extracorporeal membrane oxygenation (ECMO). This study aimed to describe the kinetics of the cefazolin, doripenem, daptomycin, and levofloxacin in heparin-coated and Xcoating ECMO circuits. Circuits were primed with bovine whole blood and maintained at a physiological pH and temperature for 24 h. Each antimicrobial agent was added to the whole blood before priming. Equivalent doses of these drugs were added to glass jars containing fresh bovine whole blood as a control. Serial blood samples were collected from the ECMO circuits and controls over 24 h, and drug concentrations were quantified using validated assays. The concentrations of cefazolin, doripenem, daptomycin, and levofloxacin did not decrease significantly over 24 h. Collectively, these antimicrobial agents can be administered without the need to consider sequestration when using either heparin-coated or Xcoating circuits.

Ceftriaxone 1 g Versus 2 g Daily for the Treatment of Enterobacterales Bacteremia: A Retrospective Cohort Study

Background: Ceftriaxone is a commonly used antibiotic for the treatment of susceptible Enterobacterales infections. There is currently limited clinical data on the optimal dose of ceftriaxone for Enterobacterales bacteremia. Objectives: To evaluate the rate of clinical failure of ceftriaxone 1 g versus 2 g daily in patients with Enterobacterales bacteremia. Methods: This was a retrospective cohort study of patients admitted to any of the 3 New York University Hospitals: Long Island, Tisch, or Brooklyn, with ceftriaxone-susceptible Enterobacterales bacteremia, receiving ceftriaxone 1 or 2 g daily from October 2019 to September 2020. The primary outcome was 90-day rate of clinical failure. Clinical failure was defined as escalation of therapy, relapse of infection, or all-cause mortality. Results: A total of 124 patients, 58% in the 1-g group and 42% in the 2-g group, were included. There was no statistically significant difference found in the primary outcome. The 90-day rate of clinical failure was 16.7% versus 9.6%, P = 0.260. There were no statistically significant secondary outcomes, although infection relapse rates at 90 days were numerically greater in the 1-g group (11.1% vs 1.9%, P = 0.078). Hypoalbuminemia was the only variable associated with an increased risk of clinical failure (odds ratio = 4.03; 95% confidence interval [CI] = 1.12-14.50, P = 0.033). Conclusion: In our exploratory findings, there was no statistically significant difference with the 90-day rate of clinical failure between ceftriaxone 1 g versus 2 g daily, although there was a numeric trend toward an increased rate of infection relapse within the 1-g group. Hypoalbuminemia was associated with an increased risk of clinical failure. Prospective studies are warranted to confirm these findings.

Chronic diseases and compliance with provincial guidelines for outpatient antibiotic prescription in cases of otitis media and respiratory infections: a population-based study of linked data in Quebec, Canada, 2010-2017

BACKGROUND

In Quebec, antibiotic use is higher among outpatients with chronic diseases. We sought to measure compliance with provincial guidelines for the treatment of otitis media and common respiratory infections, and to measure variations in compliance according to the presence of certain chronic diseases.

METHODS

We conducted a population-based study of linked data on antibiotic dispensing covered by the public drug insurance plan between April 2010 and March 2017. We included patients who had consulted a primary care physician within 2 days before being dispensed an antibiotic for an infection targeted by provincial guidelines, including bronchitis in patients with chronic obstructive pulmonary disease, otitis media, pharyngitis, pneumonia and sinusitis. We computed proportions of prescriptions compliant with guidelines (use of recommended antibiotic for children, and use of recommended antibiotic and dosage for adults) by age group (children or adults) and chronic disease (respiratory, cardiovascular, diabetes, mental disorder or none). We measured the impact of chronic diseases on compliance using robust Poisson regression.

RESULTS

We analyzed between 14 677 and 198 902 prescriptions for each infection under study. Compliance was greater than 87% among children, but was lower among children with asthma (proportion ratios between 0.97 and 1.00). In adults, the chosen antibiotic was compliant for at least 73% of prescriptions, except for pharyngitis (≤ 61%). Accounting for dosage lowered compliance to between 31% and 61%. Compliance was lower in the presence of chronic diseases (proportion ratios between 0.94 and 0.98).

INTERPRETATION

It is possible that prescribing noncompliant prescriptions was sometimes appropriate, but the high frequency of noncompliance suggests room for improvement. Given that variations associated with chronic diseases were small, disease-specific guidelines for antibiotic prescriptions are likely to have a limited impact on compliance.

Mechanisms of antibiotic action shape the fitness landscapes of resistance mutations

Antibiotic-resistant pathogens are a major public health threat. A deeper understanding of how an antibiotic's mechanism of action influences the emergence of resistance would aid in the design of new drugs and help to preserve the effectiveness of existing ones. To this end, we developed a model that links bacterial population dynamics with antibiotic-target binding kinetics. Our approach allows us to derive mechanistic insights on drug activity from population-scale experimental data and to quantify the interplay between drug mechanism and resistance selection. We find that both bacteriostatic and bactericidal agents can be equally effective at suppressing the selection of resistant mutants, but that key determinants of resistance selection are the relationships between the number of drug-inactivated targets within a cell and the rates of cellular growth and death. We also show that heterogeneous drug-target binding within a population enables resistant bacteria to evolve fitness-improving secondary mutations even when drug doses remain above the resistant strain's minimum inhibitory concentration. Our work suggests that antibiotic doses beyond this "secondary mutation selection window" could safeguard against the emergence of high-fitness resistant strains during treatment.

