In vitro activity of omadacycline against pathogens isolated from Mainland China during 2017-2018

A Review of Omadacycline for Potential Utility in the Military Health System for the Treatment of Wound Infections

INTRODUCTION

Combat-related wound infections complicate the recovery of wounded military personnel, contributing to overall morbidity and mortality. Wound infections in combat settings present unique challenges because of the size and depth of the wounds, the need to administer emergency care in the field, and the need for subsequent treatment in military facilities. Given the increase in multidrug-resistant pathogens, a novel, broad-spectrum antibiotic is desired across this continuum of care when the standard of care fails. Omadacycline was FDA-approved in 2018 for treatment of adults with acute bacterial skin and skin structure infections (ABSSSI), as well as community-acquired bacterial pneumonia (CABP). It is a broad-spectrum antibiotic with activity against gram-positive, gram-negative, and atypical bacterial pathogens, including multidrug-resistant species. Omadacycline can overcome commonly reported tetracycline resistance mechanisms, ribosomal protection proteins, and efflux pumps, and is available in once-daily intravenous or oral formulations. In this review, we discuss the potential role of omadacycline, which is included in the Department of Defense Formulary, in the context of combat wound infections.

MATERIALS AND METHODS

A literature review was undertaken for manuscripts published before July 21, 2023. This included a series of publications found via PubMed and a bibliography made publicly available on the Paratek Pharmaceuticals, Inc. website. Publications presenting primary data published in English on omadacycline in relation to ESKAPEE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter species) pathogens and Clostridioides difficile, including in vitro, in vivo, and clinical data were included.

RESULTS

Of 260 identified records, 66 were included for evidence review. Omadacycline has in vitro activity against almost all the ESKAPEE pathogens, apart from P. aeruginosa. Importantly, it has activity against the four most prevalent bacterial pathogens that cause wound infections in the military healthcare system: S. aureus, including methicillin-resistant S. aureus, A. baumannii, K. pneumoniae, and E. coli. In vivo studies in rats have shown that omadacycline is rapidly distributed in most tissues, with the highest tissue-to-blood concentration ratios in bone mineral. The clinical efficacy of omadacycline has been assessed in three separate Phase 3 studies in patients with ABSSSI (OASIS-1 and OASIS-2) and with CABP (OPTIC). Overall, omadacycline has an established safety profile in the treatment of both ABSSSI and CABP.

CONCLUSIONS

Omadacycline has broad-spectrum activity, the option to be orally administered and an established safety profile, making it a potentially attractive replacement for moxifloxacin in the military individual first aid kit, especially when accounting for the increasing resistance to fluoroquinolones. Further studies and clinical evaluation are warranted to support broader use of omadacycline to treat combat wound infections in the military healthcare system.

Evaluation of omadacycline dosing regimens in Chinese using population pharmacokinetic-pharmacodynamic analysis

PURPOSE

Omadacycline (PTK-0796) is a first-in-class aminomethylcycline for adult patients with community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible pathogens. We investigated the pharmacokinetic (PK) and pharmacodynamic (PD) profile of omadacycline, considering the impact of covariates, particularly ethnicity, on PK and determined the PK/PD cutoff values for dosing regimens.

METHODS

Utilizing nonlinear mixed-effects modeling, we pooled data from 11 clinical trials for PopPK analysis. The first-order conditional estimation with interaction (FOCEI) method in NONMEM facilitated model parameter estimation. Employing a stepwise model selection strategy, with forward addition (P < 0.01) and backward deletion (P < 0.001), we assessed the potential impacts of covariates on omadacycline PK, including baseline age, body weight, sex, race, body mass index, body surface area, baseline albumin, creatine clearance, and formulation. After validating the model through various methods, the final PopPK model underwent Monte Carlo simulations to generate the PK profile for the Chinese population. This enabled AUC calculation and assessment of the probability of target attainment (PTA) and the cumulative fraction of response (CFR) for various dosing regimens and bacterial strains.

