scholarly journals In Vitro Activity of Essential Oils Against Planktonic and Biofilm Cells of Extended-Spectrum β-Lactamase (ESBL)/Carbapenamase-Producing Gram-Negative Bacteria Involved in Human Nosocomial Infections

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 272 ◽  
Author(s):  
Ramona Iseppi ◽  
Alessandro Di Cerbo ◽  
Piero Aloisi ◽  
Mattia Manelli ◽  
Veronica Pellesi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Klebsiella Pneumoniae ◽  
Essential Oils ◽  
Disk Diffusion ◽  
Mentha Piperita ◽  
Thymus Vulgaris ◽  
Extended Spectrum ◽  
Disk Diffusion Assay ◽  
Diffusion Assay

The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), Melaleuca alternifolia, Eucalyptus globulus, Mentha piperita, and Thymus vulgaris, in preventing the development and spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa and carbapenemase (KPC)-producing Klebsiella pneumoniae. A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBL-producing E. coli, 5 K. pneumoniae, 13 KPC-producing K. pneumoniae, and 20 MBL-producing P. aeruginosa were cultured and reconfirmed as ESBL and carbapenamase producers. Polymerase chain reaction was used for the detection of genes responsible for antibiotic resistance (ESBL and KPC/MBL). Antibacterial activity of the EOs was determined using the agar disk diffusion assay, and minimal inhibitory concentrations (MICs) were also evaluated. Lastly, adhesion capability and biofilm formation on polystyrene and glass surfaces were studied in 24 randomly selected strains. M. alternifolia and T. vulgaris EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diffusion assay, M. alternifolia was the most effective, even at low concentrations. This effect was also confirmed by MICs, with values ranging from 0.5 to 16 µg/mL and from 1 to 16 µg/mL, for M. alternifolia and T. vulgaris EOs, respectively. The EOs’ antibacterial activity compared to antibiotics confirmed M. alternifolia EO as the best antibacterial agent. T. vulgaris EO also showed a good antibacterial activity with MICs lower than both reference antibiotics. Lastly, a significant anti-biofilm activity was observed for the two EOs (*P < 0.05 and **P < 0.01 for M. alternifolia and T. vulgaris EOs, respectively). A good antibacterial and anti-biofilm activity of M. alternifolia and T. vulgaris EOs against all selected strains was observed, thus demonstrating a future possible use of these EOs to treat infections caused by ESBL/carbapenemase-producing strains, even in association with antibiotics.

scholarly journals Antimicrobial Activities in Pistacia atlantica—Aphids Make a Difference!

Proceedings ◽  
2020 ◽  
Vol 66 (1) ◽  
pp. 9
Author(s):  
Yoram Gerchman
Keyword(s):  
Secondary Metabolites ◽  
Essential Oils ◽  
Organic Solvents ◽  
Antimicrobial Properties ◽  
Antimicrobial Activities ◽  
Disk Diffusion ◽  
Pistacia Atlantica ◽  
Disk Diffusion Assay ◽  
Bacteria And Fungi ◽  
Diffusion Assay

Plants have been explored and used as sources for antimicrobial extract and compounds for many years, but galls—specialized structures forms on such by diversity of organisms—have been explored much less. Aphid galls host many insects in closed, humid and sugar rich environments for long periods. We have tested the antimicrobial properties of Slavum wertheimae aphid galls on Pistacia atlantica. Secondary metabolites were extracted from leaves and galls with organic solvents, and essential oils with Clevenger, and tested by disk diffusion assay and volatile effect on bacteria and fungi, respectively. The results demonstrated that gall extracts/essential oils had much stronger activity against the diversity of bacteria and fungi. The large diversity of galls suggest they could be explored as source for novel compounds.

scholarly journals Comparison of Two Methods and Three End Points in Determination of In Vitro Activity of Micafungin against Aspergillus spp

2003 ◽  
Vol 47 (8) ◽  
pp. 2640-2643 ◽  
Author(s):  
Sevtap Arikan ◽  
Pınar Yurdakul ◽  
Gulsen Hascelik
Keyword(s):  
Vitro Activity ◽  
Disk Diffusion ◽  
In Vitro Activity ◽  
End Points ◽  
Minimum Effective Concentration ◽  
Disk Diffusion Assay ◽  
Diffusion Assay

