Antibiotics in the pipeline: a literature review (2017-2020)

Cubosome lipid nanocarriers for delivery of ultra-short antimicrobial peptides

HYPOTHESIS

Although antimicrobial peptides (AMPs) are a promising class of new antibiotics, their inherent susceptibility to degradation requires nanocarrier-mediated delivery. While cubosome nanocarriers have been extensively studied for delivery of AMPs, we do not currently understand why cubosome encapsulation improves antimicrobial efficacy for some compounds but not others. This study therefore aims to investigate the link between the mechanism of action and permeation efficiency of the peptides, their encapsulation efficacy, and the antimicrobial activity of these systems.

EXPERIMENTS

Encapsulation and delivery of Indolicidin, and its ultra-short derivative, Priscilicidin, were investigated using SAXS, cryo-TEM and circular dichroism. Molecular dynamics simulations were used to understand the loading of these peptides within cubosomes. The antimicrobial efficacy was assessed against gram-negative (E. coli) and gram-positive (MRSA) bacteria.

FINDINGS

A high ionic strength solution was required to facilitate high loading of the cationic AMPs, with bilayer encapsulation driven by tryptophan and Fmoc moieties. Cubosome encapsulation did not improve the antimicrobial efficacy of the AMPs consistent with their high permeation, as explained by a recent 'diffusion to capture model'. This suggests that cubosome encapsulation may not be an effective strategy for all antimicrobial compounds, paving the way for improved selection of nanocarriers for AMPs, and other antimicrobial compounds.

An overview of sulbactam-durlobactam approval and implications in advancing therapeutics for hospital-acquired and ventilator-associated pneumonia by acinetobacter baumannii-calcoaceticus complex: A narrative review

Purpose

Infections caused by Acinetobacter baumannii, particularly those resistant to antibiotics such as carbapenem, have become a global health crisis with a significant mortality rate. Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) resulting from the A. baumannii-calcoaceticus (ABC) complex represent a major clinical challenge. This review aimed to understand the approval process, mechanism of action, therapeutic potential, and future implications of sulbactam-durlobactam therapy (SUL-DUR).

Methods

PubMed, Web of Science, EMBASE, Clinical trials. gov, ICTRP, and CENTRAL were searched for studies on SUL-DUR for the treatment of hospital-acquired pneumonia and ventilator-associated pneumonia. Also, World Health Organization, U.S. Food and Drug Administration, and Centers for Disease Control and Prevention websites were searched for relevant information.

Results

SUL-DUR, marketed as Xacduro, is a novel pharmaceutical combination that functions as a narrow-spectrum parenterally administered antibiotic. Sulbactam acts as a β-lactamase inhibitor, whereas durlobactam protects against degradation by A. baumannii enzymes. A phase 1 trial successfully established the safety and tolerability of SUL-DUR in patients with normal and mild renal impairment. A phase 2 trial demonstrated the safety and tolerability of SUL-DUR in a larger population with urinary tract infections. A phase 3 trial showed that SUL-DUR was non-inferior to colistin in terms of mortality in A. baumannii-related VAP, HAP, and bacteremia.

Conclusion

The combination of sulbactam and durlobactam is a promising treatment option for HAP and VAP caused by ABC complex.

Cannabinoids in Integumentary Wound Care: A Systematic Review of Emerging Preclinical and Clinical Evidence

This systematic review critically evaluates preclinical and clinical data on the antibacterial and wound healing properties of cannabinoids in integument wounds. Comprehensive searches were conducted across multiple databases, including CINAHL, Cochrane library, Medline, Embase, PubMed, Web of Science, and LILACS, encompassing records up to May 22, 2024. Eighteen studies met the inclusion criteria. Eleven were animal studies, predominantly utilizing murine models (n = 10) and one equine model, involving 437 animals. The seven human studies ranged from case reports to randomized controlled trials, encompassing 92 participants aged six months to ninety years, with sample sizes varying from 1 to 69 patients. The studies examined the effects of various cannabinoid formulations, including combinations with other plant extracts, crude extracts, and purified and synthetic cannabis-based medications administered topically, intraperitoneally, orally, or sublingually. Four animal and three human studies reported complete wound closure. Hemp fruit oil extract, cannabidiol (CBD), and GP1a resulted in complete wound closure in twenty-three (range: 5-84) days with a healing rate of 66-86% within ten days in animal studies. One human study documented a wound healing rate of 3.3 cm2 over 30 days, while three studies on chronic, non-healing wounds reported an average healing time of 54 (21-150) days for 17 patients by oral oils with tetrahydrocannabinol (THC) and CBD and topical gels with THC, CBD, and terpenes. CBD and tetrahydrocannabidiol demonstrated significant potential in reducing bacterial loads in murine models. However, further high-quality research is imperative to fully elucidate the therapeutic potential of cannabinoids in the treatment of bacterial skin infections and wounds. Additionally, it is crucial to delineate the impact of medicinal cannabis on the various phases of wound healing. This study was registered in PROSPERO (CRD42021255413).

Non-Canonical Aspects of Antibiotics and Antibiotic Resistance

The understanding of antibiotic resistance, one of the major health threats of our time, is mostly based on dated and incomplete notions, especially in clinical contexts. The "canonical" mechanisms of action and pharmacodynamics of antibiotics, as well as the methods used to assess their activity upon bacteria, have not changed in decades; the same applies to the definition, acquisition, selective pressures, and drivers of resistance. As a consequence, the strategies to improve antibiotic usage and overcome resistance have ultimately failed. This review gathers most of the "non-canonical" notions on antibiotics and resistance: from the alternative mechanisms of action of antibiotics and the limitations of susceptibility testing to the wide variety of selective pressures, lateral gene transfer mechanisms, ubiquity, and societal factors maintaining resistance. Only by having a "big picture" view of the problem can adequate strategies to harness resistance be devised. These strategies must be global, addressing the many aspects that drive the increasing prevalence of resistant bacteria aside from the clinical use of antibiotics.

