In vitro susceptibility of β-lactamase-producing carbapenem-resistant Enterobacteriaceae (CRE) to eravacycline

Eravacycline: a comprehensive review of in vitro activity, clinical efficacy, and real-world applications

INTRODUCTION

The escalating threat of multidrug-resistant organisms necessitates constant exploration for novel antimicrobial agents. Eravacycline has emerged as a promising solution due to its unique chemical structure, which enhances potency and expands its spectrum of activity.

AREA COVERED

This review provides a thorough examination of eravacycline, encompassing its in vitro activity against Gram-positive and Gram-negative aerobes, carbapenem-non-susceptible organisms, anaerobes, and other bacterial strains. Additionally, it evaluates evidence from clinical studies to establish its clinical effect and safety.

EXPERT OPINION

Eravacycline, a synthetic fluorocycline, belongs to the tetracyclines class. Similar to other tetracycline, eravacycline exerts its antibacterial action by reversibly binding to the bacterial ribosomal 30S subunit. Eravacycline demonstrates potent in vitro activity against many Gram-positive and Gram-negative aerobes, anaerobes, and multidrug-resistant organisms. Randomized controlled trials and its associated meta-analysis affirm eravacycline's efficacy in treating complicated intra-abdominal infections. Moreover, real-world studies showcase eravacycline's adaptability and effectiveness in diverse clinical conditions, emphasizing its utility beyond labeled indications. Despite common gastrointestinal adverse events, eravacycline maintains an overall favorable safety profile, reinforcing its status as a tolerable antibiotic. However, ongoing research is essential for refining eravacycline's role, exploring combination therapy, and assessing its performance against biofilms, in combating challenging bacterial infections.

In Vitro Activity of Eravacycline against Carbapenemase-Producing Gram-Negative Bacilli Clinical Isolates in Central Poland

Eravacycline is a novel antibiotic of the tetracycline class with activity against a broad spectrum of clinically significant bacteria, including multi-drug-resistant organisms. For this reason, it may be an alternative to treating critical infections of this etiology. We aimed to assess the in vitro effectiveness of eravacycline to carbapenemase-producing Gram-negative bacilli clinical isolates identified in hospitals in Łódź, Poland. We analyzed 102 strains producing KPC, MBL, OXA-48, GES, and other carbapenemases. Eravacycline susceptibility was determined following the EUCAST guidelines. The highest susceptibility was found in KPC (73%) and MBL (59%) strains. Our results confirmed in vitro the efficacy of this drug against carbapenem-resistant strains. However, eravacycline has been indicated only for treating complicated intra-abdominal infections, significantly limiting its use. This aspect should be further explored to expand the indications for using eravacycline supported by evidence-based medicine. Eravacycline is one of the drugs that could play a role in reducing the spread of multidrug-resistant microorganisms.

Multicenter Clinical Evaluation of ETEST Eravacycline for Susceptibility Testing of Enterobacteriaceae and Enterococci

Eravacycline (ERV) (brand name Xerava [Tetraphase]) is a new tetracycline-class antibacterial that has been approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for treatment of complicated intra-abdominal infections (cIAIs). ETEST is a gradient diffusion method that represents a simple alternative to the broth microdilution (BMD) method for performing antimicrobial susceptibility testing (AST). A multicenter evaluation of the performance of the new ETEST ERV (bioMérieux) in comparison with BMD was conducted following FDA and International Standards Organization (ISO) recommendations, using FDA- and EUCAST-defined breakpoints. Clinical isolates of Enterobacteriaceae (n = 542) and Enterococcus spp. (n = 137) were included. Based on the BMD reference method, 92 Enterobacteriaceae isolates and 9 enterococcal isolates were nonsusceptible to ERV according to the FDA breakpoints, while 7 Escherichia coli isolates and 3 Enterococcus sp. isolates were classified as ERV resistant according the EUCAST breakpoints. Referring to FDA performance criteria, the ETEST ERV demonstrated 99.4% and 100.0% essential agreement (EA), 98.0% and 94.9% categorical agreement (CA), very major error (VME) rates of 5.4% and 33.33%, and major error (ME) rates of 1.3% and 3.1% with clinical and challenge isolates, respectively, of Enterobacteriaceae and Enterococcus spp. According to EUCAST breakpoints, E. coli and Enterococcus sp. isolate results also met ISO acceptance criteria for EA and CA (EA of 99.0% and 100.0%, respectively, and CA of 100.0% for both), without any VMEs or MEs. In conclusion, we report that ETEST ERV represents an accurate tool for performing ERV AST of Enterobacteriaceae and Enterococcus sp. isolates.

Update on the Management of Surgical Site Infections

Surgical site infections are an increasingly important issue in nosocomial infections. The progressive increase in antibiotic resistance, the ever-increasing number of interventions and the ever-increasing complexity of patients due to their comorbidities amplify this problem. In this perspective, it is necessary to consider all the risk factors and all the current preventive and prophylactic measures which are available. At the same time, given multiresistant microorganisms, it is essential to consider all the possible current therapeutic interventions. Therefore, our review aims to evaluate all the current aspects regarding the management of surgical site infections.