Application of pharmacokinetic/pharmacodynamic concepts to the development of treatment regimens for sporadic canine urinary tract infections: Challenges and paths forward

Antimicrobial efficacy can be predicted based on infection site exposure to the antimicrobial agent relative to the in vitro susceptibility of the pathogen to that agent. When infections occur in soft tissues (e.g., muscle, blood, and ligaments), exposure at the infection site is generally assumed to reflect an equilibrium between the unbound concentrations in plasma and that in the interstitial fluids. In contrast, for sporadic urinary tract infections (UTIs) in dogs and uncomplicated UTIs in humans, the primary site of infection is the bladder wall. Infection develops when bacteria invade the host bladder urothelium (specifically, the umbrella cells that form the urine-contacting layer of the stratified uroepithelium) within which these bacteria can avoid exposure to host defenses and antimicrobial agents. Traditionally, pathogen susceptibility has been estimated using standardized in vitro tests that measure the minimal concentration that will inhibit pathogen growth (MIC). When using exposure-response relationships during drug development to explore dose optimization, these relationships can either be based upon an assessment of a correlation between clinical outcome, drug exposure at the infection site, and pathogen MIC, or upon benchmark exposure-response relationships (i.e., pharmacokinetic/pharmacodynamic indices) typically used for the various drug classes. When using the latter approach, it is essential that the unbound concentrations at the infection site be considered relative to the MIC within the biological matrix to which the pathogen will be exposed. For soft tissue infections, this typically is the unbound plasma concentrations versus MICs determined in standardized media such as cation-adjusted Mueller Hinton broth, which is how many indices were originally established. However, for UTIs, it is the unbound drug concentrations within the urine versus the MICs in the actual urine biophase that needs to be considered. The importance of these relationships and how they are influenced by drug resistance, resilience, and inoculum are discussed in this review using fluoroquinolones and beta-lactams as examples.

Optimal dosing of cefotaxime and desacetylcefotaxime for critically ill paediatric patients. Can we use microsampling?

Objectives

To describe the population pharmacokinetics of cefotaxime and desacetylcefotaxime in critically ill paediatric patients and provide dosing recommendations. We also sought to evaluate the use of capillary microsampling to facilitate data-rich blood sampling.

Methods

Patients were recruited into a pharmacokinetic study, with cefotaxime and desacetylcefotaxime concentrations from plasma samples collected at 0, 0.5, 2, 4 and 6 h used to develop a population pharmacokinetic model using Pmetrics. Monte Carlo dosing simulations were tested using a range of estimated glomerular filtration rates (60, 100, 170 and 200 mL/min/1.73 m²) and body weights (4, 10, 15, 20 and 40 kg) to achieve pharmacokinetic/pharmacodynamic (PK/PD) targets, including 100% ƒT_>MIC with an MIC breakpoint of 1 mg/L.

Results

Thirty-six patients (0.2–12 years) provided 160 conventional samples for inclusion in the model. The pharmacokinetics of cefotaxime and desacetylcefotaxime were best described using one-compartmental model with first-order elimination. The clearance and volume of distribution for cefotaxime were 12.8 L/h and 39.4 L, respectively. The clearance for desacetylcefotaxime was 10.5 L/h. Standard dosing of 50 mg/kg q6h was only able to achieve the PK/PD target of 100% ƒT_>MIC in patients >10 kg and with impaired renal function or patients of 40 kg with normal renal function.

Conclusions

Dosing recommendations support the use of extended or continuous infusion to achieve cefotaxime exposure suitable for bacterial killing in critically ill paediatric patients, including those with severe or deep-seated infection. An external validation of capillary microsampling demonstrated skin-prick sampling can facilitate data-rich pharmacokinetic studies.

Evaluation of a Meropenem and Piperacillin Monitoring Program in Intensive Care Unit Patients Calls for the Regular Assessment of Empirical Targets and Easy-to-Use Dosing Decision Tools

The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1–5 × MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8–40 mg/L and 16–80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0%, piperacillin: 93.9%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7%, piperacillin 50.5%) with the lowest TA for severely impaired renal function (meropenem: 13.9%, piperacillin: 29.2%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13%, piperacillin: 4.78%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.

Higher Tissue Concentrations of Vancomycin Achieved With Low-Dose Intraosseous Injection Versus Intravenous Despite Limited Tourniquet Duration in Primary Total Knee Arthroplasty: A Randomized Trial

BACKGROUND

Vancomycin use has been suggested in high risk patients undergoing total knee arthroplasty (TKA). Previous literature has shown that a lower dose (500 mg) of vancomycin given by intraosseous regional administration (IORA) achieves tissue concentrations 4-10 times higher than intravenous (IV) administration. There is increasing interest in performing TKA with limited tourniquet inflation time. The purpose of this study is to evaluate whether IORA of vancomycin can achieve effective tissue concentrations with limited tourniquet inflation time.

METHODS

Based on prior power calculations, 24 patients undergoing primary TKA were randomized into 2 groups. Group IV-Systemic received weight-based (15 mg/kg) vancomycin with the tourniquet inflated for cementation only. Group IORA received 500 mg vancomycin via IORA after tourniquet inflation which remained inflated for 10 minutes, then reinflated for cementation only. Vancomycin concentrations from tissue, serum, and drain fluid were compared between the 2 groups.

RESULTS

Median vancomycin concentrations in tissue were significantly higher (5-15 times) at all time points in the IORA group. Concentrations in fat at the time of wound closure, after the tourniquet had been deflated for most of the procedure, were 5.2 μg/g in Group IV-Systemic and 33.1 μg/g in Group IORA (P < .001). Median bone concentrations taken just prior to cementation were 7.9 μg/g in Group IV-Systemic and 21.8 μg/g in Group IORA (P = .006). There were no complications related to IORA.

CONCLUSION

For surgeons who wish to limit tourniquet time and when indicated to use vancomycin, low-dose vancomycin IORA achieves tissue concentrations 5-15 times higher than those achieved by IV administration.

LEVEL OF EVIDENCE

Level 1 therapeutic randomized trial.

