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

Production of antibody and development of enzyme-linked immunosorbent assay for therapeutic drug monitoring of eravacycline

Eravacycline (ERC) was approved for clinical use in 2018. It is more potent than other tetracyclines and can overcome resistance, making it an attractive option for combating multidrug-resistant bacterial infections. Intensive pharmacokinetic (PK) studies are currently being conducted to ensure the effectiveness and safety of ERC in various groups of patients, including those undergoing extracorporeal therapies. This study is the first attempt to develop a simple, efficient, and high-throughput immunoassay for quantifying ERC in human or animal serum. BSA-ERC conjugate as immunogen elicited antibody production in rabbits. Monitoring of the immune response and comparison of homologous and heterologous coating antigens allowed selection of immunoreagents and development of an assay that was selective for ERC possessing sensitivity (IC50), dynamic range (IC20-IC80) and detection limit equal to 3.3 ng/mL, 0.27-54 ng/mL and 0.09 ng/mL, respectively. The developed ELISA showed acceptable recovery of ERC (85-105 %) from rabbit and human serum in the clinically relevant concentration range of 0.1-3.0 mg/L. The method was used to quantify serum ERC concentration in the pilot PK study in Soviet chinchilla rabbits. The results were confirmed by HPLC-MS/MS.

New Antibiotics Against Multidrug-Resistant Gram-Negative Bacteria in Liver Transplantation: Clinical Perspectives, Toxicity, and PK/PD Properties

Antimicrobial resistance is a growing global health problem, and it is especially relevant among liver transplant recipients where infections, particularly when caused by microorganisms with a difficult-to-treat profile, are a significant cause of morbidity and mortality. We provide here a complete dissection of the antibiotics active against multidrug-resistant Gram-negative bacteria approved over the last years, focusing on their activity spectrum, toxicity profile and PK/PD properties, including therapeutic drug monitoring, in the setting of liver transplantation. Specifically, the following drugs are presented: ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, cefiderocol, and eravacycline. Overall, studies on the safety and optimal employment of these drugs in liver transplant recipients are limited and especially needed. Nevertheless, these pharmaceuticals have undeniably enhanced therapeutic options for infected liver transplant recipients.

First-in-human study to evaluate the safety, tolerability, and population pharmacokinetic/pharmacodynamic target attainment analysis of FL058 alone and in combination with meropenem in healthy subjects

FL058 is a novel diazabicyclooctane β-lactamase inhibitor. This first-in-human study evaluated the safety, tolerability, and population pharmacokinetic (PK)/pharmacodynamic target attainment analysis of FL058 alone and in combination with meropenem in healthy subjects. The results showed that the maximum tolerated dose of FL058 was 3,000 mg after single-dose infusion. FL058 in combination with meropenem did not cause any grade 3 or higher adverse event when the dose was escalated up to 1,000 mg/2,000 mg. FL058 exposure PK parameters showed dose proportionality. FL058 was excreted primarily in urine. No significant PK interaction was found between FL058 and meropenem. Population PK model analysis indicated that the PK profiles of FL058 and meropenem were consistent with the two-compartment model. The impact of covariates, creatinine clearance, concomitant use of meropenem, body weight, sex, and FL058 dose, on FL058 exposure was less than 10%. FL058/meropenem combination was safe and well tolerated up to a 1,000-mg/2,000-mg dose in healthy adults. The recommended minimum dose of FL058/meropenem combination was 500 mg/1,000 mg by intravenous infusion over 2 h every 8 h based on target attainment analysis. The good safety, tolerability, and satisfactory PK profiles of FL058 alone and in combination with meropenem in this first-in-human study will support further clinical development of FL058 in combination with meropenem in patients with target infections (ClinicalTrials.gov identifiers: NCT05055687, NCT05058118, and NCT05058105).

