Antimicrobial and Antibiofilm Peptides

The increasing onset of multidrug-resistant bacteria has propelled microbiology research towards antimicrobial peptides as new possible antibiotics from natural sources. Antimicrobial peptides are short peptides endowed with a broad range of activity against both Gram-positive and Gram-negative bacteria and are less prone to trigger resistance. Besides their activity against planktonic bacteria, many antimicrobial peptides also show antibiofilm activity. Biofilms are ubiquitous in nature, having the ability to adhere to virtually any surface, either biotic or abiotic, including medical devices, causing chronic infections that are difficult to eradicate. The biofilm matrix protects bacteria from hostile environments, thus contributing to the bacterial resistance to antimicrobial agents. Biofilms are very difficult to treat, with options restricted to the use of large doses of antibiotics or the removal of the infected device. Antimicrobial peptides could represent good candidates to develop new antibiofilm drugs as they can act at different stages of biofilm formation, on disparate molecular targets and with various mechanisms of action. These include inhibition of biofilm formation and adhesion, downregulation of quorum sensing factors, and disruption of the pre-formed biofilm. This review focuses on the proprieties of antimicrobial and antibiofilm peptides, with a particular emphasis on their mechanism of action, reporting several examples of peptides that over time have been shown to have activity against biofilm.

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The Lactococcal dgkB (yecE) and dxsA Genes for Lipid Metabolism Are Involved in the Resistance to Cell Envelope-Acting Antimicrobials

International Journal of Molecular Sciences ◽

10.3390/ijms22031014 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1014

Author(s):

Aleksandra Tymoszewska ◽

Tamara Aleksandrzak-Piekarczyk

Keyword(s):

Antimicrobial Peptides ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Cytoplasmic Membrane ◽

Cross Resistance ◽

Resistant Bacteria ◽

Membrane Targeting ◽

Nucleotide Polymorphisms ◽

Next Generation ◽

Lipid Ii

The emergence of antibiotic-resistant bacteria led to an urgent need for next-generation antimicrobial agents with novel mechanisms of action. The use of positively charged antimicrobial peptides that target cytoplasmic membrane is an especially promising strategy since essential functions and the conserved structure of the membrane hinder the development of bacterial resistance. Aureocin A53- and enterocin L50-like bacteriocins are highly cationic, membrane-targeting antimicrobial peptides that have potential as next-generation antibiotics. However, the mechanisms of resistance to these bacteriocins and cross-resistance against antibiotics must be examined before application to ensure their safe use. Here, in the model bacterium Lactococcus lactis, we studied the development of resistance to selected aureocin A53- and enterocin L50-like bacteriocins and its correlation with antibiotics. First, to generate spontaneous resistant mutants, L.lactis was exposed to bacteriocin BHT-B. Sequencing of their genomes revealed single nucleotide polymorphisms (SNPs) in the dgkB (yecE) and dxsA genes encoding diacylglycerol kinase and 1-deoxy-D-xylulose 5-phosphate synthase, respectively. Then, selected mutants underwent susceptibility tests with a wide array of bacteriocins and antibiotics. The highest alterations in the sensitivity of studied mutants were seen in the presence of cytoplasmic membrane targeting bacteriocins (K411, Ent7, EntL50, WelM, SalC, nisin) and antibiotics (daptomycin and gramicidin) as well as lipid II cycle-blocking bacteriocins (nisin and Lcn972) and antibiotics (bacitracin). Interestingly, decreased via the SNPs accumulation sensitivity to membrane-active bacteriocins and antibiotics resulted in the concurrently increased vulnerability to bacitracin, carbenicillin, or chlortetracycline. It is suspected that SNPs may result in alterations to the efficiency of the nascent enzymes rather than a total loss of their function as neither deletion nor overexpression of dxsA restored the phenotype observed in spontaneous mutants.

