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Burns are one of the most common injuries in both civilian and combat settings and are difficult to treat. This is particularly true when the wounds are infected with antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). A new generation of safe, broadly effective, and easily applied anti-infection agents is needed to successfully prevent and treat infections. Nanoemulsions (NEs) are nanometer-sized particles with a positively charged surfactant at their oil-water interface. In the current study, we further investigated antimicrobial NEs as a treatment to address burn wounds infected by MRSA. Specifically, using a porcine skin model, we infected partial thickness thermal burn wounds with MRSA and then treated it with the nanoemulsion formulation (NB-201) or placebo controls. Bacterial viability after treatment was determined, and inflammation indexes in wounds were scored by histopathology. Topical treatment of infected wounds with NB-201 resulted in reduced colony-forming units (CFUs) compared to placebo treatment. In addition, NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. These results indicate that NB-201 is a promising new agent to treat skin burn wounds infected with MRSA., Importance: The findings of this study are focused on therapeutic applications of nanotechnology. In the current study, we demonstrated that a nanoemulsion formulation could effectively kill methicillin-resistant Staphylococcus aureus (MRSA) infection in porcine skin burn wounds. Infection of MRSA in burn wound is a common threat to public health and is usually difficult to treat due to limited therapies available. NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. Therefore, the finding of this study has a great potential to make this formulation a novel antimicrobial agent against MRSA., Competing Interests: The authors declare no conflict of interest.

With increasing health awareness of the pathogenic effects of disease-causing microorganisms, interest in and use (of medical textiles, disinfectants in medical devices, etc.) of antimicrobial substances have increased in various applications, such as medical textiles and disinfectants (alcohol-based and nonalcoholic), in medical devices There are several concerns with alcohol-based disinfectants, such as surface deformation of medical devices due to high alcohol content and damage to skin tissue caused by lipid and protein denaturation of cell membranes. Quaternary ammonium compounds (quats) were preferred because they have the potential to prepare water-based disinfectants. In this study, novel (3-chloropropyl)triethoxysilane (CPTMO) and (3-chloropropyl)triethoxysilane (CPTEO) based quaternary ammonium silane compounds (silane-quats) were developed using quats with carbon chain lengths of C12, C14, C16 and C18. Titration (ASTM D2074) was used to calculate the yield of the synthesis and the structures of the products were characterised by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy ( 13 C NMR, 1 H NMR) and gas chromatography-mass spectrometry (GC-MS).The in vitro antimicrobial activity of the synthesized samples was evaluated against Gram-positive (Staphylococcus aureus (S. aureus), Enterococcus hirae (E. hirae)) and Gram-negative (Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa)) bacteria and fungi (Candida albicans (C. albicans), Aspergillus brasiliensis (A. brasiliensis)) using the minimum inhibitory concentration (MIC) test. According to MIC tests, the silane-quats with the highest antimicrobial effects were dimethylhexadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (SQ3), which had an MIC of < 16 μg/ml (ppm) against E. coli, S. aureus, E. hirae, C. albicans, and A. brasiliensis and 32 μg/ml against P. aeruginosa. The MIC test results also showed antimicrobial activity at least 2 times greater than that of the commercially available disinfectant benzalkonium chloride (BAC). Findings suggest that SQ3 (C16) holds promise as an effective medical disinfectant, presenting a novel approach to combating microbial infections in healthcare settings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Given the ability of Staphylococcus aureus to form biofilms and produce persister cells, making infections difficult to treat with antibiotics alone, there is a pressing need for an effective antibiotic adjuvant to address this public health threat. In this study, a series of quinone derivatives were evaluated for their antimicrobial and antibiofilm activities against methicillin-susceptible and methicillin-resistant S. aureus reference strains. Following analyses using broth microdilution, growth curve analysis, checkerboard assay, time-kill experiments, and confocal laser scanning microscopy, menadione was identified as a hit compound. Menadione exhibited a notable antibacterial profile (minimum inhibitory concentration, MIC = 4-16 μg/ml; minimum bactericidal concentration, MBC = 256 μg/ml) against planktonic S. aureus and its biofilms (minimum biofilm inhibitory concentration, MBIC 50  = 0.0625-0.25 μg/ml). When combined with oxacillin, erythromycin, and vancomycin, menadione exhibited a synergistic or additive effect against planktonic cells and biofilms of two S. aureus reference strains and six clinical isolates, highlighting its potential as a suitable adjuvant for further development against S. aureus biofilm-associated infections., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Sun Tee Tay reports financial support, administrative support, equipment, drugs, or supplies, and statistical analysis were provided by Universiti Malaya. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Spiders produce webs, which are still a largely unexplored source of antibacterial compounds, although the reports of its application in the medical field. Therefore, this study aims to present an integrative review of the antibacterial activity of spider webs. The research was conducted using Google Scholar, Scielo, Web of Science, PubMed, ScienceDirect, Medline EBSCO, LILACS, and Embase. The inclusion criteria were original articles written in English that studied the antibiotic properties of the web or isolated compounds tested. The studies were compared according to the spider species studied, the type of web, treatment of the sample, type of antimicrobial test, and the results obtained. Nine hundred and seventy-three publications were found, and after applying the inclusion and exclusion criteria, sixteen articles were selected. Bacterial inhibition was found in seven studies against various species of bacteria such as Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella Typhi, Bacillus megaterium, Listeria monocytogenes, Acinetobacter baumannii, Streptococcus pneumoniae, Pasteurella multocida, and Bacillus subtilis. Additionally, there was no apparent relationship between the proximity of the spider species evaluated in the studies and the presence or absence of activity. Methodological problems detected may affected the reproducibility and reliability of the results in some studies, such as the lack of description of the web or microorganism strain, as well as the absence of adequate controls and treatments to sterilize the sample. Spider webs can be a valuable source of antibiotics; however, more studies are needed to confirm the real activity of the web or components involved., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Biofilm formation by the pathogenic bacteria generates a serious threat to the public health as it can increase the virulence potential, resistance to drugs, and escape from the host immune response mechanisms. Among the environmental factors that influence the biofilm formation, there are only limited reports available on the role of antimicrobial agents. During the antimicrobial drug administration or application for any purpose, the microbial population can expect to get exposed to the sub-minimum inhibitory concentration (sub-MIC) of the drug which will have an unprecedented impact on microbial responses. Hence, the study has been conducted to investigate the effects of sub-MIC levels of zinc oxide nanoparticles (ZnO NPs) on the biofilm formation of Klebsiella pneumoniae and Staphylococcus aureus. Here, the selected bacteria were primarily screened for the biofilm formation by using the Congo red agar method, and their susceptibility to ZnO NPs was also evaluated. Quantitative difference in biofilm formation by the selected organisms in the presence of ZnO NPs at the sub-MIC level was further carried out by using the microtiter plate-crystal violet assay. Further, the samples were subjected to atomic force microscopy (AFM) analysis to evaluate the properties and pattern of the biofilm modulated under the experimental conditions used. From these, the organisms treated with sub-MIC levels of ZnO NPs were found to have enhanced biofilm formation when compared with the untreated sample. Also, no microbial growth could be observed for the samples treated with the minimum inhibitory concentration (MIC) of ZnO NPs. The results observed in the study provide key insights into the impact of nanomaterials on clinically important microorganisms which demands critical thinking on the antimicrobial use of nanomaterials., (© 2024. Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i.)

Mechanistic investigations are of paramount importance in elucidating the modes of action of antibiotics and facilitating the discovery of novel drugs. We reported a luciferase-based reporter system using bacterial cells to unveil mechanisms of antimicrobials targeting transcription and translation. The reporter gene Nluc encoding NanoLuciferase (NanoLuc) was integrated into the genome of the Gram-positive model organism, Bacillus subtilis , to generate a reporter strain BS2019. Cellular transcription and translation levels were assessed by quantifying the amount of Nluc mRNA as well as the luminescence catalyzed by the enzyme NanoLuc. We validated this system using three known inhibitors of transcription (rifampicin), translation (chloramphenicol), and cell wall synthesis (ampicillin). The B. subtilis reporter strain BS2019 successfully revealed a decline in Nluc expression by rifampicin and NanoLuc enzyme activity by chloramphenicol, while ampicillin produced no observable effect. The assay was employed to characterize a previously discovered bacterial transcription inhibitor, CUHK242, with known antimicrobial activity against drug-resistant Staphylococcus aureus . Production of Nluc mRNA in our reporter BS2019 was suppressed in the presence of CUHK242, demonstrating the usefulness of the construct, which provides a simple way to study the mechanism of potential antibiotic candidates at early stages of drug discovery. The reporter system can also be modified by adopting different promoters and reporter genes to extend its scope of contribution to other fields of work., Importance: Discovering new classes of antibiotics is desperately needed to combat the emergence of multidrug-resistant pathogens. To facilitate the drug discovery process, a simple cell-based assay for mechanistic studies is essential to characterize antimicrobial candidates. In this work, we developed a luciferase-based reporter system to quantify the transcriptional and translational effects of potential compounds and validated our system using two currently marketed drugs. Reporter strains generated in this study provide readily available means for identifying bacterial transcription inhibitors as prospective novel antibacterials. We also provided a series of plasmids for characterizing promoters under various conditions such as stress., Competing Interests: The authors declare no conflict of interest.

