Research on New Antimicrobial Agents

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Antimicrobial Agents and Resistance".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 19631

Special Issue Editor


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Guest Editor
BioActive Research Group, Faculty of Biology, University Alexandru Ioan Cuza of Iasi, Iasi, Romania
Interests: plant–microbial interactions; PGPR; biofertilizers; biopesticides
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Antimicrobial resistance is considered one of the greatest threats facing humanity. Declared by the WHO as a top global public health menace, antimicrobial resistance is also a serious social and economic problem. The emergence and spread of drug-resistant pathogens, especially multiresistant bacteria (also known as “superbugs”) was facilitated by the misuse and overuse of antimicrobials. Consequently, our ability to treat infectious diseases with current antibiotics is being critically threatened. Moreover, the number of new antibiotics that have come into therapeutical use has decreased significantly in recent years. Therefore, finding new, effective antimicrobials to fight antimicrobial resistance is a top priority in the modern scientific world.

This Special Issue will focus on the most recent research on the discovery of new antimicrobial agents and strategies used to treat infectious diseases caused by antimicrobial-resistant pathogens. We are inviting authors to publish their latest original findings in this Microorganisms Special Issue, entitled Research on New Antimicrobial Agents.

Dr. Marius Stefan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Microorganisms is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • antimicrobial activity
  • infectious diseases
  • antibiotic resistance
  • antimicrobial peptides
  • antimicrobial flavonoids
  • nanoparticles
  • molecular docking
  • Structure-Activity Relationship (SAR)
  • antimicrobial therapy
  • cytotoxicity, synergy

Published Papers (7 papers)

