Screening of Actinobacteria for Anti-TB Activity by Agar Dilution Assay

2022 ◽  
pp. 405-406
Author(s):  
Ramachandran Chelliah ◽  
Deog-Hwan Oh
Keyword(s):  
Dilution Assay ◽  
Agar Dilution

scholarly journals Biological Activity of Bunium persicum Essential Oil from Western Himalaya

2017 ◽  
Vol 4 (02) ◽  
pp. e52-e58
Author(s):  
Iris Stappen ◽  
Nurhayat Tabanca ◽  
Abbas Ali ◽  
David Wedge ◽  
Jürgen Wanner ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Essential Oil ◽  
Western Himalaya ◽  
Cold Desert ◽  
Dilution Assay ◽  
Bunium Persicum ◽  
Solvent Control ◽  
Strawberry Anthracnose ◽  
Agar Dilution ◽  
Low Activity

AbstractThe essential oil of Bunium persicum collected from cultivated sources in the cold desert area of Lahaul-Spiti is described for its antimicrobial, larvicidal, and biting deterrent activities. Additionally, odor characterization is given. The chemical composition of the essential oil was analyzed by simultaneous GC-MS and GC-FID. γ-Terpinene and p-cymene were found to be the major compounds. Antibacterial testing by an agar dilution assay revealed low activity of the oil against all tested bacteria. Antifungal activity was evaluated against Candida albicans as well as three species of the strawberry anthracnose causing plant pathogen Colletotrichum. Bunium persicum essential oil demonstrated antifungal activity against all four pathogens. Biting deterrent activity against Aedes aegypti was greater than the solvent control, but significantly lower than DEET. The essential oil of B. persicum exhibited larvicidal activity with an LC50 value of 58.6 ppm against Ae. aegypti larvae.

Antimicrobial Effect of Thai Spices against Listeria monocytogenes and Salmonella Typhimurium DT104

2005 ◽  
Vol 68 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
CHITSIRI THONGSON ◽  
P. MICHAEL DAVIDSON ◽  
WARAPA MAHAKARNCHANAKUL ◽  
PREEYA VIBULSRESTH
Keyword(s):  
Antimicrobial Activity ◽  
Listeria Monocytogenes ◽  
Essential Oils ◽  
Salmonella Typhimurium ◽  
Pathogenic Bacteria ◽  
Apple Juice ◽  
Food System ◽  
Dilution Assay ◽  
Agar Dilution ◽  
Over Time

The objective of this study was to determine the potential antimicrobial activity of extracts and essential oils of spices from Thailand against foodborne pathogenic bacteria. The antimicrobial efficacy of ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata), and turmeric (Curcuma longa) was evaluated against five strains of Listeria monocytogenes and four strains of Salmonella enterica ssp. enterica serovar Typhimurium DT104. Antimicrobial activity was investigated in microbiological media by using an agar dilution assay and enumeration over time and a model food system, apple juice, by monitoring growth over time. In the agar dilution assay, water extracts of the three spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5 to 10% (vol/vol) inhibited most L. monocytogenes strains for 24 h in the agar dilution assay. Commercial essential oils (EO) of ginger or turmeric inhibited all L. monocytogenes at ≤0.6 or ≤10%, respectively. Fingerroot EO inhibited all strains at ≤0.4%. In the enumeration-over-time assay, a 5% fingerroot ethanol extract reduced ca. 4 log CFU/ml Listeria by around 2 log in 24 h while 10% inactivated the microorganism in 9 h. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 6 to 9 h. Neither extracts nor commercial EO had any effect on Salmonella Typhimurium DT 104 with the exception of fingerroot EO, which inhibited all strains at ≤0.7%. Addition of 0.2% fingerroot EO to apple juice reduced 4 log of L. monocytogenes Scott A and both strains of Salmonella Typhimurium to an undetectable level within 1 to 2 days. It was concluded that fingerroot EO and extract have potential for inhibiting pathogens in food systems.

scholarly journals Piper betle Leaf Extract Exhibits Anti-virulence Properties by Downregulating Rhamnolipid Gene Expression (rhlC) of Pseudomonas aeruginosa

2020 ◽  
Vol 8 (A) ◽  
pp. 928-931
Author(s):  
Irene Ratridewi ◽  
Shod Abdurrachman Dzulkarnain ◽  
Andreas Budi Wijaya ◽  
Wisnu Barlianto ◽  
Sanarto Santoso ◽  
...  
Keyword(s):  
Gene Expression ◽  
Leaf Extract ◽  
Inhibitory Concentration ◽  
Piper Betle ◽  
Chain Reaction ◽  
Dilution Assay ◽  
Beta Coefficient ◽  
Agar Dilution ◽  
Polymerase Chain ◽  
The Impact

