Tedizolid for 6 days versus linezolid for 10 days for acute bacterial skin and skin-structure infections (ESTABLISH-2): a randomised, double-blind, phase 3, non-inferiority trial

Pharmacotherapies for multidrug-resistant gram-positive infections: current options and beyond

INTRODUCTION

Infections due to multidrug-resistant organisms (MDRO) are a serious concern for public health with high morbidity and mortality. Though many antibiotics have been introduced to manage these infections, there are remaining concerns regarding the optimal management of Gram-positive MDROs.

AREAS COVERED

A literature search on the PubMed/Medline database was conducted. We applied no language and time limits for the search strategy. In this narrative review, we discuss the current options for managing Gram-positive MDROs as well as non-traditional antibacterial agents in development.

EXPERT OPINION

Despite their introduction more than 70 years ago, glycopeptides are still the cornerstone in treating Gram-positive infections: all registrative studies of new antibiotics have glycopeptides as control; these studies are designed as not inferior studies, therefore it is almost impossible to give recommendations other than the use of glycopeptides in the treatment of Gram-positive infections. The best evidence on treatments different from glycopeptides comes from post-hoc analysis and meta-analysis. Non-traditional antibacterial agents are being studied to aid in short and effective antibiotic therapies. The use of non-traditional antibacterial agents is not restricted to replacing traditional antibacterial agents with alternative therapies; instead, they should be used in combination with antibiotic therapies.

Recent advances in the exploration of oxazolidinone scaffolds from compound development to antibacterial agents and other bioactivities

Bacterial infections cause a variety of life-threatening diseases, and the continuous evolution of drug-resistant bacteria poses an increasing threat to current antimicrobial regimens. Gram-positive bacteria (GPB) have a wide range of genetic capabilities that allow them to adapt to and develop resistance to practically all existing antibiotics. Oxazolidinones, a class of potent bacterial protein synthesis inhibitors with a unique mechanism of action involving inhibition of bacterial ribosomal translation, has emerged as the antibiotics of choice for the treatment of drug-resistant GPB infections. In this review, we discussed the oxazolidinone antibiotics that are currently on the market and in clinical development, as well as an updated synopsis of current advances on their analogues, with an emphasis on innovative strategies for structural optimization of linezolid, structure-activity relationship (SAR), and safety properties. We also discussed recent efforts aimed at extending the activity of oxazolidinones to gram-negative bacteria (GNB), antitumor, and coagulation factor Xa. Oxazolidinone antibiotics can accumulate in GNB by a conjugation to siderophore-mediated β-lactamase-triggered release, making them effective against GNB.

Population pharmacokinetic rationale for intravenous contezolid acefosamil followed by oral contezolid dosage regimens

Contezolid is a novel oxazolidinone antibiotic with a promising safety profile. Oral contezolid and its intravenous (IV) prodrug contezolid acefosamil (CZA) are in development for treatment of diabetic foot and acute bacterial skin and skin structure infections (ABSSSI). The prodrug CZA is converted to active contezolid via intermediate MRX-1352. This study aimed to provide the pharmacokinetic rationale for safe, effective, and flexible dosage regimens with initial IV CZA followed by oral contezolid. We simultaneously modeled plasma concentrations from 110 healthy volunteers and 74 phase 2 patients with ABSSSI via population pharmacokinetics (using the importance sampling estimation algorithm), and optimized dosage regimens by Monte Carlo simulations. This included data on MRX-1352, contezolid, and its metabolite MRX-1320 from 66 healthy volunteers receiving intravenous CZA (150-2400 mg) for up to 28 days, and 74 patients receiving oral contezolid [800 mg every 12 h (q12h)] for 10 days. The apparent total clearance for 800 mg oral contezolid with food was 16.0 L/h (23.4% coefficient of variation) in healthy volunteers and 17.7 L/h (53.8%) in patients. CZA was rapidly converted to MRX-1352, which subsequently transformed to contezolid. The proposed dosage regimen used an IV CZA 2000 mg loading dose with 1000 mg IV CZA q12h as maintenance dose(s), followed by 800 mg oral contezolid q12h (with food). During each 24-h period, Monte Carlo simulations predicted this regimen to achieve consistent areas under the curve of 91.9 mg·h/L (range: 76.3-106 mg·h/L) under all scenarios. Thus, this regimen was predicted to reliably achieve efficacious contezolid exposures independent of timing of switch from IV CZA to oral contezolid.IMPORTANCEThis study provides the population pharmacokinetic rationale for the dosage regimen of the intravenous (IV) prodrug contezolid acefosamil (CZA) followed by oral contezolid. We developed the first integrated population model for the pharmacokinetics of the MRX-1352 intermediate prodrug, active contezolid, and its main metabolite MRX-1320 based on data from three clinical studies in healthy volunteers and phase 2 patients. The proposed regimen was predicted to reliably achieve efficacious contezolid exposures independent of timing of switch from IV CZA to oral contezolid.

Current challenges in acute bacterial skin infection management

PURPOSE OF REVIEW

There are aspects of skin and soft tissue infections (SSTIs) that remain unresolved, such as current numbers, classification criteria, how best to define severity and predict the outcome, what diagnostic tests to perform, what new treatment options are available, or what the duration of antibiotic treatment should be. We have reviewed the literature over the last 18 months to clarify these issues and provide our opinion.

RECENT FINDINGS

SSTIs are common and among the top 10 most frequent infections worldwide. They represent a burden on the healthcare system and have a major impact on the quality of life of patients. Regarding classification, the Infectious Diseases Society of America (IDSA) provides a practical guide that distinguishes between uncomplicated and complicated infections, acute and chronic wound infections, and necrotising and nonnecrotizing infections based on skin extension and tissue necrosis. With new microbiological and imaging diagnostic techniques, SSTIs can now be better diagnosed. New PCR techniques are available, and mass spectrometry can be applied to samples collected in liquid transport media. Moreover, new treatment methods such as photodynamic therapy, reactive oxygen, and phages are emerging. SSTI patients can be treated with shorter antibiotic courses if they receive an active drug with good tissue penetration. Antibiotic treatment in necrotizing infections can be shortened to 48 h after the last debridement.

SUMMARY

SSTIs remain a challenge regarding rapid and accurate diagnosis and clinical management.

Synthesis of anti-depressant molecules via metal-catalyzed reactions: a review

Depression is one of the most mutilating conditions in the world today. It has been difficult to make advancements toward better, more effective therapies since the introduction of antidepressant medicines in the late 1950s. One important field of medicinal chemistry is the synthesis of antidepressant molecules through metal-catalyzed procedures. The important role that different transition metals, including iron, nickel, ruthenium, and others, serve as catalysts in the synthesis of antidepressants is examined in this review. Key structural motifs included in antidepressant drugs such as tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and others can be synthesized in a variety of effective ways using metal-catalyzed steps. This review examines current developments in the catalytic synthesis of antidepressants and their potential application over the previous thirteen years.

Clinical practice recommendations for infectious disease management of diabetic foot infection (DFI) - 2023 SPILF

In march 2020, the International Working Group on the Diabetic Foot (IWGDF) published an update of the 2015 guidelines on the diagnosis and management of diabetic foot infection (DFI). While we (the French ID society, SPILF) endorsed some of these recommendations, we wanted to update our own 2006 guidelines and specifically provide informative elements on modalities of microbiological diagnosis and antibiotic treatment (especially first- and second-line regiments, oral switch and duration). The recommendations put forward in the present guidelines are addressed to healthcare professionals managing patients with DFI and more specifically focused on infectious disease management of this type of infection, which clearly needs a multidisciplinary approach. Staging of the severity of the infection is mandatory using the classification drawn up by the IWGDF. Microbiological samples should be taken only in the event of clinical signs suggesting infection in accordance with a strict preliminarily established protocol. Empirical antibiotic therapy should be chosen according to the IWGDF grade of infection and duration of the wound, but must always cover methicillin-sensitive Staphylococcus aureus. Early reevaluation of the patient is a fundamental step, and duration of antibiotic therapy can be shortened in many situations. When osteomyelitis is suspected, standard foot radiograph is the first-line imagery examination and a bone biopsy should be performed for microbiological documentation. Histological analysis of the bone sample is no longer recommended. High dosages of antibiotics are recommended in cases of confirmed osteomyelitis.

