scholarly journals Effective inhibition of Clostridioides difficile by the novel peptide CM-A

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257431
Author(s):  
Sirirak Arthithanyaroj ◽  
Surang Chankhamhaengdecha ◽  
Urai Chaisri ◽  
Ratchaneewan Aunpad ◽  
Amornrat Aroonnual
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Cell Membrane ◽  
Inhibitory Concentration ◽  
Cell Permeability ◽  
Resistant Bacteria ◽  
Microscopy Imaging ◽  
Antibiotic Resistant ◽  
Clostridioides Difficile ◽  
Novel Approach ◽  
Cell Depolarization

Clostridioides difficile infection is the most common cause of nosocomial and antibiotic-associated diarrhea. C. difficile treatment is increasingly likely to fail, and the recurrence rate is high. Antimicrobial peptides are considered an alternative treatment for many infectious diseases, including those caused by antibiotic resistant bacteria. In the present study, we identified a CM peptide, a hybrid of cecropin A and melittin, and its derivative which possesses potent antimicrobial activity against C. difficile strain 630. CM peptide exhibited antibacterial activity with minimum inhibitory concentration of 3.906 μg/ml (2.21 μM). A modified derivative of CM, CM-A, exhibited even greater activity with a minimum inhibitory concentration of 1.953 μg/ml (1.06 μM) and a minimum bactericidal concentration of 7.8125 μg/ml (4.24 μM), which indicates that CM-A peptide is more efficient than its parent peptide. A fluorescence-activated cell sorter analysis revealed that the membrane of C. difficile 630 could be an important target for CM-A. This peptide induced high levels of cell depolarization and cell permeability on C. difficile cell membrane. Moreover, electron microscopy imaging showed that CM-A interferes with the C. difficile cell membrane. Hence, the antimicrobial peptide CM-A may represent a promising novel approach for the treatment of C. difficile infections.

scholarly journals Characterization and partial purification of an antibacterial agent from halophilic actinomycetes Kocuria sp. strain rsk4

Bioimpacts ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 253-261 ◽  
Author(s):  
Ravi Ranjan Kumar ◽  
Vasantba J Jadeja
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Broad Spectrum ◽  
Antibacterial Agent ◽  
Pathogenic Bacteria ◽  
Inhibitory Concentration ◽  
Flash Chromatography ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Antibacterial Compound ◽  
Halophilic Actinomycetes

Introduction: The inevitable rise of antibiotic-resistant bacteria is a global health problem. These pathogens erode the utility of available antibiotics. Staphylococcus aureus is one of the major causes of community-acquired infections. The aim of work was to evaluate the marine actinomycetes for production of the antibacterial agent against pathogens. Methods: Halophilic actinomycetes were isolated, characterized and screened for production of antibacterial agent against pathogenic bacteria. The antibacterial compounds were extracted by solvent extraction and separated by TLC based bioautography. Antibacterial compound was further purified by flash chromatography followed by high-performance liquid chromatography (HPLC) techniques. The active fraction was characterized by spectroscopy techniques. The minimum inhibitory concentration of antibiotic was determined against pathogens. Results: A new halophilic actinomycetes strain rsk4 was isolated from marine water. It was designated as Kocuria sp. based on the physiological, biochemical and 16S rDNA sequence-based characters. It was able to produce broad-spectrum antibacterial compound and exhibited significant inhibitory activities against antibiotic-resistant S. aureus. The antibacterial compound was secreted optimally at 5% NaCl and neutral pH in the starch casein medium during stationary phase. The crude ethyl acetate extract was separated by chloroform-methanol, 24:1, v/v having Rf value 0.45. Bioassay of HPLC fractions confirms the presence of antibiotics picks at retention time: 3.24 minutes. The UV-Visible and mass spectra of the compound revealed that the active compound was different from other known antibiotics. The lowest minimum inhibitory concentration was recorded against S. aureus (30 µg/mL). Conclusion: The result suggests that a broad-spectrum antibacterial compound obtained from halophilic actinomycetes is effective against pathogenic bacteria. This compound may be a good alternative treatment against antibiotic-resistant pathogen S. aureus.

scholarly journals Synergistic Combinations of Antibiotics with Cumin, Oregano and Rosewood Oils as a Strategy to Preserve the Antibiotic Repertoire

2019 ◽  
Vol 5 (4) ◽  
pp. 337-353
Author(s):  
Lucy Owen ◽  
Katie Laird
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Resistant Bacteria ◽  
Positive Interactions ◽  
Antibiotic Resistant ◽  
Test Species ◽  
Clinical Sensitivity ◽  
E Coli ◽  
Time Kill ◽  
Synergistic Combinations

