Analysis of the Clinical Pipeline of Treatments for Drug-Resistant Bacterial Infections: Despite Progress, More Action Is Needed.

There is an urgent global need for new strategies and drugs to control and treat multidrug-resistant bacterial infections. In 2017, the World Health Organization (WHO) released a list of 12 antibiotic-resistant priority pathogens and began to critically analyze the antibacterial clinical pipeline. This review analyzes "traditional" and "nontraditional" antibacterial agents and modulators in clinical development current on 30 June 2021 with activity against the WHO priority pathogens mycobacteria and Clostridioides difficile. Since 2017, 12 new antibacterial drugs have been approved globally, but only vaborbactam belongs to a new antibacterial class. Also innovative is the cephalosporin derivative cefiderocol, which incorporates an iron-chelating siderophore that facilitates Gram-negative bacteria cell entry. Overall, there were 76 antibacterial agents in clinical development (45 traditional and 31 nontraditional), with 28 in phase 1, 32 in phase 2, 12 in phase 3, and 4 under regulatory evaluation. Forty-one out of 76 (54%) targeted WHO priority pathogens, 16 (21%) were against mycobacteria, 15 (20%) were against C. difficile, and 4 (5%) were nontraditional agents with broad-spectrum effects. Nineteen of the 76 antibacterial agents have new pharmacophores, and 4 of these have new modes of actions not previously exploited by marketed antibacterial drugs. Despite there being 76 antibacterial clinical candidates, this analysis indicated that there were still relatively few clinically differentiated antibacterial agents in late-stage clinical development, especially against critical-priority pathogens. We believe that future antibacterial research and development (R&D) should focus on the development of innovative and clinically differentiated candidates that have clear and feasible progression pathways to the market.

Surfactant-free purification of membrane protein complexes from bacteria: application to the staphylococcal penicillin-binding protein complex PBP2/PBP2a.

Surfactant-mediated removal of proteins from biomembranes invariably results in partial or complete loss of function and disassembly of multi-protein complexes. We determined the capacity of styrene-co-maleic acid (SMA) co-polymer to remove components of the cell division machinery from the membrane of drug-resistant staphylococcal cells. SMA-lipid nanoparticles solubilized FtsZ-PBP2-PBP2a complexes from intact cells, demonstrating the close physical proximity of these proteins within the lipid bilayer. Exposure of bacteria to (-)-epicatechin gallate, a polyphenolic agent that abolishes ß-lactam resistance in staphylococci, disrupted the association between PBP2 and PBP2a. Thus, SMA purification provides a means to remove native integral membrane protein assemblages with minimal physical disruption and shows promise as a tool for the interrogation of molecular aspects of bacterial membrane protein structure and function.

WHO's essential medicines and AWaRe: recommendations on first- and second-choice antibiotics for empiric treatment of clinical infections.

The WHO Model List of Essential Medicines (EML) prioritizes medicines that have significant global public health value. The EML can also deliver important messages on appropriate medicine use. Since 2017, in response to the growing challenge of antimicrobial resistance, antibiotics on the EML have been reviewed and categorized into three groups: Access, Watch, and Reserve, leading to a new categorization called AWaRe. These categories were developed taking into account the impact of different antibiotics and classes on antimicrobial resistance and the implications for their appropriate use. The 2023 AWaRe classification provides empirical guidance on 41 essential antibiotics for over 30 clinical infections targeting both the primary health care and hospital facility setting. A further 257 antibiotics not included on the EML have been allocated an AWaRe group for stewardship and monitoring purposes. This article describes the development of AWaRe, focussing on the clinical evidence base that guided the selection of Access, Watch, or Reserve antibiotics as first and second choices for each infection. The overarching objective was to offer a tool for optimizing the quality of global antibiotic prescribing and reduce inappropriate use by encouraging the use of Access antibiotics (or no antibiotics) where appropriate. This clinical evidence evaluation and subsequent EML recommendations are the basis for the AWaRe antibiotic book and related smartphone applications. By providing guidance on antibiotic prioritization, AWaRe aims to facilitate the revision of national lists of essential medicines, update national prescribing guidelines, and supervise antibiotic use. Adherence to AWaRe would extend the effectiveness of current antibiotics while helping countries expand access to these life-saving medicines for the benefit of current and future patients, health professionals, and the environment.

Anti-staphylococcal activity and ß-lactam resistance attenuating capacity of structural analogues of (-)-epicatechin gallate.

We examined the impact of gradual removal of hydroxyl groups from the A- and B-rings of (-)-epicatechin gallate on antibacterial activity and oxacillin resistance attenuation of an epidemic strain of methicillin resistant Staphylococcus aureus. Removal of both hydroxyls from the B-ring effected a large reduction in oxacillin MIC (from 512 to 0.25 mg/mL at a concentration of 12.5 mg/L); further hydroxyl deletion of the A-ring reduced the oxacillin effect but increased intrinsic anti-staphylococcal activity.

Reimbursement models to tackle market failures for antimicrobials: Approaches taken in France, Germany, Sweden, the United Kingdom, and the United States.