Ten common misconceptions about antibiotic use in the hospital

Antimicrobials are one of the most administered medications in hospitals. Thoughtful and rational antibiotic prescribing by clinicians are important in reducing the adverse effects to both the host that takes the antibiotic and also the individuals in the host's community. Principles informing antibiotic prescribing in the hospital are commonly rooted in misconceptions. We review 10 common myths associated with antibacterial usage in hospitalized patients and share contemporary evidence in hopes of enhancing evidence-informed practice in this patient care setting.

Non-tuberculous mycobacterial disease: progress and advances in the development of novel candidate and repurposed drugs

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens that can infect all body tissues and organs. In particular, the lungs are the most commonly involved organ, with NTM pulmonary diseases causing serious health issues in patients with underlying lung disease. Moreover, NTM infections have been steadily increasing worldwide in recent years. NTM are also naturally resistant to many antibiotics, specifically anti-tuberculosis (anti-TB) drugs. The lack of drugs targeting NTM infections and the increasing drug resistance of NTM have further made treating these mycobacterial diseases extremely difficult. The currently recommended NTM treatments rely on the extended indications of existing drugs, which underlines the difficulties of new antibiotic discovery against NTM. Another challenge is determining which drug combinations are most effective against NTM infection. To a certain extent, anti-NTM drug development depends on using already available antibiotics and compounds. Here, we aimed to review new antibiotics or compounds with good antibacterial activity against NTM, focusing on their mechanisms of action, in vitro and in vivo antibacterial activities.

New Antimicrobials for Gram-Positive Sustained Infections: A Comprehensive Guide for Clinicians

Antibiotic resistance is a public health problem with increasingly alarming data being reported. Gram-positive bacteria are among the protagonists of severe nosocomial and community infections. The objective of this review is to conduct an extensive examination of emerging treatments for Gram-positive infections including ceftobiprole, ceftaroline, dalbavancin, oritavancin, omadacycline, tedizolid, and delafloxacin. From a methodological standpoint, a comprehensive analysis on clinical trials, molecular structure, mechanism of action, microbiological targeting, clinical use, pharmacokinetic/pharmacodynamic features, and potential for therapeutic drug monitoring will be addressed. Each antibiotic paragraph is divided into specialized microbiological, clinical, and pharmacological sections, including detailed and appropriate tables. A better understanding of the latest promising advances in the field of therapeutic options could lead to the development of a better approach in managing antimicrobial therapy for multidrug-resistant Gram-positive pathogens, which increasingly needs to be better stratified and targeted.

Staph wars: the antibiotic pipeline strikes back

Antibiotic chemotherapy is widely regarded as one of the most significant medical advancements in history. However, the continued misuse of antibiotics has contributed to the rapid rise of antimicrobial resistance (AMR) globally. Staphylococcus aureus, a major human pathogen, has become synonymous with multidrug resistance and is a leading antimicrobial-resistant pathogen causing significant morbidity and mortality worldwide. This review focuses on (1) the targets of current anti-staphylococcal antibiotics and the specific mechanisms that confirm resistance; (2) an in-depth analysis of recently licensed antibiotics approved for the treatment of S. aureus infections; and (3) an examination of the pre-clinical pipeline of anti-staphylococcal compounds. In addition, we examine the molecular mechanism of action of novel antimicrobials and derivatives of existing classes of antibiotics, collate data on the emergence of resistance to new compounds and provide an overview of key data from clinical trials evaluating anti-staphylococcal compounds. We present several successful cases in the development of alternative forms of existing antibiotics that have activity against multidrug-resistant S. aureus. Pre-clinical antimicrobials show promise, but more focus and funding are required to develop novel classes of compounds that can curtail the spread of and sustainably control antimicrobial-resistant S. aureus infections.

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

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.

Linezolid-associated serotonin toxicity: a systematic review

PURPOSE

This systematic review aims to evaluate the existing evidence associating linezolid to serotonin toxicity when used as monotherapy or when co-administered with other serotonergic agents.

METHODS

A systematic literature search using PubMed (till March 2023), IDWeek meetings (2003-2023), the European Congress of Clinical Microbiology and Infectious Disease Annual Meetings (2001-2023), and the American College of Clinical Pharmacy (1999-2023) identified studies and abstracts related to linezolid and serotonin toxicity.

RESULTS

A total of 84 studies were included. The data collected in retrospective/observational studies compared the incidence of serotonin toxicity with linezolid monotherapy at 0.0050% and linezolid combination therapy at 0.0134%. All cases which discontinued linezolid and serotonergic agent/s at signs and symptoms of toxicity found symptom resolution; 75% of cases reported serotonin toxicity resolution within 24-48 h after discontinuation.

CONCLUSION

Linezolid therapy when optimal should not be deferred due to the risk of serotonin syndrome. The data collected reveals a low prevalence of serotonin toxicity in both linezolid monotherapy and linezolid concurrent with other serotonergic agents.

New Antibiotics for Staphylococcus aureus Infection: An Update from the World Association of Infectious Diseases and Immunological Disorders (WAidid) and the Italian Society of Anti-Infective Therapy (SITA)

Staphylococcus aureus is an extremely virulent pathogen that is capable of quickly evolving and developing antibiotic resistance. To overcome this problem, new antibiotics have been developed. Some of these have been licenced for use in clinical practice, mainly for the treatment of adults with acute skin and soft tissue infections, in addition to both community-acquired pneumonia (CAP) and nosocomial pneumonia (hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia). In this paper, the main characteristics and clinical use of new licenced anti-staphylococcal drugs have been discussed. In vitro studies have demonstrated that some new anti-staphylococcal antibiotics have better antimicrobial activity and, at least in certain cases, more favourable pharmacokinetic properties and higher safety and tolerability than the presently available anti-staphylococcal drugs. This suggests that they may have a potential use in reducing the risk of failure of S. aureus therapy. However, an in-depth analysis of microbiological and clinical studies carried out with these new drugs seems to indicate that further studies need to be conducted before the problem of resistance of S. aureus to the antibiotics available today can be completely solved. Considering the overall available research, the drugs that are active against S. aureus appear to present a great therapeutic opportunity for overcoming resistance to traditional therapy. There are advantages in the pharmacokinetic characteristics of some of these drugs and they have the potential to reduce hospital stays and economic costs associated with their use.

How to manage skin and soft-tissue infections in the emergency department

PURPOSE OF REVIEW

Our purpose is to review the state-of-the-art on the management of skin and soft tissue infections (SSTI) in emergency departments (ED).Although the information is scarce, SSTI may account for 3-30% of all cases presenting to an ED, of which 25-40% require hospital admission.SSTI include very different entities in aetiology, location, pathogenesis, extension, and severity. Therefore, no single management can be applied to them all. A simple approach is to classify them as non-purulent, purulent, and necrotising, to which a severity scale based on their systemic repercussions (mild, moderate, and severe) must be added.The initial approach to many SSTIs often requires no other means than anamnesis and physical examination, but imaging tests are an indispensable complement in many other circumstances (ultrasound, computerized tomography, magnetic resonance imaging…). In our opinion, an attempt at etiological filiation should be made in severe cases or where there is suspicion of a causality other than the usual one, with tests based not only on cultures of the local lesion but also molecular tests and blood cultures.

RECENT FINDINGS

Recent contributions of interest include the value of bedside ultrasound and the potential usefulness of biomarkers such as thrombomodulin to differentiate in early stages the presence of necrotising lesions not yet explicit.New antimicrobials will allow the treatment of many of these infections, including severe ones, with oral drugs with good bioavailability and for shorter periods.

SUMMARY

The ED has an essential role in managing SSTIs, in their classification, in decisions on when and where to administer antimicrobial treatment, and in the rapid convening of multidisciplinary teams that can deal with the most complex situations.