Ciprofloxacin in Patients Undergoing Extracorporeal Membrane Oxygenation (ECMO): A Population Pharmacokinetic Study

Extracorporeal membrane oxygenation (ECMO) is utilized to temporarily sustain respiratory and/or cardiac function in critically ill patients. Ciprofloxacin is used to treat nosocomial infections, but data describing the effect of ECMO on its pharmacokinetics is lacking. Therefore, a prospective, observational trial including critically ill adults (n = 17), treated with ciprofloxacin (400 mg 8–12 hourly) during ECMO, was performed. Serial blood samples were collected to determine ciprofloxacin concentrations to assess their pharmacokinetics. The pharmacometric modeling was performed (NONMEM^®) and utilized for simulations to evaluate the probability of target attainment (PTA) to achieve an AUC_0–24/MIC of 125 mg·h/L for ciprofloxacin. A two-compartment model most adequately described the concentration-time data of ciprofloxacin. Significant covariates on ciprofloxacin clearance (CL) were plasma bicarbonate and the estimated glomerular filtration rate (eGFR). For pathogens with an MIC of ≤0.25 mg/L, a PTA of ≥90% was attained. However, for pathogens with an MIC of ≥0.5 mg/L, plasma bicarbonate ≥ 22 mmol/L or eGFR ≥ 10 mL/min PTA decreased below 90%, steadily declining to 7.3% (plasma bicarbonate 39 mmol/L) and 21.4% (eGFR 150 mL/min), respectively. To reach PTAs of ≥90% for pathogens with MICs ≥ 0.5 mg/L, optimized dosing regimens may be required.

Unraveling the Nature of Antibiotics: Is It a Cure or a New Hurdle to the Patient Treatment?

Antimicrobial resistance is an increasing problem worldwide that has been exacerbated by antibiotic misuse worldwide. Growing antibiotic resistance can be attributed to as well as leads to severe infections, complications, prolonged hospital admissions, and higher mortality. One of the most important goals of administering antimicrobials is to avoid establishing antibiotic resistance during therapy. This can be done by drastically lowering worldwide antimicrobial usage, both in present and future. While current management methods to legislate antimicrobials and educate the healthcare community on the challenges are beneficial, they do not solve the problem of attaining an overall reduction in antimicrobial usage in humans. Application of rapid microbiological diagnostics for identification and antimicrobial susceptibility testing, use of inflammation markers to guide initiation and duration of therapies, reduction of standard antibiotic course durations, individualization of antibiotic treatments, and dosing considering pharmacokinetics are all possible strategies to optimize antibiotic use in everyday clinical practice and reduce the risk of inducing bacterial resistance. Furthermore, to remove any impediments to proper prescribing, strategies to improve antibiotic prescribing and antibiotic stewardship programs should enable clinical reasoning and enhance the prescribing environment. In addition, the well-established association between antimicrobial usage and resistance should motivate efforts to develop antimicrobial treatment regimens that facilitate the evolution of resistance. This review discusses the role of antibiotics, their current application in human medicine, and how the resistance has evolved to the existing antibiotics based on the existing literature.

Adherence to practice guidelines for the management of febrile neutropenia in patients undergoing hematopoietic stem cell transplantation: An observational study in a referral center in Iran

INTRODUCTION

Patients undergoing hematopoietic stem cell transplantation (HSCT) are suspected to develop febrile neutropenia (FN) and severe infections. Therefore, appropriate prescription of antibiotics in these patients is crucial to reduce the rates of morbidity, mortality, and antimicrobial resistance. The present study aimed to evaluate the physicians' prescription and adherence to the FN clinical guidelines among patients undergoing HSCT.

METHODS

This prospective observational single-center study was conducted during a 15-month period in a tertiary referral hospital in Iran. The patients with at least one episode of FN following HSCT were included in the current study. The physicians' adherence to the Infectious Diseases Society of America (IDSA) and National Comprehensive Cancer Network (NCCN) clinical guidelines for the management of FN was evaluated using prescription data and medical record reviews.

RESULTS

Two hundred and fifteen patients with 297 FN episodes were evaluated. The timing of antibiotics and the selection of the initial regimen were considered guideline-based therapy. However, antibiotic dosing and initial regimen modification were not followed in terms of the guideline recommendations in 58.1% of the patients. In particular, vancomycin was inappropriately given in 83.1% of patients. The overall adherence of physicians to the guidelines was 35.8%.

CONCLUSION

Non-adherence to clinical guidelines is high particularly in initial regimen modification and administration of vancomycin, which affects hospital stay and patient's outcome. Implementation of guideline-review sessions to raise the awareness of the physicians and to improve the rational use of antimicrobial agents may be crucial.

Ethics and antibiotic resistance

INTRODUCTION OR BACKGROUND

Antibiotic resistance raises ethical issues due to the severe and inequitably distributed consequences caused by individual actions and policies.

SOURCES OF DATA

Synthesis of ethical, scientific and clinical literature.

AREAS OF AGREEMENT

Ethical analyses have focused on the moral responsibilities of patients to complete antibiotic courses, resistance as a tragedy of the commons and attempts to limit use through antibiotic stewardship.

AREAS OF CONTROVERSY

Each of these analyses has significant limitations and can result in self-defeating or overly narrow implications for policy.

GROWING POINTS

More complex analyses focus on ethical implications of ubiquitous asymptomatic carriage of resistant bacteria, non-linear outcomes within and between patients over time and global variation in resistant disease burdens.

AREAS TIMELY FOR DEVELOPING RESEARCH

Neglected topics include the harms of antibiotic use, including off-target effects on the human microbiome, and the lack of evidence guiding most antibiotic prescription decisions.

Pharmacokinetics of Commonly Used Medications in Children Receiving Continuous Renal Replacement Therapy: A Systematic Review of Current Literature

BACKGROUND AND OBJECTIVE

The use of continuous renal replacement therapy (CRRT) for renal support has increased substantially in critically ill children compared with intermittent modalities owing to its preferential effects on hemodynamic stability. With the expanding role of CRRT, the quantification of extracorporeal clearance and the effect on primary pharmacokinetic parameters is of the utmost importance. Within this review, we aimed to summarize the current state of the literature and compare published pharmacokinetic analyses of commonly used medications in children receiving CRRT to those who are not.