Drug development concerning metallo-β-lactamases in gram-negative bacteria

β-Lactams have been a clinical focus since their emergence and indeed act as a powerful tool to combat severe bacterial infections, but their effectiveness is threatened by drug resistance in bacteria, primarily by the production of serine- and metallo-β-lactamases. Although once of less clinical relevance, metallo-β-lactamases are now increasingly threatening. The rapid dissemination of resistance mediated by metallo-β-lactamases poses an increasing challenge to public health worldwide and comprises most existing antibacterial chemotherapies. Regrettably, there have been no clinically available inhibitors of metallo-β-lactamases until now. To cope with this unique challenge, researchers are exploring multidimensional strategies to combat metallo-β-lactamases. Several studies have been conducted to develop new drug candidates or calibrate already available drugs against metallo-β-lactamases. To provide an overview of this field and inspire more researchers to explore it further, we outline some promising candidates targeting metallo-β-lactamase producers, with a focus on Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Promising candidates in this review are composed of new antibacterial drugs, non-antibacterial drugs, antimicrobial peptides, natural products, and zinc chelators, as well as their combinations with existing antibiotics. This review may provide ideas and insight for others to explore candidate metallo-β-lactamases as well as promote the improvement of existing data to obtain further convincing evidence.

New tools to mitigate drug resistance in Enterobacteriaceae - Escherichia coli and Klebsiella pneumoniae

Treatment to common bacterial infections are becoming ineffective of late, owing to the emergence and dissemination of antibiotic resistance globally. Escherichia coli and Klebsiella pneumoniae are the most notorious microorganisms and are among the critical priority pathogens listed by WHO in 2017. These pathogens are the predominant cause of sepsis, urinary tract infections (UTIs), pneumonia, meningitis and pyogenic liver abscess. Concern arises due to the resistance of bacteria to most of the beta lactam antibiotics like penicillin, cephalosporin, monobactams and carbapenems, even to the last resort antibiotics like colistin. Preventing influx by modulation of porins, extruding the antibiotics by overexpression of efflux pumps, mutations of drug targets/receptors, biofilm formation, altering the drug molecules and rendering them ineffective are few resistance mechanisms that are adapted by Enterobacteriaeceae upon exposure to antibiotics. The situation is exacerbated due to the process of horizontal gene transfer (HGT), wherein the genes encoding resistance mechanisms are transferred to the neighbouring bacteria through plasmids/phages/uptake of free DNA. Carbapenemases, other beta lactamases and mcr genes coding for colistin resistance are widely disseminated leading to limited/no therapeutic options against those infections. Development of new antibiotics can be viewed as a possible solution but it involves major investment, time and labour despite which, the bacteria can easily adapt to the new antibiotic and evolve resistance in a relatively short time. Targeting the resistance mechanisms can be one feasible alternative to tackle these multidrug resistant (MDR) pathogens. Removal of plasmid (plasmid curing) causing resistance, use of bacteriophages and bacteriotherapy can be other potential approaches to combat infections caused by MDR E. coli and K. pneumoniae. The present review discusses the efficacies of these therapies in mitigating these infections, which can be potentially used as an adjuvant therapy along with existing antibiotics.

In vitro antibacterial activity of cefiderocol against recent multidrug-resistant carbapenem-nonsusceptible Enterobacterales isolates

Cefiderocol, a siderophore-containing cephalosporin with broad-spectrum antimicrobial activity against many β-lactam-resistant Gram-negative bacteria, was tested by broth microdilution against 104 carbapenem-non-susceptible Enterobacterales clinical isolates from 2011 to 2018. Carbapenemase identification was determined using PCR followed by targeted gene sequencing or whole genome sequencing (WGS). All isolates were multidrug-resistant, 89.4% (93/104) and produced a serine (KPC or SME) carbapenemase, with as many as four β-lactamases present. A VIM-1 or NDM-1 metallo-β-lactamase was confirmed in 6.7% of the isolates (N = 5 and 2, respectively). All isolates were susceptible to cefiderocol, unlike the comparator agents. Susceptibility for comparators ranged from 24.0% for meropenem to 91.3%, 92.3% and 96.1% for imipenem-relebactam, ceftazidime-avibactam and meropenem-vaborbactam, respectively; 48.1%, 75.2% and 79.8% of the isolates were susceptible to omadacycline, colistin and eravacycline, respectively. Two isolates with cefiderocol MICs of 2 mg/L had mutations or deletions of the iron transport genes fhuA/E or fepA, as determined by WGS.