RESULTS

Omadacycline's PK can be adequately characterized by a three-compartment model. Body weight, sex, race, and drug formulation statistically influenced its PK. Asians and non-Asians exhibit similar exposure after intravenous infusion, but oral dosing results in much higher exposures than in non-Asians. Monte Carlo simulation indicates that IV-only or IV/PO sequential therapy regimens provide adequate attainment for all major pathogens causing ABSSSI and CABP. PK/PD cutoffs were generally above the MIC90 value of recent clinical isolates from China.

CONCLUSIONS

In conclusion, the approved regimen for China achieved adequate target attainment for all pathogens typically associated with these infections. The higher oral exposure observed in Asians may enhance efficacy without affecting safety or tolerability.

How to treat severe Acinetobacter baumannii infections

PURPOSE OF REVIEW

To update the management of severe Acinetobacter baumannii infections (ABI), particularly those caused by multi-resistant isolates.

RECENT FINDINGS

The in vitro activity of the various antimicrobial agents potentially helpful in treating ABI is highly variable and has progressively decreased for many of them, limiting current therapeutic options. The combination of more than one drug is still advisable in most circumstances. Ideally, two active first-line drugs should be used. Alternatively, a first-line and a second-line drug and, if this is not possible, two or more second-line drugs in combination. The emergence of new agents such as Cefiderocol, the combination of Sulbactam and Durlobactam, and the new Tetracyclines offer therapeutic options that need to be supported by clinical evidence.

SUMMARY

The apparent limitations in treating infections caused by this bacterium, the rapid development of resistance, and the serious underlying situation in most cases invite the search for alternatives to antibiotic treatment, the most promising of which seems to be bacteriophage therapy.

Combatting resistance: Understanding multi-drug resistant pathogens in intensive care units

The escalating misuse and excessive utilization of antibiotics have led to the widespread dissemination of drug-resistant bacteria, posing a significant global healthcare crisis. Of particular concern is the increasing prevalence of multi-drug resistant (MDR) opportunistic pathogens in Intensive Care Units (ICUs), which presents a severe threat to public health and contributes to substantial morbidity and mortality. Among them, MDR ESKAPE pathogens account for the vast majority of these opportunistic pathogens. This comprehensive review provides a meticulous analysis of the current prevalence landscape of MDR opportunistic pathogens in ICUs, especially in ESKAPE pathogens, illuminating their resistance mechanisms against commonly employed first-line antibiotics, including polymyxins, carbapenems, and tigecycline. Furthermore, this review explores innovative strategies aimed at preventing and controlling the emergence and spread of resistance. By emphasizing the urgent need for robust measures to combat nosocomial infections caused by MDR opportunistic pathogens in ICUs, this study serves as an invaluable reference for future investigations in the field of antibiotic resistance.

Omadacycline for treatment of acute bacterial infections: a meta-analysis of phase II/III trials

OBJECTIVE

This study aims to assess the clinical efficacy and safety of omadacycline for the treatment of acute bacterial infections.

METHODS

A search of PubMed, Embase, Cochrane Library, and Clinical Trials was conducted up to July 1, 2022. We included only randomized controlled trials (RCTs), in which omadacycline and other antibiotics were evaluated for treating acute bacterial infections in adults. The primary outcomes were clinical response and microbiological response, whereas the secondary outcome was the risk of adverse events (AEs).

RESULTS

A total of seven RCTs involving 2841 patients with acute bacterial infection were included. Overall, our study illustrated that the clinical cure ratio of omadacycline was similar to the comparators in the treatment of acute bacterial infections (OR = 1.18, 95%CI = 0.96, 1.46, I² = 29%). Omadacycline had a microbiological eradication rate similar to comparators in the treatment of acute bacterial infections (OR = 1.02, 95%CI = 0.81, 1.29, I² = 42%). No statistical differences were observed between omadacycline and the comparators in terms of infection caused by Staphylococcus aureus (OR = 1.14, 95%CI = 0.80, 1.63, I² = 0%), methicillin-resistant S. aureus (MRSA, OR = 1.28, 95%CI = 0.73, 2.24, I² = 0%), methicillin-susceptible S. aureus (MSSA, OR = 1.12, 95%CI = 0.69, 1.81, I² = 0%), and Enterococcus faecalis (OR = 2.47, 95%CI = 0.36, 16.97, I² = 7%). A significant difference was found between omadacycline and the comparators for the risk of any AEs and treatment related AEs. The risk of discontinuation of the study drug due to an AEs was lower for omadacycline than for the comparators.