New Antibiotics for the Treatment of Nosocomial Central Nervous System Infections

Nosocomial central nervous system (CNS) infections with carbapenem- and colistin-resistant Gram-negative and vancomycin-resistant Gram-positive bacteria are an increasing therapeutic challenge. Here, we review pharmacokinetic and pharmacodynamic data and clinical experiences with new antibiotics administered intravenously for the treatment of CNS infections by multi-resistant bacteria. Cefiderocol, a new siderophore extended-spectrum cephalosporin, pharmacokinetically behaves similar to established cephalosporins and at high doses will probably be a valuable addition in our therapeutic armamentarium for CNS infections. The new glycopeptides dalbavancin, telavancin, and oritavancin are highly bound to plasma proteins. Although effective in animal models of meningitis, it is unlikely that they reach effective cerebrospinal fluid (CSF) concentrations after intravenous administration alone. The β-lactam/β-lactamase inhibitor combinations have the principal problem that both compounds must achieve adequate CSF concentrations. In the commercially available combinations, the dose of the β-lactamase inhibitor tends to be too low to achieve adequate CSF concentrations. The oxazolidinone tedizolid has a broader spectrum but a less suitable pharmacokinetic profile than linezolid. The halogenated tetracycline eravacycline does not reach CSF concentrations sufficient to treat colistin-resistant Gram-negative bacteria with usual intravenous dosing. Generally, treatment of CNS infections should be intravenous, whenever possible, to avoid adverse effects of intraventricular therapy (IVT). An additional IVT can overcome the limited penetration of many new antibiotics into CSF. It should be considered for patients in which the CNS infection responds poorly to systemic antimicrobial therapy alone.

In vitro Antimicrobial Activity and Dose Optimization of Eravacycline and Other Tetracycline Derivatives Against Levofloxacin-Non-Susceptible and/or Trimethoprim-Sulfamethoxazole-Resistant Stenotrophomonas maltophilia

Purpose

To better guide clinical use, we determined the in vitro antimicrobial activity of the new drug eravacycline and other tetracycline derivatives against levofloxacin (LVFX)-non-susceptible and/or trimethoprim-sulfamethoxazole (TMP-SMZ)-resistant Stenotrophomonas maltophilia and evaluated their dosing regimens.

Methods

Seventy-seven unique strains of S. maltophilia were isolated from sputa samples and airway aspirate samples that were either LVFX-non-susceptible and/or TMP-SMZ-resistant. Monte Carlo simulations were performed for different dosing regimens according to the population pharmacokinetic parameters of antibiotics in patients with respiratory tract infections at the minimum inhibitory concentration (MIC).

Results

Eravacycline had excellent in vitro antibacterial activity against LVFX-non-susceptible and/or TMP-SMZ-resistant S. maltophilia. Monte Carlo simulations showed that for LVFX-non-susceptible strains, the cumulative fraction of response (CFR) of minocycline at the conventional recommended dose of 100 mg q12 h was 90.90%; for TMP-SMZ-resistant strains, the CFR of minocycline at a high dose of 200 mg q12 h was only 91.64%. For strains resistant to both LVFX and TMP-SMZ, the CFR of minocycline at a high dose of 200 mg q12 h was 89.81%. In contrast, the CFR of tigecycline was less than 40%, even at a dose of 100 mg q12 h.

Conclusion

For pneumonia, minocycline is better for S. maltophilia that is non-susceptible to LVFX; for TMP-SMZ-resistant strains and strains that are not susceptible to either LVFX or TMP-SMZ, the efficiency of eravacycline requires further evaluation. Eravacycline may be a better choice for extremely resistant S. maltophilia strains that are non-susceptible to LVFX, TMP-SMZ, and minocycline.

Omadacycline, Eravacycline, and Tigecycline Express Anti-Mycobacterium abscessus Activity In Vitro

Mycobacterium abscessus infections are increasing worldwide necessitating the development of new antibiotics and treatment regimens. The utility of third-generation tetracycline antibiotics was reestablished; their anti-M. abscessus activity needs further study. The activities of omadacycline (OMC), eravacycline (ERC), tigecycline (TGC), and sarecycline (SAC) were tested against two reference strains and 193 clinical M. abscessus isolates at different temperatures (30°C and 37°C). The minimum bactericidal concentrations (MBCs) of the four drugs were determined to distinguish between their bactericidal and bacteriostatic activities. The MICs of OMC, ERC, and TGC for the reference strains and clinical isolates were summarized and compared. OMC, ERC, and TGC exhibited a high level of bacteriostatic activity against M. abscessus. The MICs of OMC and ERC for M. abscess remained stable, while the MICs of TGC for the isolates/strains increased with increasing temperature. Notably, the MICs of OMC for M. abscessus isolates obtained in the United States are lower than for those obtained in China. IMPORTANCE The antimicrobial activities of four third-generation tetracycline-class drugs, omadacycline (OMC), eravacycline (ERC), tigecycline (TGC), and sarecycline (SAC), were determined for 193 M. abscessus isolates. The activities of the four drugs at two different temperatures (30°C and 37°C) were also tested. OMC, ERC, and TGC exhibited significant activity against M. abscessus. The anti-M. abscessus activity of TGC increased when the temperature was increased from 30°C to 37°C; the activities of OMC and ERC, on the other hand, remained the same. We found that in vitro MICs of OMC against Chinese and American isolates were distinct. Evaluations in in vivo models of M. abscessus disease or in the clinical setting will provide more accurate insight into potency of OMC against distinct isolates.