Epidemiology and in vitro activity of ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, eravacycline, plazomicin, and comparators against Greek carbapenemase-producing Klebsiella pneumoniae isolates

BACKGROUND

The increase in carbapenem-resistant Klebsiella pneumoniae (CRKP) infections is of great concern because of limited treatment options. New antimicrobials were recently approved for clinical therapy. This study evaluated the epidemiology of carbapenemase-producing K. pneumoniae isolates collected at a Greek university hospital during 2017-2020, and their susceptibilities to ceftazidime-avibactam (CAZ/AVI), meropenem-vaborbactam (M/V), imipenem-relebactam (I/R), eravacycline, plazomicin, and comparators.

METHODS

Minimum inhibitory concentrations (MICs) were evaluated by Etest. Only colistin MICs were determined by the broth microdilution method. Carbapenemase genes were detected by PCR. Selected isolates were typed by multilocus sequence typing (MLST).

RESULTS

A total of 266 carbapenemase-producing K. pneumoniae strains were isolated during the 4-year study period. Among them, KPC was the most prevalent (75.6%), followed by NDM (11.7%), VIM (5.6%), and OXA-48 (4.1%). KPC-producing isolates belonged mainly to ST258 and NDM producers belonged to ST11, whereas OXA-48- and VIM producers were polyclonal. Susceptibility to tigecycline, fosfomycin, and colistin was 80.5%, 83.8%, and 65.8%, respectively. Of the novel agents tested, plazomicin was the most active inhibiting 94% of the isolates at ≤ 1.5 μg/ml. CAZ/AVI and M/V inhibited all KPC producers and I/R 98.5% of them. All OXA-48 producers were susceptible to CAZ/AVI and plazomicin. The novel β-lactam/β-lactamase inhibitors (BLBLIs) tested were inactive against MBL-positive isolates, while eravacycline inhibited 61.3% and 66.7% of the NDM and VIM producers, respectively.

CONCLUSIONS

KPC remains the predominant carbapenemase among K. pneumoniae, followed by NDM. Novel BLBLIs, eravacycline, and plazomicin are promising agents for combating infections by carbapenemase-producing K. pneumoniae. However, the emergence of resistance to these agents highlights the need for continuous surveillance and application of enhanced antimicrobial stewardship.

Role of new antibiotics for KPC-producing Klebsiella pneumoniae

Klebsiella pneumoniae has accumulated a wide range of resistance determinants and has evolved into a difficult-to-treat pathogen that poses an increasing healthcare threat. KPC is an important marker for extensively drug-resistant (XDR) organisms with limited treatment options. In response to the medical need for new treatment options, several new antibiotics have been developed and registered recently. The β-lactamase inhibitor (BLI) combinations ceftazidime/avibactam, meropenem/vaborbactam and imipenem/relebactam, the cephalosporin-siderophore conjugate cefiderocol, the aminoglycoside derivative plazomicin and the tetracycline derivative eravacycline, focus on carbapenem-resistant Enterobacterales. These modified agents from old antibiotic classes illustrate the challenges of this requirement to address class-specific resistance mechanisms while critical gaps and some cross-resistance within a class, or to unrelated antibiotic classes, remain. The diverse molecular mechanisms and increasing diversification of carbapenem resistance among Klebsiella isolates requires improved rapid molecular diagnostic capabilities and stringent stewardship programmes to preserve the efficacy of new antibiotics for as long as possible.

Treatment for carbapenem-resistant Enterobacterales infections: recent advances and future directions

Carbapenem-resistant Enterobacterales (CRE) are a growing threat to human health worldwide. CRE often carry multiple resistance genes that limit treatment options and require longer durations of therapy, are more costly to treat, and necessitate therapies with increased toxicities when compared with carbapenem-susceptible strains. Here, we provide an overview of the mechanisms of resistance in CRE, the epidemiology of CRE infections worldwide, and available treatment options for CRE. We review recentlyapproved agents for the treatment of CRE, including ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, cefiderocol, and novel aminoglycosides and tetracyclines. We also discuss recent advances in phage therapy and antibiotics that are currently in development targeted to CRE. The potential for the development of resistance to these therapies remains high, and enhanced antimicrobial stewardship is imperative both to reduce the spread of CRE worldwide and to ensure continued access to efficacious treatment options.

In vitro activity of eravacycline compared with tigecycline against carbapenem-resistant Enterobacteriaceae

Eravacycline has been shown to have broad-spectrum activity against Gram-negative bacteria, including carbapenem-resistant Enterobacteriaceae (CRE). We compared the activity of eravacycline with that of tigecycline in CRE isolates cultured from patients at an academic medical centre. Eravacycline was more potent than tigecycline [mean minimum inhibitory concentration (MIC) ratio = 0.76, 95% confidence interval 0.66-0.87]; however, the MIC₉₀ observed for eravacycline was higher than previously reported at 4 μg/mL. Future studies are necessary to elucidate the mechanism driving this difference.