CONCLUSION

Omadacycline is as good as comparators in terms of efficacy and tolerance in the treatment of acute bacterial infections in adult patients. Thus, omadacycline is an appropriate option for antibiotic therapy in adult patients with acute bacterial infections.

In vitro activity of lactone ketolide nafithromycin (WCK 4873) against Streptococcus pneumoniae isolates enriched with macrolide-resistance phenotype collected from mainland China

Background

Widespread MDR Streptococcus pneumoniae in China translates clinically into a substantial pneumococcal disease burden and related morbidity and mortality, particularly in the elderly and children. Nafithromycin (WCK 4873), a novel lactone ketolide class of antibiotic designed with a 3 day, once-daily regimen is highly active against resistant pneumococci and other community respiratory pathogens. It is currently in clinical development for the treatment of community-acquired bacterial pneumonia (CABP).

Objectives

To determine the in vitro activity of nafithromycin against clinical S. pneumoniae isolates collected during 2015–21 from three hospitals in mainland China.

Methods

A total of 920 clinical isolates (one isolate per patient), which predominantly with the macrolide- and clindamycin-resistant phenotype were included in this study. The MICs of nafithromycin and other antibiotics tested were determined using the reference broth microdilution method.

Results

Clinical S. pneumoniae isolates used in this study showed high macrolide and clindamycin resistance (>95% against erythromycin and azithromycin and 80% against clindamycin) for which nafithromycin showed potent activity (MIC_50/90; 0.03/0.06 mg/L) with 100% susceptibility at a proposed pharmacokinetics/pharmacodynamics (PK/PD) breakpoint of 0.25 mg/L. Among other classes of antibiotics tested, moxifloxacin also showed good activity while amoxicillin/clavulanate and ceftriaxone showed lower susceptibility.

Conclusions

Nafithromycin exhibited therapeutically relevant in vitro antibacterial activity against contemporary highly resistant pneumococci collected from mainland China. This study supports the clinical development of nafithromycin for the management of CABP caused by pneumococci in China.

In-vitro activity of plazomicin, meropenem-vaborbactam, and omadacycline against carbapenem-resistant Gram-negative isolates in Egypt

Anti-microbial resistance is an escalating worldwide threat. Thus, there is an utmost necessity for the introduction of novel anti-microbial agents. This research aimed to evaluate the in-vitro activity of plazomicin, meropenem-vaborbactam, and omadacycline against carbapenem-resistant Gram-negative isolates gathered from one Egyptian University group of Hospitals. 210 intensive care units (ICU) and 113 non-ICU samples were included. Resistance to carbapenems was reported in 37.5% and 21.05% of the isolated Gram-negative ICU and non-ICU organisms respectively (P < 0.001). Via disc diffusion, the sensitivity rates for carbapenem-resistant non-ICU and ICU strains were 68.8% & 64.4% for plazomicin, 68.8% & 48.9% for meropenem-vaborbactam, and 56.25% & 44.5% for omadacycline, respectively. Regarding MIC₅₀/_90, it was 1/16 μg/mL for plazomicin and 4/32 μg/mL for both meropenem-vaborbactam and omadacycline separately. In conclusion, plazomicin displayed potent activity against carbapenem-resistant strains. Moreover, meropenem-vaborbactam and omadacycline demonstrated satisfactory results.

Pharmacokinetics, Safety and Pharmacokinetics/Pharmacodynamics Analysis of Omadacycline in Chinese Healthy Subjects

Objective: Omadacycline is a new type of aminomethylcycline antibiotic, having a broad antibacterial spectrum. But the pharmacokinetic characteristics and safety profile of the Chinese population remain unknown. It is also unclear whether the US-approved treatment regimen is applicable for the Chinese population.

