Colistin, Meropenem-Vaborbactam, Imipenem-Relebactam, and Eravacycline Testing in Carbapenem-Resistant Gram-Negative Rods: A Comparative Evaluation of Broth Microdilution, Gradient Test, and VITEK 2

OBJECTIVES

This study aimed to evaluate and compare the performance of different assays for antimicrobial susceptibility testing (AST) and minimum inhibitory concentration (MIC) determination for reserve antibiotics in carbapenem-resistant Enterobacterales (CREs), Pseudomonas aeruginosa (CRPAs), and Acinetobacter baumannii (CRABs).

METHODS

An analysis was conducted on 100 consecutive isolates: 50 CREs, 35 CRPAs, and 15 CRABs. Sensititre broth microdilution was used as a reference standard to evaluate the performance of VITEK 2 card AST-XN24 (bioMérieux), the respective gradient tests (bioMérieux), and UMIC colistin broth microdilution test strips (Bruker Daltonics). Errors, essential agreement (EA), and categorical agreement of MICs for colistin (COL), meropenem-vaborbactam (MVB), imipenem-relebactam (IRL), and eravacycline (ERV) were assessed.

RESULTS

The agreement between both of the COL broth microdilution (BMD) methods was perfect (100/100). The gradient test and VITEK 2 analysis yielded comparable EA rates (92/100 and 72/79, respectively), with the latter not registering any very major errors (VMEs). The MVB gradient test achieved EA in 66 of 85 isolates and VITEK 2 in 70/85. For IRL, EA was reached in 69 and 64 of 85 cases by gradient test and VITEK 2 analysis, respectively. The ERV gradient test yielded false results in nearly all (12/15) CRABs but achieved EA in 46 of 50 CREs. The VITEK system recorded EA for ERV in 60 of 65 isolates.

CONCLUSIONS

We observed substantial variability in the measured MICs between BMD and the alternative methods. In only a few constellations, VITEK 2 or gradient tests could substitute the reference method. BMD is the method of choice for COL analysis, with VITEK 2 representing an alternative method for CRPA testing. Alternative methods for MVB did not provide reliable results, except for Enterobacterales, when tested with the gradient test. However, resistant results need to be confirmed by BMD. Only BMD can be used for IRL MIC determination. VITEK 2 was mostly accurate in measuring ERV MICs, while the corresponding gradient test yielded reliable results exclusively in CREs. It is essential that laboratories are aware of which testing method provides reliable results for each combination of microorganisms and reserve antibiotics.

Use of Eravacycline for Acinetobacter baumannii Infections: A Case Series

This case series describes the clinical course of 10 patients who received eravacycline antimicrobial therapy for a variety of different Acinetobacter baumannii infection types at a community care hospital.

Management of intra-abdominal infections: recommendations by the Italian council for the optimization of antimicrobial use

Intra-abdominal infections (IAIs) are common surgical emergencies and are an important cause of morbidity and mortality in hospital settings, particularly if poorly managed. The cornerstones of effective IAIs management include early diagnosis, adequate source control, appropriate antimicrobial therapy, and early physiologic stabilization using intravenous fluids and vasopressor agents in critically ill patients. Adequate empiric antimicrobial therapy in patients with IAIs is of paramount importance because inappropriate antimicrobial therapy is associated with poor outcomes. Optimizing antimicrobial prescriptions improves treatment effectiveness, increases patients' safety, and minimizes the risk of opportunistic infections (such as Clostridioides difficile) and antimicrobial resistance selection. The growing emergence of multi-drug resistant organisms has caused an impending crisis with alarming implications, especially regarding Gram-negative bacteria. The Multidisciplinary and Intersociety Italian Council for the Optimization of Antimicrobial Use promoted a consensus conference on the antimicrobial management of IAIs, including emergency medicine specialists, radiologists, surgeons, intensivists, infectious disease specialists, clinical pharmacologists, hospital pharmacists, microbiologists and public health specialists. Relevant clinical questions were constructed by the Organizational Committee in order to investigate the topic. The expert panel produced recommendation statements based on the best scientific evidence from PubMed and EMBASE Library and experts' opinions. The statements were planned and graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence. On November 10, 2023, the experts met in Mestre (Italy) to debate the statements. After the approval of the statements, the expert panel met via email and virtual meetings to prepare and revise the definitive document. This document represents the executive summary of the consensus conference and comprises three sections. The first section focuses on the general principles of diagnosis and treatment of IAIs. The second section provides twenty-three evidence-based recommendations for the antimicrobial therapy of IAIs. The third section presents eight clinical diagnostic-therapeutic pathways for the most common IAIs. The document has been endorsed by the Italian Society of Surgery.

