How does Hoyles Agar work?

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How does Hoyles Agar work?

Hoyle’s agar is a selective medium that uses tellurite to differentially select Corynebacterium diphtheriae from other upper respiratory tract flora. The medium appears cream to yellow colored, and takes the form of a free-floating powder. It is a modification of Neill’s medium.

How does Tellurite agar work?

Tellurite inhibits growth of most upper respiratory tract bacteria and Gram-negative (G −) rods, while being reduced to tellurium intracellularly by Corynebacterium to produce a black precipitate. Cysteine in the media is degraded by these species to produce a brown halo around the colonies.

What is tinsdale Agar?

Tinsdale Agar is used for the primary isolation and identification of Corynebacterium diptheriae. The medium differentiates between C. diphtheriae and the diphtheroids found in the upper respiratory tract.

What is Tellurite blood agar?

Tellurite Blood Agar is a selective medium used for isolation and cultivation of Corynebacterium species (1, 2). It is selective due to the presence of inhibitor and differential by means of ability of organism to reduce potassium tellurite.

Why is chocolate agar used in throat culture?

It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis.

What is nutrient agar?

Nutrient agar consists of peptone, beef extract and agar. Beef extract contains water-soluble substances (carbohydrates, vitamins, nitrogen compounds and salts). Peptones are the main source of organic nitrogen, especially via amino acids and long-chain peptides. Agar is used as a gelling agent.

How does Baird Parker Agar work?

Baird-Parker agar is a type of agar used for the selective isolation of gram-positive Staphylococci species. It contains lithium chloride and tellurite to inhibit the growth of alternative microbial flora, while the included pyruvate and glycine promote the growth of Staphylococci.

How do you make a Tellurite Agar?

diphtheriae reduces potassium tellurite to tellurium and thereby produce gray-black coloured colonies. Throat or nasal swab is directly inoculated and streaked on this agar medium. Store dehydrated medium below 30°C in tightly closed container and the prepared medium at 2°C-8°C. Avoid freezing and overheating.

How do you make potassium Tellurite?

Preparation Instructions Warm the refrigerated, concentrated Potassium Tellurite Solution to 45-50 °C. Prepare the 3.5% solution by aseptically adding 9 ml of warm, sterile water and mixing. Add 3 ml of the 3.5% solution to 1,000 ml of Baird Parker Agar Base (B 1051). Mix well and pour into sterile petri plates.

What kind of media is tinsdale?

Ingredients Gm/Liter
Peptic digest of animal tissue 20 g
Sodium chloride 5 g
L-Cystine 0.24 g
Sodium thiosulfate 0.24 g

Is tinsdale Agar selective or differential?

Tinsdale Agar is used for selective isolation and differentiation of Corynebacterium diphtheriae and it is Gram-positive, facultatively anaerobic, non-motile bacteria that exhibit a fermentative metabolism (carbohydrates to lactic acid) under certain conditions.

What are Diphtheroids?

Introduction: Diphtheroids are defined as aerobic, non-sporulating, pleomorphic Gram-positive bacilli which are more uniformly stained than Corynebacterium diphtheriae, lack the metachromatic granules and are arranged in a palisade manner. They are usually commensals of the skin and mucous membranes.

What is Tellurite reduction?

When a 1% aqueous solution of tellurite is added to starch agar plates previously inoculated with vaginal discharge material, other starch-fermenting and most non-starch-fermenting bacteria rapidly reduce tellurite to produce black or gray colonies. … vaginale.

What is the principle underlying the Elek test?

Elek’s test or the Elek plate test is an in vitro test of virulence performed on specimens of Corynebacterium diphtheriae, the bacteria that causes diphtheria. It is used to test for toxigenicity of C. diphtheriae strains. The test uses immunodiffusion.

What is difference between blood agar and chocolate agar?

Blood agar consists of many ingredients but the primary ingredient is the blood, which came from a rabbit or a sheep. … The blood is treated to remove fibrin, the clotting factor of the blood. On the other hand, chocolate agar contains lysed red blood cells, which turns brown giving the medium its chocolate color.

What is the purpose of chocolate agar plate?

Chocolate Agar is an enriched general- purpose medium that supports the growth of most fastidious and non-fastidious organisms. Because it is a non-selective medium, resident flora from clinical specimens may overgrow potential fastidious pathogens, such as Neisseria species.

Does E coli grow on chocolate agar?

Yes. This is an agar upon which only Gram-negative bacteria can grow. What is more is that E. coli will grow into red colonies, as there is a pH indicator present.

What is the difference between agar and nutrient agar?

DifferencesNutrient AgarNutrient BrothType of MediumSolidLiquid

What is nutrient media?

a fluid or solid substance that is used in the laboratory or under industrial conditions for growing bacteria, yeasts, and microscopic fungi, as well as algae, protozoans, viruses, and cultures of plant or animal cells. All nutrient mediums are first sterilized in an autoclave. …

What is nutrient agar made of?