Clinical Impact of Staphylococcus aureus Skin and Soft Tissue Infections

The pathogenic bacterium Staphylococcus aureus is the most common pathogen isolated in skin-and-soft-tissue infections (SSTIs) in the United States. Most S. aureus SSTIs are caused by the epidemic clone USA300 in the USA. These infections can be serious; in 2019, SSTIs with S. aureus were associated with an all-cause, age-standardized mortality rate of 0.5 globally. Clinical presentations of S. aureus SSTIs vary from superficial infections with local symptoms to monomicrobial necrotizing fasciitis, which can cause systemic manifestations and may lead to serious complications or death. In order to cause skin infections, S. aureus employs a host of virulence factors including cytolytic proteins, superantigenic factors, cell wall-anchored proteins, and molecules used for immune evasion. The immune response to S. aureus SSTIs involves initial responders such as keratinocytes and neutrophils, which are supported by dendritic cells and T-lymphocytes later during infection. Treatment for S. aureus SSTIs is usually oral therapy, with parenteral therapy reserved for severe presentations; it ranges from cephalosporins and penicillin agents such as oxacillin, which is generally used for methicillin-sensitive S. aureus (MSSA), to vancomycin for methicillin-resistant S. aureus (MRSA). Treatment challenges include adverse effects, risk for Clostridioides difficile infection, and potential for antibiotic resistance.

Off-label use versus formal recommendations of conventional and novel antibiotics for the treatment of infections caused by multidrug-resistant bacteria

The infections caused by multidrug- and extensively drug-resistant (MDR, XDR) bacteria, including Gram-positive cocci (GPC, including methicillin-resistant Staphylococcus aureus, MDR-Streptococcus pneumoniae and vancomycin-resistant enterococci) and Gram-negative bacilli (GNB, including carbapenem-resistant [CR] Enterobacterales, CR-Pseudomonas aeruginosa and XDR/CR-Acinetobacter baumannii complex) can be quite challenging for physicians with respect to treatment decisions. Apart from complicated urinary tract and intra-abdominal infections (cUTIs, cIAIs), bloodstream infections and pneumonia, these difficult-to-treat bacteria also cause infections at miscellaneous sites (bones, joints, native/prosthetic valves and skin structures, etc.). Antibiotics like dalbavancin, oritavancin, telavancin and daptomycin are currently approved for the treatment of acute bacterial skin and skin structural infections (ABSSSIs) caused by GPC. Additionally, ceftaroline, linezolid and tigecycline have been formally approved for the treatment of community-acquired pneumonia and ABSSSI. Cefiderocol and meropenem-vaborbactam are currently approved for the treatment of cUTIs caused by XDR-GNB. The spectra of ceftazidime-avibactam and imipenem/cilastatin-relebactam are broader than that of ceftolozane-tazobactam, but these three antibiotics are currently approved for the treatment of hospital-acquired pneumonia, cIAIs and cUTIs caused by MDR-GNB. Clinical investigations of other novel antibiotics (including cefepime-zidebactam, aztreonam-avibactam and sulbactam-durlobactam) for the treatment of various infections are ongoing. Nevertheless, evidence for adequate antibiotic regimens against osteomyelitis, arthritis and infective endocarditis due to several GPC and MDR-GNB is still mostly lacking. A comprehensive review of PubMed publications was undertaken and the formal indications and off-label use of important conventional and novel antibiotics against MDR/XDR-GPC and GNB isolates cultured from miscellaneous sites are presented in this paper.

The Role of Novel Antibiotics in the Management of Diabetic Foot Infection

Diabetic foot infection is a frequent and potentially life-threatening complication of diabetes mellitus. Antibiotic treatment is the cornerstone of management of diabetic foot infection but the rising prevalence of antibiotic resistance has resulted in increasing rates of treatment failure. In this context, the development of several novel antibiotics might represent a useful tool in severe diabetic foot infections caused by multidrug-resistant bacteria. In the present review, we summarize the safety and efficacy of novel antibiotics in patients with diabetic foot infection. Relevant data are limited, and randomized controlled studies that evaluated the role of these agents in this field are lacking. Until more robust data are available, cefiderocol and dalbavancin, which have been studied more extensively in patients with bone infections, might be attractive options in carefully selected patients with severe diabetic foot infection.

Short-course antibiotics for common infections: what do we know and where do we go from here?

BACKGROUND

Over the past 25 years, researchers have performed >120 randomized controlled trials (RCTs) illustrating short courses to be non-inferior to long courses of antibiotics for common bacterial infections.

OBJECTIVE

We sought to determine whether clinical data from RCTs affirm the mantra of 'shorter is better' for antibiotic durations in 7 common infections: pneumonia, urinary tract infection, intra-abdominal infection, bacteraemia, skin and soft tissue infection, bone and joint infections, pharyngitis and sinusitis.

SOURCES

Published RCTs comparing short- versus long-course antibiotic durations were identified through searches of PubMed and clinical guideline documents.

CONTENT

Short-course antibiotic durations consistently result in similar treatment success rates as longer antibiotic courses among patients with community-acquired pneumonia, complicated urinary tract infections in women, gram-negative bacteraemia, and skin and soft tissue infections when the diagnosis is confirmed, appropriate antimicrobials are used, and patients show clinical signs of improvement. For patients with osteomyelitis, 6 weeks of antibiotics is adequate for the treatment of osteomyelitis in the absence of implanted foreign bodies and surgical debridement. Whether durations can be further shortened with debridement is unclear, although small studies are promising.

IMPLICATIONS

With few exceptions, short courses were non-inferior to long courses; future research should focus on appropriately defining the patient population, ensuring the correct choice and dose of antimicrobials and developing meaningful outcomes relevant for frontline clinicians.

Current and emerging drug treatment strategies to tackle invasive community-associated methicillin-resistant Staphylococcus aureus (MRSA) infection: what are the challenges?

INTRODUCTION

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections represent a leading cause of purulent skin and soft tissue infections in some geographical regions. Traditionally, 'old antibiotics' such as trimethoprim-sulfamethoxazole, tetracyclines, clindamycin, chloramphenicol,vancomycin, and teicoplanin have been used to treat these infections, but these were often associated with low efficacy and excessive side effects and toxicity, especially nephrotoxicity. Along with the development of new compounds, the last decade has seen substantial improvements in the management of CA-MRSA infections.

AREAS COVERED

In this review, the authors discuss the current and emerging drug treatment strategies to tackle invasive CA-MRSA infections. Articles reported in this review were selected from through literature searches using the PubMed database.

EXPERT OPINION

The availability of new drugs showing a potent in vitro activity against CA-MRSA represents a unique opportunity to face the threat of resistance while potentially reducing toxicity. All these compounds represent promising options to enhance our antibiotic armamentarium. However, data regarding the use of these new drugs in real-life studies are limited and their best placement in therapy and in terms of optimization of medical resources and balance of cost-effectiveness requires further investigation.

Escalation of antimicrobial resistance among MRSA part 2: focus on infections and treatment

INTRODUCTION

MRSA is associated with causing a variety of infections including skin and skin structure infections, catheter and device-related (e.g. central venous catheter, prosthetic heart valve) infections, infectious endocarditis, blood stream infections, bone, and joint infections (e.g. osteomyelitis, prosthetic joint, surgical site), central nervous system infections (e.g. meningitis, brain/spinal cord abscess, ventriculitis, hydrocephalus), respiratory tract infections (e.g. hospital-acquired pneumonia, ventilator-associated pneumonia), urinary tract infections, and gastrointestinal infections. The emergence and spread of multidrug resistant (MDR) MRSA clones has limited therapeutic options. Older agents such as vancomycin, linezolid and daptomycin and a variety of newer MRSA antimicrobials and combination therapy are available to treat serious MRSA infections.

AREAS COVERED

The authors discuss infections caused by MRSA as well as common older and newer antimicrobials and combination therapy for MRSA infections. A literature search of MRSA was performed via PubMed (up to September 2022), using the keywords: antimicrobial resistance; β-lactams; multidrug resistance, Staphylococcus aureus, vancomycin; glycolipopeptides.

