Oxoid CM1005B 头孢克肟鼠李糖山梨醇麦康凯琼脂基础 CR-SMAC

Oxoid CM1005B 头孢克肟鼠李糖山梨醇麦康凯琼脂基础 CR-SMAC

CEFIXIME RHAMNOSE SORBITOL MACCONKEY AGAR
(CR-SMAC Agar Base)

Code: CM1005

A selective, differential medium based on Sorbitol MacConkey Agar with added rhamnose and cefixime. This medium provides a selective base with improved differentiation of Escherichia coli O157.

一种基于山梨糖醇麦康凯琼脂的选择性差异培养基,添加了鼠李糖和头孢克肟。 该培养基提供了一种选择性碱基,可改善大肠杆菌 O157 的分化。

Typical Formula*

gm/litre

Peptone

20.0

Sorbitol

10.0

Bile Salts No. 3

1.5

Sodium chloride

5.0

Rhamnose

5.0

Neutral red

0.03

Crystal violet

0.001

Agar

15.0

pH 7.1 ± 0.2 @ 25°C
* Adjusted as required to meet performance standards

CEFIXIME SUPPLEMENT

Code: SR0191

Vial Contents (each vial is sufficient for 500ml of medium)
per vial
per litre
Cefixime

0.025mg

0.05mg

Directions
Suspend 28.25g in 500ml of distilled water. Mix well and sterilise by autoclaving at 121°C for 15 minutes. Cool to approximately 50°C and aseptically add the contents of one vial of Cefixime Supplement SR0191, reconstituted as directed. Mix well and pour into sterile Petri dishes.
To reconstitute Cefixime Supplement, aseptically add 2ml sterile distilled water to 1 vial of supplement. Mix gently to dissolve.

方向
将 28.25 克悬浮在 500 毫升蒸馏水中。 充分混合并在 121°C 高压灭菌 15 分钟进行灭菌。 冷却至约 50°C 并无菌添加一小瓶头孢克肟补充剂 SR0191 的内容物,按照指示重新配制。 充分混合并倒入无菌培养皿中。
要重新配制头孢克肟补充剂,将 2 毫升无菌蒸馏水无菌添加到 1 瓶补充剂中。 轻轻混合溶解。

Description
The addition of rhamnose to Sorbitol MacConkey Agar (SMAC) has been shown to aid the differentiation of Escherichia coli O157 from background flora. Approximately 60% of non-sorbitol fermenting Escherichia coli of serogroups other than O157 ferment rhamnose (Sheffield PHL, unpublished data). Cefixime has been shown to reduce the level of competing flora, particularly Proteus spp., that often account for large numbers of non-sorbitol fermenting colonies1.

Escherichia coli O157 do not usually ferment sorbitol or rhamnose, so will appear as straw coloured colonies. However, rhamnose is fermented by most sorbitol negative Escherichia coli of other serogroups. These colonies will be pink/red and will not be counted as presumptive Escherichia coli O157 colonies1.

Cefixime Rhamnose Sorbitol MacConkey Agar (CR-SMAC) is a selective and differential medium for the detection of Escherichia coli O157. Field trials have shown that using CR-SMAC, in conjunction with the more selective CT-SMAC, leads to a higher overall recovery of Escherichia coli O157 from enrichment broths2,3.

Technique
Inoculate the plates with a suspension of the sample. to produce separated colonies. Incubate for 24 hours at 35-37°C.

Examine the plates for straw coloured colonies; these are sorbitol and rhamnose negative organisms. Confirm suspected Escherichia coli O157 with the E. coli O157 Latex Test DR0620 or Dryspot E. coli O157 DR0120.

技术
用样品的悬浮液接种板。 产生分离的菌落。 在 35-37°C 下孵育 24 小时。

检查平板上的稻草色菌落; 这些是山梨糖醇和鼠李糖阴性微生物。 使用 E.coli O157 Latex Test DR0620 或 Dryspot E.coli O157 DR0120 确认疑似大肠杆菌 O157。

Coloured colonies may also occur:

sorbitol positive

pink to red

rhamnose positive

pink to red

Storage conditions and Shelf Life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium for up to 2 weeks at 2-8°C.

Appearance
Dehydrated medium: Straw pink coloured, free-flowing powder
Prepared medium: Red coloured gel

储存条件和保质期
将脱水培养基储存在 10-30°C 并在标签上的有效期之前使用。
将准备好的培养基在 2-8°C 下储存长达 2 周。

外貌
脱水介质:稻草粉色,自由流动的粉末
制备培养基:红色凝胶

Quality control

Positive control: Expected results
Escherichia coli O157:H7 NCTC 12900 *
(sorbitol negative, rhamnose negative)
Good growth, straw coloured colonies
Negative controls:
Escherichia coli ATCC® 25922 *
(sorbitol positive)
Good growth, pink colonies
Proteus mirabilis ATCC® 29906
(sorbitol negative, rhamnose negative)
Inhibited
* This organism is available as a Culti-Loop®

References
1.
 Chapman, P.A., Siddons, C. A., Zadik, P. M. and Jewes L. (1991) J. Med. Microbiol. 35:107-110
2. Information on file at Oxoid.
3. Wallace, J. S. and Jones, K. (1996) J. App. Bacteriology 81:663-668

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