METHODS

A systematic search of the literature within electronic databases PubMed, EMBASE, Cochrane Library, and Web of Science was conducted. Published studies that were included contained relevant information on the use of commonly administered medications to children, from neonates to adolescents, receiving CRRT. Pharmacokinetic parameters that were analyzed included volume of distribution, total clearance, extracorporeal clearance, area under the curve, and elimination half-life. Information regarding CRRT circuit, flow rates, and membrane components was analyzed to investigate differences in pharmacokinetics between each modality.

RESULTS

Forty-five studies met the final inclusion criteria within this systematic review, totaling 833 pediatric patients, with 586 receiving CRRT. Antimicrobials were the most common pharmacological class represented within the literature, representing 81% (35/43) of studies analyzed. Children receiving CRRT largely had similar volume of distribution and total clearance to critically ill children not receiving CRRT, suggesting reno-protective dose adjustments may lead to subtherapeutic dosing regimens in these patients. Overall, there was a tendency for hydrophilic agents, with a low protein binding to undergo elevated total clearance in these children. However, results should be interpreted with caution because of the large variability amongst patient populations and heterogeneity with CRRT modalities, flow rates, and use of extracorporeal membrane oxygenation within studies. This review was able to identify that variation in solute removal, or CRRT modalities, properties (i.e., flow rates), and membrane composition, may have differing effects on the pharmacokinetics of commonly administered medications.

CONCLUSIONS

The current state of the literature regarding medications administered to children receiving CRRT largely focuses on antimicrobials. Significant gaps remain with other commonly used medications such as sedatives and analgesics. Overall reporting of patient clinical characteristics, CRRT settings, and circuit composition was poor, with only 10% of articles including all relevant information to assess the impact of CRRT on total clearance. Changes in pharmacokinetics because of CRRT often required higher than labeled doses, suggesting renally adjusted or reno-protective doses may lead to subtherapeutic dosing regimens. A thorough understanding of the interplay between patient, drug, and CRRT-circuit factors are required to ensure adequate delivery of dosing regimens to this vulnerable population.

Quantitative Determination of Unbound Piperacillin and Imipenem in Biological Material from Critically Ill Using Thin-Film Microextraction-Liquid Chromatography-Mass Spectrometry

β-Lactam antibiotics are most commonly used in the critically ill, but their effective dosing is challenging and may result in sub-therapeutic concentrations that can lead to therapy failure and even promote antimicrobial resistance. In this study, we present the analytical tool enabling specific and sensitive determination of the sole biologically active fraction of piperacillin and imipenem in biological material from the critically ill. Thin-film microextraction sampling technique, followed by rapid liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis, was optimized and validated for the quantitative determination of antibiotics in blood and bronchoalveolar lavage (BAL) specimens collected from intensive care unit (ICU) patients suffering from ventilation-associated pneumonia (n = 18 and n = 9, respectively). The method was optimized and proved to meet the criteria of US Food and Drug Administration (FDA) guidelines for bioanalytical method validation. Highly selective, sensitive, accurate and precise analysis by means of thin-film microextraction–LC-MS/MS, which is not affected by matrix-related factors, was successfully applied in clinical settings, revealing poor penetration of piperacillin and imipenem from blood into BAL fluid (reflecting the site of bacterial infection), nonlinearity in antibiotic binding to plasma-proteins and drug-specific dependence on creatinine clearance. This work demonstrates that only a small fraction of biologically active antibiotics reach the site of infection, providing clinicians with a high-throughput analytical tool for future studies on personalized therapeutic drug monitoring when tailoring the dosing strategy to an individual patient.

Effect of Different Piperacillin-Tazobactam Dosage Regimens on Synergy of the Combination with Tobramycin against Pseudomonas aeruginosa for the Pharmacokinetics of Critically Ill Patients in a Dynamic Infection Model

We evaluated piperacillin-tazobactam and tobramycin regimens against Pseudomonas aeruginosa isolates from critically ill patients. Static-concentration time-kill studies (SCTK) assessed piperacillin-tazobactam and tobramycin monotherapies and combinations against four isolates over 72 h. A 120 h-dynamic in vitro infection model (IVM) investigated isolates Pa1281 (MIC_piperacillin 4 mg/L, MIC_tobramycin 0.5 mg/L) and CR380 (MIC_piperacillin 32 mg/L, MIC_tobramycin 1 mg/L), simulating the pharmacokinetics of: (A) tobramycin 7 mg/kg q24 h (0.5 h-infusions, t_1/2 = 3.1 h); (B) piperacillin 4 g q4 h (0.5 h-infusions, t_1/2 = 1.5 h); (C) piperacillin 24 g/day, continuous infusion; A + B; A + C. Total and less-susceptible bacteria were determined. SCTK demonstrated synergy of the combination for all isolates. In the IVM, regimens A and B provided initial killing, followed by extensive regrowth by 72 h for both isolates. C provided >4 log₁₀ CFU/mL killing, followed by regrowth close to initial inoculum by 96 h for Pa1281, and suppressed growth to <4 log₁₀ CFU/mL for CR380. A and A + B initially suppressed counts of both isolates to <1 log₁₀ CFU/mL, before regrowth to control or starting inoculum and resistance emergence by 72 h. Overall, the combination including intermittent piperacillin-tazobactam did not provide a benefit over tobramycin monotherapy. A + C, the combination regimen with continuous infusion of piperacillin-tazobactam, provided synergistic killing (counts <1 log₁₀ CFU/mL) of Pa1281 and CR380, and suppressed regrowth to <2 and <4 log₁₀ CFU/mL, respectively, and resistance emergence over 120 h. The shape of the concentration–time curve was important for synergy of the combination.