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Research

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15 pages, 992 KiB  
Article
Antimicrobial Potential, Antioxidant Activity, and Phenolic Content of Grape Seed Extracts from Four Grape Varieties
by Dimitrina Krasteva, Yavor Ivanov, Zlatina Chengolova and Tzonka Godjevargova
Microorganisms 2023, 11(2), 395; https://doi.org/10.3390/microorganisms11020395 - 3 Feb 2023
Cited by 19 | Viewed by 3080
Abstract
The aim of this study was to evaluate the total phenolic content, composition, and antioxidant and antibacterial activities of four grape seed extracts (Cabernet Sauvignon, Marselan, Pinot Noir, and Tamyanka). The total phenolic content (TPC) and flavonoid, anthocyanin, procyanidin, ascorbic acid, DPPH, and [...] Read more.
The aim of this study was to evaluate the total phenolic content, composition, and antioxidant and antibacterial activities of four grape seed extracts (Cabernet Sauvignon, Marselan, Pinot Noir, and Tamyanka). The total phenolic content (TPC) and flavonoid, anthocyanin, procyanidin, ascorbic acid, DPPH, and ABTS antioxidant capacities of the grape seed extracts (GSEs) were determined. The extracts showed high TPC values (79.06–111.22 mg GAE/g). The individual components in the GSEs were determined using HPLC. High contents of catechin, epicatechin, and procyanidin B1 were found in the extracts. The antimicrobial activity of the obtained GSEs against Staphylococcus aureus, Bacillus cereus, and Escherichia coli was evaluated using the agar diffusion test and a test to determine the minimum inhibitory concentration (MIC). According to the effect on the growth of pathogens, the extracts were ranked in the following order: Pinot Noir > Marselan > Cabernet Sauvignon > Tamyanka. The tested bacteria showed high sensitivity to the extracts (MIC = 0.12–0.50 mg/mL). According to the MIC values, the bacteria were in the following order: S. aureus > B. cereus > E. coli. A correlation was found between the phenolic content of the GSEs and their antibacterial potential. The obtained results show that the studied GSEs have good potential as antioxidant and antimicrobial agents. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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17 pages, 5010 KiB  
Article
Antibacterial and Anti-Inflammatory Properties of Peptide KN-17
by Qian Zhang, Shuipeng Yu, Meilin Hu, Zhiyang Liu, Pei Yu, Changyi Li and Xi Zhang
Microorganisms 2022, 10(11), 2114; https://doi.org/10.3390/microorganisms10112114 - 26 Oct 2022
Cited by 4 | Viewed by 1633
Abstract
Peri-implantitis, an infectious disease originating from dental biofilm that forms around dental implants, which causes the loss of both osseointegration and bone tissue. KN-17, a truncated cecropin B peptide, demonstrated efficacy against certain bacterial strains associated with peri-implantitis. This study aimed to assess [...] Read more.
Peri-implantitis, an infectious disease originating from dental biofilm that forms around dental implants, which causes the loss of both osseointegration and bone tissue. KN-17, a truncated cecropin B peptide, demonstrated efficacy against certain bacterial strains associated with peri-implantitis. This study aimed to assess the antibacterial and anti-inflammatory properties and mechanisms of KN-17. The effects of KN-17 on oral pathogenic bacteria were assessed by measuring its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Moreover, the cytotoxicity and anti-inflammatory effects of KN-17 were evaluated. KN-17 inhibited the growth of Streptococcus gordonii and Fusobacterium nucleatum during in vitro biofilm formation and possessed low toxicity to hBMSCs cells. KN-17 also caused RAW264.7 macrophages to transform from M1 to M2 by downregulating pro-inflammatory and upregulating anti-inflammatory factors. It inhibited the NF-κB signaling pathway by reducing IκBα and P65 protein phosphorylation while promoting IκBα degradation and nuclear P65 translocation. KN-17 might be an efficacious prophylaxis against peri-implant inflammation. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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22 pages, 7181 KiB  
Article
Computer-Based Identification of Potential Druggable Targets in Multidrug-Resistant Acinetobacter baumannii: A Combined In Silico, In Vitro and In Vivo Study
by Omar H. Badie, Ahmed F. Basyony and Reham Samir
Microorganisms 2022, 10(10), 1973; https://doi.org/10.3390/microorganisms10101973 - 5 Oct 2022
Cited by 4 | Viewed by 2877
Abstract
The remarkable rise in antimicrobial resistance is alarming for Acinetobacter baumannii, which necessitates effective strategies for the discovery of promising anti-acinetobacter agents. We used a subtractive proteomics approach to identify unique protein drug targets. Shortlisted targets passed through subtractive channels, including essentiality, [...] Read more.
