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MacConkey Agar with Sorbitol | SMAC Agar Base for E. coli O157 | AS-1284 Ausamics
  • MacConkey Agar with Sorbitol | SMAC Agar Base for E. coli O157 | AS-1284 Ausamics
MacConkey Agar with Sorbitol | SMAC Agar Base for E. coli O157 | AS-1284

MacConkey Agar with Sorbitol | SMAC Agar Base for E. coli O157 | AS-1284

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MacConkey Agar with Sorbitol | SMAC Agar Base for E. coli O157 | AS-1284
AuSaMicS Life Science • Selective Enteric Media

MacConkey Agar with Sorbitol

MacConkey Sorbitol Agar • SMAC Agar Base

Selective and differential medium for the presumptive isolation of Escherichia coli O157:H7 and other sorbitol-nonfermenting enteric bacteria. A recognized workflow medium for food, clinical, and environmental microbiology.

AS-1284 🧫 Selective / Differential ✓ Australian Stock 🧪 O157 Screening
Target workflow: E. coli O157:H7 screening Format: Dehydrated culture medium base Support: COA / SDS / TDS available

Recommended Pack Sizes

100 g AUD 49
250 g AUD 99
500 g AUD 159
1 kg AUD 259
5 kg AUD 990
Pricing strategy: 500 g positioned as best-seller, 1 kg as best-value for routine QC and food microbiology laboratories.

Overview

MacConkey Agar with Sorbitol, also known as MacConkey Sorbitol Agar or SMAC Agar, is a selective and differential medium used for the presumptive detection of Escherichia coli O157:H7 and related sorbitol-nonfermenting enteric bacteria. In contrast to conventional MacConkey Agar, sorbitol replaces lactose as the fermentable carbohydrate, enabling differentiation of organisms that fail to ferment sorbitol.

Typical E. coli strains ferment sorbitol and produce pink to red colonies, while many O157:H7 strains remain colorless or pale. Crystal violet and bile salts suppress most Gram-positive organisms, making the medium suitable for selective recovery from food, clinical, and environmental specimens.

Applications

  • Presumptive isolation of E. coli O157:H7 from food and feed samples
  • Screening of stool and clinical samples for sorbitol-nonfermenting enteric pathogens
  • Use in food safety, public health, veterinary, and environmental microbiology
  • Support medium in workflows aligned with O157 detection methods and selective supplements
  • Routine laboratory differentiation of sorbitol-fermenting vs non-fermenting colonies

Key Features

Sorbitol differentiation
Distinguishes sorbitol-fermenting colonies from colorless non-fermenters.
Selective action
Bile salts and crystal violet suppress most Gram-positive flora.
O157 workflow fit
Commonly used for presumptive O157 screening in food and clinical microbiology.
Supplement compatible
Frequently used with cefixime-tellurite supplements to improve selectivity.

Typical Composition (per Litre)

Ingredient Typical Amount Function
Tryptone 17.0 g Nitrogen and nutrient source
Proteose Peptone / HM Peptone 3.0 g Growth support and trace nutrients
D-Sorbitol 10.0 g Differential carbohydrate
Bile Salts Mixture 1.5 g Selective inhibition of Gram-positive flora
Sodium Chloride 5.0 g Osmotic balance
Neutral Red 0.03 g pH indicator
Crystal Violet 0.001 g Selective inhibition
Agar 13.5 g Solidifying agent
Typical final pH: 7.1 ± 0.2 at 25°C. Base formulations are commonly used alone or with cefixime-tellurite supplements for improved selectivity in O157 workflows.

Comparative Medium Guide

Medium Primary Readout Best Use Key Strength Limitation
SMAC Agar Base (AS-1284) Sorbitol fermentation Presumptive O157 screening Simple visual separation of many O157-type colonies Not all O157 are sorbitol-negative; confirmation still required
MacConkey Agar Lactose fermentation General enteric isolation Broad standard use Cannot separate O157 by sorbitol phenotype
CT-SMAC Sorbitol + higher selectivity Targeted O157 workflows Reduced background flora and fewer false picks Requires supplement addition
Chromogenic STEC Media Chromogenic enzyme reactions Enhanced differentiation More specific colony recognition Usually higher cost

Interpretation & Selection Notes

Typical colony logic

  • Sorbitol fermenters often appear pink to red
  • Many O157:H7 strains appear colorless or pale
  • Useful as a presumptive screening step before confirmation

Method considerations

  • Non-sorbitol fermentation alone does not confirm pathogenic O157
  • Late sorbitol fermentation and strain variability can affect screening
  • Use serology, biochemical, or molecular confirmation as required

Technical Specifications

Catalogue Number AS-1284
Product Name MacConkey Agar with Sorbitol
Synonyms MacConkey Sorbitol Agar, SMAC Agar Base
Format Dehydrated medium base
Reconstitution Approx. 50.0 g/L
Final pH 7.1 ± 0.2
Sterilization 121°C for 15 min
HS Code 3821.00.00
Shelf Life 3 years

Typical Organism Scope

  • ✓ E. coli O157:H7 screening workflows
  • ✓ Sorbitol-fermenting E. coli comparison
  • ✓ Other enteric Gram-negative bacteria
  • ✓ Food and clinical enteric flora screening

Preparation & Handling

Suspend the dehydrated medium in purified water, heat to dissolve completely, sterilize, cool to pouring temperature, and dispense into sterile plates. Where required by the method, add selective supplement according to validated SOPs. Read colony color and morphology within the specified incubation window.

Suggested Cross-Links

  • MacConkey Agar
  • CT Supplement / Cefixime-Tellurite workflows
  • EC Broth
  • TBX Agar
  • Chromogenic E. coli / STEC media

AuSaMicS Compliance & Supply Notes

Supplied for laboratory and research workflows. Batch-specific documentation may include Certificate of Analysis, Technical Data Sheet, and Safety Data Sheet depending on customer and compliance requirements.

For laboratory and research use only. Not for food, household, therapeutic, or pharmaceutical applications.

AuSaMicS Pty Ltd
31 Longview CT, Thomastown, VIC 3074, Australia
ABN 56676640467
www.ausamics.com.au
support@ausamics.com
+61 412 520 598

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