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Antibiotic susceptibility of Staphylococcus aureus with different degrees of biofilm formation

Journal of Analytical Science & Technology ◽

10.1186/s40543-021-00294-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Hyo-Jung Shin ◽

Sungtae Yang ◽

Yong Lim

Keyword(s):

Staphylococcus Aureus ◽

Biofilm Formation ◽

Antimicrobial Agents ◽

Resistance Mechanisms ◽

Minimal Bactericidal Concentration ◽

Chronic Infections ◽

Planktonic Bacteria ◽

Growth Modes ◽

Biofilm Bacteria ◽

Biofilm Development

AbstractStaphylococcus aureus is one of the most common pathogens in biofilm-associated chronic infections. S. aureus living within biofilms evades the host immune response and is more resistant to antibiotics than planktonic bacteria. In this study, we generated S. aureus with low and high levels of biofilm formation using the rbf (regulator of biofilm formation) gene and performed a BioTimer assay to determine the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of various types of antibiotics. We showed that biofilm formation by S. aureus had a greater effect on MBC than MIC, probably due to the different growth modes between planktonic and biofilm bacteria. Importantly, we found that the MBC for biofilm S. aureus was much higher than that for planktonic cells, but there was little difference in MBC between low and high levels of biofilm formation. These results suggest that once the biofilm is formed, the bactericidal activity of antibiotics is significantly reduced, regardless of the degree of S. aureus biofilm formation. We propose that S. aureus strains with varying degrees of biofilm formation may be useful for evaluating the anti-biofilm activity of antimicrobial agents and understanding antibiotic resistance mechanisms by biofilm development.

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Multidrug-Resistant Acinetobacter baumannii Genetic Characterization and Spread in Lithuania in 2014, 2016, and 2018

Life ◽

10.3390/life11020151 ◽

2021 ◽

Vol 11 (2) ◽

pp. 151

Author(s):

Tatjana Kirtikliene ◽

Aistė Mierauskaitė ◽

Ilona Razmienė ◽

Nomeda Kuisiene

Keyword(s):

Acinetobacter Baumannii ◽

Resistance Genes ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Variable Number Tandem Repeat ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Essential Information ◽

Acinetobacter Spp

Bacterial resistance to antimicrobial agents plays an important role in the treatment of bacterial infections in healthcare institutions. The spread of multidrug-resistant bacteria can occur during inter- and intra-hospital transmissions among patients and hospital personnel. For this reason, more studies must be conducted to understand how resistance occurs in bacteria and how it moves between hospitals by comparing data from different years and looking out for any patterns that might emerge. Multidrug-resistant (MDR) Acinetobacter spp. was studied at 14 healthcare institutions in Lithuania during 2014, 2016, and 2018 using samples from human bloodstream infections. In total, 194 isolates were collected and identified using MALDI-TOF and VITEK2 analyzers as Acinetobacter baumannii group bacteria. After that, the isolates were analyzed for the presence of different resistance genes (20 genes were analyzed) and characterized by using the Rep-PCR and MLVA (multiple-locus variable-number tandem repeat analysis) genotyping methods. The results of the study showed the relatedness of the different Acinetobacter spp. isolates and a possible circulation of resistance genes or profiles during the different years of the study. This study provides essential information, such as variability and diversity of resistance genes, genetic profiling, and clustering of isolates, to better understand the antimicrobial resistance patterns of Acinetobacter spp. These results can be used to strengthen the control of multidrug-resistant infections in healthcare institutions and to prevent potential outbreaks of this pathogen in the future.

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AMPing up the search: An in silico approach to identifying Antimicrobial Peptides (AMPs) with potential anti-biofilm activity

10.1101/2021.08.16.456477 ◽

2021 ◽

Author(s):

Shreeya Mhade ◽

Stutee Panse ◽

Gandhar Tendulkar ◽

Rohit Awate ◽

Snehal Kadam ◽

...

Keyword(s):

Antimicrobial Peptides ◽

In Silico ◽

Biofilm Formation ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

C Protein ◽

Pilus Biogenesis ◽

Natural And Synthetic

AbstractAntibiotic resistance is a public health threat, and the rise of multidrug-resistant bacteria, including those that form protective biofilms, further compounds this challenge. Antimicrobial peptides (AMPs) have been recognized for their anti-infective properties, including their ability to target processes important for biofilm formation. However, given the vast array of natural and synthetic AMPs, determining potential candidates for anti-biofilm testing is a significant challenge. In this study, we present an in silico approach, based on open-source tools, to identify AMPs with potential anti-biofilm activity. This approach is developed using the sortase-pilin machinery, important for adhesion and biofilm formation, of the multidrug-resistant, biofilm-forming pathogen C. striatum as the target. Using homology modeling, we modeled the structure of the C. striatum sortase C protein, resembling the semi-open lid conformation adopted during pilus biogenesis. Next, we developed a structural library of 5544 natural and synthetic AMPs from sequences in the DRAMP database. From this library, AMPs with known anti-Gram positive activity were filtered, and 100 select AMPs were evaluated for their ability to interact with the sortase C protein using in-silico molecular docking. Based on interacting residues and docking scores, we built a preference scale to categorize candidate AMPs in order of priority for future in vitro and in vivo biofilm studies. The considerations and challenges of our approach, and the resources developed, which includes a search-enabled repository of predicted AMP structures and protein-peptide interaction models relevant to biofilm studies (B-AMP), can be leveraged for similar investigations across other biofilm targets and biofilm-forming pathogens.