Ceftolozane/Tazobactam and Ceftazidime/Avibactam for Multidrug-Resistant Gram-Negative Infections in Immunocompetent Patients: A Single-Center Retrospective Study

Complicated infections from multidrug-resistant Gram-negative bacteria (MDR-GNB) represent a serious problem presenting many challenges. Resistance to many classes of antibiotics reduces the probability of an adequate empirical treatment, with unfavorable consequences, increasing morbidity and mortality. Readily available patient medical history and updated information about the local microbiological epidemiology remain critical for defining the baseline risk of MDR-GNB infections and guiding empirical treatment choices, with the aim of avoiding both undertreatment and overtreatment. There are few literature data that report real-life experiences in the use of ceftolozane/tazobactam and ceftazidime/avibactam, with particular reference to microbiological cure. Some studies reported experiences for the treatment of MDR-GNB infections in patients with hematological malignancies or specifically in Pseudomonas aeruginosa infections. We report our clinical single-center experience regarding the real-life use of ceftolozane/tazobactam and ceftazidime/avibactam to treat serious and complicated infections due to MDR-GNB and carbapenem-resistant Enterobacterales (CRE), with particular regard given to intra-abdominal and urinary tract infections and sepsis.

IGNITE4: Results of a Phase 3, Randomized, Multicenter, Prospective Trial of Eravacycline vs Meropenem in the Treatment of Complicated Intraabdominal Infections

Background

Increasing antimicrobial resistance among pathogens that cause complicated intraabdominal infections (cIAIs) supports the development of new antimicrobials. Eravacycline, a novel member of the fluorocycline family, is active against multidrug-resistant bacteria including extended-spectrum β-lactamase (ESBL) and carbapenem-resistant Enterobacteriaceae.

Methods

IGNITE4 was a prospective, randomized, double-blind trial. Hospitalized patients with cIAI received either eravacycline 1 mg/kg every 12 hours or meropenem 1 g every 8 hours intravenously for 4–14 days. The primary objective was to demonstrate statistical noninferiority (NI) in clinical cure rates at the test-of-cure visit (25–31 days from start of therapy) in the microbiological intent-to-treat population using a NI margin of 12.5%. Microbiological outcomes and safety were also evaluated.

Results

Eravacycline was noninferior to meropenem in the primary endpoint (177/195 [90.8%] vs 187/205 [91.2%]; difference, –0.5%; 95% confidence interval [CI], –6.3 to 5.3), exceeding the prespecified margin. Secondary endpoints included clinical cure rates in the modified ITT population (231/250 [92.4%] vs 228/249 [91.6%]; difference, 0.8; 95% CI, –4.1, 5.8) and the clinically evaluable population (218/225 [96.9%] vs 222/231 [96.1%]; (difference, 0.8; 95% CI –2.9, 4.5). In patients with ESBL-producing Enterobacteriaceae, clinical cure rates were 87.5% (14/16) and 84.6% (11/13) in the eravacycline and meropenem groups, respectively. Eravacycline had relatively low rates of adverse events for a drug of this class, with less than 5%, 4%, and 3% of patients experiencing nausea, vomiting, and diarrhea, respectively.

Conclusions

Treatment with eravacycline was noninferior to meropenem in adult patients with cIAI, including infections caused by resistant pathogens.

Clinical Trials Registration

NCT01844856.

Critical analysis of antibacterial agents in clinical development

The antibacterial agents currently in clinical development are predominantly derivatives of well-established antibiotic classes and were selected to address the class-specific resistance mechanisms and determinants that were known at the time of their discovery. Many of these agents aim to target the antibiotic-resistant priority pathogens listed by the WHO, including Gram-negative bacteria in the critical priority category, such as carbapenem-resistant Acinetobacter, Pseudomonas and Enterobacterales. Although some current compounds in the pipeline have exhibited increased susceptibility rates in surveillance studies that depend on geography, pre-existing cross-resistance both within and across antibacterial classes limits the activity of many of the new agents against the most extensively drug-resistant (XDR) and pan-drug-resistant (PDR) Gram-negative pathogens. In particular, cross-resistance to unrelated classes may occur by co-selection of resistant strains, thus leading to the rapid emergence and subsequent spread of resistance. There is a continued need for innovation and new-class antibacterial agents in order to provide effective therapeutic options against infections specifically caused by XDR and PDR Gram-negative bacteria.

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

In Vitro Activity of Eravacycline against Gram-Negative Bacilli Isolated in Clinical Laboratories Worldwide from 2013 to 2017