EXPERT OPINION

Innovation, discovery, and development of new and novel classes of antimicrobial agents are critical to expand effective therapeutic options. The authors encourage the judicious use of antimicrobials in accordance with antimicrobial stewardship programs along with infection-control measures to minimize the spread of MRSA.

Phage Therapy as an Alternative Treatment Modality for Resistant Staphylococcus aureus Infections

The production and use of antibiotics increased significantly after the Second World War due to their effectiveness against bacterial infections. However, bacterial resistance also emerged and has now become an important global issue. Those most in need are typically high-risk and include individuals who experience burns and other wounds, as well as those with pulmonary infections caused by antibiotic-resistant bacteria, such as Pseudomonas aeruginosa, Acinetobacter sp, and Staphylococci. With investment to develop new antibiotics waning, finding and developing alternative therapeutic strategies to tackle this issue is imperative. One option remerging in popularity is bacteriophage (phage) therapy. This review focuses on Staphylococcus aureus and how it has developed resistance to antibiotics. It also discusses the potential of phage therapy in this setting and its appropriateness in high-risk people, such as those with cystic fibrosis, where it typically forms a biofilm.

Can the Future of ID Escape the Inertial Dogma of Its Past? The Exemplars of Shorter Is Better and Oral Is the New IV

Like all fields of medicine, Infectious Diseases is rife with dogma that underpins much clinical practice. In this study, we discuss 2 specific examples of historical practice that have been overturned recently by numerous prospective studies: traditional durations of antimicrobial therapy and the necessity of intravenous (IV)-only therapy for specific infectious syndromes. These dogmas are based on uncontrolled case series from >50 years ago, amplified by the opinions of eminent experts. In contrast, more than 120 modern, randomized controlled trials have established that shorter durations of therapy are equally effective for many infections. Furthermore, 21 concordant randomized controlled trials have demonstrated that oral antibiotic therapy is at least as effective as IV-only therapy for osteomyelitis, bacteremia, and endocarditis. Nevertheless, practitioners in many clinical settings remain refractory to adopting these changes. It is time for Infectious Diseases to move beyond its history of eminent opinion-based medicine and truly into the era of evidenced-based medicine.

Antimicrobial Susceptibility Testing for Enterococci

Enterococci are major, recalcitrant nosocomial pathogens with a wide repertoire of intrinsic and acquired resistance determinants and the potential of developing resistance to all clinically available antimicrobials. As such, multidrug-resistant enterococci are considered a serious public health threat. Due to limited treatment options and rapid emergence of resistance to all novel agents, the clinical microbiology laboratory plays a critical role in deploying accurate, reproducible, and feasible antimicrobial susceptibility testing methods to guide appropriate treatment of patients with deep-seated enterococcal infections. In this review, we provide an overview of the advantages and disadvantages of existing manual and automated methods that test susceptibility of Enterococcus faecium and Enterococcus faecalis to β-lactams, aminoglycosides, vancomycin, lipoglycopeptides, oxazolidinones, novel tetracycline-derivatives, and daptomycin. We also identify unique problems and gaps with the performance and clinical utility of antimicrobial susceptibility testing for enterococci, provide recommendations for clinical laboratories to circumvent select problems, and address potential future innovations that can bridge major gaps in susceptibility testing.

Activity of Tedizolid and Comparator Agents Against Gram-positive Isolates Causing Skin and Skin Structure Infections in Pediatric Patients in United States Hospitals (2015-2019)

BACKGROUND

Tedizolid was approved by the United States Food and Drug Administration to treat acute bacterial skin and skin structure infections in adults in 2014, and in 2020, United States Food and Drug Administration expanded the approval of tedizolid to treat pediatric patients 12 years of age and older. This study assessed the activity of tedizolid and comparator agents against clinical surveillance isolates collected from pediatric patients with skin and skin structure infection in the United States.

METHODS

A total of 2747 gram-positive organisms (1 per patient) were collected in 2015 to 2019 from pediatric (≤17 years old) patients with skin and skin structure infections. The isolates were collected from 33 US medical centers and susceptibility tested against tedizolid and comparators by reference broth microdilution methods. Susceptibility results for main pathogens were stratified by patient age: ≤1 years old (851 isolates), 2 to 5 years old (623), 6 to 12 years old (754) and 13 to 17 years old (519).

RESULTS

Staphylococcus aureus (n = 2163) was the main pathogen recovered from all age groups, followed by β-hemolytic streptococci (n = 460). Tedizolid inhibited all S. aureus , including methicillin-resistant S. aureus (MRSA) isolates (41.0%), regardless of the age group. MRSA rates varied by age group; MRSA was highest among ≤1 years old (45.0%) and lowest in the 13 to 17 years old (32.7%) groups. Linezolid, daptomycin and vancomycin also displayed susceptibility rates of 100% against S. aureus isolates. Clindamycin (81.3%-98.5%), tetracycline (91.6%-97.1%) and trimethoprim-sulfamethoxazole (97.0%-100%) susceptibility rates varied among age groups and methicillin resistance profiles. Overall, tedizolid, linezolid, daptomycin and vancomycin inhibited all gram-positive pathogens in this collection.

CONCLUSIONS

Tedizolid was very active against a large collection of gram-positive pathogens causing skin and skin structure infection in pediatric patients, including MRSA isolates.

Silver Nanoparticles and Its Mechanistic Insight for Chronic Wound Healing: Review on Recent Progress

Wounds are structural and functional disruptions of skin that occur because of trauma, surgery, acute illness, or chronic disease conditions. Chronic wounds are caused by a breakdown in the finely coordinated cascade of events that occurs during healing. Wound healing is a long process that split into at least three continuous and overlapping processes: an inflammatory response, a proliferative phase, and finally the tissue remodeling. Therefore, these processes are extensively studied to develop novel therapeutics in order to achieve maximum recovery with minimum scarring. Several growth hormones and cytokines secreted at the site of lesions tightly regulates the healing processes. The traditional approach for wound management has been represented by topical treatments. Metal nanoparticles (e.g., silver, gold and zinc) are increasingly being employed in dermatology due to their favorable effects on healing, as well as in treating and preventing secondary bacterial infections. In the current review, a brief introduction on traditional would healing approach is provided, followed by focus on the potential of wound dressing therapeutic techniques functionalized with Ag-NPs.

Efficacy and safety of optional parenteral antimicrobial therapy for complicated skin and soft tissue infections: A systematic review and Bayesian network meta-analysis

BACKGROUND

Skin and soft tissue infections (SSTIs) carry significant economic burden, as well as morbidity and mortality, especially when caused by methicillin-resistant Staphylococcus aureus. This study aims to investigate the efficacy and safety of optional antimicrobial therapy for the treatment of complicated SSTIs (cSSTIs).

METHODS

We searched PubMed, Medline (Via Ovid SP), Embase (Via Ovid SP), and the Cochrane Central Register of Controlled Trials from their inception to March 22, 2021 for randomized controlled trials (RCTs) that studied the use of optional antimicrobial therapy for cSSTIs. Citations' screening, study selection, data extraction, and risk of bias assessment were independently performed by 2 authors. The primary outcomes were clinical and microbiological treatment success, and adverse events (AEs) were also assessed.

RESULTS

A total of 48 trials covering 24,381 patients assessing 20 types of antimicrobial treatment modalities were included. Overall, omadacycline was associated with the highest beneficial effect on clinical and microbiological treatment success and with the largest rank probability based on surface under the cumulative ranking curve values, avarofloxacin was closely followed. Both had, however, omadacycline was related to moderately safety profiles. Lefamulin ranked as the best option was associated with the lowest risk of severe AEs. Subgroup analysis showed similar results. The quality of primary outcomes was moderate to low.

CONCLUSIONS

The use of omadacycline was associated with higher rates of clinical and microbiological treatment success for the treatment of cSSTIs, with a relative low risk of AEs. Due to the limitations of the included RCTs, high-quality and well-designed RCTs are needed to further confirm the results.