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Releasable antimicrobial polymer-silk coatings for combating multidrug-resistant bacteria

Polymer Chemistry ◽

10.1039/d1py01219c ◽

2021 ◽

Author(s):

Erna Wulandari ◽

Rachel Budhisatria ◽

Alexander H. Soeriyadi ◽

Mark Willcox ◽

Cyrille Boyer ◽

...

Keyword(s):

Controlled Release ◽

Biofilm Formation ◽

Multidrug Resistant ◽

Bacterial Biofilm ◽

Resistant Bacteria ◽

Multidrug Resistant Bacteria ◽

Antimicrobial Polymers ◽

Planktonic Bacteria

Controlled release of synthetic cationic antimicrobial polymers from silk-based coating for preventing bacterial biofilm formation on the surface and for killing planktonic bacteria cells.

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Novel Synthetic Antimicrobial and Anti-biofilm Peptides (SAAPs)-containing coatings to prevent biomaterial-associated infection

10.5194/biofilms9-67 ◽

2020 ◽

Author(s):

Martijn Riool ◽

Anna de Breij ◽

Moniek G.J. Schmitz ◽

Leonie de Boer ◽

Jan W. Drijfhout ◽

...

Keyword(s):

Medical Devices ◽

Biofilm Formation ◽

Heart Valves ◽

Antimicrobial Agents ◽

Porous Scaffold ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Prosthetic Heart Valves ◽

Scaffold Material

The use of medical devices has grown significantly over the last decades, and has become a major part of modern medicine and our daily life. Infection of implanted medical devices (biomaterials), like catheters, prosthetic heart valves or orthopaedic implants, can have disastrous consequences, including removal of the device. For still not well understood reasons, the presence of a foreign body strongly increases susceptibility to infection. These so-called biomaterial-associated infections (BAI) are mainly caused by Staphylococcus aureus and Staphylococcus epidermidis. The risk of infection might even be higher in so-called in situ tissue engineering applications, where population or infiltration of the scaffold material by endogenous cells and thereby the formation of new/healed tissue occurs as a spatiotemporal process. Since the porous scaffold materials can form a niche for invading bacteria, the intended in situ production of novel tissue may be severely compromised by infection. Our work focuses on the development and characterization of novel antimicrobial agents and delivery systems, and their effectiveness in the prevention of BAI and other difficult-to-treat biofilm infections. The scarcity of current antibiotic-based strategies to prevent infections and their risk of resistance development prompted us to develop novel synthetic antimicrobial and anti-biofilm peptides (SAAPs) based on the primary sequences of the human antimicrobial proteins Thrombocin-11 and LL-372, and to test their potential in the fight against implant-associated and wound infections by multidrug-resistant bacteria. The lead peptide, SAAP-148, kills multidrug-resistant pathogens without inducing resistance, prevents biofilm formation and eliminates established biofilms and persister cells, and is effective against both acute and established skin infections1. As a next step, we aim to develop a new polymeric supramolecular3 scaffold material, exerting two important functions: preventing microbial adhesion - by incorporating SAAP-148 - and thereby preventing biofilm formation, and inducing endogenous (eukaryotic) cells to adhere and propagate, as a first step towards functional tissue repair. This work is supported by FP7-HEALTH-2011 grant 278890, Biofilm Alliance and by NWO NEWPOL grant SuperActive (Project No. 731.015.505) in collaboration with the Dutch Polymer Institute (DPI, P.O. Box 902, 5600 AX Eindhoven, the Netherlands). 1Riool M. & de Breij A. et al., BBA &#8211; Biomembranes (2020); 2de Breij A. & Riool M. et al., Sci. Transl. Med. (2018); 3Dankers P.Y.W. et al., Nat. Mater. (2005).