Mannheimia haemolytica is a major contributor to bovine respiratory disease (BRD), which causes substantial economic losses to the beef industry, and there is an urgent need for rapid and accurate diagnostic tests to provide evidence for treatment decisions and support antimicrobial stewardship. Diagnostic sequencing can provide information about antimicrobial resistance genes in M. haemolytica more rapidly than conventional diagnostics. Realizing the full potential of diagnostic sequencing requires a comprehensive understanding of the genetic markers of antimicrobial resistance. We identified genetic markers of resistance in M. haemolytica to macrolide class antibiotics commonly used for control of BRD. Genome sequences were determined for 99 M. haemolytica isolates with six different susceptibility phenotypes collected over 2 years from a feedlot in Saskatchewan, Canada. Known macrolide resistance genes estT , msr (E), and mph (E) were identified in most resistant isolates within predicted integrative and conjugative elements (ICEs). ICE sequences lacking antibiotic resistance genes were detected in 10 of 47 susceptible isolates. No resistance-associated polymorphisms were detected in ribosomal RNA genes, although previously unreported mutations in the L22 and L23 ribosomal proteins were identified in 12 and 27 resistant isolates, respectively. Pangenome analysis led to the identification of 79 genes associated with resistance to gamithromycin, of which 95% (75 of 79) had no functional annotation. Most of the observed phenotypic resistance was explained by previously identified antibiotic resistance genes, although resistance to the macrolides gamithromycin and tulathromycin was not explained in 39 of 47 isolates, demonstrating the need for continued surveillance for novel determinants of macrolide resistance.IMPORTANCEBovine respiratory disease is the costliest disease of beef cattle in North America and the most common reason for injectable antibiotic use in beef cattle. Metagenomic sequencing offers the potential to make economically significant reductions in turnaround time for diagnostic information for evidence-based selection of antibiotics for use in the feedlot. The success of diagnostic sequencing depends on a comprehensive catalog of antimicrobial resistance genes and other genome features associated with reduced susceptibility. We analyzed the genome sequences of isolates of Mannheimia haemolytica , a major bovine respiratory disease pathogen, and identified both previously known and novel genes associated with reduced susceptibility to macrolide class antimicrobials. These findings reinforce the need for ongoing surveillance for markers of antimicrobial resistance to support improved diagnostics and antimicrobial stewardship., Competing Interests: The authors declare no conflict of interest.

Rising antimicrobial resistance is a critical threat to worldwide public health. To address the increasing antibiotic tolerance, diverse antimicrobial agents are examined for their ability to decrease bacterial resistance. One of the most relevant and persistent human pathogens is Pseudomonas aeruginosa. Our study investigates the anti-biofilm and sensitizing activity of 12 morpholinium-based ionic liquids with herbicidal anions on four clinically relevant P. aeruginosa strains. Among all tested compounds, four ionic liquids prevented biofilm formation at sub-minimum inhibitory concentrations for all investigated strains. For the first time, we established a hormetic effect on biofilm formation for P. aeruginosa strains subjected to an ionic liquid treatment. Interestingly, while ionic liquids with 4,4-didecylmorpholinium [Dec 2 Mor] + are more efficient against planktonic bacteria, 4-decyl-4-ethylmorpholinium [DecEtMor] + showed more potent inhibition of biofilm formation. Ionic liquids with 4,4-didecylmorpholinium ([Dec 2 Mor] + ) cations even induced biofilm formation by strain 39016 at high concentrations due to flocculation. Morpholinium-based ionic liquids were also shown to enhance the efficacy of commonly used antibiotics from different chemical groups. We demonstrate that this synergy is associated with the mode of action of the antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Recently, the days of antibiotic spectrum coverage (DASC) using the antibiotic spectrum coverage (ASC) score was reported as a new tool for measuring antimicrobial use. The days of therapy (DOT) are required to calculate the DASC, making it impossible to use when patient-level information is unavailable. Therefore, we have defined a new measure of antimicrobial use for antimicrobial spectrum coverage (AUSC) using antimicrobial use density (AUD) and ASC scores. In this study, we have investigated the use of antimicrobial agents retrospectively examined for monthly prescriptions between 2016 and 2022, and whether the AUSC could be used as a new measure. Our data showed that the AUD, AUSC, DOT, and DASC increased, whereas AUSC/AUD and DASC/DOT decreased over the study period. In addition, no correlation was found between DOT and DASC/DOT (ρ = - 0.093, p = 0.399), whereas there was a weak correlation between AUD and AUSC/AUD (ρ = - 0.295, p = 0.006). Therefore, in this study, the use of AUSC is considered less beneficial when DASC can be calculated based on DOT. On the other hand, in institutional settings where DOT cannot be calculated, AUSC may be useful as a new measure to evaluate antimicrobial use., (© 2024. The Author(s).)

Diarrhoea remains an important public health concern, particularly in developing countries, and has become difficult to treat because of antibacterial resistance. The development of synergistic antimicrobial agents appears to be a promising alternative treatment against diarrhoeic infections. In this study, the combined effect of tetracycline together with either nitroxoline, sanguinarine, or zinc pyrithione (representing various classes of plant-based compounds) was evaluated in vitro against selected diarrhoeic bacteria ( Enterococcus faecalis , Escherichia coli , Listeria monocytogenes , Shigella flexneri , Vibrio parahaemolyticus , and Yersinia enterocolitica ). The chequerboard method in 96-well microtiter plates was used to determine the sum of the fractional inhibitory concentration indices (FICIs). Three independent experiments were performed per combination, each in triplicate. It was observed that the combination of tetracycline with either nitroxoline, sanguinarine, or zinc pyrithione produced synergistic effects against most of the pathogenic bacteria tested, with FICI values ranging from 0.086 to 0.5. Tetracycline-nitroxoline combinations produced the greatest synergistic action against S. flexneri at a FICI value of 0.086. The combinations of the agents tested in this study can thus be used for the development of new anti-diarrhoeic medications. However, studies focusing on their in vivo anti-diarrhoeic activity and safety are required before any consideration for utilization in human medicine.

In response to the escalating challenge of bacterial drug resistance, the imperative to counteract planktonic cell proliferation and eliminate entrenched biofilms underscores the necessity for cationic polymeric antibacterials. However, limited efficacy and cytotoxicity challenge their practical use. Here, novel imidazolium-based main-chain copolymers with imidazolium (PIm + ) as the cationic component are introduced. By adjusting precursor molecules, hydrophobicity and cationic density of each unit are fine-tuned, resulting in broad-spectrum bactericidal activity against clinically relevant pathogens. PIm + 1 stands out for its potent antibacterial performance, with a minimum inhibitory concentration of 32 µg mL -1 against Methicillin-resistant Staphylococcus aureus (MRSA), and substantial biofilm reduction in Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) biofilms. The bactericidal mechanism involves disrupting the outer and cytoplasmic membranes, depolarizing the cytoplasmic membrane, and triggering intracellular reactive oxygen species (ROS) generation. Collectively, this study postulates the potential of imidazolium-based main-chain copolymers, systematically tailored in their sequences, to serve as a promising candidate in combatting drug-resistant bacterial infections., (© 2024 Wiley‐VCH GmbH.)

Resistance to antibiotics and antimicrobial compounds is a significant problem for human and animal health globally. The development and introduction of new antimicrobial compounds are urgently needed, and copper oxide nanoparticles (CuO NPs) have found widespread application across various sectors including biomedicine, pharmacy, catalysis, cosmetics, and many others. What makes them particularly attractive is the possibility of their synthesis through biogenic routes. In this study, we synthesized biogenic green tea (GT, Camellia sinensis )-derived CuO NPs (GT CuO NPs) and examined their biophysical properties, in vitro toxicity for mammalian cells in culture, and then tested them against Neisseria gonorrhoeae , an exemplar Gram-negative bacterium from the World Health Organization's Priority Pathogen List. We compared our synthesized GT CuOP NPs with commercial CuO NPs (Com CuO NPs). Com CuO NPs were significantly more cytotoxic to mammalian cells (IC50 of 7.32 μg/mL) than GT CuO NPs (IC50 of 106.1 μg/mL). GT CuO NPs showed no significant increase in bax, bcl2, il6 , and il1β mRNA expression from mammalian cells, whereas there were notable rises after treatment with Com CuO NPs. GT-CuO NPs required concentrations of 0.625 and 3.125 μg/mL to kill 50 and 100% of bacteria, respectively, whereas Com-CuO NPs needed concentrations of 15.625 and 30 μg/mL to kill 50 and 100% of bacteria, and the antibiotic ceftriaxone killed 50 and 100% with 3.125 and 30 μg/mL. Gonococci could be killed within 30 min of exposure to GT CuO NPs and the NPs could kill up to 10 7 within 1 h. In summary, this is the first report to our knowledge that describes the bioactivity of biogenic CuO NPs against N. gonorrhoeae . Our data suggest that biogenic nanoparticle synthesis has significant advantages over traditional chemical routes of synthesis and highlights the potential of GT-CuO NPs in addressing the challenges posed by multidrug-resistant Neisseria gonorrhoeae infections.