Combining machine learning with high-content imaging to infer ciprofloxacin susceptibility in isolates of Salmonella Typhimurium

Antimicrobial resistance (AMR) is a growing public health crisis that requires innovative solutions. Current susceptibility testing approaches limit our ability to rapidly distinguish between antimicrobial-susceptible and -resistant organisms. Salmonella Typhimurium (S. Typhimurium) is an enteric pathogen responsible for severe gastrointestinal illness and invasive disease. Despite widespread resistance, ciprofloxacin remains a common treatment for Salmonella infections, particularly in lower-resource settings, where the drug is given empirically. Here, we exploit high-content imaging to generate deep phenotyping of S. Typhimurium isolates longitudinally exposed to increasing concentrations of ciprofloxacin. We apply machine learning algorithms to the imaging data and demonstrate that individual isolates display distinct growth and morphological characteristics that cluster by time point and susceptibility to ciprofloxacin, which occur independently of ciprofloxacin exposure. Using a further set of S. Typhimurium clinical isolates, we find that machine learning classifiers can accurately predict ciprofloxacin susceptibility without exposure to it or any prior knowledge of resistance phenotype. These results demonstrate the principle of using high-content imaging with machine learning algorithms to predict drug susceptibility of clinical bacterial isolates. This technique may be an important tool in understanding the morphological impact of antimicrobials on the bacterial cell to identify drugs with new modes of action.

New insides into chimeric and hybrid azines derivatives with antifungal activity

During the last decades, five or six member rings azaheterocycles compounds appear to be an extremely valuable source of antifungal agents. Their use seems to be a very attractive solution in antifungal therapy and to overcome antifungal resistance in agriculture. The present review highlights the main results obtained in the field of hybrid and chimeric azine (especially pyridine, quinoline, phenanthroline, bypyridine, naphthyridine and their fused derivatives) derivatives presented in scientific literature from the last 10 years, with emphasis on antifungal activity of the mentioned compounds. A special attention was played to hybrid and chimeric azole-azine class, having in view the high antifungal potential of azoles.

Development and Evaluation of a Novel Antibacterial Wound Dressing: A Powder Preparation Based on Cross-Linked Pullulan with Polyhexamethylene Biguanide for Hydrogel-Transition in Advanced Wound Management and Infection Control

As antibiotic resistance increasingly undermines traditional infection management strategies, there is a critical demand for innovative wound care solutions that address these emerging challenges. This study introduces a novel antibacterial wound dressing based on Cross-Linked Pullulan (Pul) and Polyhexamethylene Biguanide (PHMB) for enhanced wound management and infection control. The dressing's adsorption rate reached 200% of its original weight within 30 min, exceeded 300% after 5 h, and exhibited significant non-Newtonian fluid properties. The dressings were able to release the loaded medication completely within 20 min; additionally, the dressing demonstrated significant antibacterial activity against a broad spectrum of bacteria. Significantly, the therapeutic effects of the Pul-PHMB/GP dressing were evaluated in a mouse model. Compared to untreated wounds, wounds treated with Pul-PHMB/GP exhibited a significant gelation process within 5 min post-treatment and showed a significant increase in wound healing rate within 12 days. This powder preparation overcomes the limitations associated with liquid and gel dressings, notably in storage and precise application, preventing the premature expansion or dissolution often caused by PHMB in high-humidity environments. The powder form can transform into a gel upon contact with wound exudate, ensuring accurate coverage of irregular wounds, such as those from burns or pressure sores, and offers excellent chemical and physical stability in a dry state, which facilitates storage and transport. This makes the dressing particularly suitable for emergency medical care and precision therapy, significantly improving the efficiency and adaptability of wound treatment and providing robust support for clinical treatments and emergency responses.

Community-acquired pneumonia: a US perspective on the guideline gap

Community-acquired pneumonia continues to be one of the most common causes of morbidity and mortality due to infectious disease. The aetiologies, clinical presentations, diagnostic modalities and therapeutic options are changing and outpacing the creation of management guidelines. This educational article summarizes a roundtable activity sponsored by an unrestricted educational grant by Paratek that included US experts discussing these changes and identifying gaps in the current guidelines.

Occurrence, bioaccumulation, fate, and risk assessment of emerging pollutants in aquatic environments: A review

Significant concerns on a global scale have been raised in response to the potential adverse impacts of emerging pollutants (EPs) on aquatic creatures. We have carefully reviewed relevant research over the past 10 years. The study focuses on five typical EPs: pharmaceuticals and personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), drinking water disinfection byproducts (DBPs), brominated flame retardants (BFRs), and microplastics (MPs). The presence of EPs in the global aquatic environment is source-dependent, with wastewater treatment plants being the main source of EPs. Multiple studies have consistently shown that the final destination of most EPs in the water environment is sludge and sediment. Simultaneously, a number of EPs, such as PFASs, MPs, and BFRs, have long-term environmental transport potential. Some EPs exhibit notable tendencies towards bioaccumulation and biomagnification, while others pose challenges in terms of their degradation within both biological and abiotic treatment processes. The results showed that, in most cases, the ecological risk of EPs in aquatic environments was low, possibly due to potential dilution and degradation. Future research topics should include adding EPs detection items for the aquatic environment, combining pollution, and updating prediction models.

NhaA: A promising adjuvant target for colistin against resistant Escherichia coli

The emergence and widespread of multidrug-resistant Gram-negative bacteria have posed a severe threat to human health and environmental safety, escalating into a global medical crisis. Utilization of antibiotic adjuvants is a rapid approach to combat bacterial resistance effectively since the development of new antimicrobial agents is a formidable challenge. NhaA, driven by proton motive force, is a crucial secondary transporter on the cytoplasmic membrane of Escherichia coli. We found that 2-Aminoperimidine (2-AP), which is a specific inhibitor of NhaA, could enhance the activity of colistin against sensitive E. coli and reverse the resistance in mcr-1 positive E. coli. Mechanistic studies indicated that 2-AP induced dysfunction in cytoplasmic membrane through the suppression of NhaA, leading to metabolic inhibition and ultimately enhancing the sensitivity of E. coli to colistin. Moreover, 2-AP restored the efficacy of colistin against resistant E. coli in two animal infection models. Our findings reveal the potential of NhaA as a novel target for colistin adjuvants, providing new possibilities for the clinical application of colistin.