The remarkable rise in antimicrobial resistance is alarming for Acinetobacter baumannii, which necessitates effective strategies for the discovery of promising anti-acinetobacter agents. We used a subtractive proteomics approach to identify unique protein drug targets. Shortlisted targets passed through subtractive channels, including essentiality, non-homology to the human proteome, druggability, sub-cellular localization prediction and conservation. Sixty-eight drug targets were shortlisted; among these, glutamine synthetase, dihydrodipicolinate reductase, UDP-N-acetylglucosamine acyltransferase, aspartate 1-decarboxylase and bifunctional UDP-N-acetylglucosamine diphosphorylase/glucosamine-1-phosphate N-acetyltransferase were evaluated in vitro by determining the minimum inhibitory concentration (MIC) of candidate ligands, citric acid, dipicolinic acid, D-tartaric acid, malonic acid and 2-(N-morpholino)ethanesulfonic acid (MES), respectively, which ranged from 325 to 1500 μg/mL except for MES (25 mg/mL). The candidate ligands, citric acid, D-tartaric acid and malonic acid, showed good binding energy scores to their targets upon applying molecular docking, in addition to a significant reduction in A. baumannii microbial load in the wound infection mouse model. These ligands also exhibited good tolerability to human skin fibroblast. The significant increase in the MIC of malonic acid in β-alanine and pantothenate-supplemented media confirmed its selective inhibition to aspartate 1-decarboxylase. In conclusion, three out of sixty-eight potential A. baumannii drug targets were effectively inhibited in vitro and in vivo by promising ligands. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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16 pages, 1912 KiB  
Article
New Insights into the Antimicrobial Potential of Polyalthia longifolia—Antibiofilm Activity and Synergistic Effect in Combination with Penicillin against Staphylococcus aureus
by Mihaela Savu, Marguerite Kamdem Simo, Gabriel Xavier Fopokam, Stefan Mihaita Olaru, Oana Cioanca, Fabrice Fekam Boyom and Marius Stefan
Microorganisms 2022, 10(10), 1943; https://doi.org/10.3390/microorganisms10101943 - 30 Sep 2022
Cited by 3 | Viewed by 1765
Abstract
Widespread antibiotic resistance has led to the urgent need for the identification of new antimicrobials. Plants are considered a valuable potential resource for new effective antimicrobial compounds. Therefore, in the present study, we focused on the antimicrobial activity of Polyalthia longifolia plants harvested [...] Read more.
Widespread antibiotic resistance has led to the urgent need for the identification of new antimicrobials. Plants are considered a valuable potential resource for new effective antimicrobial compounds. Therefore, in the present study, we focused on the antimicrobial activity of Polyalthia longifolia plants harvested from Cameroon using the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assays. The mechanism of action was investigated by employing fluorescence and scanning electron microscopy. The anti-Staphylococcus aureus activity was studied using biofilm inhibition and checkerboard assays. Our results revealed that the tested extracts possess important antimicrobial activities, notably against Gram positive bacteria (MICs as low as 0.039 mg/mL). P. longifolia leaf extracts exhibited a significant bactericidal effect, with a total kill effect recorded after only 2 h of exposure at concentrations equivalent to MBC (0.078 and 0.156 mg/mL). The extracts showed a synergistic antibacterial activity in combination with penicillin against a MRSA clinical isolate and significantly inhibited S. aureus biofilm formation. The mechanism of action is related to the impairment of cell membrane integrity and cell lysis. All these findings suggest that P. longifolia could be an important source of reliable compounds used to develop new antimicrobials. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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15 pages, 1714 KiB  
Communication
Resveratrol-Schiff Base Hybrid Compounds with Selective Antibacterial Activity: Synthesis, Biological Activity, and Computational Study
by Rodrigo Sánchez-González, Patricio Leyton, Luis F. Aguilar, Mauricio Reyna-Jeldes, Claudio Coddou, Katy Díaz and Marco Mellado
Microorganisms 2022, 10(8), 1483; https://doi.org/10.3390/microorganisms10081483 - 22 Jul 2022
Cited by 4 | Viewed by 2306
Abstract
Nowadays, antimicrobial resistance is a serious concern associated with the reduced efficacy of traditional antibiotics and an increased health burden worldwide. In response to this challenge, the scientific community is developing a new generation of antibacterial molecules. Contributing to this effort, and inspired [...] Read more.
Nowadays, antimicrobial resistance is a serious concern associated with the reduced efficacy of traditional antibiotics and an increased health burden worldwide. In response to this challenge, the scientific community is developing a new generation of antibacterial molecules. Contributing to this effort, and inspired by the resveratrol structure, five new resveratrol-dimers (9a9e) and one resveratrol-monomer (10a) were synthetized using 2,5-dibromo-1,4-diaminobenzene (8) as the core compound for Schiff base bridge conformation. These compounds were evaluated in vitro against pathogenic clinical isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp., and Listeria monocytogenes. Antibacterial activity measurements of resveratrol-Schiff base derivatives (9a9e) and their precursors (48) showed high selectivity against Listeria monocytogenes, being 2.5 and 13.7 times more potent than chloramphenicol, while resveratrol showed an EC50 > 320 µg/mL on the same model. Moreover, a prospective mechanism of action for these compounds against L. monocytogenes strains was proposed using molecular docking analysis, finding a plausible inhibition of internalin C (InlC), a surface protein relevant in bacteria–host interaction. These results would allow for the future development of new molecules for listeriosis treatment based on compound 8. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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Review