Navigating Antibacterial Frontiers: A Panoramic Exploration of Antibacterial Landscapes, Resistance Mechanisms, and Emerging Therapeutic Strategies

The development of effective antibacterial solutions has become paramount in maintaining global health in this era of increasing bacterial threats and rampant antibiotic resistance. Traditional antibiotics have played a significant role in combating bacterial infections throughout history. However, the emergence of novel resistant strains necessitates constant innovation in antibacterial research. We have analyzed the data on antibacterials from the CAS Content Collection, the largest human-curated collection of published scientific knowledge, which has proven valuable for quantitative analysis of global scientific knowledge. Our analysis focuses on mining the CAS Content Collection data for recent publications (since 2012). This article aims to explore the intricate landscape of antibacterial research while reviewing the advancement from traditional antibiotics to novel and emerging antibacterial strategies. By delving into the resistance mechanisms, this paper highlights the need to find alternate strategies to address the growing concern.

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.

Comparative Activities of Novel Therapeutic Agents against Molecularly Characterized Clinical Carbapenem-Resistant Enterobacterales Isolates

Limited treatment options exist for the treatment of carbapenem-resistant Enterobacterales (CRE) bacteria. Fortunately, there are several recently approved antibiotics indicated for CRE infections. Here, we examine the in vitro activity of various novel agents (eravacycline, plazomicin, ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam) and comparators (tigecycline, amikacin, levofloxacin, fosfomycin, polymyxin B) against 365 well-characterized CRE clinical isolates with various genotypes. Nonduplicate isolates collected from the largest public health hospital in Singapore between 2007 and 2020 were subjected to antimicrobial susceptibility testing (broth microdilution or antibiotic gradient test strips). Susceptibilities were defined using Clinical and Laboratory Standards Institute (CLSI) or Food and Drug Administration (FDA) interpretative criteria. Sequence types and resistance mechanisms were characterized using short-read whole-genome sequencing. Overall, tigecycline and plazomicin exhibited the highest susceptibility rates (89.6% and 80.8%, respectively). However, the tigecycline susceptibility breakpoint utilized here may be outdated in view of prevailing pharmacokinetic-pharmacodynamic (PK/PD) data. Susceptibility varied by carbapenemase genotype; the β-lactam/β-lactamase inhibitor combinations were equally active (92.3 to 99.2% susceptible) against KPC producers, but only ceftazidime-avibactam retained high susceptibility (98.7%) against OXA-48-like producers. Against metallo-β-lactamase producers, only plazomicin exhibited moderate activity (77.0% susceptible). Aminoglycoside activity was also influenced by carbapenemase genotypes. This work provides an insight into the comparative activity and presumptive utility of novel agents in this geographic region. IMPORTANCE This study determined the susceptibilities of carbapenem-resistant Enterobacterales isolates to various novel antimicrobial agents (ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, eravacycline, and plazomicin). Whole-genome sequencing was performed for all strains. Our study findings provide insights into the comparative activities of novel agents in this geographic region. Plazomicin and ceftazidime-avibactam exhibited the lowest nonsusceptibility rates and may be considered promising agents in the management of carbapenem-resistant Enterobacterales infections. We note also that antibiotic activity is influenced by genotypes and that understanding the geographic region's molecular epidemiology could aid in the definition of the presumptive utility of novel agents and contribute to antibiotic decision-making.

Omadacycline and Clostridioides difficile: A Systematic Review of Preclinical and Clinical Evidence

OBJECTIVE

The objective of this systematic review is to summarize in vitro, preclinical, and human data related to omadacycline and Clostridioides difficile infection (CDI).

DATA SOURCES

PubMed and Google Scholar were searched for "omadacycline" AND ("Clostridium difficile" OR "C difficile" OR "Clostridioides difficile") for any studies published before February 15, 2022. The US Food and Drug Administration (FDA) Adverse Events Reporting System (AERS) was searched for omadacycline (for reports including "C. difficile" or "CDI" or "gastrointestinal infection"). The publications list publicly available at Paratek Pharmaceuticals, Inc. Web site was reviewed.

STUDY SELECTION AND DATA EXTRACTION

Publications presenting primary data on omadacycline and C. difficile published in English were included.