In vitro activity of eravacycline and comparator agents against bacterial pathogens isolated from patients with cancer

Background

Bacterial infections are common in patients with cancer, and many bacteria have developed resistance to currently used antibiotics.

Objectives

We evaluated the in vitro activity of eravacycline (a recently developed fluorocycline) and comparators against bacterial pathogens isolated from patients with cancer.

Methods

Antimicrobial susceptibility testing was performed using CLSI-approved methodology and interpretive criteria for 255 Gram-positive and 310 Gram-negative bacteria. MIC and susceptibility percentage were calculated according to CLSI and FDA breakpoints when available.

Results

Eravacycline had potent activity against most Gram-positive bacteria, including MRSA. Of 80 Gram-positive isolates with available breakpoints, 74 (92.5%) were susceptible to eravacycline. Eravacycline had potent activity against most Enterobacterales, including ESBL-producing organisms. Of 230 Gram-negative isolates with available breakpoints, 201 (87.4%) were susceptible to eravacycline. Eravacycline had the best activity among comparators against carbapenem-resistant Enterobacterales, with 83% susceptibility. Eravacycline was also active against many non-fermenting Gram-negative bacteria, with the lowest MIC₉₀ value among comparators.

Conclusions

Eravacycline was active against many clinically significant bacteria isolated from patients with cancer, including MRSA, carbapenem-resistant Enterobacterales, and non-fermenting Gram-negative bacilli. Eravacycline might play an important role in the treatment of bacterial infections in patients with cancer, and additional clinical evaluation is warranted.

In Vitro Antimicrobial Activities of Tigecycline, Eravacycline, Omadacycline, and Sarecycline against Rapidly Growing Mycobacteria

Infections caused by rapidly growing mycobacteria (RGM) have increased globally. Chemotherapy against these infections is challenging due to the minimal antimicrobial choices available. The main aim of this study was to evaluate the in vitro susceptibilities of four tetracyclines against different RGM species. The MICs of eravacycline (ERC), omadacycline (OMC), sarecycline (SAC), and tigecycline (TGC) against the reference strains of 27 RGM species and 121 RGM clinical isolates were determined by microtiter plate assay. The minimum bactericidal concentrations (MBCs) and cytotoxicities of these antibiotics were also tested. Except for SAC, the other three tetracyclines had MICs of ≤0.5 μg/mL against all 27 RGM reference strains. ERC generally presented the lowest MICs, with MIC₉₀s against the clinical isolates of Mycobacterium abscessus subsp. abscessus, Mycobacterium abscessus subsp. massiliense, and Mycobacterium fortuitum of 0.25 μg/mL, 0.25 μg/mL, and 0.06 μg/mL, respectively. TGC and OMC also showed equivalent in vitro inhibitory activities against the isolates, while the TGC MIC₉₀s for M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. fortuitum were lower than or equal to the OMC MIC₉₀s (1, 1, and 0.25 μg/mL versus 1, 2, and 2 μg/mL). In addition, the MIC₅₀s of three of the antibiotics for each species were always 2-fold lower than the corresponding MIC₉₀s. MBC and cytotoxicity assays indicated that all four tetracycline antibiotics tested were bacteriostatic agents with low toxicity to the THP-1 cell line. Tetracycline antibiotics are efficacious in RGM infection treatment, with omadacycline showing the best promise for clinical application due to its potent antimicrobial activity, safety, and convenient administration route. IMPORTANCE The global rise in antibiotic-resistant nontuberculous mycobacteria has prompted the urgent need for new antimicrobials, especially oral antibiotics. Currently, adverse effects have limited the use of tetracycline-class antibiotics, particularly tigecycline (TGC), in the treatment of rapidly growing mycobacteria (RGM). However, several new tetracycline-class antibiotics might overcome the limitations of TGC. We assessed the in vitro antibiotic susceptibilities of four tetracyclines (eravacycline, omadacycline, sarecycline, and tigecycline) against reference RGM strains and clinical isolates of different RGM species. We showed that three of these antibiotics (tigecycline, eravacycline, and omadacycline) might be efficacious in M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. fortuitum treatment. Furthermore, omadacycline was more promising for clinical application for M. abscessus infections as an oral drug, whereas sarecycline, which had the best safety parameters, should be considered a potential antibiotic for M. abscessus infections caused by susceptible strains. Our work underscores the possible clinical applications of tetracycline-class antibiotics in the treatment of RGM infections.