Structure-Activity Relationship Study to Develop Peptide Amphiphiles as Species-Specific Antimicrobials

Antimicrobial peptide amphiphiles (PAs) are a promising class of molecules that can disrupt the bacterial membrane or act as drug nanocarriers. In this study, we prepared 33 PAs to establish supramolecular structure-activity relationships. We studied the morphology and activity of the nanostructures against different Gram-positive and Gram-negative bacterial strains (such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii). Next, we used principal component analysis (PCA) to determine the key contributors to activity. We found that for S. aureus, the zeta potential was the major contributor to the activity while Gram-negative bacteria were more influenced by the partition coefficient (LogP) with the following order P. aeruginosa>E. coli>A. baumannii. We also performed a study of the mechanism of action of selected PAs on the bacterial membrane assessing the membrane permeability and depolarization, changes in zeta potential and overall integrity. We studied the toxicity of the nanostructures against mammalian cells. Finally, we performed an in vivo study using the wax moth larvae to determine the therapeutic efficacy of the active PAs. This study shows cationic PA nanostructures can be an intriguing platform for the development of nanoantibacterials.

High-throughput computational screening for identification of potential hits against bacterial Acriflavine resistance protein B (AcrB) efflux pump

Antibiotic resistance is a pressing global health challenge, driven in part by the remarkable efflux capabilities of efflux pump in AcrB (Acriflavine Resistance Protein B) protein in Gram-negative bacteria. In this study, a multi-approached computational screening strategy encompassing molecular docking, In silico absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis, druglikeness assessment, molecular dynamics simulations and density functional theory studies was employed to identify novel hits capable of acting against AcrB-mediated antibiotic resistance. Ligand library was acquired from the COCONUT database. Performed computational analyses unveiled four promising hit molecules (CNP0298667, CNP0399927, CNP0321542 and CNP0269513). Notably, CNP0298667 exhibited the highest negative binding affinity of -11.5 kcal/mol, indicating a possibility of strong potential to disrupt AcrB function. Importantly, all four hits met stringent druglikeness criteria and demonstrated favorable in silico ADMET profiles, underscoring their potential for further development. MD simulations over 100 ns revealed that the CNP0321542-4DX5 and CNP0269513-4DX5 complexes formed robust and stable interactions with the AcrB efflux pump. The identified hits represent a promising starting point for the design and optimization of novel therapeutics aimed at combating AcrB-mediated antibiotic resistance in Gram-negative bacteria.Communicated by Ramaswamy H. Sarma.

Antibiotics against Pseudomonas aeruginosa on Human Skin Cell Lines: Determination of the Highest Non-Cytotoxic Concentrations with Antibiofilm Capacity for Wound Healing Strategies

Pseudomonas aeruginosa is one of the most common microorganisms causing infections of severe skin wounds. Antibiotic or antiseptic treatments are crucial to prevent and curb these infections. Antiseptics have been reported to be cytotoxic to skin cells and few studies evaluate the impact of commonly used antibiotics. This study evaluates how clinical antibiotics affect skin cells' viability, proliferation, migration, and cytokine secretion and defines the highest non-cytotoxic concentrations that maintain antibacterial activity. Cell proliferation, viability, and migration were evaluated on cell monolayers. Cytokines related to the wound healing process were determined. The minimum inhibitory concentrations and the impact on bacterial biofilm were assessed. Results showed that 0.02 mg/mL ciprofloxacin and 1 mg/mL meropenem are the highest non-cytotoxic concentrations for fibroblasts and keratinocytes while 1.25 mg/mL amikacin and 0.034 mg/mL colistin do not affect fibroblasts' viability and cytokine secretion but have an impact on keratinocytes. These concentrations are above the minimum inhibitory concentration but only amikacin could eradicate the biofilm. For the other antibiotics, cytotoxic concentrations are needed to eradicate the biofilm. Combinations with colistin at non-cytotoxic concentrations effectively eliminate the biofilm. These results provide information about the concentrations required when administering topical antibiotic treatments on skin lesions, and how these antibiotics affect wound management therapies. This study set the basis for the development of novel antibacterial wound healing strategies such as antibiotic artificial skin substitutes.

Improving access to medicines to reduce marketing and use of substandard and falsified medicines in Africa: Scoping review

Background

Both constrained access to essential medicines and combatting marketing of substandard and falsified (SF) medicines are unmet health sector goals in Africa.

Objective

To answer the question of how improved access can reduce the continuous surge of SF medicines in Africa.

Design

We conducted a scoping review based on standard protocol.

Methods

We searched articles published in the English language from PubMed/Medline, Cochrane Library, Embase, Scopus, Web of Science, and Google Scholar by using a systematic search query.

Results

Seventy-one articles were included in this review. Access to quality essential medicines is still a major problem in developing countries in Africa and will continue as a threat for the next decade of health care. Ensuring access to quality medicines and preventing SF medicines in Africa need a systematic approach to address their underlying causes. Failure to ensure access to medicines is the major reason for the availability of SF medicines. Improving access to quality medicines can reduce SF medicine marketing and use. Manipulating the entire supply chain for efficiency, avoiding trade agreements that could reduce access, using compulsory licensing provisions, and pharmaceutical price control, providing incentives for drug development, and promoting rational use of medicines can improve access.

Conclusion

Ensuring access to medicines and preventing SF medicine marketing cannot be achieved in the planned period in developing countries in Africa unless a comprehensive strategy is used. Improving access to quality medicines can reduce SF medicine marketing and use, that is, ensuring access through uninterrupted supply, improved efficiency, enhanced local production, preventing SF medicine entry, improved medication use system, and improved affordability. Therefore, it is essential to improve supply chain capability, address challenges of the supply chain, improve leadership and governance, establish country-specific anti-counterfeiting and anti-substandardization committees, and collaborate with all relevant stakeholders.