  BACKGROUND: Piper betle (P. betle) is widely used as a traditional medicine in Indonesia, with anti-quorum sensing and anti-biofilm activity. We investigated the impact of methanolic leaf extract of P. betle against Pseudomonas aeruginosa’s (P. aeruginosa) virulence factor, which associated with rhamnolipid (rhl) genes, METHODS: Minimum biofilm inhibitory concentration of the extract was determined at a concentration of 0.4% by agar dilution assay. The expression of rhlA and rhlC gene was assessed by using real-time polymerase chain reaction. RESULTS: All P. aeruginosa isolates contained rhlA, rhlB, and rhlC genes, which associated with rhl production. The expression of the rhlC gene decreased after administration of P. betle leaf extract at concentration of 0.4%, with beta coefficient was 0.662 (p = 0.019). CONCLUSION: The methanolic leaf extract of P. betle shows inhibition of rhlC gene expression, indicating the anti-rhl properties of P. betle against P. aeruginosa infection.

scholarly journals Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis

2008 ◽  
Vol 53 (1) ◽  
pp. 146-149 ◽  
Author(s):  
Thean Yen Tan ◽  
Lily Siew Yong Ng ◽  
Jie He ◽  
Tse Hsien Koh ◽  
Li Yang Hsu
Keyword(s):  
Escherichia Coli ◽  
Three Dimensional ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Screening Methods ◽  
Dilution Assay ◽  
Multiplex Pcr Assay ◽  
Amoxicillin Clavulanate ◽  
Agar Dilution ◽  
Phenotypic Methods

ABSTRACT There are currently no standardized phenotypic methods for the screening and detection of AmpC enzymes. This study aimed to evaluate different methods to detect AmpC enzymes in Escherichia coli, Klebsiella spp., and Proteus spp., comparing the results from two disk-based methods and an agar dilution method. AmpC activity was determined for 255 clinical isolates by use of a three-dimensional enzyme assay combined with a multiplex PCR assay for plasmid-borne ampC genes. These results were compared against a disk-based inhibitor assay using various combinations of cefpodoxime and cefoxitin as antibiotic substrates and boronic acid or cloxacillin as an AmpC inhibitor. The presence of enzyme induction by disk approximation was evaluated using imipenem, cefoxitin, and amoxicillin-clavulanate as inducing agents against ceftazidime. Finally, an agar dilution assay was performed, using cefoxitin with and without added cloxacillin. AmpC activity was present in 49.8% of test isolates, 93.7% of which were positive for plasmid-borne ampC genes. CIT-like enzymes were predominant in E. coli, and DHA-like enzymes were predominant in Klebsiella spp. The disk-based inhibitor tests performed better than the agar dilution assay, while detection of AmpC by disk induction had a poor sensitivity. The cefoxitin-cloxacillin disk combination provided the best overall performance, with a sensitivity and specificity of 95%. This study confirmed the accuracy of disk-based inhibitor screening for AmpC enzymes, which proved reliable at detecting CIT- and DHA-like plasmid-borne ampC genes. The methods are simple enough for introduction into clinical microbiology laboratories.

scholarly journals Chemical Composition and Biological Activity of Essential Oils of Dracocephalum heterophyllum and Hyssopus officinalis from Western Himalaya

2015 ◽  
Vol 10 (1) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Iris Stappen ◽  
Jürgen Wanner ◽  
Nurhayat Tabanca ◽  
David E. Wedge ◽  
Abbas Ali ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Essential Oil ◽  
Essential Oils ◽  
Western Himalaya ◽  
Chemical Compositions ◽  
Main Compound ◽  
Dilution Assay ◽  
Agar Dilution ◽  
Main Components ◽  
Hyssopus Officinalis

The essential oils of two representatives of the Lamiaceae, Dracocephalum heterophyllum Benth. and Hyssopus officinalis L., are described for their antifungal, antibacterial, larvicidal and inect biting deterrent activities. Additionally, the chemical compositions of the essential oils, analyzed by simultaneous GC-MS and GC-FID, and odor descriptions are given. The main components of H. officinalis oil were pinocarvone, cis-pinocamphone, and β-pinene. Citronellol was found as the main compound of D. heterophyllum essential oil. Antibacterial testing by agar dilution assay revealed greater activity of D. heterophyllum against Staphylococcus aureus compared with H. officinalis. D. heterophyllum essential oil also showed promising antifungal activity against Colletotrichum species and was more toxic to Aedes aegypti larvae in a larvicial bioassay. Both essential oils showed high activity in the biting deterrent bioassay.

