scholarly journals In VitroBactericidal Activity of 4- and 5-Chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides against MRSA

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Iveta Zadrazilova ◽  
Sarka Pospisilova ◽  
Karel Pauk ◽  
Ales Imramovsky ◽  
Jarmila Vinsova ◽  
...  
Keyword(s):  
Minimum Bactericidal Concentration ◽  
Bacterial Count ◽  
Bactericidal Effect ◽  
Final Concentration ◽  
Control Strain ◽  
Time Points ◽  
Time Kill ◽  
Kinetics Of ◽  
Bactericidal Agent ◽  
Quality Control Strain

A series of nine substituted 2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides was assessed as prospective bactericidal agents against three clinical isolates of methicillin-resistantStaphylococcus aureus(MRSA) andS. aureusATCC 29213 as the reference and quality control strain. The minimum bactericidal concentration was determined by subculturing aliquots from MIC determination onto substance-free agar plates. The bactericidal kinetics of compounds 5-chloro-2-hydroxy-N-[(2S)-3-methyl-1-oxo-1-{[4-(trifluoromethyl)phenyl]amino}butan-2-yl]benzamide (1f),N-{(2S)-1-[(4-bromophenyl)amino]-3-methyl-1-oxobutan-2-yl}-4-chloro-2-hydroxybenzamide (1g), and 4-chloro-N-{(2S)-1-[(3,4-dichlorophenyl)amino]-3-methyl-1-oxobutan-2-yl}-2-hydroxybenzamide (1h) was established by time-kill assay with a final concentration of the compound equal to 1x, 2x, and 4x MIC; aliquots were removed at 0, 4, 6, 8, and 24 h time points. The most potent bactericidal agent was compound1fexhibiting remarkable rapid concentration-dependent bactericidal effect even at 2x MIC at 4, 6, and 8 h (with a reduction in bacterial count ranging from 3.08 to 3.75 log10 CFU/mL) and at 4x MIC at 4, 6, 8, and 24 h (5.30 log10 CFU/mL reduction in bacterial count) after incubation against MRSA 63718. Reliable bactericidal effect against other strains was maintained at 4x MIC at 24 h.

scholarly journals Bactericidal Activity, Absence of Serum Effect, and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

2014 ◽  
Vol 58 (9) ◽  
pp. 5297-5305 ◽  
Author(s):  
Tiffany R. Keepers ◽  
Marcela Gomez ◽  
Chris Celeri ◽  
Wright W. Nichols ◽  
Kevin M. Krause
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Serum ◽  
Bactericidal Activity ◽  
Minimum Bactericidal Concentration ◽  
Wild Type ◽  
Content Type ◽  
Positive Isolate ◽  
New Treatment ◽  
Time Kill ◽  
Kinetics Of

ABSTRACTAvibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18Pseudomonas aeruginosaisolates and 15Enterobacteriaceaeisolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2P. aeruginosaisolates (1blaVIM-positive isolate and 1blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10decrease in the number of CFU/ml was observed at 6 h for allEnterobacteriaceae, and a 2-log10reduction in the number of CFU/ml was observed at 6 h for 3 of the 6P. aeruginosaisolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused byEnterobacteriaceaeandP. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.

scholarly journals Pharmacodynamic Interaction ofQuercus infectoriaGalls Extract in Combination with Vancomycin against MRSA Using Microdilution Checkerboard and Time-Kill Assay

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Dayang Fredalina Basri ◽  
Radhiah Khairon
Keyword(s):  
Inhibitory Concentration ◽  
Synergistic Effects ◽  
Bactericidal Effect ◽  
Pharmacodynamic Interaction ◽  
Killing Rate ◽  
Mrsa Strains ◽  
Index Value ◽  
Time Kill ◽  
Kinetics Of ◽  
Quercus Infectoria

The galls ofQuercus infectoriaOlivier possess astringent properties which helps in the tightening of the vaginal epithelium in the post-natal period. The present study aimed to observe the time-kill kinetics of the acetone and methanol extracts of gall ofQ. infectoriain combination with vancomycin against two methicillin-resistantStaphylococcus aureus(MRSA) strains; ATCC 33591 and MU 9495 (laboratory-passaged strain). Minimum inhibitory concentration (MIC) of the extracts were determined using microdilution technique whereas the checkerboard and time-kill kinetics were employed to verify the synergistic effects of treatment with vancomycin. The FIC index value of the combinations against both MRSA strains showed that the interaction was synergistic (FIC index<0.5). Time-kill assays showed the bactericidal effect of the combination treatment at 1/8XMIC of the extract and 1/8XMIC of vancomycin, were respectively at7.2±0.28 hr against ATCC 33591 compared to complete attenuation of the growth of the same strain after 8 hr of treatment with vancomycin alone. In conclusion, the combination extracts ofQ. infectoriawith vancomycin were synergistic according to FIC index values. The time-kill curves showed that the interaction was additive with a more rapid killing rate but, which did not differ significantly with vancomycin.