DATA SYNTHESIS

Preclinical and clinical evidence was extracted from 14 studies. No case reports in indexed literature and no reports on FDA AERS were found. Omadacycline has potent in vitro activity against many C. difficile clinical strains and diverse ribotypes. In phase 3 studies, there were no reports of CDI in patients who received omadacycline for either community-acquired bacterial pneumonia or acute bacterial skin and skin structure infection.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Omadacycline should be considered a low-risk antibiotic regarding its propensity to cause CDI.

CONCLUSIONS

Reducing the burden of CDI on patients and the health care system should be a priority. Patients with appropriate indications who are at heightened risk of CDI may be suitable candidates for omadacycline therapy. In these patients, omadacycline may be preferable to antibiotics with a high CDI risk.

A Drug Repurposing Approach to Identify Therapeutics by Screening Pathogen Box Exploiting SARS-CoV-2 Main Protease

Coronavirus disease-19 (COVID-19) is caused by severe acute respiratory syndrome coronavirus -2 (SARS-CoV-2) and is responsible for a higher degree of morbidity and mortality worldwide. There is a smaller number of approved therapeutics available to target the SARS-CoV-2 virus, and the virus is evolving at a fast pace. So, there is a continuous need for new therapeutics to combat COVID-19. The main protease (Mpro ) enzyme of SARS-CoV-2 is essential for replication and transcription of the viral genome, thus could be a potent target for the treatment of COVID-19. In the present study, we performed an in-silico screening analysis of 400 diverse bioactive inhibitors with proven antibacterial and antiviral properties against Mpro drug target. Ten compounds showed a higher binding affinity for Mpro than the reference compound (N3), with desired physicochemical properties. Furthermore, in-depth docking and superimposition revealed that three compounds (MMV1782211, MMV1782220, and MMV1578574) are actively interacting with the catalytic domain of Mpro . In addition, the molecular dynamics simulation study showed a solid and stable interaction of MMV178221-Mpro complex compared to the other two molecules (MMV1782220, and MMV1578574). In line with this observation, MM/PBSA free energy calculation also demonstrated the highest binding free energy of -115.8 kJ/mol for MMV178221-Mpro compound. In conclusion, the present in silico analysis revealed MMV1782211 as a possible and potent molecule to target the Mpro and must be explored in vitro and in vivo to combat the COVID-19.

Alternatives Therapeutic Approaches to Conventional Antibiotics: Advantages, Limitations and Potential Application in Medicine

Resistance to antimicrobials and particularly multidrug resistance is one of the greatest challenges in the health system nowadays. The continual increase in the rates of antimicrobial resistance worldwide boosted by the ongoing COVID-19 pandemic poses a major public health threat. Different approaches have been employed to minimize the effect of resistance and control this threat, but the question still lingers as to their safety and efficiency. In this context, new anti-infectious approaches against multidrug resistance are being examined. Use of new antibiotics and their combination with new β-lactamase inhibitors, phage therapy, antimicrobial peptides, nanoparticles, and antisense antimicrobial therapeutics are considered as one such promising approach for overcoming bacterial resistance. In this review, we provide insights into these emerging alternative therapies that are currently being evaluated and which may be developed in the future to break the progression of antimicrobial resistance. We focus on their advantages and limitations and potential application in medicine. We further highlight the importance of the combination therapy approach, wherein two or more therapies are used in combination in order to more effectively combat infectious disease and increasing access to quality healthcare. These advances could give an alternate solution to overcome antimicrobial drug resistance. We eventually hope to provide useful information for clinicians who are seeking solutions to the problems caused by antimicrobial resistance.

New antimicrobial treatment options for severe Gram-negative infections

PURPOSE OF REVIEW

This review will provide rationale for the development of new antibiotics to treat severe or multidrug-resistant (MDR) Gram-negative infections. It will also provide an overview of recently approved and pipeline antibiotics for severe/MDR Gram-negative infections.

RECENT FINDINGS

MDR Gram-negative infections are recognized as critical threats by global and national organizations and carry a significant morbidity and mortality risk. Increasing antibiotic resistance amongst Gram-negative bacteria, including carbapenem-resistant Acinetobacter baumannii , extended-spectrum β-lactamase-producing Enterobacterales, carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa , with difficult-to-treat-resistance has made both empiric and definitive treatment of these infections increasingly problematic. In recent years, several antibiotics have been approved for treatment of MDR Gram-negative infections and ongoing clinical trials are poised to provide additional options to clinicians' armamentarium. These agents include various β-lactam/β-lactamase inhibitor combinations, eravacycline, plazomicin and cefiderocol.