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Current Mechanism of Bacterial Resistance to Antimicrobials

SAMRIDDHI A Journal of Physical Sciences Engineering and Technology ◽

10.18090/samriddhi.v10i01.8 ◽

2018 ◽

Vol 10 (01) ◽

pp. 55-64

Author(s):

Sonali Gangwar ◽

Keerti Kaushik ◽

Maya Datt Joshi

Keyword(s):

Molecular Mechanisms ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Multidrug Resistant ◽

Hospital Environment ◽

Health Concern ◽

Resistant Bacteria ◽

Drug Resistant ◽

Pathogenic Variants ◽

Drug Resistant Bacteria

Serious infectious diseases are caused by bacterial pathogens that represents a serious public health concern. Antimicrobial agents are indicated for the treatment bacterial infections.Various bacteria carries several resistance genes also called multidrug resistant (MDR). Multidrug resistant organisms have emerged not only in the hospital environment but are now often identified in community settings, suggesting the reservoirs of antibiotic resistant bacteria are present outside the hospital. Drug resistant bacteria that are selected with a single drug are also frequently multi-drug resistant against multiple structurally different drugs, thus confounding the chemotherapeutic efficacy of infectious disease caused by such pathogenic variants. The molecular mechanisms by which bacteria have common resistance to antibiotics are diverse and complex. This review highlights the mechanism of bacterial resistance to antimicrobials.

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Antibacterial activity of total flavonoids from Ilex rotunda Thunb. and different antibacterials on different multidrug-resistant bacteria alone or in combination

10.1101/457911 ◽

2018 ◽

Author(s):

Yongji Wu ◽

Beibei Chai ◽

Lizhen Wang ◽

Weijia Jiang ◽

Mei Hu ◽

...

Keyword(s):

Antibacterial Activity ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Combined Therapy ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Total Flavonoids ◽

Multidrug Resistant Bacteria ◽

Minimal Inhibitory Concentrations ◽

Ilex Rotunda

AbstractThe problem of bacterial resistance is becoming more and more serious, which has become an urgent problem to be solved in human and veterinary. One approach to control and delay bacterial resistance is combination therapy in which antibiotics are given together with other antimicrobial or non-antimicrobial agents. Studies have shown that flavonoids from Traditional Chinese medicine (TCM) possess a high level of antibacterial activity against antibiotic resistant strains. The aim of this study was to evaluate the antibacterial effects of a combined therapy of total flavonoids from Ilex rotunda Thunb. and antibiotics against seven kinds of veterinary bacteria which were multidrug resistance bacteria. A microdilution checkerboard method was used to determine the minimal inhibitory concentrations of both types of antimicrobials, alone and in combination. The fractional inhibitory concentration index was calculated and used to classify observed collective antibacterial activity as synergistic, additive, indifferent or antagonistic.From the performed tests, the total flavonoids and antimicrobial agents were combined to inhibit different multidrug-resistant bacteria, such as Escherichia coli, Streptococcus, Pseudomonas aeruginosa, Enterococcus faecalis, Proteus vulgaris, Staphylococcus aureus, Acinetobacter baumannii. For these bacteria, total flavonoids from Ilex Rotunda Thunb. presented synergistic or additive with different antibiotics and had a certain antibacterial effect on the separated multidrug-resistant bacteria. The study shows total flavonoids from Ilex rotunda Thunb. have potential as adjuvants for the treatment of animal bacterial diseases.

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Counteraction of Biofilm Formation and Antimicrobial Potential of Terminalia catappa Functionalized Silver Nanoparticles against Candida albicans and Multidrug-Resistant Gram-Negative and Gram-Positive Bacteria

Antibiotics ◽

10.3390/antibiotics10060725 ◽

2021 ◽

Vol 10 (6) ◽

pp. 725

Author(s):

Mohammad Azam Ansari ◽

Abul Kalam ◽

Abdullah G. Al-Sehemi ◽

Mohammad N. Alomary ◽

Sami AlYahya ◽

...