scholarly journals Exploring early time points of vimentin assembly in flow by fluorescence fluctuation spectroscopy

Lab on a Chip ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 735-745
Author(s):  
Eleonora Perego ◽  
Sarah Köster
Keyword(s):  
Reaction Kinetics ◽  
Photon Counting ◽  
Early Time ◽  
Fluorescence Fluctuation Spectroscopy ◽  
Microfluidic Mixing ◽  
Time Points ◽  
Photon Counting Histogram ◽  
Kinetics Of

The combination of photon counting histogram and microfluidic mixing reveals early time points in reaction kinetics of biomolecule aggregation.

scholarly journals Peptide/β-Peptoid Hybrids with Activity against Vancomycin-Resistant Enterococci: Influence of Hydrophobicity and Structural Features on Antibacterial and Hemolytic Properties

2021 ◽  
Vol 22 (11) ◽  
pp. 5617
Author(s):  
Martin Vestergaard ◽  
Bolette Skive ◽  
Ilona Domraceva ◽  
Hanne Ingmer ◽  
Henrik Franzyk
Keyword(s):  
Membrane Integrity ◽  
Bactericidal Effect ◽  
Structural Features ◽  
Intrinsic Resistance ◽  
Minimal Inhibitory Concentrations ◽  
Ic50 Values ◽  
Assay Time ◽  
Vancomycin Resistant ◽  
Conventional Antibiotics ◽  
Time Kill

Infections with enterococci are challenging to treat due to intrinsic resistance to several antibiotics. Especially vancomycin-resistant Enterococcus faecium and Enterococcus faecalis are of considerable concern with a limited number of efficacious therapeutics available. From an initial screening of 20 peptidomimetics, 11 stable peptide/β-peptoid hybrids were found to have antibacterial activity against eight E. faecium and E. faecalis isolates. Microbiological characterization comprised determination of minimal inhibitory concentrations (MICs), probing of synergy with antibiotics in a checkerboard assay, time–kill studies, as well as assessment of membrane integrity. E. faecium isolates proved more susceptible than E. faecalis isolates, and no differences in susceptibility between the vancomycin-resistant (VRE) and -susceptible E. faecium isolates were observed. A test of three peptidomimetics (Ac-[hArg-βNsce]6-NH2, Ac-[hArg-βNsce-Lys-βNspe]3-NH2 and Oct-[Lys-βNspe]6-NH2) in combination with conventional antibiotics (vancomycin, gentamicin, ciprofloxacin, linezolid, rifampicin or azithromycin) revealed no synergy. The same three potent analogues were found to have a bactericidal effect with a membrane-disruptive mode of action. Peptidomimetics Ac-[hArg-βNsce-Lys-βNspe]3-NH2 and Oct-[Lys-βNspe]6-NH2 with low MIC values (in the ranges 2–8 µg/mL and 4–16 µg/mL against E. faecium and E. faecalis, respectively) and displaying weak cytotoxic properties (i.e., <10% hemolysis at a ~100-fold higher concentration than their MICs; IC50 values of 73 and 41 µg/mL, respectively, against HepG2 cells) were identified as promising starting points for further optimization studies.

scholarly journals Synergistic Interaction of Methanol Extract fromCanarium odontophyllumMiq. Leaf in Combination with Oxacillin against Methicillin-ResistantStaphylococcus aureus(MRSA) ATCC 33591

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Dayang Fredalina Basri ◽  
Vimashiinee Sandra
Keyword(s):  
Inhibitory Concentration ◽  
Methanol Extract ◽  
Bactericidal Effect ◽  
Acetone Extract ◽  
Pharmacodynamic Interaction ◽  
Antistaphylococcal Activity ◽  
Preliminary Study ◽  
Canarium Odontophyllum ◽  
Time Kill ◽  
Acetone Extracts

Canarium odontophyllum(CO) Miq. has been considered as one of the most sought-after plant species in Sarawak, Malaysia, due to its nutritional and pharmacological benefits. This study aimed to evaluate the pharmacodynamic interaction of crude methanol and acetone extracts from CO leaves in combination with oxacillin, vancomycin, and linezolid, respectively, against MRSA ATCC 33591 as preliminary study has reported its potential antistaphylococcal activity. The broth microdilution assay revealed that both methanol and acetone extracts were bactericidal with Minimum Inhibitory Concentration (MIC) of 312.5 μg/mL and 156.25 μg/mL and Minimum Bactericidal Concentration (MBC) of 625 μg/mL and 312.5 μg/mL, respectively. Fractional Inhibitory Concentration (FIC) indices were obtained via the chequerboard dilution assay where methanol extract-oxacillin, acetone extract-oxacillin, methanol extract-linezolid, and acetone extract-linezolid combinations exhibited synergism (FIC index ≤ 0.5). The synergistic action of the methanol extract-oxacillin combination was verified by time-kill analysis where bactericidal effect was observed at concentration of 1/8 × MIC of both compounds at 9.6 h compared to oxacillin alone. As such, these findings postulated that both extracts exert their anti-MRSA mechanism of action similar to that of vancomycin and provide evidence that the leaves ofC. odontophyllumhave the potential to be developed into antistaphylococcal agents.

