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HiCrome MacConkey-Sorbitol Agar with Tellurite-Cefixime Supplement (MacConkey-Sorbitol Agar with Tellurite-Cefixime Supplement)

[所属分类:培养基配方] [发布时间:2021-11-23] [发布人:网站管理员2] [阅读次数:] [返回]

HiCrome MacConkey-Sorbitol Agar

with Tellurite-Cefixime Supplement

(MacConkey-Sorbitol Agar with

Tellurite-Cefixime Supplement)

山东拓普生物工程有限公司培养基配方 http://www.topbiol.com

Composition per 1004mL:

Casein enzymic hydrolysate .............................17.0g

Agar ..................................................................13.5g

Sorbitol..............................................................10.0g

NaCl....................................................................5.0g

Proteose peptone.................................................3.0g

Bile salts mixture ................................................1.5g

5-Bromo-4-chloro-3-indolyl-β-D-glucuronide

sodium salt....................................................0.1g

Neutral Red.......................................................0.03g

Crystal Violet ..................................................0.001g

Tellurite-cefixime supplement ........................ 4.0mL

pH 7.1 ± 0.3 at 25°C

Tellurite-Cefixime Supplement:

Composition per 4.0mL:

K2TeO3 .............................................................5.0mg

Cefiximine .......................................................0.1mg

Preparation of Tellurite-Cefixime Supple

ment: Add components to 4.0mL of distilled/deion

ized water. Mix thoroughly. Filter sterilize.

Caution: Potassium tellurite is toxic.

Source: This medium is available from Fluka, Sig

ma-Aldrich. Tellurite-cefixime supplement is avail

able from Oxoid.

Preparation of Medium: Add components, ex

cept tellurite-cefixime supplement, to distilled/

deionized water and bring volume to 1.0L. Mix thor

oughly. Gently heat while stirring and bring to boil

ing. Mix to completely dissolve components. Do not

autoclave. Cool to 50°C. Add 4.0mL sterile tellurite

cefixime supplement. Mix thoroughly. Pour into ster

ile Petri dishes.

Use: For the direct isolation and differentiation of E.

coli O157:H7-strains from foodstuffs. Recommend

ed for selective isolation of Escherichia coli

O157:H7 from food and animal feeding stuffs. The

medium contains sorbitol instead of lactose. Entero

pathogenic strains of Escherichia coli O157:H7 fer

ment lactose but do not ferment sorbitol and hence

produce colorless colonies. Sorbitol fermenting

strains of Escherichia coli produce pink-red colo

nies. The red color is due to production of acid from

sorbitol, absorption of neutral red, and a subsequent

color change of the dye when pH of the medium falls

below 6.8. The chromogenic indicator is added to de

tect the presence of an enzyme β-D-glucuronidase.

Strains of Escherichia coli possessing β-D-glucu

ronidase appear as blue colored colonies on the me

dium. Enteropathogenic strains of Escherichia coli

O157 do not possess β-D-glucuronidase activity and

thus produce colorless colonies. Escherichia coli fer

menting sorbitol and possessing β-D-glucuronidase

activity produce purple colored colonies. Most of the

gram-positive organisms are inhibited by crystal vio

let and bile salts. Addition of Tellurite-Cefixime Sup

plement makes the medium selective. Potassium Tel

lurite selects the serogroups O157 from other E. coli

serogroups and inhibits Aeromonas species and

Providencia species. Cefixime inhibits Proteus spe

cies.

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HiCrome MacConkey-Sorbitol Agar with Tellurite-Cefixime Supplement (MacConkey-Sorbitol Agar with Tellurite-Cefixime Supplement)