Patients receiving hemodialysis (HD) often develop gastrointestinal diseases. Recently, although in general population, clinical guidelines for Helicobacter pylori have strongly recommended its eradication in patients to prevent gastric cancer, optimal eradication regimen and optimal dosage of drugs for patients receiving HD have not been established, due to possible incidence of adverse events. Some antimicrobial agents used in eradication therapy, particularly amoxicillin, can exacerbate renal dysfunction. Given the delayed pharmacokinetics of drugs in patients receiving HD compared with those in healthy individuals, drug regimen and dosage should be considered to minimize adverse effects. Although previous studies have investigated the benefits of eradication therapy for patients receiving HD, because most studies were small in terms of the number of enrolled patients, it is hard to show evidence. The numbers of eradication in HD patients have recently increased, and it is important to provide an optimal regimen. The consideration of eradication in patients undergoing HD with a reduction in the drug dose by 1/2-1/3 may prevent adverse events. Additionally, another important consideration is whether adverse events can be prevented while maintaining a similar eradication rate with reduced drug dosages. Recent meta-analysis findings indicate comparable eradication rates in patients receiving HD and healthy individuals, both with the same dosage regimen and at a reduced dosage regimen, with no significant differences (relative risk [RR] for successful eradication: 0.85 [95% confidence interval (CI): 0.48-1.50]). Unlike with the same dosage regimen (RR for adverse events: 3.15 [95% CI: 1.93-5.13]), the adverse events in the dosage reduction regimen were similar to those in healthy individuals (RR: 1.26 [95% CI: 0.23-6.99]). From a pharmacological perspective, the eradication regimen in patients receiving HD should consider the dosage (1/2-1/3 dosage), dosing number (bid), dosing timing of drugs (after HD), and susceptibility to antimicrobial agents., (© 2024 John Wiley & Sons Ltd.)

Objectives: This study aimed to appraise clinical practice guidelines (CPGs) for the treatment of carbapenem-resistant Gram-negative Bacilli (CRGNB) infections and to summarise the recommendations., Methods: A systematic search of the literature published from January 2012 to March 2023 was undertaken to identify CPGs related to CRGNB infections treatment. The methodological and reporting quality of eligible CPGs were assessed using six domains of the Appraisal of Guidelines for Research and Evaluation (AGREE) II tool and seven domains of the Reporting Items for practice Guidelines in HealThcare (RIGHT) checklist. Basic information and recommendations of included CPGs were extracted and compared., Results: A total of 21 CPGs from 7953 relevant articles were included. The mean overall AGREE II score was 62.7%, and was highest for "clarity of presentation" (90.2%) and lowest for "stakeholder involvement" (44.8%). The overall reporting quality of all of the CPGs was suboptimal, with the proportion of eligible items ranging from 45.7 to 85.7%. The treatment of CRGNB infections is related to the type of pathogen, the sensitivity of antimicrobial agents, and the site of infection. In general, the recommended options mainly included novel β-lactam/ β-lactamase inhibitors, cefiderocol, ampicillin-sulbactam (mainly for carbapenem-resistant Acinetobacter baumannii [CRAB]), and combination therapy, involving polymyxin B/colistin, tigecycline (except for carbapenem-resistant Pseudomonas aeruginosa), aminoglycosides, carbapenems, fosfomycin, and sulbactam (mainly for CRAB)., Conclusions: The methodological and reporting quality of CPGs for the treatment of CRGNB infections are generally suboptimal and need further improvement. Both monotherapy with novel drugs and combination therapy play important roles in the treatment., (Copyright © 2024 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.)

Bacteriocins are highly diverse, abundant, and heterogeneous antimicrobial peptides that are ribosomally synthesized by bacteria and archaea. Since their discovery about a century ago, there has been a growing interest in bacteriocin research and applications. This is mainly due to their high antimicrobial properties, narrow or broad spectrum of activity, specificity, low cytotoxicity, and stability. Though initially used to improve food quality and safety, bacteriocins are now globally exploited for innovative applications in human, animal, and food systems as sustainable alternatives to antibiotics. Bacteriocins have the potential to beneficially modulate microbiota, providing viable microbiome-based solutions for the treatment, management, and non-invasive bio-diagnosis of infectious and non-infectious diseases. The use of bacteriocins holds great promise in the modulation of food microbiomes, antimicrobial food packaging, bio-sanitizers and antibiofilm, pre/post-harvest biocontrol, functional food, growth promotion, and sustainable aquaculture. This can undoubtedly improve food security, safety, and quality globally. This review highlights the current trends in bacteriocin research, especially the increasing research outputs and funding, which we believe may proportionate the soaring global interest in bacteriocins. The use of cutting-edge technologies, such as bioengineering, can further enhance the exploitation of bacteriocins for innovative applications in human, animal, and food systems., (© 2024. The Author(s).)

Background: The management of medication for patients undergoing urological surgery is a subject of ongoing controversy, especially in elucidating the effect of clinical pharmacists on medication rationality. This study aims to assess the influence of clinical pharmacist service on the utilization of antibacterial and hepatoprotective drugs in urological surgery patients during the perioperative period., Methods: Patients undergoing urological surgery in our hospital from January 2020, to January 2023, were consecutively selected. The patients were divided into control group (routine procedure) and observation group (routine procedure + clinical pharmacist service). The baseline data were balanced by 1:1 propensity score matching (PSM). The t test and chi-square test were used to compare the drug use, adverse reactions, and hospitalization-related indicators between the two groups., Results: A total of 292 patients were included, with 100 patients in each group after PSM. No significant difference was found in the baseline data between the two groups ( p > 0.05). The rationality of drug use (drug type, administration time, course of treatment, and combination) in the observation group was significantly better than that in the control group (χ 2 = 8.489, 10.607, 10.895, 10.666; p = 0.004, 0.001, 0.001, 0.001). The incidence of adverse reactions (6.00%) and postoperative complications (7.00%) was significantly lower (χ 2 = 4.903, 5.531; p = 0.027, 0.019). The length of hospital stay and total cost were similar ( p > 0.05). The use time and cost of antibacterial and hepatoprotective drugs in the observation group were lower than those in the control group (t = 2.935, 3.450, 3.243, 3.532; p = 0.004, 0.001, 0.001, 0.001). The types and rates of antibacterial and hepatoprotective drugs in the observation group were significantly lower than those in the control group ( p < 0.05)., Conclusions: Clinical pharmacist service can effectively improve the rationality of drug use in urological surgery patients and reduce adverse reactions and postoperative complications, hence its clinical promotion value., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s).)

Effective treatment of drug-resistant bacteria infected wound has been a longstanding challenge for healthcare systems. In particular, the development of novel strategies for controllable delivery and smart release of antimicrobial agents is greatly demanded. Herein, the design of biodegradable microcapsules carrying bactericidal gold nanoclusters (AuNCs) as an attractive platform for the effective treatment of drug-resistant bacteria infective wounds is reported. AuNC capsules are fabricated via the well-controlled layer-by-layer strategy, which possess intrinsic near-infrared fluorescence and good biocompatibility. Importantly, these AuNC capsules exhibit strong, specific antibacterial activity toward both S. aureus and methicillin-resistant S. aureus (MRSA). Further mechanistic studies by fluorescence confocal imaging and inductively coupled plasma mass spectrometry reveal that these AuNC capsules will be degraded in the S. aureus environment rather than E. coli, which then controllably release the loaded cationic AuNCs to exert antibacterial effect. Consequently, these AuNC capsules show remarkable therapeutic effect for the MRSA infected wound on a mouse model, and intrinsic fluorescence property of AuNC capsules enables in situ visualization of wound dressings. This study suggests the great potential of microcapsule-based platform as smart carriers of bactericidal agents for the effective treatment of drug-resistant bacterial infection as well as other therapeutic purposes., (© 2024 Wiley‐VCH GmbH.)

Background: Augmented renal clearance (ARC) is a phenomenon observed in critically ill patients, leading to supraphysiologic drug clearance and concern for suboptimal antibiotic concentrations. The purpose of this study was to compare the clinical outcomes of our institutional protocolized antibiotic dosing regimen in critically ill patients with bacteremia and ARC compared with critically ill patients without ARC. Patients and Methods: We performed a retrospective study comparing the efficacy of an institutional protocolized antibiotic dosing regimen in critically ill patients with bacteremia and ARC compared with critically ill patients without ARC. The primary end point was in-hospital mortality. Secondary outcomes were intensive care unit (ICU) mortality, days requiring mechanical ventilation, ICU length of stay (LOS), hospital LOS, development of drug resistance to index antibiotic agent, and documented clearance of blood cultures within 72 hours. Results: There were 75 patients included in this study. Twenty percent of patients in the ARC group died in the hospital versus 31% in the non-ARC group (p = 0.26). The results for the ARC group versus the non-ARC group for the secondary outcomes of ICU mortality (20% vs. 26%; p = 0.56), ICU LOS (14.7 days vs. 7 days; p = 0.07), hospital LOS (28.3 days vs. 21.6 days; p = 0.03), days requiring mechanical ventilation (14 days vs. 12 days; p = 0.49), duration of antibiotic therapy (7.5 days vs. 9.0 days; p = 0.39), documented clearance of blood cultures within 72 hours (41% vs. 33%; p = 0.56), and the development of drug resistance to the index antibiotic agent (0% vs. 0%; p > 0.99) were also calculated. Conclusions: Among critically ill patients with bacteremia and ARC, there was no difference in in-hospital mortality compared with critically ill patients without ARC. There was a difference in hospital LOS, with a shorter duration of stay for the non-ARC group. There was no development of multi-drug-resistant organisms in either group.