An Iterative Approach Guides Discovery of the FabI Inhibitor Fabimycin, a Late-Stage Antibiotic Candidate with In Vivo Efficacy against Drug-Resistant Gram-Negative Infections

Genomic studies and experiments with permeability-deficient strains have revealed a variety of biological targets that can be engaged to kill Gram-negative bacteria. However, the formidable outer membrane and promiscuous efflux pumps of these pathogens prevent many candidate antibiotics from reaching these targets. One such promising target is the enzyme FabI, which catalyzes the rate-determining step in bacterial fatty acid biosynthesis. Notably, FabI inhibitors have advanced to clinical trials for Staphylococcus aureus infections but not for infections caused by Gram-negative bacteria. Here, we synthesize a suite of FabI inhibitors whose structures fit permeation rules for Gram-negative bacteria and leverage activity against a challenging panel of Gram-negative clinical isolates as a filter for advancement. The compound to emerge, called fabimycin, has impressive activity against >200 clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii, and does not kill commensal bacteria. X-ray structures of fabimycin in complex with FabI provide molecular insights into the inhibition. Fabimycin demonstrates activity in multiple mouse models of infection caused by Gram-negative bacteria, including a challenging urinary tract infection model. Fabimycin has translational promise, and its discovery provides additional evidence that antibiotics can be systematically modified to accumulate in Gram-negative bacteria and kill these problematic pathogens.

It's about the patients: Practical antibiotic stewardship in outpatient settings in the United States

Antibiotic-resistant pathogens cause over 35,000 preventable deaths in the United States every year, and multiple strategies could decrease morbidity and mortality. As antibiotic stewardship requirements are being deployed for the outpatient setting, community providers are facing systematic challenges in implementing stewardship programs. Given that the vast majority of antibiotics are prescribed in the outpatient setting, there are endless opportunities to make a smart and informed choice when prescribing and to move the needle on antibiotic stewardship. Antibiotic stewardship in the community, or "smart prescribing" as we suggest, should factor in antibiotic efficacy, safety, local resistance rates, and overall cost, in addition to patient-specific factors and disease presentation, to arrive at an appropriate therapy. Here, we discuss some of the challenges, such as patient/parent pressure to prescribe, lack of data or resources for implementation, and a disconnect between guidelines and real-world practice, among others. We have assembled an easy-to-use best practice guide for providers in the outpatient setting who lack the time or resources to develop a plan or consult lengthy guidelines. We provide specific suggestions for antibiotic prescribing that align real-world clinical practice with best practices for antibiotic stewardship for two of the most common bacterial infections seen in the outpatient setting: community-acquired pneumonia and skin and soft-tissue infection. In addition, we discuss many ways that community providers, payors, and regulatory bodies can make antibiotic stewardship easier to implement and more streamlined in the outpatient setting.

Target Therapeutic Ranges of Anti-MRSA Drugs, Linezolid, Tedizolid and Daptomycin, and the Necessity of TDM

The target therapeutic ranges of vancomycin, teicoplanin, and arbekacin have been determined, and therapeutic drug monitoring (TDM) is performed in clinical practice. However, TDM is not obligatory for daptomycin, linezolid, or tedizolid. In this study, we examined whether TDM will be necessary for these 3 drugs in the future. There was no significant difference in therapeutic effects on acute bacterial skin and skin structure infection between linezolid and tedizolid by meta-analysis. Concerning the therapeutic effects on pneumonia, the rate of effectiveness after treatment with tedizolid was significantly lower than with linezolid. With respect to safety, the incidences of gastrointestinal adverse events and blood/lymphatic system disorders related to tedizolid were significantly lower than those related to linezolid. Linezolid exhibits potent therapeutic effects on pneumonia, but the appearance of adverse reactions is indicated as a problem. There was a dose-dependent decrease in the platelet count, and the target trough concentration (C_trough) was estimated to be 4-6 or 2-7 µg/mL in accordance with the patient's condition. The efficacy of linezolid may be obtained while minimizing the appearance of adverse reactions by performing TDM. The target therapeutic range of tedizolid cannot be achieved in immunocompromised or severe patients. Therefore, we concluded that TDM was unnecessary, considering step-down therapy with oral drugs, use in non-severe patients, and high-level safety. Concerning daptomycin, high-dose administration is necessary to achieve an area under the curve (AUC) of ≥666 as an index of efficacy. To secure its safety, C_trough (<20 µg/mL) monitoring is important. Therefore, TDM is necessary.

A pharmacokinetic-pharmacodynamic (PKPD) model-based analysis of tedizolid against enterococci using the hollow-fibre infection model

BACKGROUND

Tedizolid is a novel oxazolidinone antibiotic. Considering the higher antibacterial effect in immunocompetent compared with immunosuppressed animals, it is not recommended in immunocompromised patients.

OBJECTIVES

In this study, we assessed the 'pure' pharmacokinetic-pharmacodynamic (PKPD) relationship for tedizolid against Enterococcus in the hollow-fibre infection model (HFIM).

METHODS

Unbound plasma concentration time profiles (200-5000 mg/day IV) were simulated in the HFIM over 120 h against an Enterococcus faecalis strain and two clinical isolates of Enterococcus faecium (VRE-vanB and VRE-vanA). Next, a PKPD model describing tedizolid efficacy against bacterial isolates was developed. A population PK model was linked to the developed PKPD model and utilized to predict the bacterial kinetics in plasma and in target tissues [adipose, muscle, epithelial lining fluid (ELF) and sputum] over 120 h of therapy.

RESULTS

The PKPD model adequately described the bacterial kill kinetics for all bacterial populations. At the human recommended dose of 200 mg/day, bacterial growth was predicted in plasma and all tissues, except for ELF. Bacteriostasis was observed only at a higher dose of 1200 mg/day over 120 h. An fAUC/MIC of 80 related to stasis over 120 h. Subpopulations resistant to 3 × MIC were amplified in plasma and target tissues, except for ELF, at doses of 200-800 mg/day.

CONCLUSIONS

The human dose of 200 mg/day was insufficient to suppress bacterial growth in the HFIM, indicating that further components contribute to the clinical effect of tedizolid. This study supports the warning/precaution for tedizolid to limit its use in immunocompromised patients.

Diagnosis and management of infections caused by multidrug-resistant bacteria: guideline endorsed by the Italian Society of Infection and Tropical Diseases (SIMIT), the Italian Society of Anti-Infective Therapy (SITA), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Association of Clinical Microbiologists (AMCLI) and the Italian Society of Microbiology (SIM)

Management of patients with infections caused by multidrug-resistant organisms is challenging and requires a multidisciplinary approach to achieve successful clinical outcomes. The aim of this paper is to provide recommendations for the diagnosis and optimal management of these infections, with a focus on targeted antibiotic therapy. The document was produced by a panel of experts nominated by the five endorsing Italian societies, namely the Italian Association of Clinical Microbiologists (AMCLI), the Italian Group for Antimicrobial Stewardship (GISA), the Italian Society of Microbiology (SIM), the Italian Society of Infectious and Tropical Diseases (SIMIT) and the Italian Society of Anti-Infective Therapy (SITA). Population, Intervention, Comparison and Outcomes (PICO) questions about microbiological diagnosis, pharmacological strategies and targeted antibiotic therapy were addressed for the following pathogens: carbapenem-resistant Enterobacterales; carbapenem-resistant Pseudomonas aeruginosa; carbapenem-resistant Acinetobacter baumannii; and methicillin-resistant Staphylococcus aureus. A systematic review of the literature published from January 2011 to November 2020 was guided by the PICO strategy. As data from randomised controlled trials (RCTs) were expected to be limited, observational studies were also reviewed. The certainty of evidence was classified using the GRADE approach. Recommendations were classified as strong or conditional. Detailed recommendations were formulated for each pathogen. The majority of available RCTs have serious risk of bias, and many observational studies have several limitations, including small sample size, retrospective design and presence of confounders. Thus, some recommendations are based on low or very-low certainty of evidence. Importantly, these recommendations should be continually updated to reflect emerging evidence from clinical studies and real-world experience.