Tetracyclines and bone: Unclear actions with potentially lasting effects

Tetracyclines are a broad-spectrum class of antibiotics that have unclear actions with potentially lasting effects on bone metabolism. Initially isolated from Streptomyces, tetracycline proved to be an effective treatment for Gram +/- infections. The emergence of resistant bacterial strains commanded the development of later generation agents, including minocycline, doxycycline, tigecycline, sarecycline, omadacycline, and eravacycline. In 1957, it was realized that tetracyclines act as bone fluorochrome labels due to their high affinity for the bone mineral matrix. Over the course of the next decade, researchers discerned that these compounds are retained in the bone matrix at high levels after the termination of antibiotic therapy. Studies during this period provided evidence that tetracyclines could disrupt prenatal and early postnatal skeletal development. Currently, tetracyclines are most commonly prescribed as a long-term systemic therapy for the treatment of acne in healthy adolescents and young adults. Surprisingly, the impact of tetracyclines on physiologic bone modeling/remodeling is largely unknown. This article provides an overview of the pharmacology of tetracycline drugs, summarizes current knowledge about the impact of these agents on skeletal development and homeostasis, and reviews prior work targeting tetracyclines' effects on bone cell physiology. The need for future research to elucidate unclear effects of tetracyclines on the skeleton is addressed, including drug retention/release mechanisms from the bone matrix, signaling mechanisms at bone cells, the impact of newer third generation tetracycline antibiotics, and the role of the gut-bone axis.

An integrated approach to evaluate different tetracycline derivatives for formulary decisions

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Stenotrophomonas maltophilia has emerged as a critical opportunistic pathogen associated with significant morbidity and mortality. Tetracycline derivatives have been recognized as alternative treatment options, but they have varied pharmacokinetic properties. An integrated approach to different tetracycline derivatives for formulary decisions is reported.

METHODS

The minimum inhibitory concentration (MIC) data from clonally diverse bloodstream S. maltophilia isolates were examined, along with the pharmacokinetic profiles of 4 tetracycline derivatives, to predict achievable pharmacodynamic exposures with standard intravenous dosing regimens. Antimicrobial therapy was assessed using the ratio of daily drug acquisition cost relative to the ratio of the free-drug area under the time-concentration curve (fAUC) to the 90th percentile for minimum inhibitory concentration (MIC) values for isolates (fAUC/MIC90).

RESULTS

In our analysis, minocycline had the greatest fAUC/MIC90. Doxycycline was the most financially preferred agent, as calculated using 2020 average wholesale price for base-case estimates of drug acquisition cost.

CONCLUSION

An integrated evaluation for antimicrobial formulary decision-making addressed local susceptibility data, pharmacokinetics, pharmacodynamics, dosing regimens, and drug acquisition costs. This comprehensive method is more objective than the conventional approach and warrants validation.