ABSTRACT We investigated the in vitro activity of micafungin against clinical Aspergillus isolates (n = 37) (Aspergillusfumigatus [n = 21], Aspergillusflavus [n = 14], and Aspergillus niger [n = 2]) by using NCCLS M38A microdilution and an investigational disk diffusion assay. Microdilution assay results were evaluated by using the end points of a MIC-2 (measured in micrograms per milliliter) and minimum effective concentration (MEC, measured in micrograms per milliliter; the lowest concentration of micafungin that produces short and aberrant hyphal branchings microscopically). Disk diffusion results were interpreted by measuring the zone(s) of inhibition (ZOI, measured in millimeters). Micafungin proved to be similarly active against all Aspergillus species tested. At 24 h, MIC-2s and MECs were identical. At 48 h, however, MIC-2s increased unpredictably, leading to the loss of a consistent correlation between the two end points. MECs and ZOI remained consistent and correlated at both reading times, suggesting their use as relevant end points in susceptibility testing of micafungin against Aspergillus. All Aspergillus isolates yielded intrazonal growth on disk diffusion agar plates. The intrazonal colonies contained short, aberrant hyphal branchings microscopically. The in vivo significance of these findings remains to be further investigated.

scholarly journals Tumor cell growth inhibition by several Annonaceous acetogenins in an in vitro disk diffusion assay

1995 ◽  
Vol 96 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Nicholas H. Oberlies ◽  
Julie L. Jones ◽  
Thomas H. Corbett ◽  
Sophia S. Fotopoulos ◽  
Jerry L. McLaughlin
Keyword(s):  
Cell Growth ◽  
Tumor Cell ◽  
Growth Inhibition ◽  
Disk Diffusion ◽  
Tumor Cell Growth ◽  
Cell Growth Inhibition ◽  
Annonaceous Acetogenins ◽  
Disk Diffusion Assay ◽  
Diffusion Assay

scholarly journals Novel Disk Diffusion Assay on Magnesium Oxalate Agar To Evaluate the Susceptibility of Yersinia pestis to Type III Secretion System Inhibitors

2021 ◽  
Author(s):  
Sukriti Prashar ◽  
Miguel Portales Guemes ◽  
Poorandai Shivbaran ◽  
Eugenia Jimenez Alvarez ◽  
Christopher Soha ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Growth Inhibition ◽  
Virulence Factors ◽  
Type Iii Secretion ◽  
Antimicrobial Agents ◽  
Secretion System ◽  
Disk Diffusion ◽  
Disk Diffusion Assay ◽  
Magnesium Oxalate ◽  
Diffusion Assay

Disk diffusion assays have traditionally been used as a simple and effective way to screen compounds for antibacterial activity and to determine the susceptibility of pathogens to antibiotics; however, they are limited to detecting growth inhibition only. Consequently, antimicrobial agents that inhibit virulence factors, but not growth, would not be detected.

scholarly journals Sigmoid E max Modelling to Define the Fixed Concentration of Enmetazobactam for MIC Testing in Combination with Cefepime

2021 ◽  
Author(s):  
Philipp Knechtle ◽  
Stuart Shapiro ◽  
Ian Morrissey ◽  
Cyntia De Piano ◽  
Adam Belley
Keyword(s):  
Antibacterial Activity ◽  
Minimum Inhibitory Concentration ◽  
Klebsiella Pneumoniae ◽  
Inhibitory Concentration ◽  
Carbapenem Resistance ◽  
Clinical Isolates ◽  
Extended Spectrum ◽  
Fixed Concentration

Use of carbapenem antibiotics to treat infections caused by Enterobacterales expressing increasingly aggressive extended-spectrum β-lactamases (ESBL) has contributed to the emergence of carbapenem resistance. Enmetazobactam is a novel ESBL inhibitor being developed in combination with cefepime as a carbapenem-sparing option for infections caused by ESBL-producing Enterobacterales . Cefepime-enmetazobactam checkerboard minimum inhibitory concentration (MIC) profiles were obtained for a challenge panel of cefepime-resistant ESBL-producing clinical isolates of Klebsiella pneumoniae . Sigmoid E max modelling described cefepime MIC as a function of enmetazobactam concentration with no bias. A concentration of 8 μg/ml enmetazobactam proved sufficient to restore >95% of cefepime antibacterial activity in vitro against >95% of isolates tested. These results support a fixed concentration of 8 μg/ml of enmetazobactam for MIC testing.