Methods: In a randomized, double-blinded, placebo-controlled dose-escalated trial, the pharmacokinetics of omadacycline was evaluated by a non-compartmental and compartmental model. Monte Carlo simulations were performed using the pharmacokinetic data from the Chinese population to evaluate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of the US FDA-approved dose regimen.

Results: The three-compartment model successfully described the rapid distribution and slow elimination of omadacycline after the intravenous infusion (i.v.). The double-peak concentration-time curve of the oral absorption (p.o.) was explained by the two-compartment model with two absorption compartments. The steady-state AUC of 100 mg omadacycline i.v. and 300 mg omadacycline p. o. were 12.1 and 19.4 mg h/L, respectively. Pharmacokinetics/pharmacodynamics (PK/PD) analysis showed that the omadacycline dosing regimen with a loading dose (200 mg i.v. q24 h, 100 mg i.v. q12 h, 450 mg p. o. q24 h × 2 days or 300 mg p. o. q12 h) and maintenance dose (100 mg i.v. q24 h or 300 mg p. o. q24 h) could cover the main pathogens of the indications acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP): Staphylococcus aureus and Streptococcus pneumoniae. Also, omadacycline had showed a good safety profile in the Chinese population.

Conclusions: With the evidence provided, omadacycline could be a novel treatment option to Chinese patients with ABSSSI and CABP.

Infectious Diseases Society of America 2022 Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa)

BACKGROUND

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant infections. The initial guidance document on infections caused by extended-spectrum β-lactamase producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa) was published on 17 September 2020. Over the past year, there have been a number of important publications furthering our understanding of the management of ESBL-E, CRE, and DTR-P. aeruginosa infections, prompting a rereview of the literature and this updated guidance document.

METHODS

A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections reviewed, updated, and expanded previously developed questions and recommendations about the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Because of differences in the epidemiology of resistance and availability of specific anti-infectives internationally, this document focuses on the treatment of infections in the United States.

RESULTS

Preferred and alternative treatment recommendations are provided with accompanying rationales, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, duration of therapy, and other management considerations are also discussed briefly. Recommendations apply for both adult and pediatric populations.

CONCLUSIONS

The field of antimicrobial resistance is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of antimicrobial-resistant infections. This document is current as of 24 October 2021. The most current versions of IDSA documents, including dates of publication, are available at www.idsociety.org/practice-guideline/amr-guidance/.

Infectious Diseases Society of America Guidance on the Treatment of AmpC β-lactamase-Producing Enterobacterales, Carbapenem-Resistant Acinetobacter baumannii, and Stenotrophomonas maltophilia Infections

BACKGROUND

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant infections. A previous guidance document focused on infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa). Here, guidance is provided for treating AmpC β-lactamase-producing Enterobacterales (AmpC-E), carbapenem-resistant Acinetobacter baumannii (CRAB), and Stenotrophomonas maltophilia infections.

METHODS

A panel of six infectious diseases specialists with expertise in managing antimicrobial-resistant infections formulated questions about the treatment of AmpC-E, CRAB, and S. maltophilia infections. Answers are presented as suggestions and corresponding rationales. In contrast to guidance in the previous document, published data on optimal treatment of AmpC-E, CRAB, and S. maltophilia infections are limited. As such, guidance in this document is provided as "suggested approaches" based on clinical experience, expert opinion, and a review of the available literature. Because of differences in the epidemiology of resistance and availability of specific anti-infectives internationally, this document focuses on the treatment of infections in the United States.

RESULTS

Preferred and alternative treatment suggestions are provided, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, duration of therapy, and other management considerations are also discussed briefly. Suggestions apply for both adult and pediatric populations.

CONCLUSIONS

The field of antimicrobial resistance is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of antimicrobial-resistant infections. This document is current as of September 17, 2021 and will be updated annually. The most current versions of IDSA documents, including dates of publication, are available at www.idsociety.org/practice-guideline/amr-guidance-2.0/.