New options for bloodstream infections caused by colistin- or ceftazidime/avibactam-resistant Klebsiella pneumoniae

Concerns regarding carbapenem-resistant Klebsiella pneumoniae (CR-Kp), especially in bloodstream infections (BSIs), are continuing to increase worldwide. Several novel agents with activity against BSI CR-Kp have been approved or are in late-stage clinical development. In this study, the antibacterial effects of ceftazidime/avibactam (CZA), aztreonam/avibactam (AZA), meropenem/vaborbactam (MEV), imipenem-cilastatin/relebactam (ICR) and eravacycline (ERV) against three colistin-resistant CR-Kp (COLR-Kp) and four CZA-resistant CR-Kp (CZAR-Kp) were tested by time-kill assay. Klebsiella pneumoniae ATCC® BAA-1705TM was used as a control strain. Two COLR-Kp isolates carried the blaKPC-2 gene and four CAZR-Kp isolates carried metallo-β-lactamase genes. The results revealed that ERV resulted in re-growth of seven tested isolates. CZA and MEV showed a bactericidal effect against isolates harbouring blaKPC-2. ICR reduced the population of six isolates to >5 log10 CFU/mL compared with the initial count. AZA showed a bactericidal effect (>5 log10 CFU/mL) against seven isolates and a bacteriostatic effect (<3 log10 CFU/mL) against one CZAR-Kp isolate. Therefore, AZA and ICR are effective therapeutic candidates for COLR-Kp and CZAR-Kp isolates.

Eravacycline, a novel tetracycline derivative, does not induce Clostridioides difficile infection in an in vitro human gut model

OBJECTIVES

The approval of new antibiotics is essential to combat infections caused by antimicrobial-resistant pathogens; however, such agents should be tested to determine their effect on the resident microbiota and propensity to select for opportunistic pathogens, such as Clostridioides difficile. Eravacycline is a new antibiotic for the treatment of complicated intra-abdominal infections. Here, we determined the effects of eravacycline compared with moxifloxacin on the microbiota and if these were conducive to induction of C. difficile infection (CDI).

METHODS

We seeded in vitro chemostat models, which simulate the physiological conditions of the human colon, with a human faecal slurry and instilled gut-reflective concentrations of either eravacycline or moxifloxacin.

RESULTS

Eravacycline instillation was associated with decreased Bifidobacterium, Lactobacillus and Clostridium species, which recovered 1 week after exposure. However, Bacteroides spp. levels decreased to below the limit of detection and did not recover prior to the end of the experiment. Post-eravacycline, a bloom of aerobic bacterial species occurred, including Enterobacteriaceae, compared with pre-antibiotic, which remained high for the duration of the experiment. These changes in microbiota were not associated with induction of CDI, as we observed a lack of C. difficile spore germination and thus no toxin was detected. Moxifloxacin exposure sufficiently disrupted the microbiota to induce simulated CDI, where C. difficile spore germination, outgrowth and toxin production were seen.

CONCLUSIONS

These model data suggest that, despite the initial impact of eravacycline on the intestinal microbiota, similar to clinical trial data, this novel tetracycline has a low propensity to induce CDI.

A Real-World Assessment of Clinical Outcomes and Safety of Eravacycline: A Novel Fluorocycline

Background

Eravacycline is a novel fluorocycline approved for treatment of intraabdominal infections, with a broad spectrum of activity against a range of pathogens including multidrug-resistant species, including ESBL- or KPC-producing isolates. It is approved for twice-daily dosing with no need for adjustment in renal dysfunction. In the concomitant administration with CYP 3A4-inducing drugs, eravacycline dosing should be modified.

Objective

To evaluate the efficacy and safety of eravacycline in a range of infections such as intraabdominal infections, pneumonia and diabetic foot infections in seriously ill patients.

Methods

A retrospective observational cohort study using electronic patient records of 50 consecutive patients administered eravacycline during inpatient acute care admission or as part of outpatient antibiotic therapy (OPAT).

Results

Therapy of 1.5 mg/kg q24h was initiated in the hospital in most patients, although some of the less sick were managed in the office or OPAT setting. All patients concluded their management outside of the hospital. Of the 50 patients, 47 (94%) achieved clinical resolution of their infection and 3 (6%) clinical failures occurred. Only three (6%) patients did not have comorbidities, three had a single comorbidity (6%), and the majority (88%) of patients had two or more comorbidities. Most common infections were intraabdominal (36%), pneumonia (18%), diabetic foot (12%), spontaneous bacterial peritonitis (8%) and empyema (8%). Almost half of infections had more than one pathogen isolated, and resistant isolates were frequent. The drug was well tolerated with only two reports of nausea, which did not result in treatment discontinuation, and in 30 days of post-eravacycline therapy only one case of Clostridiodes difficile.