Functional Proteomics Analysis of Norfloxacin-Resistant Edwardsiella tarda

Multidrug-resistant Edwardsiella tarda threatens both sustainable aquaculture and human health, but the control measure is still lacking. In this study, we adopted functional proteomics to investigate the molecular mechanism underlying norfloxacin (NOR) resistance in E. tarda. We found that E. tarda had a global proteomic shift upon acquisition of NOR resistance, featured with increased expression of siderophore biosynthesis and Fe3+-hydroxamate transport. Thus, either inhibition of siderophore biosynthesis with salicyl-AMS or treatment with another antibiotic, kitasamycin (Kit), which was uptake through Fe3+-hydroxamate transport, enhanced NOR killing of NOR-resistant E. tarda both in vivo and in vitro. Moreover, the combination of NOR, salicyl-AMS, and Kit had the highest efficacy in promoting the killing effects of NOR than any drug alone. Such synergistic effect not only confirmed in vitro and in vivo bacterial killing assays but also applicable to other clinic E. tarda isolates. Thus, our data suggest a proteomic-based approach to identify potential targets to enhance antibiotic killing and propose an alternative way to control infection of multidrug-resistant E. tarda.

Computer-aided drug repurposing to tackle antibiotic resistance based on topological data analysis

The progressive emergence of antimicrobial resistance has become a global health problem in need of rapid solution. Research into new antimicrobial drugs is imperative. Drug repositioning, together with computational mathematical prediction models, could be a fast and efficient method of searching for new antibiotics. The aim of this study was to identify compounds with potential antimicrobial capacity against Escherichia coli from US Food and Drug Administration-approved drugs, and the similarity between known drug targets and E. coli proteins using a topological structure-activity data analysis model. This model has been shown to identify molecules with known antibiotic capacity, such as carbapenems and cephalosporins, as well as new molecules that could act as antimicrobials. Topological similarities were also found between E. coli proteins and proteins from different bacterial species such as Mycobacterium tuberculosis, Pseudomonas aeruginosa and Salmonella Typhimurium, which could imply that the selected molecules have a broader spectrum than expected. These molecules include antitumor drugs, antihistamines, lipid-lowering agents, hypoglycemic agents, antidepressants, nucleotides, and nucleosides, among others. The results presented in this study prove the ability of computational mathematical prediction models to predict molecules with potential antimicrobial capacity and/or possible new pharmacological targets of interest in the design of new antibiotics and in the better understanding of antimicrobial resistance.

Growing Utilization of Radical Chemistry in the Synthesis of Pharmaceuticals

Our current unhealthy lifestyle and the exponential surge in the population getting affected by a variety of diseases have made pharmaceuticals or drugs an imperative part of life, making the development of innovative strategies for drug discovery or the introduction of refined, cost-effective and modern technologies for the synthesis of clinically used drugs, a need of the hour. Ever since their discovery, free radicals and radical cations or anions as reactive intermediates have captivated the chemists, resulting in an exceptional utilization of these moieties throughout the field of chemical synthesis, owing to their unprecedented and widespread reactivity. Sticking with the idea of not judging the book by its cover, despite the conventional thought process of radicals being unstable and difficult to control entities, scientists and academicians around the globe have done an appreciable amount of work utilizing both persistent as well as transient radicals for a variety of organic transformations, exemplifying them with the synthesis of significant biologically active pharmaceutical ingredients. This review truly accounts for the organic radical transformations including radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling with metal-complexes and radical cations coupling with nucleophiles, that offers fascinating and unconventional approaches towards the construction of intricate structural frameworks of marketed APIs with high atom- and step-economy; complementing the otherwise employed traditional methods. This tutorial review presents a comprehensive package of diverse methods utilized for radical generation, featuring their reactivity to form critical bonds in pharmaceutical total synthesis or in building key starting materials or intermediates of their synthetic journey, acknowledging their excellence, downsides and underlying mechanisms, which are otherwise poorly highlighted in the literature. Despite great achievements over the past few decades in this area, many challenges and obstacles are yet to be unraveled to shorten the distance between the academics and the industry, which are all discussed in summary and outlook.

A review of current antibiotic resistance and promising antibiotics with novel modes of action to combat antibiotic resistance

The emergence and transmission of antibiotic resistance is a global public health crisis with significant burden on healthcare systems, resulting in high mortality and economic costs. In 2019, almost five million deaths were associated with drug-resistant infections, and if left unchecked, the global economy could lose $100 trillion by 2050. To effectively combat this crisis, it is essential for all countries to understand the current situation of antibiotic resistance. In this review, we examine the current driving factors leading to the crisis, impact of critical superbugs in three regions, and identify novel mechanisms of antibiotic resistance. It is crucial to monitor the phenotypic characteristics of drug-resistant pathogens and describe the mechanisms involved in preventing the emergence of cross-resistance to novel antimicrobials. Additionally, maintaining an active pipeline of new antibiotics is essential for fighting against diverse antibiotic-resistant pathogens. Developing antibacterial agents with novel mechanisms of action is a promising way to combat increasing antibiotic-resistant pathogens.

Cupferron impairs the growth and virulence of Escherichia coli clinical isolates

AIMS

Multidrug resistance is a worrying problem worldwide. The lack of readily available drugs to counter nosocomial infections requires the need for new interventional strategies. Drug repurposing represents a valid alternative to using commercial molecules as antimicrobial agents in a short time and with low costs. Contextually, the present study focused on the antibacterial potential of the ammonium salt N-nitroso-N-phenylhydroxylamine (Cupferron), evaluating the ability to inhibit microbial growth and influence the main virulence factors.

METHODS AND RESULTS

Cupferron cytotoxicity was checked via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and hemolysis assays. The antimicrobial activity was assessed through the Kirby-Bauer disk diffusion test, broth microdilution method, and time-killing kinetics. Furthermore, the impact on different stages of the biofilm life cycle, catalase, swimming, and swarming motility was estimated via MTT and crystal violet (CV) assay, H2O2 sensitivity, and motility tests, respectively. Cupferron exhibited <15% cytotoxicity at 200 µg/mL concentration. The 90% bacterial growth inhibitory concentrations (MIC90) values recorded after 24 hours of exposure were 200 and 100 µg/mL for multidrug-resistant (MDR) and sensitive strains, respectively, exerting a bacteriostatic action. Cupferron-treated bacteria showed increased susceptibility to biofilm production, oxidative stress, and impaired bacterial motility in a dose-dependent manner.