Eravacycline is a novel, fully synthetic fluorocycline antibiotic developed for the treatment of serious infections, including those caused by multidrug-resistant (MDR) pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a global collection of frequently encountered clinical isolates of Gram-negative bacilli. The CLSI broth microdilution method was used to determine MIC data for isolates of Enterobacterales (n = 13,983), Acinetobacter baumannii (n = 2,097), Pseudomonas aeruginosa (n = 1,647), and Stenotrophomonas maltophilia (n = 1,210) isolated primarily from respiratory, intra-abdominal, and urinary specimens by clinical laboratories in 36 countries from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. Multidrug-resistant (MDR) isolates were defined by resistance to agents from ≥3 different antimicrobial classes. The MIC₉₀s ranged from 0.25 to 1 μg/ml for Enterobacteriaceae and were 1 μg/ml for A. baumannii and 2 μg/ml for S. maltophilia, Proteus mirabilis, and Serratia marcescens Eravacycline's potency was up to 4-fold greater than that of tigecycline against genera/species of Enterobacterales, A. baumannii, and S. maltophilia The MIC₉₀s for five of six individual genera/species of Enterobacterales and A. baumannii were within 2-fold of the MIC₉₀s for their respective subsets of MDR isolates, while the MDR subpopulation of Klebsiella spp. demonstrated 4-fold higher MIC₉₀s. Eravacycline demonstrated potent in vitro activity against the majority of clinical isolates of Gram-negative bacilli, including MDR isolates, collected over a 5-year period. This study further underscores the potential benefit of eravacycline in the treatment of infections caused by MDR Gram-negative pathogens.

Evaluation of Eravacycline: A Novel Fluorocycline

Eravacycline (ERV), formerly known as TP-434, is a novel tetracycline (TET) antibiotic that exhibits in vitro activity against various gram-positive, gram-negative aerobic and anaerobic pathogens, including those exhibiting TET-specific acquired resistance mechanisms. Similar to other TETs, it inhibits protein synthesis through binding to the 30S ribosomal subunit. Eravacycline was approved by the United States Food and Drug Administration (FDA) in August 2018 for the treatment of complicated intraabdominal infections (cIAIs) in adults following the Investigating Gram-Negative Infections Treated with Eravacycline (IGNITE)1 and IGNITE4 phase III trials. In these two, double-blind, multicenter clinical trials, ERV was proven noninferior in terms of clinical response in comparison to ertapenem and meropenem, respectively. Eravacycline was well tolerated with nausea, vomiting, and infusion site reactions being the most commonly reported adverse reactions. Clinicians now have ERV as a novel therapeutic option for the treatment of adults with intraabdominal infections, allergies to β-lactam agents, Clostridioides difficile-associated diarrhea, or if tolerability to other agents is a concern.

Eravacycline: a new treatment option for complicated intra-abdominal infections in the age of multidrug resistance

Aim: Recently approved for use in complicated intra-abdominal infection, eravacycline is a novel fluorocycline with broad spectrum of activity against resistant Gram-negative pathogens. This manuscript is a pooled analysis of two Phase III trials. Clinical efficacy: Clinical cure rates were 86.8% for eravacycline versus 87.6% for ertapenem, and 90.8% for eravacycline versus 91.2% for meropenem in the Intent to Treat (micro-ITT) populations, and 87.0% for eravacycline versus 88.8% ertapenem, and 92.4 versus 91.6% for meropenem in the Modified Intent to Treat (MITT) populations. Safety: Eravacycline is well tolerated, with lower rates of nausea, vomiting and diarrhea than other tetracyclines. Conclusion: Eravacycline is an effective new option for use in complicated intra-abdominal infections, and in particular, for the treatment of extended-spectrum β-lactamase- and carbapenem-resistant Enterobacteriaceae-expressing organisms.

The antimicrobial peptide thanatin disrupts the bacterial outer membrane and inactivates the NDM-1 metallo-β-lactamase

New Delhi metallo-β-lactamase-1 (NDM-1) is the most prevalent type of metallo-β-lactamase and hydrolyzes almost all clinically used β-lactam antibiotics. Here we show that the antimicrobial peptide thanatin disrupts the outer membrane of NDM-1-producing bacteria by competitively displacing divalent cations on the outer membrane and inducing the release of lipopolysaccharides. In addition, thanatin inhibits the enzymatic activity of NDM-1 by displacing zinc ions from the active site, and reverses carbapenem resistance in NDM-1-producing bacteria in vitro and in vivo. Thus, thanatin’s dual mechanism of action may be useful for combating infections caused by NDM-1-producing pathogens.

The NDM-1 metallo-β-lactamase confers resistance to β-lactam antibiotics. Here, the authors show that the antimicrobial peptide thanatin is active against NDM-1-producing bacteria through a dual mechanism of action consisting of disruption of outer membrane integrity and inhibition of the NDM-1 enzymatic activity.

Antimicrobial resistance in nephrology

The prevalence of antimicrobial resistance among many common bacterial pathogens is increasing. The emergence and global dissemination of these antibiotic-resistant bacteria (ARB) is fuelled by antibiotic selection pressure, inter-organism transmission of resistance determinants, suboptimal infection prevention practices and increasing ease and frequency of international travel, among other factors. Patients with chronic kidney disease, particularly those with end-stage renal disease who require dialysis and/or kidney transplantation, have some of the highest rates of colonization and infection with ARB worldwide. These ARB include methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp. and several multidrug-resistant Gram-negative organisms. Antimicrobial resistance limits treatment options and increases the risk of infection-related morbidity and mortality. Several new antibiotic agents with activity against some of the most common ARB have been developed, but resistance to these agents is already emerging and highlights the dire need for new treatment options as well as consistent implementation and improvement of basic infection prevention practices. Clinicians involved in the care of patients with renal disease must be familiar with the local epidemiology of ARB, remain vigilant for the emergence of novel resistance patterns and adhere strictly to practices proven to prevent transmission of ARB and other pathogens.