scholarly journals Antimicrobial Properties of 8-Hydroxyserrulat-14-en-19-oic Acid for Treatment of Implant-Associated Infections

2012 ◽  
Vol 57 (1) ◽  
pp. 333-342 ◽  
Author(s):  
Justyna Nowakowska ◽  
Hans J. Griesser ◽  
Marcus Textor ◽  
Regine Landmann ◽  
Nina Khanna
Keyword(s):  
Structural Changes ◽  
Treatment Options ◽  
Antimicrobial Properties ◽  
Bactericidal Effect ◽  
Mouse Tissue ◽  
Logarithmic Phase ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Time Kill

ABSTRACTTreatment options are limited for implant-associated infections (IAI) that are mainly caused by biofilm-forming staphylococci. We report here on the activity of the serrulatane compound 8-hydroxyserrulat-14-en-19-oic acid (EN4), a diterpene isolated from the Australian plantEremophila neglecta. EN4 elicited antimicrobial activity toward various Gram-positive bacteria but not to Gram-negative bacteria. It showed a similar bactericidal effect against logarithmic-phase, stationary-phase, and adherentStaphylococcus epidermidis, as well as against methicillin-susceptible and methicillin-resistantS. aureuswith MICs of 25 to 50 μg/ml and MBCs of 50 to 100 μg/ml. The bactericidal activity of EN4 was similar againstS. epidermidisand its Δicamutant, which is unable to produce polysaccharide intercellular adhesin-mediated biofilm. In time-kill studies, EN4 exhibited a rapid and concentration-dependent killing of staphylococci, reducing bacterial counts by >3 log10CFU/ml within 5 min at concentrations of >50 μg/ml. Investigation of the mode of action of EN4 revealed membranolytic properties and a general inhibition of macromolecular biosynthesis, suggesting a multitarget activity.In vitro-tested cytotoxicity on eukaryotic cells was time and concentration dependent in the range of the MBCs. EN4 was then tested in a mouse tissue cage model, where it showed neither bactericidal nor cytotoxic effects, indicating an inhibition of its activity. Inhibition assays revealed that this was caused by interactions with albumin. Overall, these findings suggest that, upon structural changes, EN4 might be a promising pharmacophore for the development of new antimicrobials to treat IAI.

Antimicrobial Effects of Novel H2O2-Ag+ Complex on Membrane Damage to Staphylococcus aureus,Escherichia coli and Salmonella typhimurium

2021 ◽  
Author(s):  
Bing Han ◽  
Xiaoyu Han ◽  
Mengmeng Ren ◽  
Yilin You ◽  
Jicheng Zhan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Staphylococcus Aureus ◽  
Salmonella Typhimurium ◽  
Membrane Damage ◽  
Bactericidal Effect ◽  
E Coli ◽  
Bacterial Cell Membrane ◽  
Time Kill ◽  
Environmental Disinfection

Diseases caused by harmful microorganisms pose a serious threat to human health. Safe and environment-friendly disinfectants are, therefore, essential in preventing and controlling such pathogens. This study aimed to investigate the antimicrobial activity and mechanism of a novel hydrogen peroxide and silver (H 2 O 2 -Ag + ) complex (HSC) in combatting Staphylococcus aureus ATCC 29213, Escherichia coli O157:H7 NCTC 12900 and Salmonella typhimurium SL 1344. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against S. aureus were found to be 0.014 % H 2 O 2 -3.125 mg/L Ag + , while 0.028 % H 2 O 2 -6.25 mg/L Ag + for both E. coli and S. typhimurium . Results of the growth curve assay and time-kill trial suggest that the HSC could inhibit the growth of the tested bacteria, as 99.9 % of viable cells were killed following treatment at the 1 MIC for 3 h. Compared with Oxytech D10 disinfectant (0.25 % H 2 O 2 -5 mg/L Ag + ), the HSC exhibited better antibacterial efficacy at a lower concentration (0.045 % H 2 O 2 -10 mg/L Ag + ). The mechanism of antibacterial action of HSC was found including the disruption of the bacterial cell membrane, followed by entry into the bacteria cell to reduce intracellular adenosine triphosphate (ATP) concentration, and inhibit the activity of antioxidases, superoxide dismutase (SOD) and catalase (CAT). The enhanced bactericidal effect of hydrogen peroxide combined with silver indicates a potential for its application in environmental disinfection, particularly in the food industry.