CONCLUSIONS

In the new antimicrobial compounds active research scenario, the results indicated that Cupferron could be an interesting candidate for tackling Escherichia coli infections.

A protein-free vaccine stimulates innate immunity and protects against nosocomial pathogens

Traditional vaccines are difficult to deploy against the diverse antimicrobial-resistant, nosocomial pathogens that cause health care-associated infections. We developed a protein-free vaccine composed of aluminum hydroxide, monophosphoryl lipid A, and fungal mannan that improved survival and reduced bacterial burden of mice with invasive blood or lung infections caused by methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, extended-spectrum beta-lactamase-expressing Escherichia coli, and carbapenem-resistant strains of Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The vaccine also conferred protection against the fungi Rhizopus delemar and Candida albicans. Efficacy was apparent by 24 hours and lasted for up to 28 days after a single vaccine dose, with a second dose restoring efficacy. The vaccine acted through stimulation of the innate, rather than the adaptive, immune system, as demonstrated by efficacy in the absence of lymphocytes that were abrogated by macrophage depletion. A role for macrophages was further supported by the finding that vaccination induced macrophage epigenetic alterations that modulated phagocytosis and the inflammatory response to infection. Together, these data show that this protein-free vaccine is a promising strategy to prevent deadly antimicrobial-resistant health care-associated infections.

Activity-based probes in pathogenic bacteria: Investigating drug targets and molecule specificity

Bacteria comprise complex communities within our bodies and largely have beneficial roles, however a small percentage are pathogenic. While all pathogens are important to public health, immediate action is necessary to combat bacterial strains developing pan- and multi-resistance to antibiotics. As present therapeutics fail to tackle this problem, novel strategies are required to address this threat. Activity-based probes (ABPs) are one method to investigate proteins of interest in pathogens. These probes can serve multiple purposes to better our understanding of bacterial pathogenicity. Herein, we highlight recent studies that used ABPs to identify new drug targets or visualize antibiotic resistance- or bacterial virulence-associated proteins, and introduce strategies to determine the specificity of ABPs within a targeted enzyme class.

Impact of an Antimicrobial Stewardship Program on Broad Spectrum Antibiotics Consumption in the Intensive Care Setting

Background and objectives

Antibiotics are the most commonly exploited agents in intensive care units. An antimicrobial stewardship program (ASP) helps in the optimal utilization of antibiotics and prevents the development of antibiotic resistance. The aim of this study was to assess the impact of ASP on broad-spectrum antibiotic consumption in terms of defined daily dose (DDD) and days of therapy (DOT) before and after the implementation of an ASP.

Materials and methods

It was a prospective, quasi-experimental, pre- and post-study. Group A consisted of 5 months of ASP data, ASP activities were implemented during the next 2 months and continued. Group B (post-ASP) data was collected for the next 5 months. Total and individual DDDs and DOTs of broad-spectrum antibiotics utilized were compared between group A and group B.

Results

Total DDDs used per 100 patient bed days were reduced by 18.72% post-ASP implementation (103.46 to 84.09 grams). The total DOT per 100 patient bed days used was 90.91 vs 71.25 days (21.62% reduction). As per the WHO classification of antibiotics use, the watch category (43.4% vs 43.04%) as well as reserve category (56.6% vs 56.97%) used between the two groups were found similar. The average length of stay (8.9 ± 2 days) after ASP was found significantly lesser than baseline (10.8 ± 3.4 days) (p < 0.05), however, there was no significant change in mortality between the two groups.

Conclusion

Antimicrobial stewardship program implementation may reduce overall antibiotic consumption both in terms of DDD and DOT.

How to cite this article

Zirpe KG, Kapse US, Gurav SK, Tiwari AM, Deshmukh AM, Suryawanshi PB, et al. Impact of an Antimicrobial Stewardship Program on Broad Spectrum Antibiotics Consumption in the Intensive Care Setting. Indian J Crit Care Med 2023;27(10):737-742.

The Expression of Antibacterial Peptide Turgencin A in Pichia pastoris and an Analysis of Its Antibacterial Activity

Antibiotic resistance to pathogenic bacteria is becoming an increasing public health threat, and identifying alternatives to antibiotics would be an effective solution to the problem of drug resistance. Antimicrobial peptides are small peptides produced by various organisms; they are considered to be adequate antibiotic substitutes because they have intense, broad-spectrum antibacterial activity and stability, are widely available, and target strains do not quickly develop resistance. Recent research on antimicrobial peptides has shown that they have broad potential for applications in medicine, agriculture, food, and animal feed. Turgencin A is a potent antimicrobial peptide isolated from the Arctic sea squirt. We established a His-tagged expression system for Pichia pastoris and developed a rTurgencin A using the recombinant expression in Pichia pastoris with nickel column purification. This antimicrobial peptide showed intense antimicrobial activity against Gram-positive and Gram-negative bacteria and a good stability at most temperatures and pHs, as well as in various protease and salt ion concentrations, but underwent a significant decrease in stability in high-temperature and low-pH environments. Turgencin A induced bacterial membrane rupture, resulting in content leakage and subsequent cell death. It was also shown to have low hemolytic activity. This study provides primary data for the industrial production and application of the antimicrobial peptide Turgencin A.

Novel hydroxy- and amidino-substituted benzimidazoles and benzothiazoles as antibacterial and antiproliferative agents

Aim: The aim was synthesis of novel benzazoles bearing amidino and 2-hydroxyphenyl substituents to explore their biological activity. Methods: Condensation of 5-substituted salicylaldehydes and intermediates gave new benzazoles by previously published and developed procedures, which were tested for antibacterial and antiproliferative activity in vitro. Results: The best antibacterial activity showed benzimidazole with 2-imidazolinyl group 27 and benzothiazole with an unsubstituted amidine 48 (minimum inhibitory concentration 8 μg/ml). Benzothiazole 53 proved most potent at inhibiting proliferation of all cancer cells (IC50: 1.2-2.0 μM). Conclusion: Most active compounds have been recognized as lead compounds for additional optimization to improve their biological activity. The type of amidine moiety markedly influenced the biological activity. Benzothiazoles showed improved antiproliferative activity in comparison to benzimidazoles.