SUMMARY

Severe/MDR Gram-negative infections continue to be important infections due to their impact on patient outcomes, especially in critically ill and immunocompromised hosts. The availability of new antibiotics offers an opportunity to improve empiric and definitive treatment of these infections.

Evaluating the Efficacy of Eravacycline and Omadacycline against Extensively Drug-Resistant Acinetobacter baumannii Patient Isolates

For decades, the spread of multidrug-resistant (MDR) Acinetobacter baumannii has been rampant in critically ill, hospitalized patients. Traditional antibiotic therapies against this pathogen have been failing, leading to rising concerns over management options for patients. Two new antibiotics, eravacycline and omadacycline, were introduced to the market and have shown promising results in the treatment of Gram-negative infections. Since these drugs are newly available, there is limited in vitro data about their effectiveness against MDR A. baumannii or even susceptible strains. Here, we examined the effectiveness of 22 standard-of-care antibiotics, eravacycline, and omadacycline against susceptible and extensively drug-resistant (XDR) A. baumannii patient isolates from Cooper University Hospital. Furthermore, we examined selected combinations of eravacycline or omadacycline with other antibiotics against an XDR strain. We demonstrated that this collection of strains is largely resistant to monotherapies of carbapenems, fluoroquinolones, folate pathway antagonists, cephalosporins, and most tetracyclines. While clinical breakpoint data are not available for eravacycline or omadacycline, based on minimum inhibitory concentrations, eravacycline was highly effective against these strains. The aminoglycoside amikacin alone and in combination with eravacycline or omadacycline yielded the most promising results. Our comprehensive characterization offers direction in the treatment of this deadly infection in hospitalized patients.

Designing prototype rapid test device at qualitative performance to detect residue of tetracycline in chicken carcass

Background and Aim:

Human health problems due as a microbial resistance or tumors and cancers because consumption of the carcasses containing residues of tetracycline are main global problems in the context of fight against antimicrobial resistance phenomena. Explanation of the sustainable development goals, particularly point 3, is well recognized that all animal products for human consumption must be safe to live a healthy life. This study aimed to design a prototype of rapid test devices (RTD) based on principles of precipitate to obtain a specific color change after the process of reactions as an indicator to determine tetracycline residues in the carcass.

Materials and Methods:

Five samples of tetracycline-containing poultry carcasses using artificial add the tetracycline at pharmaceutics grade were examined using a prototype of a strong reaction solution for tetracycline fixation based on the concept bonded by ion Fe(III) at atom O in position atom C-1 at the ring of tetracycline and ion N⁺ as the functional branch of tetracycline. RTD detection was evaluated using a yellow color presentation and an absorbance spectrometric technique at a wavelength of 273 nm.

Results:

The following chemicals were used to create the best-fixed tetracycline residue: HCl and H₂SO₄ dissolved in H₂O, chromatographic grade of 0.1 N and 0.5 N of HNO₃, and 1% Fe (III) Cl. The RTD had a higher limit of detection (LOD) than the ultraviolet-visible spectrophotometer.

Conclusion:

The results of this study revealed that RTD, as constructed in this study, can be used to detect residue at LOD 44.764 mg/mL during 120 min of exposure through a light-emitting diode at 980 nm wavelength (p<0.05). The necessity for using RTD was because of the apparent limitations of conventional devices.

Development and Research Progress of Anti-Drug Resistant Bacteria Drugs

Bacterial resistance has become increasingly serious because of the widespread use and abuse of antibiotics. In particular, the emergence of multidrug-resistant bacteria has posed a serious threat to human public health and attracted the attention of the World Health Organization (WHO) and the governments of various countries. Therefore, the establishment of measures against bacterial resistance and the discovery of new antibacterial drugs are increasingly urgent to better contain the emergence of bacterial resistance and provide a reference for the development of new antibacterial drugs. In this review, we discuss some antibiotic drugs that have been approved for clinical use and a partial summary of the meaningful research results of anti-drug resistant bacterial drugs in different fields, including the antibiotic drugs approved by the FDA from 2015 to 2020, the potential drugs against drug-resistant bacteria, the new molecules synthesized by chemical modification, combination therapy, drug repurposing, immunotherapy and other therapies.