Real-World Use of Tedizolid Phosphate for 28 Days or More: A Case Series Describing Tolerability and Clinical Success

Tedizolid has activity against Gram-positive pathogens as well as Mycobacterium spp and Nocardia spp. Real-world evidence supporting long-term tolerability and clinical success of tedizolid is lacking. Prolonged tedizolid therapy (median, 188 days; interquartile range, 62-493 days) appeared to be well tolerated in 37 patients (8.1% experienced adverse effect leading to discontinuation). Clinical success was 81.3% in those evaluated.

The impact of antibiotics on clinical response over time in uncomplicated cellulitis: a systematic review and meta-analysis

PURPOSE

Antibiotic treatment of uncomplicated cellulitis is highly variable with respect to agent, dose, and route of administration. As there is uncertainty about optimal/appropriate time to reassess, we aimed to assess time to clinical response.

METHODS

We conducted a systematic review of randomized controlled trials reporting clinical response of uncomplicated cellulitis to antibiotic treatment over multiple timepoints. PubMed, Embase, CENTRAL, WHO ICTRP, and clinicaltrials.gov were searched from inception to June 2021 without language restrictions. The primary outcome was time to clinical response. Other outcomes were components of clinical response (pain, severity score, redness, edema measured at ≥ 2 timepoints) and the proportion of patients with treatment failure. We performed a pooled estimate of the average time to clinical response together with 95% confidence intervals using a random effects model.

RESULTS

We included 32 randomized controlled trials (n = 13,576 participants). The mean time to clinical response was 1.68 days (95%CI 1.48-1.88; I² = 76%). The response to treatment for specific components was as follows: ~ 50% reduction of pain and severity score by day 5, a ~ 33% reduction in area of redness by day 2-3, and a 30-50% reduction of proportion of patients with edema by day 2-4. Treatment failure was variably defined with an overall failure rate of 12% (95%CI 9-16%).

CONCLUSION

The best available data suggest the optimal time to clinical reassessment is between 2 and 4 days, but this must be interpreted with caution due to considerable heterogeneity and small number of included studies.

New drugs for methicillin-resistant Staphylococcus aureus skin and soft tissue infections

PURPOSE OF REVIEW

Staphylococcus aureus is a pathogen incriminated in skin and soft tissue infections (SSTIs), with methicillin-resistant S. aureus (MRSA) becoming the predominant cause and representing a significant burden to the healthcare system. The last updated Infectious Diseases Society of America (IDSA) guidelines concerning MRSA infections and SSTIs management were published in 2011 and 2014, respectively. The UK updated guidelines for MRSA infection treatment were published in 2021. Older treatment options may be associated with toxicity and require frequent dosing. There is a paucity of recent reviews on the armamentarium of new agents for MRSA SSTIs treatment.

RECENT FINDINGS

Since 2005, several new antibiotics received a fast-track approval by the Food and Drug Administration (FDA) for SSTI treatment. These drugs include delafloxacin, omadacycline, tedizolid, ceftaroline, dalbavancin, oritavancin and telavancin. In this manuscript, we will review the data that led to these new drugs approval and discuss their advantages and disadvantages in MRSA SSTIs management.

SUMMARY

MRSA is a major cause of SSTIs. Several novel therapies covering MRSA were FDA-approved for SSTIs. However, the current IDSA guidelines for MRSA infection and SSTIs as well as the recently published UK guidelines on MRSA treatment only consider these drugs as alternative choices or do not mention them at all.

Current international and national guidelines for managing skin and soft tissue infections

PURPOSE OF REVIEW

Skin and soft tissue infections account for a significant percentage of both community and nosocomial infections. Several nosological entities are included in this concept. However, there is a very scarce body of doctrine for their treatment based on randomised trials. Therefore, we considered it necessary to review current treatment guidelines to bring new recommendations and improvements to our colleagues. In this review of recent literature, we identified updated guidelines in this area by searching the databases PubMed, evidence-based medicine online, York University reviewers group, Cochrane, MBE-Trip and Sumsearch using the terms: soft tissue infection, therapy, guideline.

RECENT FINDINGS

Developments focus on using new antimicrobials and on the prescription of shorter antibiotic treatment courses.

SUMMARY

With the development of new drugs and the current evidence of their use, there is a need to refine the appropriate drug's decision-making. Drugs with a long half-life, which allows weekly administration, can reduce hospital admission and length of stay with fewer healthcare resources. Shorter courses of antibiotics are recommended. The role of stewardship programmes will continue to expand. The surgical indication and its value are evident in many patients. Therefore, management should rely on a collaborative group with experience in this disease.

Ceftaroline Fosamil for the Empiric Treatment of Hospitalized Adults with cSSTI: An Economic Analysis from the Perspective of the Spanish National Health System

Purpose

Complicated skin and soft tissue infections (cSSTI) are associated with high healthcare resource use and costs. The emergency nature of cSSTI hospitalizations requires starting immediate empiric intravenous (IV) antibiotic treatment, making the appropriate choice of initial antibiotic therapy crucial.

Patients and Methods

The use of ceftaroline fosamil (CFT) as an alternative to other IV antibiotic therapies for the empiric treatment of hospitalized adults with cSSTI (vancomycin, linezolid, daptomycin, cloxacillin, tedizolid) was evaluated through cost consequences analysis. The model structure was a decision tree accounting for four different pathways: patients demonstrating early response (ER) either discharged early (with oral antibiotic) or remaining in hospital to continue the initial therapy; non-responders either remaining on the initial IV therapy or switching to a second-line antibiotic. The model perspective was the Spanish National Health System.

Results

CFT resulted in average percentage of patients discharged early (PDE) of 24.6% (CI 19.49–30.2%) with average total cost per patient of €6763 (€6268–€7219). Vancomycin, linezolid, daptomycin and tedizolid resulted in average PDE of 22% (17.34–27.09%), 26.4% (20.5–32.32%), 28.6% (22.08–35.79%) and 26.5% (20.39–33.25%), respectively, for a total cost per patient of €6,619 (€5,902–€6,929), €6,394 (€5,881–€6,904), €6,855 (€5,800–€7,410) and €7,173 (€6,608–€7,763), respectively. Key model drivers were ER and antibiotic treatment duration, with hospital costs accounting for over 83% of the total expenditures.

Conclusion

Given its clinical and safety profile, CFT is an acceptable choice for cSSTI empiric therapy providing comparable ER and costs to other relevant antibiotic options.

Different Surgeon, Different Duration: Lack of Consensus on the Appropriate Duration of Antimicrobial Prophylaxis and Therapy in Surgical Practice

Background: The principles of antimicrobial stewardship promote the appropriate prescribing of agents with respect to efficacy, safety, duration, and cost. Antibiotic resistance often results from inappropriate use (e.g., indication, selection, duration). We evaluated practice variability in duration of antimicrobials in surgical infection treatment (Rx) or prophylaxis (Px). Hypothesis: There is lack of consensus regarding the duration of antibiotic Px and Rx for many common indications. Methods: A survey was distributed to the Surgical Infection Society (SIS) regarding the use of antimicrobial agents for a variety of scenarios. Standard descriptive statistics were used to compare survey responses. Heterogeneity among question responses were compared using the Shannon Index, expressed as natural units (nats). Results: Sixty-three SIS members responded, most of whom (67%) have held a leadership position within the SIS or contributed as an annual meeting moderator or discussant; 76% have been in practice for more than five years. Regarding peri-operative Px, more than 80% agreed that a single dose is adequate for most indications, with the exceptions of gangrenous cholecystitis (40% single dose, 38% pre-operative +24 hours) and inguinal hernia repair requiring a bowel resection (70% single dose). There was more variability regarding the use of antibiotic Px for various bedside procedures with respondents split between none needed (range, 27%-66%) versus a single dose (range, 31%-67%). Opinions regarding the duration of antimicrobial Rx for hospitalized patients who have undergone a source control operation or procedure varied widely based on indication. Only two of 20 indications achieved more than 60% consensus despite available class 1 evidence: seven days for ventilator-associated pneumonia (77%), and four plus one days for perforated appendicitis (62%). Conclusions: Except for peri-operative antibiotic Px, there is little consensus regarding antibiotic duration among surgical infection experts, despite class 1 evidence and several available guidelines. This highlights the need for further high-level research and better dissemination of guidelines.