Outcomes of Intravenous Push versus Intermittent Infusion Administration of Cefepime in Critically Ill Patients

The equivalence of intravenous push (IVP) and piggyback (IVPB) administration has not been evaluated in the critically ill population for most medications, but it is especially relevant for antibiotics, such as cefepime, that exhibit time-dependent bactericidal activity. A single center, retrospective, observational pre/post-protocol change study included critically ill adults who received cefepime as empiric therapy between August 2015 and 2021. The primary outcome was treatment failure, which was defined as a composite of escalation of antibiotic regimen or all-cause mortality. Secondary outcomes included adverse drug events, days of cefepime therapy, total days of antibiotic therapy, and ICU and hospital length of stay. Outcomes were compared using Chi-squared, Mann Whitney U, and binary logistic regression as appropriate. A total of 285 patients were included: 87 IVPB and 198 IVP. Treatment failure occurred in 18% (n = 16) of the IVPB group and 27% (n = 54) of the IVP group (p = 0.109). There were no significant differences in secondary outcomes. Longer duration of antibiotics (odds ratio [OR] 1.057, 95% confidence interval [CI] 1.013-1.103), SOFA score (OR 1.269, 95% CI 1.154-1.397) and IVP administration of cefepime (OR 2.370, 95% CI 1.143-4.914) were independently associated with treatment failure. Critically ill patients who received IVP cefepime were more likely to experience treatment failure in an adjusted analysis. The current practice of IVP cefepime should be reevaluated, as it may not provide similar clinical outcomes in the critically ill population.

Fabrication of graphene oxide/copper synergistic antibacterial coating for medical titanium substrate

Titanium (Ti) was an excellent medical metal material, but the lack of good antibacterial activity confined its further practical application. To solve this dilemma, a coating containing graphene oxide (GO) and copper (Cu) was prepared on the surface of Ti sheet (Ti/APS/GO/Cu). First, physical sterilization could be carried out through the sharp-edged sheet structure of GO. Second, the oxygen-containing functional group on the surface of GO and the released Cu²⁺ would generate reactive oxygen species for chemical sterilization. The synergistic effect of GO and Cu substantially enhanced the in vitro and in vivo antibacterial property of Ti sheet, thereby reducing bacterial-related inflammation. Quantitatively, the antibacterial rate of Ti/APS/GO/Cu against E. coli or S. aureus reached over 99%. Besides, Ti/APS/GO/Cu showed excellent biocompatibility and no toxicity to cell. Such work developed multiple sterilization avenues to design non-antibiotic, safe and efficient antibacterial implant material for the biomedical domain.

Characterisation of OXA-48-like carbapenemases in Escherichia coli and Klebsiella pneumoniae from North India

The oxacillinase-48 (OXA-48)-like carbapenemases are class D β-lactamases and increasingly reported in Enterobacterial species. The detection of these carbapenemases is challenging and little information is available on the epidemiology and plasmid characteristics of OXA-48-like carbapenemase producers. We detected the presence of OXA-48-like carbapenemases in 500 clinical isolates of Escherichia coli and Klebsiella pneumoniae, followed by detection of other carbapenemases, extended spectrum β-lactamases (ESBLs) and 16S rRNA methyltransferases in OXA-48 producers. Clonal relatedness was studied using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Finally, plasmid characterisation was performed through conjugation experiment, S1-PFGE and Southern hybridisation. Around 40% of E. coli and K. pneumoniae isolates harboured OXA-48-like β-lactamases. Two OXA-48 allele variants, OXA-232 and OXA-181 were detected in our study. OXA-48 producers co-harbored diverse drug-resistant genes belonging to other classes of carbapenemases, ESBLs and 16S rRNA methyltransferases. OXA-48-like carbapenemase producers exhibited high clonal diversity. Bla OXA-48 carrying plasmids were conjugative, untypable and their size was ~ 45 kb and ~ 104.5 kb in E. coli and K. pneumoniae respectively. In conclusion, OXA-48-like carbapenemases have emerged as major cause of carbapenem resistance in Enterobacteriaceae and probably still being under reported. Strict surveillance and adequate detection methods are needed to prevent the dissemination of OXA-48-like carbapenemases.

Expanding therapeutic potential of Bdellovibrio bacteriovorus against multidrug-resistant pathogens

Novel treatments toward Gram-negative bacteria are urgently needed to prevent even higher mortality levels associated with resistant bacterial infections. Predatory bacteria have been studied as a new type of treatment against pathogenic bacteria, including resistant species. However, because of limitations related to eradication efficacy, combination therapy using predatory bacteria with other agents has also been tested. Here, we discuss recent advances in the use of predatory bacteria to treat infections and propose novel combinatory strategies with antivirulence compounds. Teaser: The increasing number of resistant bacteria requires the implementation of new strategies to avoid mortality. Studies about predatory bacteria indicate a field to be explored in different ways that can lead to new treatment solutions.

Evolutionary and in silico guided development of novel peptide analogues for antibacterial activity against ESKAPE pathogens

According to WHO, to combat the resistant strains, new effective anti-microbial agents are needed on an urgent basis and global researchers should focus their efforts and discovery programs on developing them against antibiotic-resistant pathogens or priority pathogens like ESKAPE. In this context, Cationic antimicrobial peptides (AMPs) are being explored extensively as promising next-generation antimicrobials due to their broad range, fast kinetics and multifunctional role. Despite recent advances, it is still a daunting challenge to identify and design a potent AMP with no cytotoxicity, but with broad specific antimicrobial activity, stability and efficacy under in vivo conditions in a cost-effective and robust manner. In this work, as a proof of concept, we designed novel potent AMPs using artificial intelligence based in silico programs. Shortlisted peptide sequences were synthesized using the fmoc chemistry approach, assessed their antimicrobial activity, cell selectivity, mode of action and in vivo efficacy using a series of experiments. The synthesized peptide analogues demonstrated their antimicrobial activity (MIC in the range of 2.5-80 μM) against bacteria. The identified potential lead molecules showed antibacterial activity in physiological conditions with no signs of cytotoxicity. We further tested the antimicrobial activity of peptide analogues for treating wounds infected with Pseudomonas aeruginosa in the mice burn wound model. In drug-development programs, the identification of lead antimicrobial agents is always challenging and involves screening a large number of molecules which is time-consuming and expensive. This work demonstrates the utility of artificial intelligence based in silico analysis programs in discovering novel antimicrobial agents in an economical, robust way.