Conclusions

In this real-world setting, eravacycline demonstrated a similar high level of clinical efficacy as seen in clinical trials, 94%, in a variety of infections, including against multidrug-resistant bacteria, and was well tolerated.

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.

Colistin-sparing approaches with newer antimicrobials to treat carbapenem-resistant organisms: Current evidence and future prospects

Antimicrobial resistance is on the rise across the globe. Increasing incidence of infections due to carbapenem resistance organisms is becoming difficult to treat, due to the limited availability of therapeutic agents. Very few agents such as colistin, fosfomycin, tigecycline and minocycline are widely used, despite its toxicity. However, with the availability of novel antimicrobials, beta-lactam/beta-lactamase inhibitor-based and non-beta-lactam-based agents could be of great relief. This review covers three important aspects which include (i) current management of carbapenem-resistant infections, (ii) determination of specific types of carbapenemases produced by multidrug-resistant and extensively drug-resistant Gram-negative pathogens and (iii) the currently available novel beta-lactam/beta-lactamase inhibitors and non-beta-lactam-based agents' laboratory findings, clinical outcome and implications.

Eravacycline: A Review in Complicated Intra-Abdominal Infections

Eravacycline (Xerava™), a novel fully synthetic fluorocycline, consists of the tetracyclic core scaffold with unique modifications in the tetracyclic D ring; consequently, it exhibits potent in vitro activity against Gram-positive and -negative bacterial strains expressing certain common tetracycline-specific acquired resistance mechanisms. In vitro, eravacycline exhibits potent activity against a broad spectrum of clinically relevant Gram-positive and -negative aerobic and anaerobic bacteria. Intravenous eravacycline is approved in several countries for the treatment of complicated intra-abdominal infections (cIAIs) in adult patients. In two pivotal double-blind, multinational trials in this patient population, eravacycline (infusion ≈ 1 h) was noninferior to intravenous ertapenem or meropenem at the test-of-cure visit in terms of clinical response rates in all prespecified populations. Eravacycline had an acceptable tolerability profile, with infusion site reactions, nausea, vomiting and diarrhoea the most commonly reported adverse reactions, most of which were of mild to moderate severity. Given its broad spectrum of activity against common clinically relevant pathogens (including those expressing certain tetracycline- and other antibacterial-specific acquired resistance mechanisms) and its more potent in vitro activity and better tolerability profile than tigecycline, eravacycline provides a novel emerging option for the treatment of adult patients with cIAIs, especially as empirical therapy when coverage of resistant pathogens is required.

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.

Treatment Options for Colistin Resistant Klebsiella pneumoniae: Present and Future

Multidrug-resistant (MDR) Klebsiella pneumoniae represents an increasing threat to human health, causing difficult-to-treat infections with a high mortality rate. Since colistin is one of the few treatment options for carbapenem-resistant K. pneumoniae infections, colistin resistance represents a challenge due to the limited range of potentially available effective antimicrobials, including tigecycline, gentamicin, fosfomycin and ceftazidime/avibactam. Moreover, the choice of these antimicrobials depends on their pharmacokinetics/pharmacodynamics properties, the site of infection and the susceptibility profile of the isolated strain, and is sometimes hampered by side effects. This review describes the features of colistin resistance in K. pneumoniae and the characteristics of the currently available antimicrobials for colistin-resistant MDR K. pneumoniae, as well as the characteristics of novel antimicrobial options, such as the soon-to-be commercially available plazomicin and cefiderocol. Finally, we consider the future use of innovative therapeutic strategies in development, including bacteriophages therapy and monoclonal antibodies.