Laboratory proficiency in susceptibility testing of Helicobacter pylori using agar dilution and E test methods

2001 ◽  
Vol 120 (5) ◽  
pp. A586-A587
Author(s):  
L BEST ◽  
S JO ◽  
V VANZANTEN ◽  
D HALDANE ◽  
V LOO ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Susceptibility Testing ◽  
Test Methods ◽  
Agar Dilution

scholarly journals Evaluation of the Antimicrobial Activity of Some Components of the Essential Oils of Plants Used in the Traditional Medicine of the Tehuacán-Cuicatlán Valley, Puebla, México

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 295
Author(s):  
Sebastián Candelaria-Dueñas ◽  
Rocío Serrano-Parrales ◽  
Marisol Ávila-Romero ◽  
Samuel Meraz-Martínez ◽  
Julieta Orozco-Martínez ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oils ◽  
Qualitative Evaluation ◽  
Bactericidal Effect ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Diffusion Technique ◽  
Agar Dilution

In Tehuacán-Cuicatlán valley (Mexico), studies have been carried out on the essential oils of medicinal plants with antimicrobial activity and it was found that they present compounds in common such as: α-pinene, β-pinene, carvacrol, eugenol, limonene, myrcene, ocimene, cineole, methyl salicylate, farnesene, and thymol. The goal of this study was to assess the antimicrobial activity of essential oils’ compounds. The qualitative evaluation was carried out by the Kirby Baüer agar diffusion technique in Gram-positive bacteria (11 strains), Gram-negative bacteria (18 strains), and yeasts (8 strains). For the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the agar dilution method was used. All the evaluated compounds presented antimicrobial activity. The compounds eugenol and carvacrol showed the largest inhibition zones. Regarding yeasts, the compounds ocimene, cineole, and farnesene did not show any activity. The compounds eugenol, carvacrol, and thymol presented the lowest MIC; bactericidal effect was observed at MIC level for S. aureus 75MR, E. coli 128 MR, and C albicans CUSI, for different compounds, eugenol, carvacrol, and thymol. Finally, this study shows that the essential oils of plants used by the population of Tehuacán-Cuicatlán valley share compounds and some of them have antibacterial and fungicidal activity.

scholarly journals 652. Comparison of fosfomycin (FOF) activity and prevalence of subpopulations between Escherichia coli (EC) and Klebsiella pneumoniae (KP) during susceptibility testing

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S384-S384
Author(s):  
Jadyn C Anderson ◽  
Amanda R Krueger ◽  
Elizabeth C Smith ◽  
Morgan L Bixby ◽  
Hunter V Brigman ◽  
...  
Keyword(s):  
Clinical Efficacy ◽  
Inhibitory Concentration ◽  
Panel Member ◽  
Colony Growth ◽  
The United States ◽  
Research Support ◽  
Review Panel ◽  
Agreement Rate ◽  
Future Studies ◽  
Agar Dilution

Abstract Background In the United States, interpretive criteria for FOF are established only for EC, yet those criteria are often extrapolated to KP. Recent studies have highlighted both inferior clinical outcomes after FOF treatment and difficulties in interpretation of inner colony subpopulations, the presence of which may affect clinical efficacy. We sought to compare FOF activity against EC and KP and to determine the prevalence of inner colony subpopulations following disk diffusion (DD) testing of the two species. Methods A convenience collection of 73 KP and 42 EC isolates from 3 U.S. institutions were included. Minimal inhibitory concentration (MIC) testing was performed in duplicate on separate days using agar dilution (AD) and DD as recommended by the Clinical and Laboratory Standards Institute guidelines, with application of EC susceptibility (≤ 64mg/L) breakpoints. The frequency and counts of inner colonies observed during DD testing was calculated, and colonies were subcultured for use in future studies. Results MIC50/90 values were 1/16 mg/L and 32/256 mg/L for EC and KP respectively. All EC isolates were considered susceptible and therefore categorical agreement was 100%. The majority of KP isolates were considered susceptible (83.6% with AD and 86.3% with DD) and categorical agreement between the methods was 84.9%. Inner colonies were observed during DD testing in 88.1% of EC isolates and 80.8% of KP isolates during at least one replicate, with 47.6% of EC isolates and 39.7% of KP isolates showing inner colony growth during both DD test replicates. More than 10 inner colonies were observed in 50% of EC isolates compared to 12.3% of KP isolates. Conclusion KP isolates demonstrated considerably higher FOF MIC values compared to EC, as evidenced by MIC50/90 values 4-5 dilutions higher than those for EC. The categorical agreement rate was higher among EC than KP, highlighting concerns regarding the practice of extrapolating FOF susceptibility breakpoints for EC to KP. The high frequency of inner colonies observed in DD for both species necessitates further studies to determine best practices for interpreting their relevance, fitness, and resistance in order to identify potential impacts to clinical efficacy of FOF. Disclosures Elizabeth B. Hirsch, PharmD, Merck (Grant/Research Support)Nabriva Therapeutics (Advisor or Review Panel member)

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