The Development of Third-Generation Tetracycline Antibiotics and New Perspectives

The tetracycline antibiotic class has acquired new valuable members due to the optimisation of the chemical structure. The first modern tetracycline introduced into therapy was tigecycline, followed by omadacycline, eravacycline, and sarecycline (the third generation). Structural and physicochemical key elements which led to the discovery of modern tetracyclines are approached. Thus, several chemical subgroups are distinguished, such as glycylcyclines, aminomethylcyclines, and fluorocyclines, which have excellent development potential. The antibacterial spectrum comprises several resistant bacteria, including those resistant to old tetracyclines. Sarecycline, a narrow-spectrum tetracycline, is notable for being very effective against Cutinebacterium acnes. The mechanism of antibacterial action from the perspective of the new compound is approached. Several severe bacterial infections are treated with tigecycline, omadacycline, and eravacycline (with parenteral or oral formulations). In addition, sarecycline is very useful in treating acne vulgaris. Tetracyclines also have other non-antibiotic properties that require in-depth studies, such as the anti-inflammatory effect effect of sarecycline. The main side effects of modern tetracyclines are described in accordance with published clinical studies. Undoubtedly, this class of antibiotics continues to arouse the interest of researchers. As a result, new derivatives are developed and studied primarily for the antibiotic effect and other biological effects.

Inadequate Cerebrospinal Fluid Concentrations of Available Salvage Agents Further Impedes the Optimal Treatment of Multidrug-Resistant Enterococcus faecium Meningitis and Bacteremia

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VRE) in particular has evolved as an important cause of hospital acquired infection, especially in immunocompromised hosts.

METHODS

We present a complex case of a patient with relapsed acute myeloid leukemia who underwent allogenic hematopoietic stem cell transplantation complicated by persistent VRE bacteremia and meningitis. To optimize therapy, various blood and cerebrospinal fluid (CSF) samples were sent to a research laboratory for extensive susceptibility testing, pharmacokinetic analyses, and time-kill experiments.

RESULTS

In vitro testing revealed resistance to all first-line treatment options and CSF sampling demonstrated sub-optimal central nervous system concentrations achieved by each antimicrobial agent administered in relation to their respective MIC value. Time-kill analyses at observed CSF concentrations confirmed the lack of bactericidal activity despite use of a four-drug combination regimen.

CONCLUSIONS

This work is the first to report CSF concentrations of oritavancin and tedizolid in humans and adds to the limited data regarding in vitro susceptibility of new antimicrobial agents such as eravacycline, omadacycline, and lefamulin against VRE. Our study provides new insights into various aspects of treatment of extensively drug-resistant Enterococcus faecium meningitis and bacteremia and supports the continued pursuit of precision medicine for these challenging cases.

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.

Exploiting drug delivery systems for oral route in the peptic ulcer disease treatment

Peptic ulcer disease (PUD) is a common condition that is induced by acid and pepsin causing lesions in the mucosa of the duodenum and stomach. The pathogenesis of PUD is a many-sided scenario, which involves an imbalance between protective factors, such as prostaglandins, blood flow, and cell renewal, and aggressive ones, like alcohol abuse, smoking, Helicobacter pylori colonisation, and the use of non-steroidal anti-inflammatory drugs. The standard oral treatment is well established; however, several problems can decrease the success of this therapy, such as drug degradation in the gastric environment, low oral bioavailability, and lack of vectorisation to the target site. In this way, the use of strategies to improve the effectiveness of these conventional drugs becomes interesting. Currently, the use of drug delivery systems is being explored as an option to improve the drug therapy limitations, such as antimicrobial resistance, low bioavailability, molecule degradation in an acid environment, and low concentration of the drug at the site of action. This article provides a review of oral drug delivery systems looking for improving the treatment of PUD.

An Update on Eight "New" Antibiotics against Multidrug-Resistant Gram-Negative Bacteria

Infections in the ICU are often caused by Gram-negative bacteria. When these microorganisms are resistant to third-generation cephalosporines (due to extended-spectrum (ESBL) or AmpC beta-lactamases) or to carbapenems (for example carbapenem producing Enterobacteriales (CPE)), the treatment options become limited. In the last six years, fortunately, there have been new antibiotics approved by the U.S. Food and Drug Administration (FDA) with predominant activities against Gram-negative bacteria. We aimed to review these antibiotics: plazomicin, eravacycline, temocillin, cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, meropenem/vaborbactam, and imipenem/relebactam. Temocillin is an antibiotic that was only approved in Belgium and the UK several decades ago. We reviewed the in vitro activities of these new antibiotics, especially against ESBL and CPE microorganisms, potential side effects, and clinical studies in complicated urinary tract infections (cUTI), intra-abdominal infections (cIAI), and hospital-acquired pneumonia/ventilator-associatedpneumonia (HAP/VAP). All of these new antibiotics are active against ESBL, and almost all of them are active against CPE caused by KPC beta-lactamase, but only some of them are active against CPE due to MBL or OXA beta-lactamases. At present, all of these new antibiotics are approved by the U.S. Food and Drug Administration for cUTI (except eravacycline) and most of them for cIAI (eravacycline, ceftazidime/avibactam, ceftolozane/tazobactam, and imipenem/relebactam) and for HAP or VAP (cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, and imipenem/relebactam).