MEMBRANE-ACTIVE METHANOLIC CRUDE EXTRACT OF THERMOTOLERANT, Aspergillus fumigatus SSH01 AND ITS MODE OF ACTION AGAINST GRAM-POSITIVE PATHOGENS

2017 ◽  
Vol 80 (1) ◽  
Author(s):  
Mohamad Khairil Radzali ◽  
Akmal Hayat Abdul Karim ◽  
Syahida Ahmad ◽  
Wan Zuhainis Saad
Keyword(s):  
Aspergillus Fumigatus ◽  
Crude Extract ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Antibacterial Properties ◽  
Bacterial Membrane ◽  
Antibacterial Effects ◽  
Gram Positive ◽  
Bacillus Subtilis Atcc ◽  
Time Kill

This study was undertaken to investigate the antibacterial properties and the mode of actions of crude extract of Aspergillus fumigatus SSH01. Antibacterial properties was observed against Gram-positive pathogens and showed inhibition against Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, methicillin-resistant S. aureus S547 (MRSA) and Listeria monocytogenes L10 with minimum inhibitory concentration (MIC, 0.097- 12.5 mg/ml) and minimum bactericidal concentration (MBC, 0.195 – 25 mg/ml). No surviving cells were detected after 15 h of treatment with the 2MIC of extracts for time-kill assay. Leakage of cellular contents of the treated test pathogens were identified and increased as the concentrations of the extracts increased. The study of morphological surface has shown the bacterial membrane was disrupted and caused loss of viability. This implies the antibacterial effects of A. fumigatus SSH01 extract may serve as the potential antibiotic. 

scholarly journals Kinetics of Genetic Variation of the Mycoplasma genitalium MG192 Gene in Experimentally Infected Chimpanzees

2015 ◽  
Vol 84 (3) ◽  
pp. 747-753 ◽  
Author(s):  
Liang Ma ◽  
Jørgen S. Jensen ◽  
Miriam Mancuso ◽  
Leann Myers ◽  
David H. Martin
Keyword(s):  
Sequence Analysis ◽  
Sequence Variation ◽  
Variable Region ◽  
Mycoplasma Genitalium ◽  
Immune Selection ◽  
Content Type ◽  
Time Points ◽  
Single Colony ◽  
Nucleotide Sequence Variation ◽  
Kinetics Of

Mycoplasma genitalium, a human pathogen associated with sexually transmitted diseases, is capable of causing chronic infections, though mechanisms for persistence remain unclear. Previous studies have found that variation of the MgPa operon occurs by recombination of repetitive chromosomal sequences (known as MgPars) into the MG191 and MG192 genes carried on this operon, which may lead to antigenic variation and immune evasion. In this study, we determined the kinetics of MG192 sequence variation during the course of experimental infection using archived specimens from two chimpanzees infected withM. genitaliumstrain G37. The highly variable region of MG192 was amplified by PCR fromM. genitaliumisolates obtained at various time points postinfection (p.i.). Sequence analysis revealed that MG192 sequence variation began at 5 weeks p.i. With the progression of infection, sequence changes accumulated throughout the MG192 variable region. The presence of MG192 variants at specific time points was confirmed by variant-specific PCR assays and sequence analysis of single-colony clonedM. genitaliumorganisms. MG192 nucleotide sequence variation correlated with estimated recombination events, predicted amino acid changes, and time of seroconversion, a finding consistent with immune selection of MG192 variants. In addition, we provided evidence that MG192 sequence variation occurred during the process ofM. genitaliumsingle-colony cloning. Such spontaneous variation suggests that some MG192 variation is independent of immune selection but may form the basis for subsequent immune selection.

scholarly journals Draft Genome Sequence of Pseudomonas aeruginosa ATCC 9027, Originally Isolated from an Outer Ear Infection

2017 ◽  
Vol 5 (48) ◽  
Author(s):  
Ambikesh Jayal ◽  
Benjamin E. Johns ◽  
Kevin J. Purdy ◽  
Sarah E. Maddocks
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Genome Sequence ◽  
Otitis Externa ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Control Strain ◽  
Content Type ◽  
Antibiofilm Agents ◽  
Quality Control Strain

ABSTRACT Pseudomonas aeruginosa ATCC 9027 was isolated in 1943 from a case of otitis externa and is commonly employed as a quality control strain for sterility, assessment of antibiofilm agents, and in vitro study of wound infection. Here, we present the 6.34-Mb draft genome sequence and highlight some pertinent genes that are associated with virulence.

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