The escalating mortality rate resulting from multidrug-resistant (MDR) bacteria has intensified the urgency for innovative antimicrobial agents. Currently, the antimicrobial activity of compounds is usually assessed by testing the minimum inhibitory concentration (MIC) on a standardized laboratory medium. However, such screening conditions differ from the in vivo environment, making it easy to overlook some antibacterial agents that are active in vivo but less active in vitro. Herein, by using tissue medium RPMI, we uncover that anthracyclines, especially mitoxantrone (MX), exhibit improved bacteriostatic and bactericidal effects against various MDR bacteria in host-like media. Transcriptome results reveal that LPS modification-related genes of bacterial membrane surfaces and metabolic genes are significantly down-regulated in RPMI media. Mechanistic studies demonstrate that MX leads to more substantial membrane damage, increased ROS production, and DNA damage in host-mimicking conditions. Furthermore, we demonstrate that MX and colistin exhibit strong synergistic effects against mcr -positive strains in host-mimicking media by disrupting iron homeostasis. In an experimental murine infection model, MX monotreatment demonstrates therapeutic efficacy in reducing bacterial burdens. Overall, our work suggests that mimicking the host condition is an effective strategy to identify new antimicrobial agents and highlights the therapeutic potential of anthracycline drugs in combating MDR pathogens.

Staphylococcus aureus is a highly adaptable opportunistic pathogen that can form biofilms and generate persister cells, leading to life-threatening infections that are difficult to treat with antibiotics alone. Therefore, there is a need for an effective S. aureus biofilm inhibitor to combat this public health threat. In this study, a small library of indolenine-substituted pyrazoles and pyrimido[1,2-b]indazole derivatives were synthesised, of which the hit compound exhibited promising antibiofilm activities against methicillin-susceptible S. aureus (MSSA ATCC 29213) and methicillin-resistant S. aureus (MRSA ATCC 33591) at concentrations significantly lower than the planktonic growth inhibition. The hit compound could prevent biofilm formation and eradicate mature biofilms of MSSA and MRSA, with a minimum biofilm inhibitory concentration (MBIC 50 ) value as low as 1.56 µg/mL and a minimum biofilm eradication concentration (MBEC 50 ) value as low as 6.25 µg/mL. The minimum inhibitory concentration (MIC) values of the hit compound against MSSA and MRSA were 50 µg/mL and 25 µg/mL, respectively, while the minimum bactericidal concentration (MBC) values against MSSA and MRSA were > 100 µg/mL. Preliminary structure-activity relationship analysis reveals that the fused benzene ring and COOH group of the hit compound are crucial for the antibiofilm activity. Additionally, the compound was not cytotoxic to human alveolar A549 cells, thus highlighting its potential as a suitable candidate for further development as a S. aureus biofilm inhibitor., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Antimicrobial resistance increases infection morbidity in both adults and children, necessitating the development of new therapeutic options. Telavancin, an antibiotic approved in the United States for certain bacterial infections in adults, has not been examined in pediatric patients. The objectives of this study were to evaluate the short-term safety and pharmacokinetics (PK) of a single intravenous infusion of telavancin in pediatric patients. Single-dose safety and PK of 10 mg/kg telavancin was investigated in pediatric subjects >12 months to ≤17 years of age with known or suspected bacterial infection. Plasma was collected up to 24-h post-infusion and analyzed for concentrations of telavancin and its metabolite for noncompartmental PK analysis. Safety was monitored by physical exams, vital signs, laboratory values, and adverse events following telavancin administration. Twenty-two subjects were enrolled: 14 subjects in Cohort 1 (12-17 years), 7 subjects in Cohort 2 (6-11 years), and 1 subject in Cohort 3 (2-5 years). A single dose of telavancin was well-tolerated in all pediatric age cohorts without clinically significant effects. All age groups exhibited increased clearance of telavancin and reduced exposure to telavancin compared to adults, with mean peak plasma concentrations of 58.3 µg/mL (Cohort 1), 60.1 µg/mL (Cohort 2), and 53.1 µg/mL (Cohort 3). A 10 mg/kg dose of telavancin was well tolerated in pediatric subjects. Telavancin exposure was lower in pediatric subjects compared to adult subjects. Further studies are needed to determine the dose required in phase 3 clinical trials in pediatrics., Competing Interests: J.S.B., J.L.G., L.P.J., and A.A. were investigators on this clinical study. B.K. and B.H.Y.G. are employees of Cumberland Pharmaceuticals.

The analysis of antimicrobial activity is usually MIC- and minimal bactericidal concentration (MBC)-focused, though also crucial are resistance-related parameters, e.g., the frequency of spontaneous mutant selection (FSMS), the mutant prevention concentration (MPC), and the mutant selection window (MSW). In vitro -determined MPCs, however, are sometimes variable, poorly repeatable, and not always reproducible in vivo . We propose a new approach to the in vitro determination of MSWs, along with novel parameters: MPC-D, MSW-D (for dominant mutants, i.e., selected with a high frequency, without a fitness loss), and MPC-F, MSW-F (for inferior mutants, i.e., with an impaired fitness). We also propose a new method for preparing the high-density inoculum (>10 11 CFU/mL). In this study, the MPC and MPC-D (limited by FSMS of <10 -10 ) of ciprofloxacin, linezolid, and novel benzosiloxaborole (No37) were determined for Staphylococcus aureus ATCC 29213 using the standard agar method, while the MPC-D and MPC-F were determined by the novel broth method. Regardless of the method, MSWs 10 10 of linezolid and No37 were the same. However, MSWs 10 10 of ciprofloxacin in the broth method was narrower than in the agar method. In the broth method, the 24-h incubation of ~10 10 CFU in a drug-containing broth differentiates the mutants that can dominate the cell population from those that can only be selected under exposure. We consider MPC-Ds in the agar method to be less variable and more repeatable than MPCs. Meanwhile, the broth method may decrease discrepancies between in vitro and in vivo MSWs. The proposed approaches may help establish MPC-D-related resistance-restricting therapies., Competing Interests: The authors declare no conflict of interest.

Background: Antimicrobial prescriptions for serious chronic or acute illness nearing its end stages raise concerns about the potential for futile use, adverse events, increased multidrug-resistant organisms, and significant patient and social cost burdens. This study investigated the nationwide situation of how antibiotics are prescribed to patients during the last 14 days of life to guide future actions., Methods: This nationwide multicenter retrospective cohort study was conducted at 13 hospitals in South Korea from November 1 to December 31, 2018. All decedents were included in the study. Antibiotic use during the last two weeks of their lives was investigated., Results: A total of 1,201 (88.9%) patients received a median of two antimicrobial agents during the last two weeks of their lives. Carbapenems were prescribed to approximately half of the patients (44.4%) in the highest amount (301.2 days of therapy per 1,000 patient-days). Among the patients receiving antimicrobial agents, 63.6% were inappropriate and only 327 patients (27.2%) were referred by infectious disease specialists. The use of carbapenem (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.13-2.03; P = 0.006), underlying cancer (OR, 1.56; 95% CI, 1.20-2.01, P = 0.047), underlying cerebrovascular disease (OR, 1.88; 95% CI, 1.23-2.89, P = 0.004), and no microbiological testing (OR, 1.79; 95% CI, 1.15-2.73; P = 0.010) were independent predictors for inappropriate antibiotic prescribing., Conclusion: A considerable number of antimicrobial agents are administered to patients with chronic or acute illnesses nearing their end-of-life, a high proportion of which are prescribed inappropriately. Consultation with an infectious disease specialist, in addition to an antimicrobial stewardship program, may be necessary to induce the optimal use of antibiotics., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2023 The Korean Academy of Medical Sciences.)

Carbapenem-resistant Enterobacteriaceae (CRE) are emerging pathogens that cause variety of severe infections. CRE evade antibiotic treatments because these bacteria produce enzymes that degrade a wide range of antibiotics including carbapenems and β-lactams. The formation of biofilms aggravates CRE infections, especially in a wound environment. These difficulties lead to persistent infection and non-healing wounds. This creates the need for new compounds to overcome CRE antimicrobial resistance and disrupt biofilms. Recent studies in our lab show that 600 Da branched polyethyleneimine (BPEI) and its derivative PEG350-BPEI can overcome antimicrobial resistance and eradicate biofilms in methicillin-resistant S. aureus, methicillin-resistant S. epidermidis, P. aeruginosa, and E. coli. In this study, the ability of 600 Da BPEI and PEG350-BPEI to eradicate carbapenem-resistant Enterobacteriaceae bacteria and their biofilms is demonstrated. We show that both BPEI and PEG350-BPEI have anti-biofilm efficacy against CRE strains expressing Klebsiella pneumoniae carbapenemases (KPCs) and metallo-β-lactamases (MBLs), such as New Delhi MBL (NDM-1). Furthermore, our results illustrate that BPEI affects planktonic CRE bacteria by increasing bacterial length and width from the inability to proceed with normal cell division processes. These data demonstrate the multi-functional properties of 600 Da BPEI and PEG350-BPEI to reduce biofilm formation and mitigate virulence in carbapenem-resistant Enterobacteriaceae., (© 2022 Wiley-VCH GmbH.)