Eravacycline: The Tetracyclines Strike Back

Objective: To review the pharmacology, pharmacokinetics, efficacy, safety, and place in therapy of eravacycline, a novel fluorocycline antibiotic from the tetracycline family. Data Sources: A PubMed search was conducted for data between 1946 and March 2019 using MeSH terms eravacycline and TP-434. An internet search was conducted for unpublished clinical research. Study Selection and Data Extraction: The literature search was limited to English-language studies that described clinical efficacy, safety, and pharmacokinetics in humans and animals. Abstracts featuring prepublished data were also evaluated for inclusion. Data Synthesis: Eravacycline has in vitro activity against multidrug-resistant organisms, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, extended-spectrum β-lactamase-producing and carbapenem-resistant Enterobacteriaceae, and Acinetobacter. It was approved for the treatment of complicated intra-abdominal infections (cIAIs) in adults following favorable results of 2 phase III trials, IGNITE 1 and IGNITE 4, compared with ertapenem and meropenem, respectively. The most common adverse drug events associated with eravacycline were infusion site reactions (7.7%), nausea (6.5%), vomiting (3.7%), and diarrhea (2.3%). Relevance to Patient Care and Clinical Practice: Eravacycline will likely be most useful for resistant infections when lack of tolerability, resistant phenotypes, or allergies prevent the use of β-lactams. Conclusions: Eravacycline is a new tetracycline antibiotic with a broad spectrum of activity that has demonstrated efficacy in the treatment of cIAIs. Although it has activity against multidrug-resistant organisms, data are limited for other indications.

Management of carbapenem-resistant Enterobacteriaceae infections

BACKGROUND

Carbapenem resistance is defined as in vitro non-susceptibility to any carbapenem and/or documented production of a carbapenemase. This feature has rapidly spread worldwide among clinical isolates of Enterobacteriaceae, mostly Klebsiella spp., and is associated with diverse molecular mechanisms. Carbapenem resistance is often associated with resistance to all traditional β-lactams and other classes of antibiotics, denoting a typical example of an extensively drug-resistant phenotype.

OBJECTIVES

To summarize and interpret in a balanced manner the most clinically relevant data in terms of carbapenem-resistant Enterobacteriaceae (CRE) infection management.

SOURCES

Data were extracted by PubMed and clinicaltrials.gov search and manual scrutiny among references of analysed articles.

CONTENT

Features of newer and older, rediscovered antimicrobial options for CRE are described. Observational studies and randomized clinical trials (RCT) of CRE treatment are summarized, with a specific focus on the effects of monotherapy compared with combination treatment.

IMPLICATIONS

The available evidence on the current management of CRE mostly comes from observational, non-comparative, retrospective, small studies, with a high risk of selection bias. Very little evidence comes from RCT. Conflicting results of RCT and observational studies call for caution before combination therapies are deemed superior to monotherapy. Data on newer agents have spurred enthusiasm but remain limited as concerns severe CRE infections. A balanced approach should guide the clinician in the choice of old or new drugs, and of monotherapies or combination regimens. Efforts should be made to perform adequately sized clinical trials answering well-defined research questions.

Infections Caused by Carbapenem-Resistant Enterobacteriaceae: An Update on Therapeutic Options

Carbapenems are considered as last-resort antibiotics for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. With the increasing use of carbapenems in clinical practice, the emergence of carbapenem-resistant pathogens now poses a great threat to human health. Currently, antibiotic options for the treatment of carbapenem-resistant Enterobacteriaceae (CRE) are very limited, with polymyxins, tigecycline, fosfomycin, and aminoglycosides as the mainstays of therapy. The need for new and effective anti-CRE therapies is urgent. Here, we describe the current understanding of issues related to CRE and review combination therapeutic strategies for CRE infections, including high-dose tigecycline, high-dose prolonged-infusion of carbapenem, and double carbapenem therapy. We also review the newly available antibiotics which have potential in the future treatment of CRE infections: ceftazidime/avibactam, which is active against KPC and OXA-48 producers; meropenem/vaborbactam, which is active against KPC producers; plazomicin, which is a next-generation aminoglycoside with in vitro activity against CRE; and eravacycline, which is a tetracycline class antibacterial with in vitro activity against CRE. Although direct evidence for CRE treatment is still lacking and the development of resistance is a concern, these new antibiotics provide additional therapeutic options for CRE infections. Finally, we review other potential anti-CRE antibiotics in development: imipenem/relebactam and cefiderocol. Currently, high-dose and combination strategies that may include the new β-lactam/β-lactamase inhibitors should be considered in severe CRE infections to maximize treatment success. In the future, when more treatment options are available, therapy for CRE infections should be individualized and based on molecular phenotypes of resistance, susceptibility profiles, disease severity, and patient characteristics. More high-quality studies are needed to guide effective treatment for infections caused by CRE.