Pharmacokinetics and Pharmacodynamics of Tedizolid

Tedizolid is an oxazolidinone antibiotic with high potency against Gram-positive bacteria and currently prescribed in bacterial skin and skin-structure infections. The aim of the review was to summarize and critically review the key pharmacokinetic and pharmacodynamic aspects of tedizolid. Tedizolid displays linear pharmacokinetics with good tissue penetration. In in vitro susceptibility studies, tedizolid exhibits activity against the majority of Gram-positive bacteria (minimal inhibitory concentration [MIC] of ≤ 0.5 mg/L), is four-fold more potent than linezolid, and has the potential to treat pathogens being less susceptible to linezolid. Area under the unbound concentration–time curve (fAUC) related to MIC (fAUC/MIC) was best correlated with efficacy. In neutropenic mice, fAUC/MIC of ~ 50 and ~ 20 induced bacteriostasis in thigh and pulmonary infection models, respectively, at 24 h. The presence of granulocytes augmented its antibacterial effect. Hence, tedizolid is currently not recommended for immunocompromised patients. Clinical investigations with daily doses of 200 mg for 6 days showed non-inferiority to twice-daily dosing of linezolid 600 mg for 10 days in patients with acute bacterial skin and skin-structure infections. In addition to its use in skin and skin-structure infections, the high pulmonary penetration makes it an attractive option for respiratory infections including Mycobacterium tuberculosis. Resistance against tedizolid is rare yet effective antimicrobial surveillance and defining pharmacokinetic/pharmacodynamic targets for resistance suppression are needed to guide dosing strategies to suppress resistance development.

MDR Tuberculosis Treatment

Multidrug-resistant (MDR) tuberculosis (TB), resistant to isoniazid and rifampicin, continues to be one of the most important threats to controlling the TB epidemic. Over the last few years, there have been promising pharmacological advances in the paradigm of MDR TB treatment: new and repurposed drugs have shown excellent bactericidal and sterilizing activity against Mycobacterium tuberculosis and several all-oral short regimens to treat MDR TB have shown promising results. The purpose of this comprehensive review is to summarize the most important drugs currently used to treat MDR TB, the recommended regimens to treat MDR TB, and we also summarize new insights into the treatment of patients with MDR TB.

White paper on antimicrobial stewardship in solid organ transplant recipients

Antimicrobial stewardship programs (ASPs) have made immense strides in optimizing antibiotic, antifungal, and antiviral use in clinical settings. However, although ASPs are required institutionally by regulatory agencies in the United States and Canada, they are not mandated for transplant centers or programs specifically. Despite the fact that solid organ transplant recipients in particular are at increased risk of infections from multidrug-resistant organisms, due to host and donor factors and immunosuppressive therapy, there currently are little rigorous data regarding stewardship practices in solid organ transplant populations, and thus, no transplant-specific requirements currently exist. Further complicating matters, transplant patients have a wide range of variability regarding their susceptibility to infection, as factors such as surgery of transplant, intensity of immunosuppression, and presence of drains or catheters in situ may modify the risk of infection. As such, it is not feasible to have a "one-size-fits-all" style of stewardship for this patient population. The objective of this white paper is to identify opportunities, risk factors, and ASP strategies that should be assessed with solid organ transplant recipients to optimize antimicrobial use, while producing an overall improvement in patient outcomes. We hope it may serve as a springboard for development of future guidance and identification of research opportunities.

Population Pharmacokinetics, Exposure-Response, and Probability of Target Attainment Analyses for Tedizolid in Adolescent Patients with Acute Bacterial Skin and Skin Structure Infections

Tedizolid phosphate is an oxazolidinone antibacterial agent approved for the treatment of Gram-positive acute bacterial skin and skin structure infections (ABSSSIs) in patients aged ≥12 years. To support the use of tedizolid phosphate in adolescents with ABSSSIs, a population pharmacokinetic (PK) model, developed using adult and pediatric data, was updated to include PK data from a phase 3 clinical trial (PN012) that evaluated the safety and efficacy of once-daily oral or intravenous 200-mg tedizolid phosphate treatment in adolescents (12 to <18 years) with ABSSSIs, along with emerging data from a phase 1 trial (PN013) in children (2 to <12 years). Updated PK parameter estimates remained similar to those of the previous model. Body weight was a statistically significant covariate on clearance and volume parameters, with no clinically meaningful effects on exposure in adolescents. Tedizolid exposures in adolescents from PN012 were slightly higher with largely overlapped area under the concentration-time curve distribution compared with adults from previous phase 2 and 3 trials. The probability of PK/pharmacodynamic target attainment at the MIC susceptibility breakpoint of 0.5 μg/ml for Staphylococcus and Streptococcus sp. was 100%. As most participants from the PN012 trial were cured, no significant exposure-efficacy relationship was identified. Tedizolid exposures were similar between participants with and without a safety event from PN012; no clear relationship was detected between exposure and safety. Despite lower body weight and higher exposures in adolescents, safety profiles in adolescents were similar those in adults. These results support the 200-mg, once-daily intravenous or oral dose of tedizolid phosphate in adolescents with ABSSSIs.

Effect of Antibiotic-Prescribing Feedback to High-Volume Primary Care Physicians on Number of Antibiotic Prescriptions: A Randomized Clinical Trial

IMPORTANCE

Antibiotic overuse contributes to adverse drug effects, increased costs, and antimicrobial resistance.

OBJECTIVE

To evaluate peer-comparison audit and feedback to high-prescribing primary care physicians (PCPs) and assess the effect of targeted messaging on avoiding unnecessary antibiotic prescriptions and avoiding long-duration prescribing.

DESIGN, SETTING, AND PARTICIPANTS

In this 3-arm randomized clinical trial, administrative data collected from IQVIA's Xponent database were used to recruit the highest quartile of antibiotic-prescribing PCPs (n = 3500) in Ontario, Canada.

INTERVENTIONS

Physicians were randomized 3:3:1 to receive a mailed letter sent in December 2018 addressing antibiotic treatment initiation (n = 1500), a letter addressing prescribing duration (n = 1500), or no letter (control; n = 500). Outliers at the 99th percentile at baseline for each arm were excluded from analysis.

MAIN OUTCOMES AND MEASURES

The primary outcome was total number of antibiotic prescriptions over 12 months postintervention. Secondary outcomes were number of prolonged-duration prescriptions (>7 days) and antibiotic drug costs (in Canadian dollars). Robust Poisson regression controlling for baseline prescriptions was used for analysis.

RESULTS

Of the 3465 PCPs included in analysis, 2405 (69.4%) were male, and 2116 (61.1%) were 25 or more years from their medical graduation. At baseline, PCPs receiving the antibiotic initiation letter and duration letter prescribed an average of 988 and 1000 antibiotic prescriptions, respectively; at 12 months postintervention, these PCPs prescribed an average of 849 and 851 antibiotic prescriptions, respectively. For the primary outcome of total antibiotic prescriptions 12 months postintervention, there was no statistically significant difference in total antibiotic use between PCPs who received the initiation letter compared with controls (relative risk [RR], 0.96; 97.5% CI, 0.92-1.01; P = .06) and a small statistically significant difference for the duration letter compared with controls (RR, 0.95; 97.5% CI, 0.91-1.00; P = .01). For PCPs receiving the duration letter, this corresponds to an average of 42 fewer antibiotic prescriptions over 12 months. There was no statistically significant difference between the letter arms. For the initiation letter, compared with controls there was an RR of 0.98 (97.5% CI, 0.93-1.03; P = .42) and 0.97 (97.5% CI, 0.92-1.02; P = .19) for the outcomes of prolonged-duration prescriptions and antibiotic drug costs, respectively. At baseline, PCPs who received the duration letter prescribed an average of 332 prolonged-duration prescriptions with $14 470 in drug costs. There was an 8.1% relative reduction (RR, 0.92; 97.5% CI, 0.87-0.97; P < .001) in prolonged-duration prescriptions, and a 6.1% relative reduction in antibiotic drug costs (RR, 0.94; 97.5% CI, 0.89-0.99; P = .01). This corresponds to an average of 24 fewer prolonged-duration prescriptions and $771 in drug cost savings per PCP over 12 months.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, a single mailed letter to the highest-prescribing PCPs in Ontario, Canada providing peer-comparison feedback, including messaging on limiting antibiotic-prescribing durations, led to statistically significant reductions in total and prolonged-duration antibiotic prescriptions, as well as drug costs.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03776383.