Antibiotics represent a first line of defense of diverse microorganisms, which produce and use antibiotics to counteract natural enemies or competitors for nutritional resources in their nearby environment. For antimicrobial activity, nature has invented a great variety of antibiotic modes of action that involve the perturbation of essential bacterial structures or biosynthesis pathways of macromolecules such as the bacterial cell wall, DNA, RNA, or proteins, thereby threatening the specific microbial lifestyle and eventually even survival. However, along with highly inventive modes of antibiotic action, nature also developed a comparable set of resistance mechanisms that help the bacteria to circumvent antibiotic action. Microorganisms have evolved specific adaptive responses that allow to appropriately react to the presence of antimicrobial agents, thereby ensuring survival during antimicrobial stress. In times of rapid development and spread of antibiotic (multi-)resistance, new resistance-breaking strategies to counteract bacterial infections are desperately needed. This chapter is an update to Chapter 1 of the first edition of this book and intends to give an overview of common antibiotics and their target pathways. It will also present examples for new antibiotics with novel modes of action, illustrating that nature's repertoire of innovative new antimicrobial agents has not been fully exploited yet, and we still might find new drugs that help to evade established antimicrobial resistance strategies., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Staphylococcus epidermidis is implicated in a multitude of human infections and is one of the major causes of clinical infections in hospitals, especially at surgical sites and on indwelling medical devices, such as orthopedic implants. These infections are especially dangerous because of the S. epidermidis propensity to form biofilms, which increases resistance to antibiotics and the natural immune response. This study investigated pulsed electromagnetic fields (PEMF) as a potential treatment to combat such infections, as PEMF exposure was expected to disrupt the electrostatic forces that adhere staphylococcal cells to surfaces and to one another. To test the effect of PEMF on biofilms, S. epidermidis cultures were exposed to PEMF at various durations either during the growth phase or after a full biofilm had formed. In addition, cells were exposed to PEMF and concomitant antibiotic treatment. Biofilm viability was quantified by both crystal violet and alamarBlue assays and scanning electron microscopy. The results demonstrated that PEMF significantly inhibited biofilm formation and disrupted preformed biofilms in vitro while also showing synergistic biofilm inhibition when combined with antibiotics. These combined results indicate that PEMF should be considered a promising novel technique for treating S. epidermidis biofilm infections and undergo further testing in vivo . IMPORTANCE Antibiotic resistance and biofilm infections are major issues in health care because of the lack of a successful treatment modality and poor patient outcomes. These infections are a particular issue following orthopedic surgery or trauma wherein an infection may form on an orthopedic implant or patient's bone. The presented study demonstrates that pulsed electromagnetic fields may be a promising novel treatment for such infections and can overcome the medical challenges presented by biofilm formation. Furthermore, the effects demonstrated are even greater when combining pulsed electromagnetic field therapy with traditional antibiotics.

Background: Our study investigated the susceptibility rate of ceftazidime-avibactam and the risk factors associated with its resistance by analyzing gram-negative bacteria isolated from various patient samples., Methods: Between March and November 2020, 1119 gram-negative bacteria strains were isolated from patient samples in Acıbadem Healthcare Group hospitals; ceftazidime-avibactam susceptibility results were evaluated using a 10/4µg (Oxoid, UK) disc and evaluated according to Eucast 2020 recommendations. Patient and isolate characteristics that could be risk factors were retrospectively investigated and statistically analyzed using SPSS 25.0., Results: Male patients made up 52% (n = 581) of the study's total patient population, and they averaged 55.5 ± 24.9 years old. Of 1119 gram-negative strains culture and antibiogram, 1023 (91.4%) were sensitive to ceftazidime-avibactam. An increased risk of resistance was observed with female gender (OR = 2.29; CI 95% [1.45-3.61]; p < 0.05), Pseudomonas aeruginosa (OR = 1.67, CI 95% [1.03-2.7]; p < 0.05), the presence of multidrug-resistance (MDR) (OR = 4.07, CI 95% [2.47-6.7]; p < 0.05) pandrug-resistance (PDR) (OR = 12, (CI) 95% [9.9-14.7] ]; p < 0.05) and admission to intensive care unit (ICU) (OR = 1.89, CI 95% [1.22-2.93]; p < 0.05)., Discussion: The resistance rate of ceftazidime-avibactam was found to be 8.6%, and it was thought that resistant strains produced metallo-ß-lactamase (MBL) type carbapenemase. Risk factors were female gender, Pseudomonas aeruginosa, MDR, PDR, and admission to ICU. Therefore, studying the ceftazidime-avibactam susceptibility test together with gram-negative bacteria identification, especially in groups at risk for resistance, is one of the important factors that can positively affect the success of treatment.

To investigate the contribution of a tet (A) variant to tigecycline resistance in Enterobacter hormaechei and the recombination events that occurred during transmission of this variant. MICs were determined by broth microdilution. E. hormaechei G17 was characterized by PCR, transfer assay, S1-PFGE, Southern blot hybridization, and WGS analysis. A tet (A) variant conferring resistance to tigecycline was present in E. hormaechei G17. This strain harbored two resistance plasmids (pG17-1, 264,084 bp and pG17-2, 68,610 bp) and its E. coli transformant T m -G17 TGC one resistance plasmid (pTm-G17, 93,013 bp). The comparative analysis of pG17-1, pG17-2, and pTm-G17 showed that a tet (A) variant-carrying multiresistance gene cluster (~23 kb) originating from pG17-1 had integrated into pG17-2, forming the novel plasmid pTm-G17. In a first step, this multiresistance gene cluster was excised from pG17-1 by recombination of homologous sequences, including △Tn As1 at both termini, thereby generating an unconventional circularizable structure (UCS). In a second step, this UCS integrated into pG17-2 via recombination between homologous sequences, including IS 26 present on both, the UCS and pG17-2, thereby giving rise to the new plasmid pTm-G17. In summary, a tet (A) variant conferring resistance to tigecycline was reported in E. hormaechei . Transfer of a tet (A) variant-carrying multiresistance gene cluster between plasmids occurred in a two-step recombination process, in which homologous sequences, including either △Tn As1 or IS 26 , were involved. IMPORTANCE Tigecycline is an important last-resort broad spectrum antimicrobial agent. This study describes the two-step recombination processes resulting in the transfer of the tet (A) variant gene between different plasmids in E. hormaechei , which depicts the role of recombination processes in the generation of UCSs and new plasmids, both carrying a tet (A) variant conferring resistance to tigecycline. Such processes enhance the dissemination of resistance genes, which is of particular relevance for resistance genes, such as the tet (A) variant. The presence and transmission of a tet (A) variant in E. hormaechei will compromise the efficacy of tigecycline treatment for E. hormaechei associated infection.

Antimicrobial peptides (AMPs) are being explored as alternatives to traditional antibiotics to combat the rising antimicrobial resistance. Insects have proven to be a valuable source of new, potent AMPs with large structural diversity. For example, the black soldier fly has one of the largest AMP repertoires ever recorded in insects. Currently, however, this AMP collection has not yet undergone antimicrobial evaluation or in-depth in vitro characterization. This study evaluated the activity of a library of 36 black soldier fly AMPs against a panel of human pathogens (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Aspergillus fumigatus) and a human cell line (MRC5-SV2). The activity profile of two cecropins (Hill-Cec1 and Hill-Cec10) with potent Gram-negative activity, was further explored by characterizing their hemolysis, time-to-kill kinetics, membrane-permeabilization properties, and anti-biofilm activity. Hill-Cec1 and Hill-Cec10 also showed high activity against other bacterial species, including Klebsiella pneumoniae and multi-drug resistant P. aeruginosa. Both AMPs are bactericidal and have a rapid onset of action with membrane-permeabilizing effects. Hill-Cec1 and Hill-Cec10 were also able to prevent P. aeruginosa biofilm formation, but no relevant effect was seen on biofilm eradication. Overall, Hill-Cec1 and Hill-Cec10 are promising leads for new antimicrobial development to treat critical infections caused by Gram-negative pathogens such as P. aeruginosa. IMPORTANCE With the ever growing antimicrobial resistance, finding new candidates for antimicrobial drug development is indispensable. Antimicrobial peptides have steadily gained attention as alternatives for conventional antibiotics, due to some highly desirable characteristics, such as their low propensity for resistance development. With this article, we aim to upgrade the knowledge on the activity of black soldier fly antimicrobial peptides and their potential as future therapeutics. To achieve this, we have evaluated for the first time a library of 36 synthetically produced peptides from the black soldier fly against a range of human pathogens and a human cell line. Two selected peptides have undergone additional testing to characterize their antimicrobial profile against P. aeruginosa, a clinically important Gram-negative pathogen with a high established resistance. Overall, this research has contributed to the search for new peptide drug leads to combat the rising antimicrobial resistance.