Artificial intelligence and machine learning assisted drug delivery for effective treatment of infectious diseases

In the era of antimicrobial resistance, the prevalence of multidrug-resistant microorganisms that resist conventional antibiotic treatment has steadily increased. Thus, it is now unquestionable that infectious diseases are significant global burdens that urgently require innovative treatment strategies. Emerging studies have demonstrated that artificial intelligence (AI) can transform drug delivery to promote effective treatment of infectious diseases. In this review, we propose to evaluate the significance, essential principles, and popular tools of AI in drug delivery for infectious disease treatment. Specifically, we will focus on the achievements and key findings of current research, as well as the applications of AI on drug delivery throughout the whole antimicrobial treatment process, with an emphasis on drug development, treatment regimen optimization, drug delivery system and administration route design, and drug delivery outcome prediction. To that end, the challenges of AI in drug delivery for infectious disease treatments and their current solutions and future perspective will be presented and discussed.

Applying cefepime population pharmacokinetics on critically ill patients receiving continuous renal replacement therapy

Patients admitted to the intensive care unit (ICU) may need continuous renal replacement therapy (CRRT) due to acute kidney injury or worsening of underlying chronic kidney disease. This will affect their antimicrobial exposure and may have a significant impact on the treatment. We aim to develop a cefepime pharmacokinetic (PK) model in CRRT ICU patients and generate the posterior predictions for a group and assess their therapy outcomes. Adult patients, admitted to the ICU, received cefepime, and had its concentration measured while on CRRT were included from three different datasets. In two datasets, samples were collected from the predialyzer, postdialyzer ports, and effluent fluid at different times within the same dosing interval. The third dataset had only cefepime plasma concentration measured as part of clinical service. Patients' demographics, cefepime regimens and concentration, CRRT parameters, and therapy outcomes were recorded. NPAG was used for population PK and posterior predictions. A total of 125 patients were included. Cefepime was described by a five-compartment model, and the CRRT flow rates described the rates of cefepime transfer between compartments. The posterior predictions were generated for the third dataset and the median (range) fT_>MIC was 100% (27%-100%) and fT_>4×MIC was 64% (0%-100%). The mortality rate was 53%. There was no difference in target attainment in terms of clinical cure and 30-day mortality. This model can be used as a precision dosing tool in CRRT patients. Future studies may address other PK/PD targets in a larger population.

Time Above All Else: Pharmacodynamic Analysis of β-Lactams in Critically Ill Patients

β-Lactams are the most commonly used antibiotics in intensive care units (ICUs). As critically ill patients often experience pharmacokinetic aberrations, and rates of antimicrobial resistance vary between hospital settings, reliance on tertiary sources or package labeling to guide empiric dosing often results in suboptimal β-lactam exposure. The primary objective was to identify β-lactam regimens capable of achieving ≥90% cumulative fraction of response (CFR) against 7 Gram-negative pathogens within 4 ICUs at our institution. Unit-specific minimal inhibitory concentration (MIC) distribution data was used in combination with published pharmacokinetic parameters in critically ill patients to perform Monte Carlo simulations. The percentage of time for which the unbound concentration of antibiotic remained above the MIC (%ƒT > MIC) was used as the pharmacodynamic target: 70%ƒT >MIC for cefepime, 40%ƒT > MIC for meropenem, and 50%ƒT > MIC for piperacillin/tazobactam. Regimens were modeled to determine the likelihood of achieving ≥90% CFR. Overall, intermittently dosed cefepime, meropenem, and piperacillin/tazobactam failed to achieve ≥90% CFR for every organism. Cefepime 2 g intermittent bolus every 8 hours failed to achieve ≥90% CFR for Klebsiella pneumoniae or Enterobacter cloacae despite susceptibility rates exceeding 90%. Piperacillin/tazobactam 4.5 g prolonged infusion (PI) every 6 hours achieved <85% CFR for Pseudomonas aeruginosa and <50% CFR for Acinetobacter baumannii in every ICU. Meropenem 2 g PI every 8 hours and meropenem 2 g PI every 6 hours were the only regimens capable of achieving ≥90% CFR for P aeruginosa in all units. Use of Monte Carlo simulations, with incorporation of local MIC distribution data, provides a mechanism to effectively predict optimal agent and dose selection within specific hospital systems, thereby enhancing pharmacokinetic/pharmacodynamic optimization and improving clinical efficacy.

Plasma and Lung Tissue Pharmacokinetics of Ceftaroline Fosamil in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass: an In Vivo Microdialysis Study

Ceftaroline fosamil, a fifth-generation cephalosporin antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA), is currently approved for the treatment of pneumonia and complicated skin and soft tissue infections. However, pharmacokinetics data on free lung tissue concentrations in critical patient populations are lacking. The aim of this study was to evaluate the pharmacokinetics of the high-dose regimen of ceftaroline in plasma and lung tissue in cardiac surgery patients during intermittent and continuous administration. Nine patients undergoing elective cardiac surgery on cardiopulmonary bypass were included in this study and randomly assigned to intermittent or continuous administration. Eighteen hundred milligrams of ceftaroline fosamil was administered intravenously as either 600 mg over 2 h every 8 h (q8h) (intermittent group) or 600 mg over 2 h (loading dose) plus 1,200 mg over 22 h (continuous group). Interstitial lung tissue concentrations were measured by in vivo microdialysis. Relevant pharmacokinetics parameters were calculated for each group. Plasma exposure levels during intermittent and continuous administration were comparable to those of previously published studies and did not differ significantly between the two groups. In vivo microdialysis demonstrated reliable and adequate penetration of ceftaroline into lung tissue during intermittent and continuous administration. The steady-state area under the concentration-time curve from 0 to 8 h (AUCss 0-8) and the ratio of AUCSS 0-8 in lung tissue and AUC in plasma (AUClung/plasma) were descriptively higher in the continuous group. Continuous administration of ceftaroline fosamil achieved a significantly higher proportion of time for which the free drug concentration remained above 4 times the minimal inhibitory concentration (MIC) during the dosing interval (% fT>4xMIC) than intermittent administration for pathogens with a MIC of 1 mg/liter. Ceftaroline showed adequate penetration into interstitial lung tissue of critically ill patients undergoing major cardiothoracic surgery, supporting its use for pneumonia caused by susceptible pathogens.