INTRODUCTION: The pipeline of new antibacterials remains limited. Reasons include low research investments, limited commercial prospects, and scientific challenges. To complement existing initiatives such as research grants, governments are exploring policy options for providing new market incentives to drug developers. MATERIALS AND METHODS: Reimbursement interventions for antibacterials in France, Germany, Sweden, US, and UK were reviewed and analysed by the authors. RESULTS: In France, Germany, and the US, implemented interventions centre on providing exceptions in cost-containment mechanisms to allow higher prices for certain antibacterials. In the US, also, certain antibacterials are granted additional years of protection from generic competition (exclusivity) and faster regulatory review. The UK is piloting a model that will negotiate contracts with manufacturers to pay a fixed annual fee for ongoing supply of as many units as needed. Sweden is piloting a model that will offer manufacturers of selected antibacterials contracts that would guarantee a minimum annual revenue. A similar model of guaranteed minimal annual revenues is under consideration in the US (PASTEUR Act). CONCLUSIONS: The UK and Sweden are piloting entirely novel procurement and reimbursement models. Existing interventions in the US, France, and Germany represent important, but relatively minor interventions. More countries should explore the use of novel models and international coordination will be important for 'pull' incentives to be effective. If adopted, the PASTEUR legislation in the US would constitute a significant 'pull' incentive.

A novel pre-clinical antibacterial pipeline database.

The clinical pipeline continues to be insufficient to contain antimicrobial resistance, and further investment and research is needed to ensure that a robust pipeline is built to treat the WHO priority pathogens list of antibiotic-resistant bacteria. To shed light further upstream on the preclinical pipeline the WHO has undertaken a review of the antibacterial preclinical pipeline and published the data of all identified projects in a publicly accessible database. The database captures 252 unique antibacterial agents in preclinical development being developed by 145 individual institutions, of which the majority are smaller biotech companies and academic institutions. There is a higher degree of innovation in the preclinical pipeline with a significant number of non-traditional approaches being pursued. For even a fraction of these projects to reach clinical development or the market, there is a need to shift the market dynamics for new antibacterials through the identification of new solutions beyond push and pull incentives.

Feasibility Study of the World Health Organization Health Care Facility-Based Antimicrobial Stewardship Toolkit for Low- and Middle-Income Countries.

Antimicrobial stewardship (AMS) has emerged as a systematic approach to optimize antimicrobial use and reduce antimicrobial resistance. To support the implementation of AMS programs, the World Health Organization developed a draft toolkit for health care facility AMS programs in low- and middle-income countries. A feasibility study was conducted in Bhutan, the Federated States of Micronesia, Malawi, and Nepal to obtain local input on toolkit content and implementation of AMS programs. This descriptive qualitative study included semi-structured interviews with national- and facility-level stakeholders. Respondents identified AMS as a priority and perceived the draft toolkit as a much-needed document to further AMS program implementation. Facilitators for implementing AMS included strong national and facility leadership and clinical staff engagement. Barriers included lack of human and financial resources, inadequate regulations for prescription antibiotic sales, and insufficient AMS training. Action items for AMS implementation included improved laboratory surveillance, establishment of a stepwise approach for implementation, and mechanisms for reporting and feedback. Recommendations to improve the AMS toolkit's content included additional guidance on defining the responsibilities of the committees and how to prioritize AMS programming based on local context. The AMS toolkit was perceived to be an important asset as countries and health care facilities move forward to implement AMS programs.

Analysis of the clinical antibacterial and antituberculosis pipeline.

This analysis of the global clinical antibacterial pipeline was done in support of the Global Action Plan on Antimicrobial Resistance. The study analysed to what extent antibacterial and antimycobacterial drugs for systemic human use as well as oral non-systemic antibacterial drugs for Clostridium difficile infections were active against pathogens included in the WHO priority pathogen list and their innovativeness measured by their absence of cross-resistance (new class, target, mode of action). As of July 1, 2018, 30 new chemical entity (NCE) antibacterial drugs, ten biologics, ten NCEs against Mycobacterium tuberculosis, and four NCEs against C difficile were identified. Of the 30 NCEs, 11 are expected to have some activity against at least one critical priority pathogen expressing carbapenem resistance. The clinical pipeline is dominated by derivatives of established classes and most development candidates display limited innovation. New antibacterial drugs without pre-existing cross-resistance are under-represented and are urgently needed, especially for geographical regions with high resistance rates among Gram-negative bacteria and M tuberculosis.

Antimicrobial resistance and universal health coverage.

The WHO launched a Global Action Plan on antimicrobial resistance (AMR) in 2015. World leaders in the G7, G20 and the UN General Assembly have declared AMR to be a global crisis. World leaders have also adopted universal health coverage (UHC) as a key target under the sustainable development goals. This paper argues that neither initiative is likely to succeed in isolation from the other and that the policy goals should be to both provide access to appropriate antimicrobial treatment and reduce the risk of the emergence and spread of resistance by taking a systems approach. It focuses on outpatient treatment of human infections and identifies a number of interventions that would be needed to achieve these policy goals. It then shows how a strategy for achieving key attributes of a health system for UHC can take into account the need to address AMR as part of a UHC strategy in any country. It concludes with a list of recommended priority actions for integrating initiatives on AMR and UHC.