Eravacycline, a newly approved fluorocycline

Complicated intra-abdominal infections (cIAIs) are commonly associated with multimicroorganisms and treatment choices are becoming narrower due to developing resistance, especially in the gram-negative Enterobacteriaceae species. Eravacycline is a newly developed, fully synthetic tetracycline derivative that has shown potent broad-spectrum activity against a wide variety of microorganisms, including those such as extended spectrum β-lactamase producing Enterobacteriaceae and Acinetobacter. Eravacycline has shown activity against many gram-positive organisms such as methicillin-resistant S. aureus and vancomycin resistant Enterococcus faecalis and Enterococcus faecium (VRE), gram-negative organisms such as Escherichia coli, and anaerobic species of microorganisms such as Bacteroides. This fluorocycline has been compared to ertapenem and meropenem for the treatment of complicated intra-abdominal infections and levofloxacin for the treatment of complicated urinary tract infections. Eravacycline was shown to be noninferior to ertapenem but did not meet noninferiority criteria in comparison to levofloxacin. Oral and IV formulations on eravacycline were tested in clinical trials, but at this time, only the IV formulation is FDA approved. Eravacycline has been noted to have a half-life of 20 h with protein binding around 80%; AUC over minimum inhibitory concentration (MIC) has also been shown to be eravacycline's best predictor of efficacy. Of note, eravacycline does not require any renal dose adjustments, as the majority of its clearance is by nonrenal pathways.

Developments on antibiotics for multidrug resistant bacterial Gram-negative infections

Introduction: The constantly increasing spread of severe infections due to multidrug-resistant (MDR) Gram-negative bacteria (GNB) is a critical threat to the global medical community. After a long period of antibiotic pipeline pause, new antibiotic compounds are commercially available or are at late stages of clinical evaluation, promising to augment the therapeutic armamentarium of clinicians against deadly pathogens. Areas covered: This review summarizes available data regarding agents with potent activity against critical MDR Gram-negative pathogens, which urgently require new efficient antibiotics. Recently approved antibiotic formulations; and agents in advanced stages of development, including combinations of β-lactam/β-lactamase inhibitor, novel cephalosporins (cefiderocol), tetracyclines (eravacycline), aminoglycosides (plazomicin), quinolones (delafloxacin and finafloxacin) and pleuromutilins (lefamulin) are discussed in this review. Expert opinion: The recent introduction of new antibiotics into clinical practice is an encouraging step after a long period of pipeline stagnation. New formulations will be a useful option for clinicians to treat serious infections caused by several MDR Gram-negative pathogens. However, most of the new compounds are based on modifications of traditional antibiotic structures challenging their longevity as therapeutic options. More investment is needed for the discovery and clinical development of truly innovative and effective antibiotics without cross-resistance to currently used antibiotics.

In Vitro Activity of New Tetracycline Analogs Omadacycline and Eravacycline against Drug-Resistant Clinical Isolates of Mycobacterium abscessus

Tigecycline is used in multidrug regimens for salvage therapy of Mycobacterium abscessus infections but is often poorly tolerated and has no oral formulation. Here, we report similar in vitro activity of two newly approved tetracycline analogs, omadacycline and eravacycline, against 28 drug-resistant clinical isolates of M. abscessus complex. Since omadacycline and eravacycline appear to be better tolerated than tigecycline and since omadacycline is also formulated for oral dosing, these tetracycline analogs may represent new treatment options for M. abscessus infections.

Mass Balance and Drug Interaction Potential of Intravenous Eravacycline Administered to Healthy Subjects

Eravacycline is a novel, fully synthetic fluorocycline that is approved for the treatment of complicated intra-abdominal infections (cIAI) in adult patients. We report results from three studies in healthy subjects that investigated the distribution, metabolism, and excretion of intravenous (i.v.) eravacycline and the effect of a CYP3A4 inhibitor (itraconazole) and inducer (rifampin) on the pharmacokinetics (PK) of i.v. eravacycline. In the mass balance study, the majority of total radioactivity from [¹⁴C]eravacycline was recovered in the feces, suggesting biliary/fecal elimination is the major route of excretion for eravacycline and its metabolites after IV administration. The volume of distribution (217 liters) was greater than that of extracellular fluid, which suggests distribution beyond the central compartment. In the drug-drug interaction studies, mean area under the concentration-time curve from 0 h to the last time point (AUC_{0 -t} ) and half-life were increased approximately 30% to 40% after a concomitant dose of i.v. eravacycline and itraconazole and clearance (CL) was decreased. A reduction in total eravacycline exposure (AUC) of approximately 25% to 35% and an increase in CL of approximately 50% occurred with concomitant eravacycline and rifampin treatment. The dose of eravacycline should be increased to 1.5 mg/kg of body weight every 12 h when coadministered with a strong CYP3A inducer.