Advances in culture media design (Chromogen and Inhibigen compounds)

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Advances in culture media design (Chromogen and
Inhibigen compounds)

• Neal Parker
• Industrial account manager

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Introduction

• Background and principles of Chromogens
• Why do we use them?
• Background and principles of Inhibigens
• Why do we use them?

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Background and principles of chromogenic
media

• Chromogen a chemical compound, itself without
  colour, that can be transformed into a coloured
  compound, or can react with another material to
  form a coloured compound

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Background and principles of chromogenic
media
Chromogen
Chromophore component (e.g. indoxyl derivative
such as 5-bromo-4-chloro-3-indoxyl)
Sugar component (e.g. galactose)
Uptake
E. coli
Enzyme
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Background and principles of chromogenic
media
E. coli
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Background and principles of chromogenic
media
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Why use Chromogens?
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Why use Chromogens?

• Improve overall specificity of a diagnostic
  medium.
• Positive colonies are easy to identify.
• Reduce number of sub-cultures required.

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Current chromogen situation

• The large scale synthesis of chromogens means
  compounds are affordable for use in culture media
• There are now chromogenic media available for
  almost all organisms of interest in both the
  Industrial and Clinical environments
• gt30 chromogenic media formulations are currently
  available for the differentiation of E. coli and
  coliforms
• gt10 formulations for Salmonella

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From chromogens to inhibigens
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Background and principles of Inhibigens

• Inhibigen an inhibitor molecule linked to a
  specific substrate. In this bound state, the
  inhibitor is non-toxic. However, if taken up by a
  cell and cleaved from the substrate, the
  Inhibigen molecule will prevent the organism from
  replicating

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Background and principles of Inhibigens
Uptake
Inhibition of cell wall synthesis
Loss of viability
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Why use Inhibigens?

• XLD

• Brilliance Salmonella (InhibigenTM)

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Why use Inhibigens?

• Reduce stress on target organism
• Improve sensitivity
• Reduce growth of non-target organisms

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Current Inhibigen Situation

• Inhibigens are a patented concept
• Small scale manufacture
• Currently only one product containing Inhibigen
  compounds
• Many more are in the pipeline