Efficacy and safety of eravacycline: A meta-analysis

OBJECTIVES

This study was conducted to evaluate the efficacy and safety of eravacycline, a recently approved fluorocycline for treatment of complicated intra-abdominal infections (cIAIs).

METHODS

PubMed, EMBASE and three trial registries were searched for randomised controlled trials (RCTs) comparing the efficacy and safety of eravacycline versus comparators. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using random-effects models. The study outcomes included clinical response, all-cause mortality and adverse events (AEs).

RESULTS

Three RCTs (1128 patients) with cIAIs were included. There were no significant differences in clinical response in the modified intention-to-treat (ITT) (OR, 0.91, 95% CI 0.62-1.35; I² = 0%), microbiological ITT (OR, 0.93, 95% CI 0.61-1.41; I² = 0%) and clinically evaluable (OR, 0.98, 95% CI 0.55-1.75; I² = 0%) populations or in all-cause mortality (OR, 1.18, 95% CI 0.16-8.94; I² = 0%). Eravacycline was associated with significantly greater odds of total AEs (OR, 1.55, 95% CI 1.20-1.99; I² = 0%) and nausea (OR, 5.29, 95% CI 1.77-15.78; I² = 1.70%) but the increase in vomiting was non-significant (OR, 1.44, 95% CI 0.73-2.86; I² = 1.70%). There were no significant differences in serious AEs or discontinuation due to AEs.

CONCLUSION

This meta-analysis of RCTs found similar clinical efficacy and mortality for eravacycline compared with carbapenems for treatment of cIAIs. However, the odds of total AEs and specifically nausea was higher with eravacycline, while no significant differences were observed in vomiting (although numerically higher), serious AEs or discontinuation due to AEs.

In vitro activity of eravacycline, a novel synthetic halogenated tetracycline, against the malaria parasite Plasmodium falciparum

OBJECTIVES

Eravacycline is a novel synthetic halogenated tetracycline derivative with a broad antibacterial spectrum. Antibiotics, including tetracyclines, have been used for prophylaxis and, more rarely, for the treatment of malaria for several decades. The rise in drug-resistant malaria parasites renders the search for new treatment candidates urgent. We determined the in vitro potency of eravacycline against Plasmodium falciparum and investigated the apicoplast as a potential drug target.

METHODS

Four tetracyclines, including eravacycline, tetracycline, tigecycline, and doxycycline, and the lincosamide clindamycin, were tested in 3-day and 6-day in vitro susceptibility assays of P. falciparum laboratory strain 3D7 and/or of clinical isolates obtained from 33 P. falciparum infected individuals from Gabon in 2018. Assays with isopentenyl pyrophosphate substitution were performed to investigate whether apicoplast-encoded isoprenoid biosynthesis is inhibited by these antibiotics.

RESULTS

Eravacycline showed the highest activity of all tetracyclines tested in clinical isolates in the 3-day and 6-day assays. Substitution of isopentenyl pyrophosphate in vitro using the laboratory strain 3D7 reversed the activity of eravacycline and comparator antibiotics, indicating the apicoplast to be the main target organelle.

CONCLUSIONS

These results demonstrate the potential of novel antibiotics, and eravacycline, as candidate antimalarial therapies.

Planktonic and Biofilm Activity of Eravacycline against Staphylococci Isolated from Periprosthetic Joint Infections

MIC and minimum biofilm bactericidal concentration (MBBC) values of eravacycline against 185 staphylococci from periprosthetic joint infections were determined. Staphylococcus aureus had MICs of ≤0.25 μg/ml. MICs for methicillin-susceptible and -resistant Staphylococcus epidermidis were ≤1 and ≤2 μg/ml, respectively. S. aureus and S. epidermidis MBBC₅₀ and MBBC₉₀ values were 8 and 16 μg/ml for each, showing poor anti-staphylococcal biofilm activity using the method studied.