Keyword(s):

Silver Nanoparticles ◽

Cell Wall ◽

Candida Albicans ◽

Biofilm Formation ◽

Antimicrobial Agents ◽

Membrane Integrity ◽

Multidrug Resistant ◽

Ultrastructural Changes ◽

Resistant Bacteria ◽

Terminalia Catappa

Biofilms not only protect bacteria and Candida species from antibiotics, but they also promote the emergence of drug-resistant strains, making eradication more challenging. As a result, novel antimicrobial agents to counteract biofilm formation are desperately needed. In this study, Terminalia catappa leaf extract (TCE) was used to optimize the TCE-capped silver nanoparticles (TCE-AgNPs) via a one-pot single-step method. Varied concentrations of TCE have yielded different sized AgNPs. The physico-chemical characterization of TCE-AgNPs using UV-Vis, SEM, TEM, FTIR, and Raman spectroscopy have confirmed the formation of nanostructures, their shape and size and plausible role of TCE bio-active compounds, most likely involved in the synthesis as well as stabilization of NPs, respectively. TCE-AgNPs have been tested for antibiofilm and antimicrobial activity against multidrug-resistant Pseudomonas aeruginosa (MDR-PA), methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans using various microbiological protocols. TCE-Ag-NPs−3 significantly inhibits biofilm formation of MDR-PA, MRSA, and C. albicans by 73.7, 69.56, and 63.63%, respectively, at a concentration of 7.8 µg/mL, as determined by crystal violet microtiter assay. Furthermore, SEM micrograph shows that TCE-AgNPs significantly inhibit the colonization and adherence of biofilm forming cells; individual cells with loss of cell wall and membrane integrity were also observed, suggesting that the biofilm architecture and EPS matrix were severely damaged. Moreover, TEM and SEM images showed that TCE-AgNPs brutally damaged the cell wall and membranes of MDR-PA, MRSA, and C. albicans. Additionally, extreme ultrastructural changes such as deformation, disintegration, and separation of cell wall and membrane from the cells, have also been observed, indicating significant loss of membrane and cell wall integrity, which eventually led to cell death. Overall, the research revealed a simple, environmentally friendly, and low-cost method for producing colloidal TCE-AgNPs with promising applications in advanced clinical settings against broad-spectrum biofilm-forming antibiotic-resistant bacteria and candida strains.

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Antibacterial and Antibiofilm Effects of Synbiotics against Multidrug-Resistant bacteria: Acinetobacter baumannii and Enterococcus faecalis

10.21203/rs.3.rs-16459/v1 ◽

2020 ◽

Author(s):

Niki Laal-Kargar ◽

Samaneh Dolatabadi ◽

Mahnaz Mohtashami

Keyword(s):

Acinetobacter Baumannii ◽

Biofilm Formation ◽

Multidrug Resistant ◽

Inhibitory Effect ◽

Resistant Bacteria ◽

Dilution Method ◽

Antibiofilm Activity ◽

Drug Resistant ◽

Study Support ◽

And Control

Abstract Background: Acinetobacter baumannii and Enterocoocus faecalis increase their resistance against antibiotic by producing biofilm. Antibiotic resistance has become a massive public health threat that require novel effective antibacterial and antibiofilm alternatives. The use of probiotics is interested to prevent and control certain infections. The objective of this study was to investigate the antibacterial and antibiofilm property of probiotics and synbiotics against multidrug-resistant A. baumannii and E. faecalis. Methods: The antimicrobial and the antibiofilm activities of cell- free supernatants of four strains of Lactobacillus against 20 clinical multi-drug resistant (MDR) isolates of Acinetobacter baumannii and Enterocoocus faecalis were determined in the presence of 0.3% of sorbitol, raffinose, citrate, trehalose, inulin, and riboflavin using well diffusion agar and micro-dilution method. Results: The cell- free supernatant of L. rhamnosus with citrate and trehalose showed the best antibacterial activity against MDR A. baumannii (28.8±2.1mm, 1.128 μL/mL), and L. rhamnosus with all of prebiotics against MDR E. faecalis (29.8±0 mm, 1.128 μL/mL) compare to probiotic alone. The prebiotics could improve the inhibitory effect of probiotics against the Gram-negative A. baumannii higher than Gram-positive E. faecalis. Biofilm formation was reduced in both pathogens in presence of synbiotics. L. plantarum with riboflavin and L. rhamnosus with or without inulin potently inhibits E. faecalis (50±0.86%) and A. baumannii (75±6.5%) biofilm formation, respectively. Conclusions: The results of current study support the antibiofilm activity of metabolites produced by synbiotics, and suggest their use as suitable adjuvants as well as biocontrol agents for treatment.

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