MIC-based dose adjustment: facts and fables-authors' response

Clinical pharmacological considerations in an early intravenous to oral antibiotic switch: are barriers real or simply perceived?

BACKGROUND

Traditionally, there has been a common belief that ongoing i.v. antibiotic therapy is superior to an early i.v. to oral switch, especially for severe infections. However, this may be at least partly based on early observations rather than robust, high-quality data and contemporary clinical studies. It is important to examine whether these traditional views align with clinical pharmacological considerations, or conversely, if these considerations may support the broader application of an early i.v. to oral switch under appropriate circumstances.

OBJECTIVES

To examine the rationale for an early i.v. to oral antibiotic switch in the context of clinical pharmacokinetic and pharmacodynamic principles and to discuss whether commonly encountered pharmacological barriers are real or simply perceived.

SOURCES

We conducted PubMed searches on barriers and clinicians' perceptions about an early i.v. to oral switch, clinical studies comparing switching with i.v.-only dosing, and pharmacological factors affecting oral antimicrobials.

CONTENT

We focused on general pharmacological and clinical pharmacokinetic and pharmacodynamic principles and considerations that are relevant when clinicians ponder whether to switch from i.v. to oral antimicrobial dosing. The main focus of this review was on antibiotics. The discussion of the general principles is accompanied by specific examples from the literature.

IMPLICATIONS

Clinical pharmacological considerations and an imposing and increasing number of clinical studies, including randomized clinical trials, support an early i.v. to oral switch for the treatment of a number of infection types, under appropriate circumstances. We hope that the information provided here will add to calls for a critical examination of the role of i.v. to oral switching for many infections that are currently treated almost exclusively with i.v.-only therapy, and that it will inform health policy and guideline development by infectious diseases organizations.

Therapeutic drug monitoring of carbapenem antibiotics in critically ill patients: an overview of principles, recommended dosing regimens, and clinical outcomes

INTRODUCTION

The importance of antibiotic treatment for sepsis in critically ill septic patients is well established. Consistently achieving the dose of antibiotics required to optimally kill bacteria, minimize the development of resistance, and avoid toxicity is challenging. The increasing understanding of the pharmacokinetic and pharmacodynamic (PK/PD) characteristics of antibiotics, and the effects of critical illness on key PK/PD parameters, is gradually re-shaping how antibiotics are dosed in critically ill patients.

AREAS COVERED

The PK/PD characteristics of commonly used carbapenem antibiotics, the principles of the application of therapeutic drug monitoring (TDM), and current as well as future methods of utilizing TDM to optimally devise dosing regimens will be reviewed. The limitations and evidence-base supporting the use of carbapenem TDM to improve outcomes in critically ill patients will be examined.

EXPERT OPINION

It is important to understand the principles of TDM in order to correctly inform dosing regimens. Although the concept of TDM is attractive, and the ability to utilize PK software to optimize dosing in the near future is expected to rapidly increase clinicians' ability to meet pre-defined PK/PD targets more accurately, current evidence provides only limited support for the use of TDM to guide carbapenem dosing in critically ill patients.

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.

Therapeutic Drug Monitoring of Antibiotics in Critically Ill Patients: Current Practice and Future Perspectives With a Focus on Clinical Outcome

PURPOSE

Early initiation of antibiotics is essential for ameliorating infections in critically ill patients. The correct dosage of antibiotics is imperative to ensure their adequate exposure. Critically ill patients have altered pharmacokinetic parameters and are often infected by less susceptible microorganisms. Differences in drug disposition are not considered with standard doses of antibiotics. This can lead to suboptimal antibiotic exposure in critically ill patients. To overcome this problem of suboptimal dosing, therapeutic drug monitoring (TDM) is a strategy commonly used to support individualized dosing of antibiotics. It is routinely used for vancomycin and aminoglycosides in clinical practice. In recent years, it has become apparent that TDM may also be used in other antibiotics.

METHODS

This review summarizes the evidence for TDM of antibiotics in critically ill patients, focuses on clinical outcomes, and summarizes possibilities for optimized TDM in the future.

RESULTS AND CONCLUSION

After reviewing the literature, we can conclude that general TDM implementation is advised for glycopeptides and aminoglycosides, as evidence of the relationship between TDM and clinical outcome is present. For antibiotics, such as beta-lactams, fluoroquinolones, and linezolid, it seems rational to perform TDM in specific patient cases. TDM involving other antibiotics is supported by individual cases, specifically to decrease toxicity. When focusing on future possibilities to improve TDM of antibiotics in critically ill patients, implementation of model-informed precision dosing should be investigated because it can potentially streamline the TDM process. The logistics of TDM, such as turnaround time and available equipment, are challenging but may be overcome by rapid bioanalytical techniques or real-time monitoring of drug concentrations through biosensors in the future. Education, clinical information on targets, and clinical outcome studies are other important factors that facilitate TDM implementation.