scholarly journals Essential oils in ocular pathology: an experimental study

2015 ◽  
Vol 9 (06) ◽  
pp. 650-654 ◽  
Author(s):  
Sara Cannas ◽  
Donatella Usai ◽  
Antonio Pinna ◽  
Stefania Benvenuti ◽  
Roberta Tardugno ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oils ◽  
Bacterial Infections ◽  
In Vitro Cytotoxicity ◽  
Rosmarinus Officinalis ◽  
Mentha Piperita ◽  
Thymus Vulgaris ◽  
Melaleuca Alternifolia ◽  
Natural Drugs

Introduction: The antimicrobial activity of essential oils (EOs) has been known for ages; in particular, the EOs of Melaleuca alternifolia, Thymus vulgaris, Mentha piperita, and Rosmarinus officinalis have been used for the treatment of fungal and bacterial infections. Methodology: This study focused on the in vitro cytotoxicity to normal human conjunctiva cells and antimicrobial activity of 20 EOs. Results: The oils tested showed no cytotoxic effect at very low concentrations. Rosmarinus officinalis, Melaleuca alternifolia, and Thymus vulgaris L. red thyme geraniol sel oils had good antimicrobial activity against Gram-positive and Gram-negative strains. Conclusions: The results of this study are of great interest and may have a major impact on public health, providing useful tips to optimize the therapeutic use of some natural drugs.

scholarly journals Disk with High Oxacillin Content Discriminates between Methicillin-Resistant and Borderline Methicillin-SusceptibleStaphylococcus aureus Strains in Disk Diffusion Assays Using a Low Salt Concentration

1999 ◽  
Vol 37 (6) ◽  
pp. 2047-2050 ◽  
Author(s):  
Ann Cathrine Petersson ◽  
Carl Kamme ◽  
Håkan Miörner
Keyword(s):  
Salt Concentration ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Group V ◽  
Phage Group ◽  
Disk Diffusion Assay ◽  
Agar Dilution ◽  
Diffusion Assay

A separation between mecA + strains ofStaphylococcus aureus and strains lacking mecAwas achieved by the disk diffusion assay and the agar dilution method, utilizing disks containing 5 μg of oxacillin and inocula of approximately 5 × 105 CFU/spot, respectively, provided that agar with 0 to 0.5% NaCl and incubation at 30°C were employed. The 5-μg oxacillin disks clearly discriminated between borderline methicillin-susceptible and mecA +strains. The oxacillin MICs were more affected by the inoculum density and salt concentration than were the methicillin MICs, and oxacillin MICs of 4 to 16 μg/ml were obtained for strains lackingmecA. Significantly higher levels of β-lactamase production and reduced oxacillin susceptibilities were recorded for strains lacking mecA, in particular strains of phage group V, when agar with ≥2% NaCl was used than when agar with 0 to 0.5% NaCl was employed. The results indicate that the borderline methicillin-susceptible phenotype is a salt-dependent in vitro phenomenon of questionable clinical relevance.

scholarly journals In VitroAntibacterial Activity of Essential Oils againstStreptococcus pyogenes

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Julien Sfeir ◽  
Corinne Lefrançois ◽  
Dominique Baudoux ◽  
Séverine Derbré ◽  
Patricia Licznar
Keyword(s):  
Antibacterial Activity ◽  
Essential Oils ◽  
Antimicrobial Agents ◽  
Antibacterial Activities ◽  
Diffusion Method ◽  
Thymus Vulgaris ◽  
Dilution Method ◽  
Origanum Compactum ◽  
Broth Dilution

Streptococcus pyogenesplays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate thein vitroantibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants againstS. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity againstS. pyogenes. Among themCinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, andSatureja montanaessential oils exhibited significant antibacterial activity. Thein vitroresults reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred.

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