Background: Formulations employing synergistic combinations of antibiotics with Essential Oils (EOs) could help preserve the antibiotic repertoire by improving their activity against resistant bacteria. Objective: Antimicrobial interactions between double and triple combinations of EOs, EO components and antibiotics were determined using the checkerboard method. The most active triple combinations were then assessed by a time-kill assay. Methods: Two synergistic EO-antibiotic combinations and eight additive EO-antibiotic combinations reduced the antibiotic minimum inhibitory concentration below clinical sensitivity breakpoints according to the checkerboard method. However, all the tested combinations were additive according to the time-kill assay; while the combinations completely killed S. aureus, E. coli and P. aeruginosa cells in 2 h. At least one EO compound from the combination alone completely killed the cells of test species. Results: Two synergistic EO-antibiotic combinations and eight additive EO-antibiotic combinations reduced the antibiotic minimum inhibitory concentration below clinical sensitivity breakpoints according to the checkerboard method. However, all the tested combinations were additive according to the time-kill assay; while the combinations completely killed S. aureus, E. coli and P. aeruginosa cells in 2 h. At least one EO compound from the combination alone completely killed the cells of test species. Conclusion: Positive interactions support the use of EOs or EO components to enhance antibiotic efficacy against antibiotic resistant bacteria. The EO-antibiotic combinations tested by the time kill assay were indifferent; therefore, the observed antimicrobial activity did not arise from synergistic mechanisms as indicated by the checkerboard method. Investigation of other synergistic combinations identified by the checkerboard method could reveal more promising candidates.

scholarly journals Antibiogram signatures of non-cholera causing Vibrio species recovered from environmental niches in Eastern Cape, South Africa.

2021 ◽  
Author(s):  
Oluwakemi Victoria Ayodele ◽  
Anthony Ifeanyi Okoh
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Nalidixic Acid ◽  
Vibrio Parahaemolyticus ◽  
Inhibitory Concentration ◽  
Vibrio Vulnificus ◽  
Diffusion Method ◽  
Morbidity Rate ◽  
Antibiotic Resistant ◽  
Mortality And Morbidity ◽  
Vibrio Fluvialis

Abstract Background: The use of antibiotics globally has helped reduce mortality and morbidity rate due to its ability to effectively treat bacterial infections in both humans and animals. However, the menace of antimicrobial resistance has become a challenge to public health due to its increased mortality and morbidity rate. This study determined the antibiogram pattern of non-cholera causing Vibrio species against a panel of 11 antibiotics that are wildly used for treatment. Multiple antibiotic resistance phenotype, multiple antibiotic resistant indices and minimum inhibitory concentration (MIC) of test antibiotics were also determined.Results: Polymerase chain reaction (PCR) was used to confirm 100 isolates of Vibrio parahaemolyticus, 82 and 46 isolates of Vibrio vulnificus and Vibrio fluvialis respectively, collected from the culture collections of the Applied and Environmental Microbiology Research Group (AEMREG), University of Fort Hare. Thereafter, disc diffusion method was used to determine the antibiogram pattern of target non-cholera causing Vibrio species against a panel of 11 antibiotics that are of clinical importance. The highest rate of Vibrio parahaemolyticus resistance was observed against tetracycline (22 %) and nalidixic acid (16 %). Vibrio fluvialis also displayed highest rate of resistance against tetracycline (28 %) and nalidixic acid (28 %), while Vibrio vulnificus isolates exhibited highest rate resistance against imipenem (40 %) and tetracycline (22 %). A total of 38 MARP patterns were observed and the MAR indices ranged between 0.3 and 0.8. Against the resistant Vibrio parahaemolyticus and Vibrio fluvialis isolates, minimum inhibitory concentration ranged from 16 µg/ml to 2048 µg/ml for both tetracycline and nalidixic acid, while against Vibrio vulnificus isolates, minimum inhibitory concentration ranged from 8 µg/ml to 256 µg/ml for both imipenem and nalidixic acid. Conclusions: Results obtained from this study is an indication that antibiotic resistant bacteria that could pose as threat to health of humans and animals are present in the environment.

scholarly journals Determination of Drug Efflux Pump Efficiency in Drug-Resistant Bacteria Using MALDI-TOF MS

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 639 ◽  
Author(s):  
Wen-Jung Lu ◽  
Hsuan-Ju Lin ◽  
Pang-Hung Hsu ◽  
Hong-Ting Victor Lin
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Resistant Bacteria ◽  
Pump Efficiency ◽  
Drug Efflux ◽  
Maldi Tof Ms ◽  
E Coli ◽  
Maldi Tof ◽  
Conventional Methods ◽  
Tof Ms