[Bacterial resistance, a current crisis.]

Bacterial resistance is a constant battle representing a Public Health trouble. So much, that the World Health Organization considerate Public Health as a priority in health, due to the impact that generates as much as in health (giving that recent projections indicate that by 2050 it'll be produced more deaths because of this than the ones occasioned because of cancer) as its economic impact (which, according to a recent study in the United Kingdom, it'll cost the world's economy an estimated of 100 trillion dollars). The quick appearance of multidrug-resistant and pandrug-resistant bacteria is a world nature phenomenon, questioning the antibiotics efficiency. Implement protocols and recommendations is essential, just as essential and necessary as give awareness to health personnel, taking as base the knowledge of resistance generation and its impact through the years, empowered by the actual pandemic of COVID 19.

Darobactins Exhibiting Superior Antibiotic Activity by Cryo-EM Structure Guided Biosynthetic Engineering

Over recent decades, the pipeline of antibiotics acting against Gram-negative bacteria is running dry, as most discovered candidate antibiotics suffer from insufficient potency, pharmacokinetic properties, or toxicity. The darobactins, a promising new small peptide class of drug candidates, bind to novel antibiotic target BamA, an outer membrane protein. Previously, we reported that biosynthetic engineering in a heterologous host generated novel darobactins with enhanced antibacterial activity. Here we utilize an optimized purification method and present cryo-EM structures of the Bam complex with darobactin 9 (D9), which served as a blueprint for the biotechnological generation of twenty new darobactins including halogenated analogs. The newly engineered darobactin 22 binds more tightly to BamA and outperforms the favorable activity profile of D9 against clinically relevant pathogens such as carbapenem-resistant Acinetobacter baumannii up to 32-fold, without observing toxic effects.

Natural products in antibiotic development: is the success story over?

Natural product (NP)-based antibiotics have been exploited for more than eighty years and continue saving uncountable lives every year. However, antimicrobial R&D is inadequate to counteract antimicrobial resistance. The majority of marketed antibiotics are inspired by NP classes that were discovered more than 50 years ago. With the advent of advanced genomic approaches, cultivation methods, and modern analytical techniques, NP discovery holds promise that there are way more powerful antibiotic scaffolds to be discovered. However, the currently lean antibiotic R&D pipeline shows a clear trend away from NP-based programs and innovative compounds are also rare in early stages. Within this review, we give an overview of the current NP antibiotic development pipeline, elaborate constraints the field is facing, and suggest measures to streamline NP-based antibiotic discovery. It is unlikely that NPs have lost significance, but reinforcement of discovery will require more targeted efforts and support to revitalize this established source.

Epidemiology and In Vitro Activity of Ceftazidime/Avibactam, Meropenem/Vaborbactam and Imipenem/Relebactam against KPC-Producing K. pneumoniae Collected from Bacteremic Patients, 2018 to 2020

The management of KPC-producing K. pneumoniae (KPC-Kp) in bloodstream infections (BSIs) represent a serious clinical challenge. In this study, the aim is to assess the incidence of resistance to novel β-lactams-β-lactamase inhibitor combinations (βL-βLICs), such as ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MER-VAB) and imipenem-relebactam (IMI-REL), in KPC-Kp strains collected during a three-year period from patients with bacteremia. KPC-Kp strains resistant to βL-βLICs were selected for whole-genome sequencing. A total of 133 K. pneumoniae strains were isolated, and KPC-Kp strains were the most represented (87.2%). In 2018, resistance to CAZ-AVI and MER-VAB was 6.5% and 14.5%, respectively. In 2019, KPC-Kp resistance to CAZ-AVI and MER-VAB remained at low levels, with values of 12.9% and 3.2%, respectively. During 2020, CAZ-AVI resistance was detected in 2/23 of KPC-Kp strains (8.7%). IMI-REL was the most active βL-βLIC, inhibiting >98% of the isolates, while CAZ-AVI and MER-VAB inhibited 87−93% and 85−97% of the KPC producers, respectively. Correlations between genotypic traits and resistance to βL-βLICs showed that KPC-Kp strains resistant to CAZ-AVI harbored a mutation within the blaKPC-3 gene, while all KPC-Kp strains resistant to CAZ-AVI, MER-VAB and/or IMI-REL carried the blaKPC-3 gene. Moreover, genetic analysis of porin genes showed that 14/16 of KPC-Kp resistant isolates possessed a truncated OmpK35 and glycine (G) and aspartic acid (D) insertions at positions 134−135 within OmpK36, whereas 2/16 displayed truncated OmpK35 and OmpK36 porins. Novel βL-βLICs are promising agents against KPC-Kp infections; however, the emergence of resistance to these agents highlights the need for continuous surveillance and application of enhanced antimicrobial stewardship.

Isolation and identification of endophytic actinobacteria from Citrullus colocynthis (L.) Schrad and their antibacterial properties

BACKGROUND

Antibiotic resistance poses a major threat to human health globally. Consequently, new antibiotics are desperately required to discover and develop from unexplored habitats to treat life-threatening infections. Microbial natural products (NP) are still remained as primary sources for the discovery of new antibiotics. Endophytic actinobacteria (EA) which are well-known producers of bioactive compounds could provide novel antibiotic against pathogenic bacteria. This research aimed to isolate EA from the Citrullus colocynthis plant and explore the antibacterial properties of their metabolites against pathogenic bacteria.