Antibiotic resistance is a continually growing challenge in the treatment of various bacterial infections worldwide. New drugs and new drug targets are necessary to curb the threat of infectious diseases caused by multidrug-resistant pathogens. The tryptophan biosynthesis pathway is essential for bacterial growth but is absent in higher animals and humans. Drugs that can inhibit the bacterial biosynthesis of tryptophan offer a new class of antibiotics. In this work, we combined a structure-based strategy using in silico docking screening and molecular dynamics (MD) simulations to identify compounds targeting the α subunit of tryptophan synthase with experimental methods involving the whole-cell minimum inhibitory concentration (MIC) test, solution state NMR, and crystallography to confirm the inhibition of L-tryptophan biosynthesis. Screening 1,800 compounds from the National Cancer Institute Diversity Set I against α subunit revealed 28 compounds for experimental validation; four of the 28 hit compounds showed promising activity in MIC testing. We performed solution state NMR experiments to demonstrate that a one successful inhibitor, 3-amino-3-imino-2-phenyldiazenylpropanamide (Compound 1) binds to the α subunit. We also report a crystal structure of Salmonella enterica serotype Typhimurium tryptophan synthase in complex with Compound 1 which revealed a binding site at the αβ interface of the dimeric enzyme. MD simulations were carried out to examine two binding sites for the compound. Our results show that this small molecule inhibitor could be a promising lead for future drug development., (© 2021 The Protein Society.)

The emergence of bacterial multidrug resistance and the lack of new antimicrobial agents urgently demand the discovery and development of novel antibacterials that avoid bacterial resistance. Antimicrobial peptidomimetics represent a promising approach for overcoming antibiotic resistance. Herein we report the synthesis and evaluation of indole-based amphiphilic antimicrobial peptidomimetics, bearing hydrophobic side chains and hydrophilic cationic moieties. Among these derivatives, compound 28 demonstrated potent antimicrobial activity against Gram-positive bacteria, low hemolytic activity and low toxicity towards mammalian cells, as well as good stability in salt conditions. Moreover, compound 28 showed the rapid killing of bacteria via membrane-targeting action without developing bacterial resistance. More importantly, compound 28 displayed high antimicrobial potency against Gram-positive bacteria in a murine model of bacterial keratitis, and was found to be more efficient than vancomycin. Thus, compound 28 had great potential as a promising lead compound for the treatment of Gram-positive bacterial infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Staphylococcal-associated device-related infections (DRIs) represent a significant clinical challenge causing major medical and economic sequelae. Bacterial colonization, proliferation, and biofilm formation after adherence to surfaces of the indwelling device are probably the primary cause of DRIs. To address this issue, we incorporated constructs of silica-binding peptide (SiBP) with ClyF, an anti-staphylococcal lysin, into functionalized coatings to impart bactericidal activity against planktonic and sessile Staphylococcus aureus . An optimized construct, SiBP1-ClyF, exhibited improved thermostability and staphylolytic activity compared to its parental lysin ClyF. SiBP1-ClyF-functionalized coatings were efficient in killing MRSA strain N315 (>99.999% within 1 h) and preventing the growth of static and dynamic S. aureus biofilms on various surfaces, including siliconized glass, silicone-coated latex catheter, and silicone catheter. Additionally, SiBP1-ClyF-immobilized surfaces supported normal attachment and growth of mammalian cells. Although the recycling potential and long-term stability of lysin-immobilized surfaces are still affected by the fragility of biological protein molecules, the present study provides a generic strategy for efficient delivery of bactericidal lysin to solid surfaces, which serves as a new approach to prevent the growth of antibiotic-resistant microorganisms on surfaces in hospital settings and could be adapted for other target pathogens as well.

The antimicrobial resistance (AMR) is an intractable problem for the world. Metal ions are essential for the cell process and biological function in microorganisms. Many metal-based complexes with the potential for releasing ions are more likely to be absorbed for their higher lipid solubility. Hence, this review highlights the clinical potential of organometallic compounds for the treatment of infections caused by bacteria or fungi in recent five years. The common scaffolds, including antimicrobial peptides, N-heterocyclic carbenes, Schiff bases, photosensitive-grand-cycle skeleton structures, aliphatic amines-based ligands, and special metal-based complexes are summarized here. We also discuss their therapeutic targets and the risks that should be paid attention to in the future studies, aiming to provide information for researchers on metal-based complexes as antimicrobial agents and inspire the design and synthesis of new antimicrobial drugs., Competing Interests: Declaration of competing interest We declare that we have no financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Liposomal delivery systems have been widely explored for targeting superbugs such as S. aureus and MRSA, overcoming antimicrobial resistance associated with conventional dosage forms. They have the significant advantage of delivering hydrophilic and lipophilic antimicrobial agents, either singularly as monotherapy or in combination as combination therapy, due to their bilayers with action-site-specificity, resulting in improved targeting compared to conventional dosage forms. Herein, we present an extensive and critical review of the different liposomal delivery systems employed in the past two decades for the delivery of both antibiotics of different classes and non-antibiotic antibacterial agents, as monotherapy and combination therapy to eradicate infections caused by S. aureus and MRSA. The review also identifies future research and strategies potentiating the applications of liposomal delivery systems against S. aureus and MRSA. This review confirms the potential application of liposomal delivery systems for effective delivery and specific targeting of S. aureus and MRSA infections., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Efficient, environmentally and economically sustainable, and nontoxic antibacterial products are of global relevance in the fight against microorganism contamination. In this work, an easy and straightforward method for the synthesis of bis-morpholino triazine quaternary ammonium salts (bis-mTQAS) is reported, starting from 2,4,6-trichloro-1,3,5-triazine or 2,4-dichloro-6-methoxy-1,3,5-triazine and various N-alkylmorpholines. Bis-mTQAS were tested as antimicrobials against Gram-negative and Gram-positive bacterial strains. The best-performing bis-mTQAS were found to achieve total disinfection against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 at 50 and 400 μg/mL, respectively. Distinctively, bis-mTQAS with the highest antimicrobial efficiency had lowest cytotoxicity., (© 2021 The Authors. ChemMedChem published by Wiley-VCH GmbH.)

Two white colony-forming, Gram-stain-negative, non-sporulating and motile bacteria, designated G-4-1-8 T and RP-4-7 T , were isolated from forest soil and Arctic soil, respectively. Both strains showed antimicrobial activity against Gram-negative pathogens ( Pseudomonas aeruginosa and Escherichia coli ) and could grow at a pH range of pH 4.0-11.0 (optimum, pH 7.0-9.0). Phylogenetic analyses based on their 16S rRNA gene sequences indicated that strains G-4-1-8 T and RP-4-7 T formed a lineage within the family Burkholderiaceae and were clustered as members of the genus Paraburkholderia . Strain G-4-1-8 T showed the highest 16S rRNA sequence similarity to Paraburkholderia monticola JC2948 T (98.1 %), while strain RP-4-7 T showed the highest similarity to Paraburkholderia metrosideri DNBP6-1 T (98.8 %). The only respiratory quinone in both strains was ubiquinone Q-8. Their principal cellular fatty acids were C 16 : 0 , cyclo-C 17 : 0 , summed feature 3 (iso-C 15 :0 2-OH and/or C 16 :1 ω 7 c ) and summed feature 8 (C 18 : 1  ω 7 c and/or C 18 : 1  ω 6 c ). Their major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unidentified aminophospholipid. The DNA G+C content of strains G-4-1-8 T and RP-4-7 T were 63.7 and 61.3 mol%, respectively, while their genome lengths were 7.44 and 9.67 Mb, respectively. The genomes of both strains showed at least 12 putative biosynthetic gene clusters. The average nucleotide identity and in silico DNA-DNA hybridization relatedness values between both strains and most closely related Paraburkholderia species were below the species threshold values. Based on a polyphasic study, these isolated strains represent novel species belonging to the genus Paraburkholderia , for which the names Paraburkholderia antibiotica sp. nov. (G-4-1-8 T = KACC 21617 T =NBRC 114603 T ) and Paraburkholderia polaris sp. nov. (RP-4-7 T =KACC 21621 T =NBRC 114605 T ) are proposed.