A Phase 3, Randomized, Double-Blind Study Comparing Tedizolid Phosphate and Linezolid for Treatment of Ventilated Gram-Positive Hospital-Acquired or Ventilator-Associated Bacterial Pneumonia

BACKGROUND

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) are associated with high mortality rates. We evaluated the efficacy and safety of tedizolid (administered as tedizolid phosphate) for treatment of gram-positive ventilated HABP/VABP.

METHODS

In this randomized, noninferiority, double-blind, double-dummy, global phase 3 trial, patients were randomized 1:1 to receive intravenous tedizolid phosphate 200 mg once daily for 7 days or intravenous linezolid 600 mg every 12 hours for 10 days. Treatment was 14 days in patients with concurrent gram-positive bacteremia. The primary efficacy end points were day 28 all-cause mortality (ACM; noninferiority margin, 10%) and investigator-assessed clinical response at test of cure (TOC; noninferiority margin, 12.5%) in the intention-to-treat population.

RESULTS

Overall, 726 patients were randomized (tedizolid, n = 366; linezolid, n = 360). Baseline characteristics, including incidence of methicillin-resistant Staphylococcus aureus (31.3% overall), were well balanced. Tedizolid was noninferior to linezolid for day 28 ACM rate: 28.1% and 26.4%, respectively (difference, -1.8%; 95% confidence interval [CI]: -8.2 to 4.7). Noninferiority of tedizolid was not demonstrated for investigator-assessed clinical cure at TOC (tedizolid, 56.3% vs linezolid, 63.9%; difference, -7.6%; 97.5% CI: -15.7 to 0.5). In post hoc analyses, no single factor accounted for the difference in clinical response between treatment groups. Drug-related adverse events occurred in 8.1% and 11.9% of patients who received tedizolid and linezolid, respectively.

CONCLUSIONS

Tedizolid was noninferior to linezolid for day 28 ACM in the treatment of gram-positive ventilated HABP/VABP. Noninferiority of tedizolid for investigator-assessed clinical response at TOC was not demonstrated. Both drugs were well tolerated.

CLINICAL TRIALS REGISTRATION

NCT02019420.

Serious adverse events with tedizolid and linezolid: pharmacovigilance insights through the FDA adverse event reporting system

BackgroundTo investigate the adverse event (AE) profile of tedizolid and linezolid in post-marketing surveillance.Research design and methodsWe queried the worldwide FDA Adverse Event Reporting System and selected all records where tedizolid and linezolid were reported as suspect by removing potential duplicates. Disproportionality analysis was performed investigating designated medical events (DMEs) and specific AEs of clinical interest reported with tedizolid. The reporting odds ratios (RORs) were calculated, deemed significant by a lower limit of the 95% confidence interval (LL95%CI)>1, using linezolid as comparator. Case-by-case assessment of AEs reported in at least three cases with tedizolid was performed.ResultsOverall, 271 and 11,259 reports mentioning respectively tedizolid and linezolid were recorded, of which respectively 59 and 4,473 patients with DMEs or selected AEs were found. No difference emerged for the selected AEs except for increased reporting of hepatic failure (N = 3; LL95%CI = 1.06) with tedizolid considering reports collected after 2014. Extensive off-label use in terms of therapeutic indications (83.6%) and treatment duration was reported with tedizolid.ConclusionsSimilar AE reporting between the two oxazolidinones was found. Considering limitations of pharmacovigilance, this hypothesis of comparable safety profile should be tested prospectively through dedicated real-world studies.

Antibiotic Approvals in the Last Decade: Are We Keeping Up With Resistance?

OBJECTIVE

To review the spectrum of activity, efficacy, safety, and role in therapy of all antibiotics and related biologics approved by the Food and Drug Administration (FDA) in the last decade.

DATA SOURCES

A literature search was performed using PubMed and Google Scholar (2010 to end May 2021) with the search terms' name of the antibiotic or the biologic. Data were also obtained from the prescribing information, FDA, and ClinicalTrials.gov websites.

STUDY SELECTION

All relevant English-language, late phase clinical trials assessing the safety and efficacy of the identified drugs were included. Review articles and references of retrieved articles were evaluated for relevant data.

DATA SYNTHESIS

Antibiotic resistance is a public health crisis, and antibiotic development is imperative to outpace the ability of bacteria to develop resistance. Only 17 new systemic antibiotics and 1 related biologic have been approved by the FDA since 2010. Among these drugs, 14 were approved for common bacterial infections, 1 was approved for Clostridioides difficile infection (CDI), 1 was licensed to prevent CDI recurrence, and 2 were approved for drug-resistant tuberculosis. Very few antibiotics are in clinical development.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The arrival of these new antibiotics was welcomed with great enthusiasm, particularly when they met previously unmet medical needs. Unfortunately, the majority of them represent modifications to existing chemical structures rather than new drug classes. Despite the availability of these antibiotics, managing patients with deep-seated infections and those with extensively resistant gram-negative organisms remains challenging.

CONCLUSIONS

The number of new antibiotics and their indications are not keeping up with resistance and the needs of the patients.

Current Landscape and Future Perspective of Oxazolidinone Scaffolds Containing Antibacterial Drugs

The widespread use of antibiotics has made the problem of bacterial resistance increasingly serious, and the study of new drug-resistant bacteria has become the main direction of antibacterial drug research. Among antibiotics, the fully synthetic oxazolidinone antibacterial drugs linezolid and tedizolid have been successfully marketed and have achieved good clinical treatment effects. Oxazolidinone antibacterial drugs have good pharmacokinetic and pharmacodynamic characteristics and unique antibacterial mechanisms, and resistant bacteria are sensitive to them. This Perspective focuses on reviewing oxazolidinones based on the structural modification of linezolid and new potential oxazolidinone drugs in the past 10 years, mainly describing their structure, antibacterial activity, safety, druggability, and so on, and discusses their structure-activity relationships, providing insight into the reasonable design of safer and more potent oxazolidinone antibacterial drugs.

Assessment of Data Supporting the Efficacy of New Antibiotics for Treating Infections Caused by Multidrug-resistant Bacteria

BACKGROUND

Infections caused by multidrug-resistant (MDR) bacteria are a major public health threat. We aimed to assess the data supporting US Food and Drug Administration (FDA) approval of new agents aimed to treat MDR bacterial infections and the data provided by postmarketing studies.

METHODS

We identified all drugs with in vitro activity against MDR bacteria initially approved by the FDA between January 2010 and December 2018. Characteristics of trials supporting approval and regulatory pathways were collected from Drugs@FDA. Characteristics of postmarketing studies were extracted from drug labels and ClinicalTrials.gov entries effective 1 June 2019.

RESULTS

Initial approval of 11 newly approved antibiotics with anti-MDR activity was supported by 20 trials, all with noninferiority design. All initially approved indications were for common infections, mostly acute bacterial skin and skin-structure infections, regardless of causative microorganism. The proportion of MDR bacteria in most trials was low (<10% for gram-negative infections, <1% for gram-positive pneumonia). Most trials (90%) excluded immunocompromised and critically ill patients. Of 16 additional postmarketing randomized controlled trials identified through ClinicalTrials.gov, only 2 exclusively included infections caused by MDR bacteria, comprising 116 patients. No drug was granted accelerated approval, which would mandate postmarketing efficacy studies.

CONCLUSIONS

The approval of new drugs with potential clinical activity against MDR bacteria is supported by trials evaluating infections caused by non-MDR organisms, using noninferiority design and excluding the patients most likely to require these agents. Subsequent postmarketing efficacy data against these organisms are scarce. Healthcare professionals and regulators should demand more robust data to support clinical decision making.