Jump to: Research

20 pages, 1247 KiB  
Review
Innovative Strategies to Overcome Antimicrobial Resistance and Tolerance
by M. Iqbal Choudhary, Ute Römling, Faiza Nadeem, Hafiz Muhammad Bilal, Munirah Zafar, Humera Jahan and Atta ur-Rahman
Microorganisms 2023, 11(1), 16; https://doi.org/10.3390/microorganisms11010016 - 21 Dec 2022
Cited by 5 | Viewed by 4445
Abstract
Antimicrobial resistance and tolerance are natural phenomena that arose due to evolutionary adaptation of microorganisms against various xenobiotic agents. These adaptation mechanisms make the current treatment options challenging as it is increasingly difficult to treat a broad range of infections, associated biofilm formation, [...] Read more.
Antimicrobial resistance and tolerance are natural phenomena that arose due to evolutionary adaptation of microorganisms against various xenobiotic agents. These adaptation mechanisms make the current treatment options challenging as it is increasingly difficult to treat a broad range of infections, associated biofilm formation, intracellular and host adapted microbes, as well as persister cells and microbes in protected niches. Therefore, novel strategies are needed to identify the most promising drug targets to overcome the existing hurdles in the treatment of infectious diseases. Furthermore, discovery of novel drug candidates is also much needed, as few novel antimicrobial drugs have been introduced in the last two decades. In this review, we focus on the strategies that may help in the development of innovative small molecules which can interfere with microbial resistance mechanisms. We also highlight the recent advances in optimization of growth media which mimic host conditions and genome scale molecular analyses of microbial response against antimicrobial agents. Furthermore, we discuss the identification of antibiofilm molecules and their mechanisms of action in the light of the distinct physiology and metabolism of biofilm cells. This review thus provides the most recent advances in host mimicking growth media for effective drug discovery and development of antimicrobial and antibiofilm agents. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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22 pages, 1538 KiB  
Review
Bioactive Antimicrobial Peptides: A New Weapon to Counteract Zoonosis
by Luisa Zupin, Carlos André dos Santos-Silva, Aya R. Hamad Al Mughrbi, Livia Maria Batista Vilela, Ana Maria Benko-Iseppon and Sergio Crovella
Microorganisms 2022, 10(8), 1591; https://doi.org/10.3390/microorganisms10081591 - 7 Aug 2022
Cited by 3 | Viewed by 2572
Abstract
Zoonoses have recently become the center of attention of the general population and scientific community. Notably, more than 30 new human pathogens have been identified in the last 30 years, 75% of which can be classified as zoonosis. The complete eradication of such [...] Read more.
Zoonoses have recently become the center of attention of the general population and scientific community. Notably, more than 30 new human pathogens have been identified in the last 30 years, 75% of which can be classified as zoonosis. The complete eradication of such types of infections is far out of reach, considering the limited understanding of animal determinants in zoonoses and their causes of emergence. Therefore, efforts must be doubled in examining the spread, persistence, and pathogenicity of zoonosis and studying possible clinical interventions and antimicrobial drug development. The search for antimicrobial bioactive compounds has assumed great emphasis, considering the emergence of multi-drug-resistant microorganisms. Among the biomolecules of emerging scientific interest are antimicrobial peptides (AMPs), potent biomolecules that can potentially act as important weapons against infectious diseases. Moreover, synthetic AMPs are easily tailored (bioinformatically) to target specific features of the pathogens to hijack, inducing no or very low resistance. Although very promising, previous studies on SAMPs’ efficacy are still at their early stages. Indeed, further studies and better characterization on their mechanism of action with in vitro and in vivo assays are needed so as to proceed to their clinical application on human beings. Full article
(This article belongs to the Special Issue Research on New Antimicrobial Agents)
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