Bacterial infections are nowadays among the major threats to public health worldwide. Thus, there is an urgent and increased need for new antimicrobial agents. As a result, the exploration of the antimicrobial properties of different substances including ionic liquids (ILs) has recently attracted great attention. The present work is aimed at evaluating how the addition of halogens and hydrophobic substituents on alkylimidazolium units of ILs as well as the increase in their chain lengths affects the antimicrobial properties of such ILs. After their synthesis, the antibacterial activities of these compounds against Pseudomona aeruginosa, Escherichia coli, and Staphylococcus aureus are determined by measuring their minimal inhibitory concentrations (MICs). Key features in ILs-membrane interactions are also studied using long-term all-atom molecular dynamics simulations (MDs). The results show that these ILs have good antibacterial activity against S. aureus, E. coli, and P. aeruginosa, with MIC values range from <7.81 to 62.50 μM. The antimicrobial property of tert-butyl N-methylphenolimidazolium salts (denoted as 8b and 8c) is particularly better with MIC values of < 7.81 μM. The antibacterial efficacy is also found to depend on the alkyl chain length and substituents on the phenolic ring. Finally, MDs done for ILs in a phosphatidylcholine (POPC) bilayer show key features in the mechanism of IL-induced membrane disruption, where the ILs are inserted as clusters into one side of the bilayer until saturation is reached. This insertion increases "leaflet strain" up to critical threshold, likely triggering the morphological disruption of the membranes in the microbes., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The global spread of microbial resistance coupled with high costs and slow pace in the discovery of a new antibiotic have made drug repositioning an attractive and promising alternative in the treatment of infections caused by multidrug resistant (MDR) microorganisms. The reuse involves the production of compounds with lower costs and development time, using diversified production technologies. The present systematic review aimed to present a selection of studies published in the last 20 years, which report the antimicrobial activity of non-antibiotic drugs that are candidates for repositioning, which could be used against the current microbial multidrug resistance. A search was performed in the PubMed, SciELO and Google Scholar databases using the following search strategies: [(drug repurposing) OR (drug repositioning) OR (repositioning) AND (non-antibiotic) AND (antibacterial activity) AND (antimicrobial activity)]. Overall, 112 articles were included, which explored the antimicrobial activity in antidepressants, antihypertensives, anti-inflammatories, antineoplastics, hypoglycemic agents, among other drugs. It was concluded that they have significant antimicrobial activity in vitro and in vivo, against standard strain and clinical isolates (Gram-negative and Gram-positive) and fungi. When associated with antibacterials, most of these drugs had their antibacterial activity enhanced. It was also a consensus of the studies included in this review that the presence of aromatic rings in the molecular structure contributes to antimicrobial activity. This review highlights the potential repositioning of several classes of non-antibiotic drugs as promising candidates for repositioning in the treatment of severe bacterial infections of MDR bacteria, extensively resistant (XDR) and pan-resistant (PDR) to drugs., Competing Interests: Declaration of Competing Interest None declarated, (Copyright © 2021. Published by Elsevier Ltd.)

What Is Known and Objective: Sepsis is a life-threatening organ dysfunction associated with a high rate of morbidity and mortality. Appropriate antibiotic therapy remains the cornerstone of sepsis and septic shock management., Comment: Although the early initiation of antimicrobial agents in the treatment of sepsis is widely acknowledged, the selection and adjustment to optimal dosage can be equally important. Since significant pathophysiological changes in the critically ill patients lead to altered pharmacokinetics of antibiotics, early consideration of pharmacokinetic/pharmacodynamic (PK/PD) properties is necessary for optimal antibiotic dosing in sepsis and should be integrated in practice., What Is New and Conclusion: Where possible, an individualized antibiotic dosing approach through the application of therapeutic drug monitoring (TDM) service should replace the conventional dosing in critically ill patients with sepsis. Finally, antimicrobial stewardship can help improve clinical outcomes., (© 2021 John Wiley & Sons Ltd.)

Antimicrobial peptides are evolving as novel therapeutic options against the increasing problem of multidrug-resistant microorganisms, and nisin is one such avenue. However, some bacteria possess a specific nisin resistance system (NSR), which cleaves the peptide reducing its bactericidal efficacy. NSR-based resistance was identified in strains of Streptococcus uberis, a ubiquitous pathogen that causes mastitis in dairy cattle. Previous studies have demonstrated that a nisin A derivative termed nisin PV, featuring S29P and I30V, exhibits enhanced resistance to proteolytic cleavage by NSR. Our objective was to investigate the ability of this nisin derivative to eradicate and inhibit biofilms of S. uberis DPC 5344 and S. uberis ATCC 700407 ( nsr + ) using crystal violet (biomass), 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) (viability) assays, and confocal microscopy (viability and architecture). When preestablished biofilms were assessed, both peptides reduced biofilm biomass by over 60% compared to that of the untreated controls. However, a 42% higher reduction in viability was observed following treatment with nisin PV compared to that of nisin A. Accordingly, confocal microscopy analysis revealed significantly more dead cells on the biofilm upper surface and a reduced thickness following treatment with nisin PV. When biofilm inhibition was assessed, nisin PV inhibited biofilm formation and decreased viability up to 56% and 85% more than nisin A, respectively. Confocal microscopy analysis revealed a lack of biofilm for S. uberis ATCC 700407 and only dead cells for S. uberis DPC 5344. These results suggest that nisin PV is a promising alternative to effectively reduce the biofilm formation of S. uberis strains carrying NSR. IMPORTANCE One of the four most prevalent species of bovine mastitis-causing pathogens is S. uberis. Its ability to form biofilms confers on the bacteria greater resistance to antibiotics, requiring higher doses to be more effective. In a bid to limit antibiotic resistance development, the need for alternative antimicrobials is paramount. Bacteriocins such as nisin represent one such alternative that could alleviate the impact of mastitis caused by S. uberis. However, many strains of S. uberis have been shown to possess nisin resistance determinants, such as the nisin resistance protein (NSR). In this study, we demonstrate the ability of nisin and a nisin derivative termed PV that is insensitive to NSR to prevent and remove biofilms of NSR-producing S. uberis strains. These findings will add new information to the antimicrobial bacteriocins and control of S. uberis research fields specifically in relation to biofilms and nsr + mastitis-associated strains.

Nitazoxanide (NTZ) is an orally active drug with significant postmarketing experience including more than 75 million adults and children. Presently, this drug is widely used for a number of infectious conditions and diseases. It has a wide range of applications such as antiprotozoal, anthelmintic and antiviral against various types of Gram-positive and Gram-negative bacteria, parasites and certain viruses. Chemically, NTZ nitrothiazole is a [2-[(5-nitro-1,3- thiazol-2-yl) carbamoyl]phenyl] acetate compound. A number of clinical trials have suggested that it can be used in cryptosporidiosis, hepatitis B, hepatitis C, ovarian cancer, viral infections and helicobacter infection. Recent research has proposed its beneficial effect in treating the symptoms of coronavirus infection. It is proposed that the activity of NTZ is due to interference with pyruvate-ferredoxin oxidoreductase (PFOR), which is an enzyme that catalyzes the ferredoxin-dependent electron transfer reaction completed in anaerobiotic energy metabolism. The available literature suggested the importance of NTZ and its efficiency against various bacterial infections as well as in viral infectious diseases. The aim of this review is to examine and discuss the most important aspects of NTZ in different types of microbial infections., (Copyright 2021 Clarivate Analytics.)

Antimicrobial resistance (AMR) is a pressing global health crisis, which has been fueled by the sustained use of certain classes of antimicrobials, including fluoroquinolones. While the genetic mutations responsible for decreased fluoroquinolone (ciprofloxacin) susceptibility are known, the implications of ciprofloxacin exposure on bacterial growth, survival, and interactions with host cells are not well described. Aiming to understand the influence of inhibitory concentrations of ciprofloxacin in vitro, we subjected three clinical isolates of Salmonella enterica serovar Typhimurium to differing concentrations of ciprofloxacin, dependent on their MICs, and assessed the impact on bacterial growth, morphology, and transcription. We further investigated the differential morphology and transcription that occurred following ciprofloxacin exposure and measured the ability of ciprofloxacin-treated bacteria to invade and replicate in host cells. We found that ciprofloxacin-exposed S. Typhimurium is able to recover from inhibitory concentrations of ciprofloxacin and that the drug induces specific morphological and transcriptional signatures associated with the bacterial SOS response, DNA repair, and intracellular survival. In addition, ciprofloxacin-treated S. Typhimurium has increased capacity for intracellular replication in comparison to that of untreated organisms. These data suggest that S. Typhimurium undergoes an adaptive response under ciprofloxacin perturbation that promotes cellular survival, a consequence that may justify more measured use of ciprofloxacin for Salmonella infections. The combination of multiple experimental approaches provides new insights into the collateral effects that ciprofloxacin and other antimicrobials have on invasive bacterial pathogens. IMPORTANCE Antimicrobial resistance is a critical concern in global health. In particular, there is rising resistance to fluoroquinolones, such as ciprofloxacin, a first-line antimicrobial for many Gram-negative pathogens. We investigated the adaptive response of clinical isolates of Salmonella enterica serovar Typhimurium to ciprofloxacin, finding that the bacteria adapt in short timespans to high concentrations of ciprofloxacin in a way that promotes intracellular survival during early infection. Importantly, by studying three clinically relevant isolates, we were able to show that individual isolates respond differently to ciprofloxacin and that for each isolate, there was a heterogeneous response under ciprofloxacin treatment. The heterogeneity that arises from ciprofloxacin exposure may drive survival and proliferation of Salmonella during treatment and lead to drug resistance.