RESULTS

The healthy samples were collected, dissected and surface-sterilized before cultured on four different selection media at 28 °C. Six endophytic actinobacteria were isolated from Citrullus colocynthis plant. They were taxonomically classified into two family namely Streptomycetaceae and Nocardiopsaceae, based on colony morphological features, scanning electron microscope analysis and molecular identification of isolates. This is the first report on the identification of EA form Citrullus colocynthis and their antibacterial activity. The strains generated a chain of vibrio-comma, cubed or cylindrical shaped spores with indenting or smooth surfaces. Three of those were reported as endophytes for the first time. The strain KUMS-C1 showed 98.55% sequence similarity to its closely related strains which constitutes as a novel species/ strain for which the name Nocardiopsis colocynthis sp. was proposed for the isolated strain. Five isolated strains had antagonist activity against S. aureus, P. aeruginosa, and E. coli. Among those, stain KUMS-C6 showed the broadest spectrum of antibacterial activity against all test bacteria, whereas the strain KUMS-C4 had no antibacterial activity.

CONCLUSIONS

NPs have a long history of safe and efficient use for development of pharmaceutical products. Our study highlights that Citrullus colocynthis is an untapped source for the isolation of EA, generating novel and bioactive metabolites by which might lead to discovery of new antibiotic(s). This study reveals the future of new antibiotic developments looks bright against multi-drug resistance diseases by mining under- or unexplored habitats.

Perspectives for Uses of Propolis in Therapy against Infectious Diseases

Propolis has gained wide popularity over the last decades in several parts of the world. In parallel, the literature about propolis composition and biological properties increased markedly. A great number of papers have demonstrated that propolis from different parts of the world is composed mainly of phenolic substances, frequently flavonoids, derived from plant resins. Propolis has a relevant role in increasing the social immunity of bee hives. Experimental evidence indicates that propolis and its components have activity against bacteria, fungi, and viruses. Mechanisms of action on bacteria, fungi, and viruses are known for several propolis components. Experiments have shown that propolis may act synergistically with antibiotics, antifungals, and antivirus drugs, permitting the administration of lower doses of drugs and higher antimicrobial effects. The current trend of growing resistance of microbial pathogens to the available drugs has encouraged the introduction of propolis in therapy against infectious diseases. Because propolis composition is widely variable, standardized propolis extracts have been produced. Successful clinical trials have included propolis extracts as medicine in dentistry and as an adjuvant in the treatment of patients against COVID-19. Present world health conditions encourage initiatives toward the spread of the niche of propolis, not only as traditional and alternative medicine but also as a relevant protagonist in anti-infectious therapy. Production of propolis and other apiary products is environmentally friendly and may contribute to alleviating the current crisis of the decline of bee populations. Propolis production has had social-economic relevance in Brazil, providing benefits to underprivileged people.

Antimicrobial Treatment Options for Difficult-to-Treat Resistant Gram-Negative Bacteria Causing Cystitis, Pyelonephritis, and Prostatitis: A Narrative Review

Urinary tract infections, including cystitis, acute pyelonephritis, and prostatitis, are among the most common diagnoses prompting antibiotic prescribing. The rise in antimicrobial resistance over the past decades has led to the increasing challenge of urinary tract infections because of multidrug-resistant and "difficult-to-treat resistance" among Gram-negative bacteria. Recent advances in pharmacotherapy and medical microbiology are modernizing how these urinary tract infections are treated. Advances in pharmacotherapy have included not only the development and approval of novel antibiotics, such as ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, ceftolozane/tazobactam, cefiderocol, plazomicin, and glycylcyclines, but also the re-examination of the potential role of legacy antibiotics, including older aminoglycosides and tetracyclines. Recent advances in medical microbiology allow phenotypic and molecular mechanism of resistance testing, and thus antibiotic prescribing can be tailored to the mechanism of resistance in the infecting pathogen. Here, we provide a narrative review on the clinical and pre-clinical studies of drugs that can be used for difficult-to-treat resistant Gram-negative bacteria, with a particular focus on data relevant to the urinary tract. We also offer a pragmatic framework for antibiotic selection when encountering urinary tract infections due to difficult-to-treat resistant Gram-negative bacteria based on the organism and its mechanism of resistance.

Metallo-β-Lactamase Inhibitor Phosphonamidate Monoesters

Being the second leading cause of death and the leading cause of disability-adjusted life years worldwide, infectious diseases remain-contrary to earlier predictions-a major consideration for the public health of the 21^st century. Resistance development of microbes to antimicrobial drugs constitutes a large part of this devastating problem. The most widely spread mechanism of bacterial resistance operates through the degradation of existing β-lactam antibiotics. Inhibition of metallo-β-lactamases is expected to allow the continued use of existing antibiotics, whose applicability is becoming ever more limited. Herein, we describe the synthesis, the metallo-β-lactamase inhibition activity, the cytotoxicity studies, and the NMR spectroscopic determination of the protein binding site of phosphonamidate monoesters. The expression of single- and double-labeled NDM-1 and its backbone NMR assignment are also disclosed, providing helpful information for future development of NDM-1 inhibitors. We show phosphonamidates to have the potential to become a new generation of antibiotic therapeutics to combat metallo-β-lactamase-resistant bacteria.

Antibiotic Discovery and Resistance: The Chase and the Race

The history of antimicrobial resistance (AMR) evolution and the diversity of the environmental resistome indicate that AMR is an ancient natural phenomenon. Acquired resistance is a public health concern influenced by the anthropogenic use of antibiotics, leading to the selection of resistant genes. Data show that AMR is spreading globally at different rates, outpacing all efforts to mitigate this crisis. The search for new antibiotic classes is one of the key strategies in the fight against AMR. Since the 1980s, newly marketed antibiotics were either modifications or improvements of known molecules. The World Health Organization (WHO) describes the current pipeline as bleak, and warns about the scarcity of new leads. A quantitative and qualitative analysis of the pre-clinical and clinical pipeline indicates that few antibiotics may reach the market in a few years, predominantly not those that fit the innovative requirements to tackle the challenging spread of AMR. Diversity and innovation are the mainstays to cope with the rapid evolution of AMR. The discovery and development of antibiotics must address resistance to old and novel antibiotics. Here, we review the history and challenges of antibiotics discovery and describe different innovative new leads mechanisms expected to replenish the pipeline, while maintaining a promising possibility to shift the chase and the race between the spread of AMR, preserving antibiotic effectiveness, and meeting innovative leads requirements.