Multidrug efflux pumps play an essential role in antibiotic resistance. The conventional methods, including minimum inhibitory concentration and fluorescent assays, to monitor transporter efflux activity might have some drawbacks, such as indirect evidence or interference from color molecules. In this study, MALDI-TOF MS use was explored for monitoring drug efflux by a multidrug transporter, and the results were compared for validation with the data from conventional methods. Minimum inhibitory concentration was used first to evaluate the activity of Escherichia coli drug transporter AcrB, and this analysis showed that the E. coli overexpressing AcrB exhibited elevated resistance to various antibiotics and dyes. Fluorescence-based studies indicated that AcrB in E. coli could decrease the accumulation of intracellular dyes and display various efflux rate constants for different dyes, suggesting AcrB’s efflux activity. The MALDI-TOF MS analysis parameters were optimized to maintain a detection accuracy for AcrB’s substrates; furthermore, the MS data showed that E. coli overexpressing AcrB led to increased ions abundancy of various dyes and drugs in the extracellular space at different rates over time, illustrating continuous substrate efflux by AcrB. This study concluded that MALDI-TOF MS is a reliable method that can rapidly determine the drug pump efflux activity for various substrates.

scholarly journals Overview of Quantitative Methodologies to Understand Antimicrobial Resistance via Minimum Inhibitory Concentration

Animals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1405
Author(s):  
Alec Michael ◽  
Todd Kelman ◽  
Maurice Pitesky
Keyword(s):  
Logistic Regression ◽  
Minimum Inhibitory Concentration ◽  
Antimicrobial Resistance ◽  
Model Selection ◽  
Inhibitory Concentration ◽  
Failure Time ◽  
Resistant Bacteria ◽  
Accelerated Failure Time ◽  
Clinical Resistance ◽  
Interval Censored

The development of antimicrobial resistance (AMR) represents a significant threat to humans and food animals. The use of antimicrobials in human and veterinary medicine may select for resistant bacteria, resulting in increased levels of AMR in these populations. As the threat presented by AMR increases, it becomes critically important to find methods for effectively interpreting minimum inhibitory concentration (MIC) tests. Currently, a wide array of techniques for analyzing these data can be found in the literature, but few guidelines for choosing among them exist. Here, we examine several quantitative techniques for analyzing the results of MIC tests and discuss and summarize various ways to model MIC data. The goal of this review is to propose important considerations for appropriate model selection given the purpose and context of the study. Approaches reviewed include mixture models, logistic regression, cumulative logistic regression, and accelerated failure time–frailty models. Important considerations in model selection include the objective of the study (e.g., modeling MIC creep vs. clinical resistance), degree of censoring in the data (e.g., heavily left/right censored vs. primarily interval censored), and consistency of testing parameters (e.g., same range of concentrations tested for a given antibiotic).

scholarly journals Synthesis and Anti-Saprolegnia Activity of New 2’,4’-Dihydroxydihydrochalcone Derivatives

Antibiotics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 317
Author(s):  
Enrique Werner ◽  
Iván Montenegro ◽  
Bastian Said ◽  
Patricio Godoy ◽  
Ximena Besoain ◽  
...  
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Cell Membrane ◽  
Inhibitory Concentration ◽  
Addition Compound ◽  
Saprolegnia Parasitica ◽  
Different Strains ◽  
Positive Controls

In the present study, seven 2’,4’-dihydroxydihydrochalcone derivatives (compounds 3–9) were synthesized and their capacity as anti-Saprolegnia agents were evaluated against Saprolegnia parasitica, S. australis, S. diclina. Derivative 9 showed the best activity against the different strains, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values between 100–175 μg/mL and 100–200 μg/mL, respectively, compared with bronopol and fluconazole as positive controls. In addition, compound 9 caused damage and disintegration cell membrane of all Saprolegnia strains over the action of commercial controls.

scholarly journals Antibacterial activity of Cathormion umbellatum

2021 ◽  
Vol 16 (3) ◽  
pp. 91-95
Author(s):  
Surachai Rattanasuk ◽  
Rujirek Boongapim ◽  
Tannatorn Phiwthong
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Antibacterial Effect ◽  
Colorimetric Assay ◽  
Inhibition Zone ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Diffusion Assay