Antimicrobial pharmacokinetics and preclinical in vitro models to support optimized treatment approaches for uncomplicated lower urinary tract infections

INTRODUCTION

Urinary tract infections (UTIs) are extremely common. Millions of people, particularly healthy women, are affected worldwide every year. One-in-two women will have a recurrence within 12-months of an initial UTI. Inadequate treatment risks worsening infection leading to acute pyelonephritis, bacteremia and sepsis. In an era of increasing antimicrobial resistance, it is critical to provide optimized antimicrobial treatment.

AREAS COVERED

Literature was searched using PubMed and Google Scholar (up to 06/2020), examining the etiology, diagnosis and oral antimicrobial therapy for uncomplicated UTIs, with emphasis on urinary antimicrobial pharmacokinetics (PK) and the application of dynamic in vitro models for the pharmacodynamic (PD) profiling of pathogen response.

EXPERT OPINION

The majority of antimicrobial agents included in international guidelines were developed decades ago without well-described dose-response relationships. Microbiology laboratories still apply standard diagnostic methodology that has essentially remained unchanged for decades. Furthermore, it is uncertain how relevant standard in vitro susceptibility is for predicting antimicrobial efficacy in urine. In order to optimize UTI treatments, clinicians must exploit the urine-specific PK of antimicrobial agents. Dynamic in vitro models are valuable tools to examine the PK/PD and urodynamic variables associated with UTIs, while informing uropathogen susceptibility reporting, optimized dosing schedules, clinical trials and treatment guidelines.

Omadacycline: A Novel Oral and Intravenous Aminomethylcycline Antibiotic Agent

Omadacycline is a novel aminomethylcycline antibiotic developed as a once-daily, intravenous and oral treatment for acute bacterial skin and skin structure infection (ABSSSI) and community-acquired bacterial pneumonia (CABP). Omadacycline, a derivative of minocycline, has a chemical structure similar to tigecycline with an alkylaminomethyl group replacing the glycylamido group at the C-9 position of the D-ring of the tetracycline core. Similar to other tetracyclines, omadacycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. Omadacycline possesses broad-spectrum antibacterial activity against Gram-positive and Gram-negative aerobic, anaerobic, and atypical bacteria. Omadacycline remains active against bacterial isolates possessing common tetracycline resistance mechanisms such as efflux pumps (e.g., TetK) and ribosomal protection proteins (e.g., TetM) as well as in the presence of resistance mechanisms to other antibiotic classes. The pharmacokinetics of omadacycline are best described by a linear, three-compartment model following a zero-order intravenous infusion or first-order oral administration with transit compartments to account for delayed absorption. Omadacycline has a volume of distribution (V_d) ranging from 190 to 204 L, a terminal elimination half-life (t_½) of 13.5-17.1 h, total clearance (CL_T) of 8.8-10.6 L/h, and protein binding of 21.3% in healthy subjects. Oral bioavailability of omadacycline is estimated to be 34.5%. A single oral dose of 300 mg (bioequivalent to 100 mg IV) of omadacycline administered to fasted subjects achieved a maximum plasma concentration (C_max) of 0.5-0.6 mg/L and an area under the plasma concentration-time curve from 0 to infinity (AUC_0-∞) of 9.6-11.9 mg h/L. The free plasma area under concentration-time curve divided by the minimum inhibitory concentration (i.e., fAUC_24h/MIC), has been established as the pharmacodynamic parameter predictive of omadacycline antibacterial efficacy. Several animal models including neutropenic murine lung infection, thigh infection, and intraperitoneal challenge model have documented the in vivo antibacterial efficacy of omadacycline. A phase II clinical trial on complicated skin and skin structure infection (cSSSI) and three phase III clinical trials on ABSSSI and CABP demonstrated the safety and efficacy of omadacycline. The phase III trials, OASIS-1 (ABSSSI), OASIS-2 (ABSSSI), and OPTIC (CABP), established non-inferiority of omadacycline to linezolid (OASIS-1, OASIS-2) and moxifloxacin (OPTIC), respectively. Omadacycline is currently approved by the FDA for use in treatment of ABSSSI and CABP. Phase II clinical trials involving patients with acute cystitis and acute pyelonephritis are in progress. Mild, transient gastrointestinal events are the predominant adverse effects associated with use of omadacycline. Based on clinical trial data to date, the adverse effect profile of omadacycline is similar to studied comparators, linezolid and moxifloxacin. Unlike tigecycline and eravacycline, omadacycline has an oral formulation that allows for step-down therapy from the intravenous formulation, potentially facilitating earlier hospital discharge, outpatient therapy, and cost savings. Omadacycline has a potential role as part of an antimicrobial stewardship program in the treatment of patients with infections caused by antibiotic-resistant and multidrug-resistant Gram-positive [including methicillin-resistant Staphylococcus aureus (MRSA)] and Gram-negative pathogens.