Eco-Friendly UPLC-MS/MS Quantitation of Delafloxacin in Plasma and Its Application in a Pharmacokinetic Study in Rats

A novel UPLC-MS/MS assay was developed for rapid quantification of delafloxacin (a novel fluoroquinolone antibiotic in plasma samples by one step sample cleanup procedure. Delafloxacin (DFX) and internal standard (losartan) were separated on a UPLC BEH C18 column (50 × 2.1 mm; 1.7 μm) by using gradient programing of a mobile phase containing 0.1% formic acid in acetonitrile and 0.1% formic acid in water. The quantification was performed by a using triple-quadrupole mass detector at an electrospray ionization interface in positive mode. The precursor to the product ion transition of 441.1 → 379.1 for the qualifier and 441.1 → 423.1 for the quantifier was used for DFX monitoring, whereas 423.1 → 207.1 was used for the internal standard. The validation was performed as per guidelines of bioanalytical method validation, and the evaluated parameters were within the acceptable range. The greenness assessment of the method was evaluated by using AGREE software covering all 12 principles of green analytical chemistry. The final score obtained was 0.78, suggesting excellent greenness of the method. Moreover, Deming regression analysis showed an excellent linear relationship between this method and our previously reported method, and it is suitable for high-throughput analysis for routine application. The proposed method was effectively applied in a pharmacokinetic study of novel formulation (self-nanoemulsifying drug delivery systems) of DFX in rats.

Tylosin Dosage Adjustment Based on Allometric Scaling in Male Turkeys

Turkeys' body weight (BW) increases 10-fold within only 2.5 months, leading to a change in the pharmacokinetics (PK) of drugs according to allometric principles. Thus, the same dosage may lead to age-dependent variability in efficacy, in particular, to treatment failure and/or selection for resistance. The study aimed to investigate whether a non-linear dosage based on a published allometric model for tylosin clearance, may optimize the internal exposure in growing turkeys. The single dose PK study was performed on turkeys aged 6, 9.5, 13 and 17 weeks (BW from 1.75 kg to 15.75 kg). Tylosin was administered intravenously (i.v.) or orally (p.o.) according to following protocols: Dose = 31.6 × BW0.58 or Dose = 158 × BW0.58, respectively. Plasma tylosin was measured using high-performance liquid chromatography and non-compartmental PK analysis was performed. The area under the curve (AUClast) after i.v. administration was 8.90 ± 1.01; 7.51 ± 1.11; 6.54 ± 1.20 and 8.01 ± 1.75 mg × h/L in 6-; 9.5-; 13- and 17-week-old turkeys, respectively. After p.o. administration AUClast was 4.80 ± 2.92; 4.60 ± 2.45; 3.00 ± 1.49 and 3.24 ± 2.00 mg × h/L in respective age groups indicating high variability. For i.v. administration, the non-linear dosage allowed to minimize the age-dependent variability in AUC. However, due to low oral bioavailability (8-12%) and resulting interindividual variability, the proposed approach may not improve tylosin efficacy in turkeys under farm conditions.

Initial antimicrobial management of sepsis

Sepsis is a common consequence of infection, associated with a mortality rate > 25%. Although community-acquired sepsis is more common, hospital-acquired infection is more lethal. The most common site of infection is the lung, followed by abdominal infection, catheter-associated blood steam infection and urinary tract infection. Gram-negative sepsis is more common than gram-positive infection, but sepsis can also be due to fungal and viral pathogens. To reduce mortality, it is necessary to give immediate, empiric, broad-spectrum therapy to those with severe sepsis and/or shock, but this approach can drive antimicrobial overuse and resistance and should be accompanied by a commitment to de-escalation and antimicrobial stewardship. Biomarkers such a procalcitonin can provide decision support for antibiotic use, and may identify patients with a low likelihood of infection, and in some settings, can guide duration of antibiotic therapy. Sepsis can involve drug-resistant pathogens, and this often necessitates consideration of newer antimicrobial agents.

When More is Still Not Enough: A Case of Ceftazidime-Avibactam Resistance in a Burn Patient

Burn patients have numerous risk factors for multidrug resistant organisms (MDROs) and altered pharmacokinetics, which both independently increase the risk of treatment failure. Data on appropriate antimicrobial dosing are limited in this population and therapeutic drug monitoring (TDM) for beta-lactams is impractical at most facilities. 1-3 Technology is available that can detect genetic markers of resistance, but they are not all encompassing, and often require specialized facilities that can detect less common genetic markers. 4-5 Newer antimicrobials can help combat MDROs, but additional resistance patterns may evolve during treatment. Considering drug shortages and antimicrobial formularies, clinicians must remain vigilant when treating infections. This case report describes the development of resistance to ceftazidime-avibactam in a burn patient. The patient was a 54- year-old burn victim with a 58% total body surface area (TBSA) thermal burn who underwent multiple courses of antibiotics for various Pseudomonal infections. The initial Pseudomonal wound infection was sensitive to cefepime, aminoglycosides, and meropenem. A subsequent resistant pseudomonal pneumonia was treated with ceftazidime-avibactam 2.5 grams every 6 hours due to the elevated MIC to cefepime (16mcg/mL) and meropenem (>8mcg/mL). Although, the patient improved over 7 days, the patient again spiked fevers and had increased white blood counts (WBC). Repeat blood cultures demonstrated a multidrug resistant (MDR) Pseudomonas with a minimum inhibitory concentration (MIC) to ceftazidime-avibactam of 16mcg/mL, which is above the Clinical and Laboratory Standards Institute (CLSI) breakpoint of 8mcg/mL. At first, resistance was thought to have occurred due to inadequate dosing, but genetic work demonstrated multiple genes encoding beta-lactamases.