The aim of this study was to determine the antibacterial activity of Cathormion umbellatum extracts against seven antibiotic-resistant bacteria. The pods, leaves and branches of C. umbellatum were extracted with ethanol and methanol. The disc diffusion assay was used to screen the antibacterial activity and broth microdilution and colorimetric assay were used to measure the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. The result indicated that the highest inhibition zone (11 mm) was presented in ethanolic pods extract against multidrug resistance Klebsiella pneumoniae. The lowest MIC value of 0.05 mg/mL was obtained from branch extracted with ethanol against colistin resistant Pseudomonas aeruginosa. The lowest MBC values of 1.56 mg/mL were obtained when using C. umbellatum leaves extracted with methanol against all test antibiotic-resistant bacteria. This is the first report presented C. umbellatum extracts have the potential to eliminate antibiotic-resistant bacteria in patients. These findings show the antibacterial effect of C. umbellatum.

scholarly journals Evaluation of the Sensitivity of Staphylococcus aurous Isolated from Nasal Swabs to Natural Honey

2020 ◽  
pp. 56-64
Author(s):  
A Molanaei ◽  
SA Seyedoshohadaei ◽  
S Hasani ◽  
P Sharifi ◽  
M Rashidian ◽  
...  
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Antibacterial Agents ◽  
Bacterial Resistance ◽  
Inhibitory Concentration ◽  
Antibacterial Properties ◽  
Resistant Bacteria ◽  
Nasal Swabs ◽  
Vancomycin Resistant ◽  
Dilution Tube ◽  
Natural Honey

Introduction: Bacterial resistance to antibacterial agents is a very serious threat to public health. Where some antibacterial agents prove ineffective, the antibacterial properties of honey have been shown to be highly efficacious against several human bacterial pathogens. The purpose of this study is to investigate the sensitivity of Staphylococcus aureus isolated from the nursing staff of a hospital to natural honey. Methods: In this study, 35 strains of methicillin-resistant S. aurous samples were selected from hospital staff's nasal swabs. Two strains were vancomycin-resistant. The serial dilution tube test methodwas used to determine minimum inhibitory concentration (MIC) .The susceptibility of each strain of staph bacteria to natural honey without wax was determined and compared with that of a glucose solution with the same density. Results: In all strains, except for the two strains resistant to vancomycin, MIC level was < 8.3% (v/v). The MIC of glucose as dense as honey was four times higher. The two vancomycin-resistant strains were completely resistant to natural honey. Conclusions: This study has therefore demonstrated that inhibiting bacterial growth is not merely done by purely natural honey not because of osmolality, but vancomycin-resistant bacteria are not sensitive to natural honey. Keywords: sensitivity, Staphylococcus aurous, natural honey, minimum inhibitory concentration

Opposite effect of vancomycin and D-Cycloserine combination in both vancomycin resistant Staphylococcus aureus and enterococci

2020 ◽  
Vol 367 (8) ◽  
Author(s):  
Abdelhakim Boudrioua ◽  
Yanyan Li ◽  
Axel Hartke ◽  
Caroline Giraud
Keyword(s):  
Staphylococcus Aureus ◽  
Opposite Effect ◽  
Inhibitory Concentration ◽  
Health Concern ◽  
Resistant Bacteria ◽  
Glycopeptide Antibiotic ◽  
Antibiotic Resistant ◽  
Peptidoglycan Biosynthesis ◽  
Vancomycin Resistant ◽  
Type Strains

ABSTRACT The increasing spread of antibiotic resistant bacteria is a major human health concern. The challenging development of new effective antibiotics has led to focus on seeking synergistic antibiotic combinations. Vancomycin (VAN) is a glycopeptide antibiotic used to treat Staphylococcus aureus and enterococci infections. It is targeting D-Alanyl-D-Alanine dimers during peptidoglycan biosynthesis. D-cycloserine (DCS) is a D-Alanine analogue that targets peptidoglycan biosynthesis by inhibiting D-Alanine:D-Alanine ligase (Ddl). The VAN-DCS combination was found to be synergistic in VAN resistant S. aureus strains lacking van genes cluster. We hypothesize that this combination leads to opposite effects in S. aureus and enterococci strains harboring van genes cluster where VAN resistance is conferred by the synthesis of modified peptidoglycan precursors ending in D-Alanyl-D-Lactate. The calculated Fractional Inhibitory Concentration of VAN-DCS combination in a van- vancomycin-intermediate, VanA type, and VanB type strains were 0.5, 5 and 3, respectively. As a result, VAN-DCS combination leads to synergism in van-lacking strains, and to antagonism in strains harboring van genes cluster. The VAN-DCS antagonism is due to a mechanism that we named van-mediated Ddl inhibition bypass. Our results show that antibiotic combinations can lead to opposite effects depending on the genetic backgrounds.

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