Nutrient agar is used as a general-purpose medium for the growth of a wide variety of non-fastidious microorganisms. It consists of peptone, beef extract, and agar. This relatively simple formulation provides the nutrients necessary for the replication of a large number of non-fastidious microorganisms.

What makes Baird-Parker Agar selective?

7,8 BD Baird-Parker Agar contains the carbon and nitrogen sources necessary for growth. Glycine, lithium chloride and potassium tellurite act as selective agents. Egg yolk is the substrate to detect lecithinase production, and, in addition, lipase activity.

Can E coli grow on Baird-Parker Agar?

OrganismsGrowthEscherichia coliLarge brown-black, Negative for lecithinase

How does S aureus appear on Baird-Parker Agar?

Staphylococci produce dark gray to black colonies due to tellurite reduction; staphylococci that produce lecithinase break down the egg yolk and cause clear zones around respective colonies. … An opaque zone of precipitation may form due to lipase activity (S. aureus).

What is sheep blood agar?

Blood agar contains general nutrients and 5% sheep blood. It is useful for cultivating fastidious organisms and for determining the hemolytic capabilities of an organism. Some bacteria produce exoenzymes that lyse red blood cells and degrade hemoglobin; these are called hemolysins.

What type of media is cystine tellurite blood agar?

Remel Cystine Tellurite Blood Agar is a solid medium recommended for use in qualitative procedures for the isolation and cultivation of Corynebacterium diphtheriae. Peptone provides nitrogen and carbon compounds, amino acids, and trace minerals which are essential for bacterial growth.

What is Albert stain?

Albert’s staining technique is a type of special staining technique since it is used to demonstrate a special structure in bacteria. It is chiefly used to demonstrate metachromatic granules found in Corynebacterium diphtheriae. This bacterium is responsible for the disease diphtheria.

Which is the selective media for Corynebacterium Diphtheriae?

The clinical diagnosis of diphtheria requires bacteriologic laboratory confirmation of toxigenic C diphtheriae in throat or lesion cultures. For primary isolation, a variety of media may be used: Loeffler agar, Mueller-Miller tellurite agar, or Tinsdale tellurite agar.

Which selective medium is used for isolation of Corynebacterium Diphtheriae?

BD Tellurite Agar (Hoyle) is a partially selective and differential medium for the isolation of Corynebacterium diphtheriae from clinical specimens.

How can you differentiate between Corynebacterium Diphtheriae strains using Hoyles Tellurite Agar?

A differential stain such as Neisser stain must be performed either from the specimen or from Loeffler Serum slants, which are inoculated with the specimen or with a culture of the isolated strain. On BD Tellurite Agar (Hoyle), Corynebacterium diphtheriae produces gray to black colonies on the medium.

Why are Corynebacterium commonly called as klebs Loeffler bacillus?

Corynebacterium diphtheriae is the pathogenic bacterium that causes diphtheria. It is also known as the Klebs–Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich Löffler (1852–1915).

Is Corynebacterium Diphtheriae beta hemolytic?

CORYNEBACTERIA – CULTIVATION ON BLOOD AGAR on media with blood with a weak beta-hemolysis (C. diphtheriae biotype mitis and gravis) or is nonhemolytic (biotype intermedius).

What is the composition of MacConkey Agar?

MacConkey agar contains four key ingredients (lactose, bile salts, crystal violet, and neutral red) that make it a selective and differential media. Bile salts and crystal violet act as selective agents that inhibit the growth of Gram-positive organisms, and proliferate the selective growth of gram-negative bacteria.

What are Diphtheroids examples?

Coryneform bacilli, also known as diphtheroids, are Gram-positive, irregular rod-shaped bacteria that encompass a wide range of genera, such as Corynebacterium, Brevibacterium, Dermabacter, Microbacterium, and Cellulomonas.

Where is Diphtheroids found?

Coryneform bacteria (“diphtheroids”) are ubiquitous in nature. They are found on human skin and mucous membranes, on plants, in soil, and in freshwater and saltwater. Humans are the only known reservoir of C. diphtheriae, although a novel strain was isolated from cats in West Virginia.

Where do Diphtheroids occur?

Diphtheroid bacilli are often found in the healthy mouth and pharynx. They also occur frequently on the skin and can be isolated from the nose and urogenital tract. They are ubiquitous saprophytes which only occasionally become pathogenic for man.

What shape is TeO3?

NamesMolecular shapepyramidal at TeRelated compoundsOther anionsSelenous acid Sulfurous acidOther cationsSodium tellurite

What does tellurite mean?

Definition of tellurite 1 : a salt of tellurous acid. 2 : a mineral TeO2 that consists of tellurium dioxide and occurs sparingly in tufts of white or yellowish crystals.

What is the chemical name for TeO3?

PubChem CID83481StructureFind Similar StructuresMolecular FormulaO3TeSynonymsTellurium trioxide 13451-18-8 Tellurium oxide (TeO3) tellurium(VI) oxide EINECS 236-620-5 More…Molecular Weight175.6

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