Pharmacokinetic/Pharmacodynamic Adequacy of Novel β-Lactam/β-Lactamase Inhibitors against Gram-Negative Bacterial in Critically Ill Patients

The optimal regimens of novel β-lactam/β-lactamase inhibitors (BLBLIs), ceftazidime/avibactam, ceftolozane/tazobactam, and meropenem/vaborbactam, are not well defined in critically ill patients. This study was conducted to identify optimal regimens of BLBLIs in these patients. A Monte Carlo simulation was performed using the published data to calculate the joint probability of target attainment (PTA) and the cumulative fraction of response (CFR). For the target of β-lactam of 100% time with free drug concentration remains above minimal inhibitory concentrations, the PTAs of BLBLIs standard regimens were <90% at a clinical breakpoint for Enterobacteriaceae and Pseudomonas aeruginosa. For ceftazidime/avibactam, 2000 mg/500 mg/8 h by 4 h infusion achieved >90% CFR for Escherichia coli; even for 4000 mg/1000 mg/6 h by continuous infusion, CFR for Klebsiella pneumoniae was <90%; the CFRs of 3500 mg/875 mg/6 h by 4 h infusion and 4000 mg/1000 mg/8 h by continuous infusion were appropriate for Pseudomonas aeruginosa. For ceftolozane/tazobactam, the CFR of standard regimen was >90% for Escherichia coli, however, 2000 mg/1000 mg/6 h by continuous infusion achieved <90% CFRs for Klebsiella pneumoniae and Pseudomonas aeruginosa. For meropenem/vaborbactam, standard regimen achieved optimal attainments for Escherichia coli and Klebsiella pneumoniae; 2000 mg/2000 mg/6 h by 5 h infusion, 2500 mg /2500 mg/6 h by 4 h infusion, 3000 mg/3000 mg/6 h by 3 h infusion and 4000 mg/4000 mg/8 h by 5 h infusion achieved >90% CFRs for Pseudomonas aeruginosa. The CFRs of three BLBLIs were similar for Escherichia coli, but meropenem/vaborbactam were superior for Klebsiella pneumoniae and Pseudomonas aeruginosa.

Cefazolin prophylaxis in children undergoing cardiac surgery with the use of cardiopulmonary bypass-is the dosing correct?

OBJECTIVES

To determine the recommended concentrations of cefazolin to be used for antibiotic prophylaxis during paediatric cardiac surgery with extracorporeal circulation (ECC).

METHODS

Twenty paediatric patients undergoing cardiac surgery with ECC and cefazolin antibiotic prophylaxis were included in the study. Blood samples for measurement of total cefazolin plasma concentration were collected at the following measurement time points: directly after skin incision, 15 min after ECC start, 5 min after ECC cessation and at skin closure. The target concentration was set for ≥40 mg/l, which corresponded to ≥8 mg/l of unbound cefazolin concentration.

RESULTS

The median total cefazolin plasma concentrations at the measurement time points were 62.8, 67.7, 45.8 and 34.2 mg/l, respectively, and target concentrations were achieved in 90%, 85%, 65% and 40% of children, respectively. Among patients who received ≥30 mg of cefazolin per 100 ml of ECC priming, target concentrations after ECC cessation were reached in 80% of patients, while in those with <30 mg cefazolin per 100 ml in 20% of patients (P = 0.031).

CONCLUSIONS

Direct extrapolation of antibiotic prophylaxis recommendations from adults to children may result in suboptimal antibiotic concentrations. An additional cefazolin dose to ECC priming appears necessary and the dosing should be based on ECC priming volume rather than on the weight of the patient.

Relationship Between Multidrug-Resistant Enterobacterales and Obesity in Older Adults

Purpose

The objective of our study was to determine if obesity is associated with the presence of multidrug-resistant (MDR) bacteria among Enterobacterales.

Patients and Methods

This two-center cohort study included adult hospitalized patients with at least one specimen sampled from any site for bacterial culture yielding an Enterobacterales bacterial species from November 2016 to May 2017. Study groups were stratified by obesity status based on body mass index <30 kg/m² (non-obese) and ≥30 kg/m² (obese). The primary outcome was the presence of gram-negative MDR bacteria defined as presumptive extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales (ceftriaxone resistance) or carbapenem-resistant Enterobacterales (CRE). A multivariable logistic regression model was fit to estimate the adjusted odds ratio while controlling for potential confounders.

Results

A total of 366 patients, 238 non-obese and 128 obese, were included. The most common gram-negative bacterial species identified was Escherichia coli (64.2%). There was a higher proportion of gram-negative MDR bacteria in obese versus non-obese patients (18.8 versus 11.3%, P=0.057). Obesity was independently associated with gram-negative MDR bacteria after controlling for confounders (adjusted odds ratio, 1.92; 95% CI 1.03–3.60). The association did not significantly vary by diabetes status (interaction term P=0.792).

Conclusion

Among older adult hospitalized patients, obesity was independently associated with the presence of a gram-negative MDR bacteria (presumptive ESBL or CRE) in a culture.

A Retrospective, Observational Study on Antimicrobial Drug Use in Beef Fattening Operations in Northwestern Italy and Evaluation of Risk Factors Associated with Increased Antimicrobial Usage

Simple Summary

Antimicrobial usage in veterinary medicine is thought to be a source of antimicrobial resistance, with possible implications for human health. Certain antibiotics are considered critical for human health, and their use is being judiciously reduced in animal productions. The monitoring of antimicrobial consumption in animal production is key to lowering the risk of the development of antimicrobial resistance. With this study, we quantified antimicrobial usage in beef fattening operations in northwestern Italy before the implementation of a program intended to control antimicrobial usage in veterinary medicine. We found that antimicrobials defined as critical for human health (e.g., fluroquinolones) were often used also for metaphylactic treatment.