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.

How to manage KPC infections

Carbapenemase-producing Enterobacteriaceae represent an increasing global threat worldwide and Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) has become one of the most important contemporary pathogens, especially in endemic areas. Risk stratification and rapid diagnostics laboratory workflows are of paramount importance and indication for therapy of KPC-KP infection must be individualized according to the baseline characteristics of the patient and severity of infection. The optimal treatment of infection because of KPC-KP organisms is uncertain and antibiotic options are limited. The knowledge of the patient's pathophysiology, infection site, and application of the pharmacokinetic/pharmacodynamic principles on the basis of minimum inhibitory concentration (MIC) has progressively gained major relevance. Combination therapies including high-dose meropenem, colistin, fosfomycin, tigecycline, and aminoglycosides are widely used, with suboptimal results. In the past few years, new antimicrobials targeting KPC-KP have been developed and are now at various stages of clinical research. However, their optimal use should be guaranteed in the long term for delaying, as much as possible, the emergence of resistance. Strict infection control measures remain necessary. The aim of this review is to discuss the challenges in the management and treatment of patients with infections because KPC-KP and provide an expert opinion.

Real-World Experience With Ceftazidime-Avibactam for Multidrug-Resistant Gram-Negative Bacterial Infections

Background

We conducted this study to describe the clinical characteristics, microbiology, and outcomes of patients treated with ceftazidime-avibactam (CZA) for a range of multidrug-resistant Gram-negative (MDR-GN) infections.

Methods

This is a multicenter, retrospective cohort study conducted at 6 medical centers in the United States between 2015 and 2019. Adult patients who received CZA (≥72 hours) were eligible. The primary outcome was clinical failure defined as a composite of 30-day all-cause mortality, 30-day microbiological failure, and/or failure to resolve or improve signs or symptoms of infection on CZA.

Results

In total, data from 203 patients were evaluated. Carbapenem-resistant Enterobacteriaceae (CRE) and Pseudomonas spp were isolated from 117 (57.6%) and 63 (31.0%) culture specimens, respectively. The most common infection sources were respiratory (37.4%), urinary (19.7%), and intra-abdominal (18.7%). Blood cultures were positive in 22 (10.8%) patients. Clinical failure, 30-day mortality, and 30-day recurrence occurred in 59 (29.1%), 35 (17.2%), and 12 (5.9%) patients, respectively. On therapy, CZA resistance developed in 1 of 62 patients with repeat testing. Primary bacteremia or respiratory tract infection and higher SOFA score were positively associated with clinical failure (adjusted odds ratio [aOR] = 2.270, 95% confidence interval [CI] = 1.115–4.620 and aOR = 1.234, 95% CI = 1.118–1.362, respectively). Receipt of CZA within 48 hours of infection onset was protective (aOR, 0.409; 95% CI, 0.180–0.930). Seventeen (8.4%) patients experienced a potential drug-related adverse effect (10 acute kidney injury, 3 Clostridioides difficile infection, 2 rash, and 1 each gastrointestinal intolerance and neutropenia)

Conclusions

Ceftazidime-avibactam is being used to treat a range of MDR-GN infections including Pseudomonas spp as well as CRE.

Carbapenemases in Enterobacteriaceae: Detection and Antimicrobial Therapy

Carbapenem-resistant Enterobacteriaceae (CRE) have spread rapidly around the world in the past few years, posing great challenges to human health. The plasmid-mediated horizontal transmission of carbapenem-resistance genes is the main cause of the surge in the prevalence of CRE. Therefore, the timely and accurate detection of CRE, especially carbapenemase-producing Enterobacteriaceae, is very important for the clinical prevention and treatment of these infections. A variety of methods for the rapid detection of CRE phenotypes and genotypes have been developed for use in clinical microbiology laboratories. To overcome the lack of efficient antibiotics, CRE infections are often treated with combination therapies. Moreover, novel drugs and emerging strategies appeared successively and in various stages of development. In this article, we summarized the global distribution of various carbapenemases. And we focused on summarizing and comparing the advantages and limitations of the detection methods and the therapeutic strategies of CRE primarily.