The antibiotic arms race: current and emerging therapy for Klebsiella pneumoniae carbapenemase (KPC) - producing bacteria

Introduction: The rapid spread of Klebsiella pneumoniae Carbapenemase (KPC)-producing bacteria comprises one of the greatest challenges to global health. Historically, clinicians were limited to therapies with suboptimal efficacy and intolerable toxicity until the FDA approved ceftazidime-avibactam and meropenem-vaborbactam, adding two essential pharmacotherapies to our antibiotic armamentarium. These agents display superior efficacy and safety compared to historical treatment options; however, resistance has already been reported. Several antimicrobials currently in the drug pipeline exhibit early promise and may fill needed gaps in therapy. Areas covered: This article encompasses both the past and present treatment options for the management of KPC-producing bacterial infections via an extensive review and critical appraisal of the current literature. Expert opinion: Traditional treatment options can no longer be recommended as first-line options for the management of KPC-producing bloodstream infections. Ceftazidime-avibactam or meropenem-vaborbactam plus or minus an aminoglycoside or polymyxin should be utilized as backbone therapies given their superior efficacy and safety profiles when compared to traditional treatment options. For susceptible KPC-producing urinary tract infections, it is reasonable to consider treatment with an aminoglycoside or with fosfomycin as a monotherapy. All of these decisions should be based on patient-specific characteristics, severity of infection and source control, susceptibility patterns, and input from infectious diseases experts.

Randomized, Double-Blind, Placebo-Controlled Studies of the Safety and Pharmacokinetics of Single and Multiple Ascending Doses of Eravacycline

Eravacycline is a novel, fully synthetic fluorocycline antibiotic with in vitro activity against aerobic and anaerobic Gram-positive and Gram-negative pathogens, including multidrug-resistant (MDR) bacteria. The pharmacokinetics (PK), urinary excretion, and safety/tolerability of intravenous (i.v.) eravacycline were evaluated in single- and multiple-ascending-dose studies.

Eravacycline is a novel, fully synthetic fluorocycline antibiotic with in vitro activity against aerobic and anaerobic Gram-positive and Gram-negative pathogens, including multidrug-resistant (MDR) bacteria. The pharmacokinetics (PK), urinary excretion, and safety/tolerability of intravenous (i.v.) eravacycline were evaluated in single- and multiple-ascending-dose studies. Healthy subjects received single i.v. doses of 0.1 to 3 mg/kg of body weight or 10 days of treatment with 0.5 or 1.5 mg/kg every 24 h (q24h) over 30 min, 1.5 mg/kg q24h over 60 min, or 1 mg/kg q12h over 60 min. After single doses, total exposure (the area under the plasma concentration-time curve [AUC]) and the maximum plasma concentrations (C_max) of eravacycline increased in an approximately dose-proportional manner. After multiple doses, steady state was achieved within 5 to 7 days. Accumulation ranged from approximately 7% to 38% with the q24h dosing regimens and was 45% with 1 mg/kg q12h. Eravacycline was generally well tolerated, with dose-related nausea, infusion site effects, and superficial phlebitis that were mild or moderate occurring. These results provide support for the 1-mg/kg q12h regimen used in clinical studies of eravacycline.

Evaluation of the In Vitro Activity of Eravacycline against a Broad Spectrum of Recent Clinical Anaerobic Isolates

The novel fluorocycline antibiotic eravacycline is in development for use in the treatment of serious infections caused by susceptible and multidrug-resistant (MDR) aerobic and anaerobic Gram-negative and Gram-positive pathogens. Eravacycline and 11 comparator antibiotics were tested against recent anaerobic clinical isolates, including MDR Bacteroides spp. and Clostridium difficile Eravacycline was potent in vitro against all the isolates tested, including strains with tetracycline-specific resistance determinants and MDR anaerobic pathogens resistant to carbapenems and/or β-lactam-β-lactamase inhibitor combinations.