Lanthipeptides are ribosomally synthesized and posttranslationally modified peptides, with modifications that are incorporated during biosynthesis by dedicated enzymes. Various modifications of the peptides are possible, resulting in a highly diverse group of bioactive peptides that offer a potential reservoir for use in the fight against a plethora of diseases. Their activities range from the antimicrobial properties of lantibiotics, especially against antibiotic-resistant strains, to antiviral activity, immunomodulatory properties, antiallodynic effects, and the potential to alleviate cystic fibrosis symptoms. Lanthipeptide biosynthetic genes are widespread within bacterial genomes, providing a substantial repository for novel bioactive peptides. Using genome mining tools, novel bioactive lanthipeptides can be identified, and coupled with rapid screening and heterologous expression technologies, the lanthipeptide drug discovery pipeline can be significantly sped up. Lanthipeptides represent a group of bioactive peptides that hold great potential as biotherapeutics, especially at a time when novel and more effective therapies are required. With this review, we provide insight into the latest developments made toward the therapeutic applications and production of lanthipeptides, specifically looking at heterologous expression systems.

Phage (endo)lysins are thought to be a viable alternative to usual antibiotic chemotherapy to fight resistant bacterial infections. However, a comprehensive view of lysins' structure and properties regarding their function, with an applied focus, is somewhat lacking. Current literature suggests that specific features typical of lysins from phages infecting Gram-negative bacteria (G-) (higher net charge and amphipathic helices) are responsible for improved interaction with the G- envelope. Such antimicrobial peptide (AMP)-like elements are also of interest for antimicrobial molecule design. Thus, this study aims to provide an updated view on the primary structural landscape of phage lysins to clarify the evolutionary importance of several sequence-predicted properties, particularly for the interaction with the G- surface. A database of 2,182 lysin sequences was compiled, containing relevant information such as domain architectures, data on the phages' host bacteria, and sequence-predicted physicochemical properties. Based on such classifiers, an investigation of the differential appearance of certain features was conducted. This analysis revealed different lysin architectural variants that are preferably found in phages infecting certain bacterial hosts. In particular, some physicochemical properties (higher net charge, hydrophobicity, hydrophobic moment, and aliphatic index) were associated with G- phage lysins, appearing specifically at their C-terminal end. Information on the remarkable genetic specialization of lysins regarding the features of the bacterial hosts is provided, specifically supporting the nowadays-common hypothesis that lysins from G- usually contain AMP-like regions. IMPORTANCE Phage-encoded lytic enzymes, also called lysins, are one of the most promising alternatives to common antibiotics. The potential of lysins as novel antimicrobials to tackle antibiotic-resistant bacteria not only arises from features such as a lower chance to provoke resistance but also from their versatility as synthetic biology parts. Functional modules derived from lysins are currently being used for the design of novel antimicrobials with desired properties. This study provides a view of the lysin diversity landscape by examining a set of phage lysin genes. We have uncovered the fundamental differences between the lysins from phages that infect bacteria with different superficial architectures and, thus, the reach of their specialization regarding cell wall structures. These results provide clarity and evidence to sustain some of the common hypotheses in current literature, as well as making available an updated and characterized database of lysins sequences for further developments.

A series of bis-acryl functionalized porphyrins and their corresponding metalloporphyrins (M=Co, Mn) were synthesized and investigated for their antimicrobial properties through MIC screening and bacteria time-kill kinetic studies. The Mn(III) 4-(bis)methylphenyl-substituted-porphyrins showed superior batericidal activities even in the dark with low hemotoxicity and good cytotoxicity profile., (© 2021 Wiley-VCH GmbH.)

The development and spread of antimicrobial resistance are major concerns for human and animal health. The effects of the overuse of antimicrobials in domestic animals on the dissemination of resistant microbes to humans and the environment are of concern worldwide. Rhodococcus equi is an ideal model to illustrate the spread of antimicrobial resistance at the animal-human-environment interface because it is a natural soil saprophyte that is an intracellular zoonotic pathogen that produces severe bronchopneumonia in many animal species and humans. Globally, R. equi is most often recognized as causing severe pneumonia in foals that results in animal suffering and increased production costs for the many horse-breeding farms where the disease occurs. Because highly effective preventive measures for R. equi are lacking, thoracic ultrasonographic screening and antimicrobial chemotherapy of subclinically affected foals have been used for controlling this disease during the last 20 years. The resultant increase in antimicrobial use attributable to this "screen-and-treat" approach at farms where the disease is endemic has likely driven the emergence of multidrug-resistant (MDR) R. equi in foals and their environment. This review summarizes the factors that contributed to the development and spread of MDR R. equi , the molecular epidemiology of the emergence of MDR R. equi , the repercussions of MDR R. equi for veterinary and human medicine, and measures that might mitigate antimicrobial resistance at horse-breeding farms, such as alternative treatments to traditional antibiotics. Knowledge of the emergence and spread of MDR R. equi is of broad importance for understanding how antimicrobial use in domestic animals can impact the health of animals, their environment, and human beings., (Copyright © 2021 American Society for Microbiology.)

Pseudomonas aeruginosa is a multi-drug resistant (MDR) pathogen. It is classified by WHO as one of the most life-threatening pathogens causing nosocomial infections. Some of its clinical isolates and their subpopulations show high persistence to many antibiotics that are recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Thus, there is a need for non-traditional classes of antibiotics to fight the increasing threat of MDR P. aeruginosa. Ionic liquids (IL) are one such promising class of novel antibiotics. We selected four strains of P. aeruginosa and studied the growth inhibition and other effects of 12 different ILs. We used the well-characterized P. aeruginosa PAO1 (ATCC 15692) as model strain and compared it to three other isolates from chronic lung infection (LES B58), skin burn infection (UCBPP-PA14) and keratitis infection (39016), respectively. The ILs consisted of either 4,4-didecylmorpholinium [Dec 2 Mor] + or 4-decyl-4-ethylmorpholinium [DecEtMor] + cations combined with different anions. We found that the ILs with 4,4-didecylmorpholinium [Dec 2 Mor] + cations most effectively inhibited bacterial growth as well as reduced strain fitness and virulence factor production. Our results indicate that these ILs could be used to treat P. aeruginosa infections., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2021 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Antimicrobial drug development generally initiates with target identification and mode of action studies. Often, emergence of resistance and/or undesired side effects that are discovered only after prolonged clinical use, result in discontinuation of clinical use. Since the cost and time required for improvement of existing drugs are considerably lower than those required for the development of novel drugs, academic and pharmaceutical company researchers pursue this direction. In this account we describe selected examples of how chemical probes generated from antimicrobial drugs and chemical and enzymatic modifications of these drugs have been used to modify modes of action, block mechanisms of resistance, or reduce side effects, improving performance. These examples demonstrate how new and comprehensive mechanistic insights can be translated into fresh concepts for development of next-generation antimicrobial agents., (© 2021 The Chemical Society of Japan & Wiley-VCH GmbH.)

Background: Drug reaction with eosinophilia and systemic symptoms syndrome (DRESS) is a delayed infrequent potentially life-threatening idiosyncratic drug reaction. Aromatic anticonvulsants and allopurinol are the most frequent causative agents. However, various reports of antibiotic-induced DRESS are available. In this review, we try to summarize reports of antibacterial antibiotic-induced DRESS focusing on characteristics of DRESS induced by each antibiotic group., Methods: The data were collected by searching PubMed/MEDLINE and ScienceDirect. The keywords used as search terms were "DRESS syndrome," "drug-induced hypersensitivity syndrome (DIHS)," "antibiotics," "antimicrobial," and names of various antimicrobial groups. Finally, 254 relevant cases with a definite or probable diagnosis of DRESS based on RegiSCAR criteria were found until 30 May 2020 and reviewed., Results and Conclusion: Totally, 254 cases of antibacterial antibiotic-induced DRESS are reported. Most of them are related to antituberculosis drugs, vancomycin, and sulfonamides, respectively. Rash and fever were most frequent clinical findings. Eosinophilia and liver injury were the most reported hematologic and visceral organ involvement, respectively. Most of the patients are managed with systemic corticosteroids. The death occurred in 16 patients which most of them experienced liver or lung involvement. The reactivation of various viruses especially HHV-6 is reported in 33 cases. The mean latency period was 29 days. It is necessary to perform thorough epidemiological, genetic, and immunological studies, also systematic case review and causality assessment, as well as well-designed clinical trials for better management of antibiotic-induced DRESS.

Combination treatments are commonly prescribed for enhancing drug efficacy, as well as for preventing the evolution of resistance. The interaction between drugs is typically evaluated near the MIC, using growth rate as a measure of treatment efficacy. However, for infections in which the killing activity of the treatment is important, measurements far above the MIC are needed. In this regime, the killing rate often becomes weakly concentration dependent, and a different metric is needed to characterize drug interactions. We evaluate the interaction metric on killing using an easy visual assay, the interaction tolerance detection test (iTDtest), that estimates the survival of bacteria under antibiotic combinations. We identify antibiotic combinations that enable the eradication of tolerant bacteria. Furthermore, the visualization of the antibiotic interactions reveals directional drug interactions and enables predicting high-order combination outcomes, therefore facilitating the determination of optimal treatments. IMPORTANCE The killing efficacy of antibiotic combinations is rarely measured in the clinical setting. However, in cases where the treatment is required to kill the infecting organism and not merely arrest its growth, the information on the killing efficacy is important, especially when tolerant strains are implicated. Here, we report on an easy method for the determination of the killing efficacy of antibiotic combinations which enabled to reveal combinations effective against tolerant bacteria. The results could be generally used to guide antimicrobial therapy in life-threatening infections.