Abstract

The abuse or misuse of antimicrobials in animal production is thought to be a potential factor in the development of antimicrobial resistance in veterinary and human medicine. With this study, we wanted to quantify antimicrobial usage in beef fattening operations in northwestern Italy and to identify factors potentially influencing antimicrobial usage. The sample was composed of 26 beef fattening operations that import heifers and bulls from France. Data were extracted from the 2014 and 2015 treatment registers kept by the farmers. The mean (±SD) number of animal daily doses per animal (nADDa) per year for each farm was 3 (±2.1) during the study period (2014–2015). Group antimicrobial treatments (57.5% of all treatments) were often administered orally (70.5%) and consisted overwhelmingly of doxycycline (97%). Individual treatments (42.5% of all treatments) were administered parenterally (98.1%) and the most often used active substances were florfenicol (19.9%), marbofloxacin (19.5%), and tylosin (12.4%). There was a negative correlation between the nADDa for total and group treatments and average batch weight at arrival and between the amount of straw added per animal per day and the nADDa (p ≤ 0.05). Our data show that antimicrobials critical for human medicine were often used in beef fattening operations in northwestern Italy before the European guidelines for the prudent use of antimicrobials in veterinary medicine were issued. Additionally, the use of antimicrobials as a preventive group treatment was still widespread, mostly in lighter weight animals.

Cefepime Population Pharmacokinetics and Target Attainment in Critically Ill Patients on Continuous Renal Replacement Therapy

Sepsis causes half of acute kidney injuries in the intensive care unit (ICU). ICU patients may need continuous renal replacement therapy (CRRT), which will affect their antimicrobial exposure. We aimed to build a cefepime population pharmacokinetic (PK) model in CRRT ICU patients and perform simulations to assess target attainment. Patients who were ≥18 years old, were admitted to the ICU, and received cefepime 2 g every 8 h as a 4-h infusion while on CRRT were enrolled prospectively. Samples were collected from the predialyzer ports, postdialyzer ports, and effluent fluid at 1, 2, 3, 4, and 8 h after the first dose and at steady state. Age, sex, weight, urine output, and CRRT parameters were recorded. Pmetrics was used for population PK and simulations. The target exposure was 100% of the dosing interval during which the free beta-lactam concentration is above the MIC (fT _>MIC). Ten patients were included; their mean age was 53 years, and mean weight was 119 kg. Seventy percent were males. Cefepime was described by a five-compartment model. The downtime was applied to the CRRT flow rates, which were used to describe the rates of transfer between the compartments. At MICs of ≤8 mg/liter, intermittent infusion of 2 g cefepime every 8 h achieved good target attainment both early in therapy and at steady state. Only extended- and continuous-infusion regimens achieved good target attainment at MICs of 16 mg/liter. In conclusion, 2 g cefepime infused over 30 min followed by extended infusion of 2 g every 8 h achieved good target attainment at MICs of ≤16 mg/liter with different CRRT flow rates and may be considered in resistant bacterial infections.

Substantial impact of post-vaccination contacts on cumulative infections during viral epidemics

Background: The start of 2021 was marked by the initiation of a global vaccination campaign against the novel coronavirus SARS-CoV-2. Formulating an optimal distribution strategy under social and economic constraints is challenging. Optimal distribution is additionally constrained by the potential emergence of vaccine resistance. Analogous to chronic low-dose antibiotic exposure, recently inoculated individuals who are not yet immune play an outsized role in the emergence of resistance. Classical epidemiological modelling is well suited to explore how the behavior of the inoculated population impacts the total number of infections over the entirety of an epidemic. Methods: A deterministic model of epidemic evolution is analyzed, with seven compartments defined by their relationship to the emergence of vaccine-resistant mutants and representing three susceptible populations, three infected populations, and one recovered population. This minimally computationally intensive design enables simulation of epidemics across a broad parameter space. The results are used to identify conditions minimizing the cumulative number of infections. Results: When an escape variant is only modestly less infectious than the originating strain within a naïve population, the cumulative number of infections does not monotonically decrease with the rate of vaccine distribution. Analysis of the model also demonstrates that inoculated individuals play a major role in the mitigation or exacerbation of vaccine-resistant outbreaks. Modulating the rate of host-host contact for the inoculated population by less than an order of magnitude can alter the cumulative number of infections by more than 20%. Conclusions: Mathematical modeling shows that limiting post-vaccination contacts can perceptibly affect the course of an epidemic. The consideration of limitations on post-vaccination contacts remains relevant for the entire duration of any vaccination campaign including the current status of SARS-CoV-2 vaccination.

Substantial impact of post-vaccination contacts on cumulative infections during viral epidemics

Background: The start of 2021 was marked by the initiation of a global vaccination campaign against the novel coronavirus SARS-CoV-2. Formulating an optimal distribution strategy under social and economic constraints is challenging. Optimal distribution is additionally constrained by the potential emergence of vaccine resistance. Analogous to chronic low-dose antibiotic exposure, recently inoculated individuals who are not yet immune play an outsized role in the emergence of resistance. Classical epidemiological modelling is well suited to explore how the behavior of the inoculated population impacts the total number of infections over the entirety of an epidemic. Methods: A deterministic model of epidemic evolution is analyzed, with seven compartments defined by their relationship to the emergence of vaccine-resistant mutants and representing three susceptible populations, three infected populations, and one recovered population. This minimally computationally intensive design enables simulation of epidemics across a broad parameter space. The results are used to identify conditions minimizing the cumulative number of infections. Results: When an escape variant is only modestly less infectious than the originating strain within a naïve population, there exists an optimal rate of vaccine distribution. Exceeding this rate increases the cumulative number of infections due to vaccine escape. Analysis of the model also demonstrates that inoculated individuals play a major role in the mitigation or exacerbation of vaccine-resistant outbreaks. Modulating the rate of host-host contact for the inoculated population by less than an order of magnitude can alter the cumulative number of infections by more than 20%. Conclusions: Mathematical modeling shows that optimization of the vaccination rate and limiting post-vaccination contacts can perceptibly affect the course of an epidemic. The consideration of limitations on post-vaccination contacts remains relevant for the entire duration of any vaccination campaign including the current status of SARS-CoV-2 vaccination.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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