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

In vitro activity of eravacycline against 2213 Gram-negative and 2424 Gram-positive bacterial pathogens isolated in Canadian hospital laboratories: CANWARD surveillance study 2014-2015

Gram-negative (n=2213) and Gram-positive (n=2424) pathogens isolated from patients in 13 Canadian hospitals in 2014 and 2015 were tested for in vitro susceptibility to eravacycline and comparators using the Clinical and Laboratory Standards Institute broth microdilution method. The concentration of eravacycline inhibiting 90% of isolates (MIC₉₀) ranged from 0.5 to 2μg/mL for 9 species of Enterobacteriaceae tested (n=2067). Eravacycline activity was largely unaffected by extended-spectrum β-lactamase phenotypes in Escherichia coli (n=141) and Klebsiella pneumoniae (n=21). Eravacycline was active against Acinetobacter baumannii (n=28; MIC₉₀, 0.5μg/mL) and Stenotrophomonas maltophilia (n=118; MIC₉₀, 4μg/mL). Eravacycline MIC₉₀ for staphylococci (n=1653), enterococci (n=289), and streptococci (n=482) ranged from 0.12 to 0.25, 0.06 to 0.12, and 0.015 to 0.06μg/mL, respectively. Eravacycline's potency was equivalent to or 2- to 4-fold greater than tigecycline against Enterobacteriaceae and Gram-positive cocci tested. Eravacycline demonstrates promising activity against recent clinical Gram-negative and Gram-positive bacteria, including multidrug-resistant pathogens.

Management of KPC-producing Klebsiella pneumoniae infections

BACKGROUND

Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) has become one of the most important contemporary pathogens, especially in endemic areas.

AIMS

To provide practical suggestion for physicians dealing with the management of KPC-KP infections in critically ill patients, based on expert opinions.

SOURCES

PubMed search for relevant publications related to the management of KPC-KP infections.

CONTENTS

A panel of experts developed a list of 12 questions to be addressed. In view of the current lack of high-level evidence, they were asked to provide answers on the bases of their knowledge and experience in the field. The panel identified several key aspects to be addressed when dealing with KPC-KP in critically ill patients (preventing colonization in the patient, preventing infection in the colonized patient and colonization of his or her contacts, reducing mortality in the infected patient by rapidly diagnosing the causative agent and promptly adopting the best therapeutic strategy) and provided related suggestions that were based on the available observational literature and the experience of panel members.

IMPLICATIONS

Diagnostic technologies could speed up the diagnosis of KPC-KP infections. Combination treatment should be preferred to monotherapy in cases of severe infections. For non-critically ill patients without severe infections, results from randomized clinical trials are needed for ultimately weighing benefits and costs of using combinations rather than monotherapy. Multifaceted infection control interventions are needed to decrease the rates of colonization and cross-transmission of KPC-KP.

New agents for the treatment of infections with Gram-negative bacteria: restoring the miracle or false dawn?

BACKGROUND

Antibiotic resistance in Gram-negative resistance has developed without a commensurate response in the successful development of antibiotic agents, though recent progress has been made.

AIMS

This review aims to provide a summary of the existing evidence on efficacy, spectrum of activity and the development of resistance of new agents that have been licensed or have completed advanced clinical trials and that possess activity against resistant Gram-negative organisms.

SOURCES

A review of the published literature via MEDLINE database was performed. Relevant clinical trials were identified with the aid of the clinicaltrials.gov registry. Further data were ascertained from review of abstracts from recent international meetings and pharmaceutical companies.

CONTENT

Data on the mechanism of action, microbiological spectrum, clinical efficacy and development of resistance are reported for new agents that have activity against Gram-negative organisms. This includes the β-lactam/β-lactamase inhibitor combinations ceftazidime/avibactam, ceftolozane/tazobactam, imipenem/cilastatin/relebactam, meropenem/vaborbactam and aztreonam/avibactam; cefiderocol, a siderophore cephalosporin; plazomicin and eravacycline.

IMPLICATIONS

The development of new agents with activity against multidrug-resistant Gram-negative pathogens has provided important therapeutic options for clinicians. Polymyxins appear to have been supplanted by new agents as first-line therapy for Klebsiella pneumoniae carbapenemase producers. Cefiderocol and ceftazidime/avibactam/aztreonam are promising options for metallo-β-lactamase producers, and cefiderocol and ceftolozane/tazobactam for multiply resistant Pseudomonas aeruginosa, but definitive data showing clinical efficacy is as yet lacking. Reports of the development of resistance early after the release and use of new agents is of concern. Orally administered options and agents active effective against Acinetobacter baumannii are under-represented in clinical development.

Unusual Escherichia coli PBP 3 Insertion Sequence Identified from a Collection of Carbapenem-Resistant Enterobacteriaceae Tested In Vitro with a Combination of Ceftazidime-, Ceftaroline-, or Aztreonam-Avibactam

Carbapenemase-producing Enterobacteriaceae isolates (n = 110) from health care centers in central Indiana (from 2010 to 2013) were tested for susceptibility to combinations of avibactam (4 μg/ml) with ceftazidime, ceftaroline, or aztreonam. MIC50/MIC90 values were 1/2 μg/ml (ceftazidime-avibactam), 0.5/2 μg/ml (ceftaroline-avibactam), and 0.25/0.5 μg/ml (aztreonam-avibactam.) A β-lactam MIC of 8 μg/ml was reported for the three combinations against one Escherichia coli isolate with an unusual TIPY insertion following Tyr344 in penicillin-binding protein 3 (PBP 3) as the result of gene duplication.