New β-Lactam Antibiotics and Ceragenins - A Study to Assess Their Potential in Treatment of Infections Caused by Multidrug-Resistant Strains of Pseudomonas aeruginosa

Background

The increasing number of infections caused by antibiotic resistant strains of Pseudomonas aeruginosa posed a very serious challenge for clinical practice. This standing is driving scientists to develop new antibiotics against these microorganisms.

Methods

In this study, we measured the MIC/MBC values and estimated the ability of tested molecules to prevent bacterial biofilm formation to explore the effectiveness of β-lactam antibiotics ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, and ceragenins CSA-13, CSA-44, and CSA-131 against 150 clinical isolates of Pseudomonas aeruginosa that were divided into five groups, based on their antibiotic resistance profiles to beta-lactams. Selected strains of microorganisms from each group were also subjected to prolonged incubations (20 passages) with ceragenins to probe the development of resistance towards those molecules. Cytotoxicity of tested ceragenins was evaluated using human red blood cell (RBCs) hemolysis and microscopy observations of human lung epithelial A549 cells after ceragenin treatment. Poloxamer 407 (pluronic F-127) at concentrations ranging from 0.5% to 5% was tested as a potential drug delivery substrate to reduce ceragenin toxicity.

Results

Collected data proved that ceragenins at low concentrations are highly active against clinical strains of Pseudomonas aeruginosa regardless of their resistance mechanisms to conventional antibiotics. Ceragenins also show low potential for resistance development, high antibiofilm activity, and controlled toxicity when used together with poloxamer 407.

Conclusion

This data strongly supports the need for further study directed to develop this group of molecules as new antibiotics to fighting infections caused by antibiotic resistant strains of Pseudomonas aeruginosa.

Inhibitors of bacterial RNA polymerase transcription complex

A series of hybrid compounds that incorporated anthranilic acid with activated 1H-indoles through a glyoxylamide linker were designed to target bacterial RNA polymerase holoenzyme formation using computational docking. Synthesis, in vitro transcription inhibition assays, and biological testing of the hybrids identified a range of potent anti-transcription inhibitors with activity against a range of pathogenic bacteria with MICs as low as 3.1 μM. A structure activity relationship study identified the key structural components necessary for inhibition of both bacterial growth and transcription. Correlation of in vitro transcription inhibition activity with in vivo mechanism of action was established using fluorescence microscopy and resistance passaging using Gram-positive bacteria showed no resistance development over 30 days. Furthermore, no toxicity was observed from the compounds in a wax moth larvae model, establishing a platform for the development of a series of new antibacterial drugs with an established mode of action.

Molecular epidemiology of mcr gene group

Colistin and polymyxin B are the “last reserve” antimicrobials for the treatment of extensively drug-resistant Gram-negative bacterial infections. The rapidly increasing prevalence of polymyxin resistance mediated by the mcr gene localized on plasmid DNA currently poses a high epidemiological threat. In order to control a distribution of mcr genes, it is necessary to develop highly accurate, highly sensitive and easy-to-use diagnostic tools. This paper provides a review of the most relevant studies on the molecular epidemiology as well as current approaches to microbiological and molecular detection of mcr group genes.

Isoniazid Resistance in Mycobacterium tuberculosis Is a Heterogeneous Phenotype Composed of Overlapping MIC Distributions with Different Underlying Resistance Mechanisms

MIC testing using the Bactec mycobacteria growth indicator tube system 960 of 70 phylogenetically diverse, isoniazid-resistant clinical strains of Mycobacterium tuberculosis revealed a complex pattern of overlapping MIC distributions. Whole-genome sequencing explained most of the levels of resistance observed.

MIC testing using the Bactec mycobacteria growth indicator tube system 960 of 70 phylogenetically diverse, isoniazid-resistant clinical strains of Mycobacterium tuberculosis revealed a complex pattern of overlapping MIC distributions. Whole-genome sequencing explained most of the levels of resistance observed. The MIC distribution of strains with only inhA promoter mutations was split by the current concentration endorsed by the Clinical and Laboratory Standards Institute to detect low-level resistance to isoniazid and is, consequently, likely not optimally set.