Microbiology

• Oxoid Charcoal Agar Base (Bordetella Selective Medium) is used for selective isolation of B. pertussis and B. parapertussis.
• Requires addition of Bordetella Selective Supplement, Part No. SR0082E.

Charcoal Agar Base, Oxoid Composition

Charcoal Agar, Oxoid Preparation:
Suspend 51g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Cool to 50°C, add 10% of defibrinated blood and mix gently. The medium is made selective for the isolation of Bordetella pertussis and Bordetella parapertussis by the addition of Bordetella Selective Supplement SR0082.

To one vial add 2ml of sterile distilled water and dissolve the contents completely. Add this solution to 500ml of sterile, molten Charcoal Agar, cooled to 50°C, together with 10% v/v defibrinated horse blood SR0050. Mix well before pouring into sterile Petri dishes.
For Haemophilus influenzae, omit the selective agents and convert to `chocolate’ agar.

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 plates of medium at 2-8°C.

Precautions
Stuart’s transport medium or similar formulation media should not be used for Bordetella-containing specimens.
Two pernasal swabs should be taken from each patient, one through each nostril.
Make sure the charcoal remains in suspension when dispensing the medium by gently swirling the flask.
Lysed horse blood is used in the transport medium but whole blood is used in the isolation medium.
Most naso-pharyngeal flora are inhibited by cephalexin but Pseudomonas aeruginosa and some fungi may grow through. Amphotericin B can be added (12mg/ml) as an antifungal agent to prevent the growth of filamentous fungi. However, this level of amphotericin B can be inhibitory to Bordetella pertussis and should not be used routinely.

Enumerate and differentiate bacteria in dairy products with this standard Thermo Scientific™ Oxoid™ China Blue Lactose Agar (Dehydrated). China Blue Lactose Agar, originally formulated by Brandl and Sobeck-skal, is a standard non-inhibitory solid medium used for the differentiation of lactose fermenters from non-lactose fermenters in milk.

The china blue in the medium serves as a pH indicator to differentiate lactose fermenters from non-lactose fermenters. The medium does not contain any inhibitory substances therefore all the organisms present in milk sample grow luxuriantly on this medium.

China Blue Lactose Agar Base, Oxoid Composition

China Blue Lactose Agar, Oxoid Preparation:
Suspend 35g in 1 litre of distilled water. Boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes.

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 at 2-8°C.

Precautions
It is important to remember that Gram positive and negative cocci and bacilli can grow on this medium. Always confirm the organism morphology and Gram reaction.

For the isolation of yeast and molds associated with spoilage, add Oxoid Chloramphenicol Selective Supplement to DRBC Agar Base, Part No. CM0727B; for the enumeration of yeast and molds in foods, add to Rose Bengal Chloramphenicol Agar Base, Part No. CM0549B.

Chloramphenicol Selective Supplement, Oxoid Composition

Chloramphenicol Selective Medium, Oxoid Preparation:
Reconstitute one vial SR0078H per 2 litres medium as directed. Add the vial contents to base medium and mix gently. Sterilise by autoclaving (see media for full details), cool to 50°C, mix gently and pour into Petri dishes.

For the isolation of yeast and molds associated with spoilage, add Oxoid Chloramphenicol Selective Supplement to DRBC Agar Base, Part No. CM0727B; for the enumeration of yeast and molds in foods, add to Rose Bengal Chloramphenicol Agar Base, Part No. CM0549B.

Chloramphenicol Selective Supplement, Oxoid Composition

Chloramphenicol Selective Medium, Oxoid Preparation:
Reconstitute one vial SR0078E per 500ml medium as directed. Add the vial contents to base medium and mix gently. Sterilise by autoclaving (see media for full details), cool to 50°C, mix gently and pour into Petri dishes.

This product has been discontinued, please refer to CM1212B

Isolate, enumerate and differentiate Listeria species and Listeria monocytogenes from food samples with Thermo Scientific™ Oxoid™ Chromogenic Listeria Agar (ISO) (Dehydrated). Chromogenic Listeria Agar (ISO) contains lithium chloride, polymyxin B, nalidixic acid, and amphotericin which act to inhibit non-target organisms. A combination of chromogenic and phospholipase enzyme reactions easily differentiate Listeria monocytogenes (blue colonies surrounded by an opaque halo) from other Listeria spp. (blue colonies without an opaque halo).

Chromogenic Listeria Agar (ISO), Oxoid Composition

Modified ISO Preparation:
Suspend 34.5g of Chromogenic Listeria Agar (ISO) in 480ml of distilled water. Mix well and sterilize by autoclaving at 121°C for 15 minutes. Cool the medium to 46°C and add one vial of Chromogenic Listeria Selective Supplement (ISO), reconstituted as directed and one vial of Brilliance Listeria Differential Supplement. Mix well and pour into sterile Petri dishes.

ISO Preparation:
Suspend 34.5g of Chromogenic Listeria Agar (ISO) Base in 480ml of distilled water. Mix well and sterilise by autoclaving at 121ºC for 15 minutes. Cool the medium to around 50ºC, and add one vial of Chromogenic Listeria Selective Supplement (ISO), re-suspended as directed, and one vial of OCLA (ISO) Differential Supplement. Mix well and pour into sterile Petri dishes.

Storage conditions and Shelf life
The dehydrated medium should be stored at 10-30°C and used before the expiry date on the label.
Prepared medium may be stored for up to 2 weeks at 2-8°C.

• Oxoid Chromogenic Salmonella Agar Base is a selective chromogenic medium for the presumptive identification of Salmonella spp. from clinical and food samples.
• Also available Salmonella Selective Supplement, Part No. SR0194E and Brilliance™ Salmonella Agar Base, Part No. CM1092B.

Chromogenic Salmonella Agar Base, Oxoid Composition

Chromogenic Salmonella Agar, Oxoid Preparation:
Suspend 25g in 500ml of distilled water and add the contents of one vial of Salmonella Selective Supplement (SR0194) reconstituted as directed. Mix well and bring to the boil with frequent agitation. DO NOT AUTOCLAVE. DO NOT HOLD AT BOILING TEMPERATURE. Cool to 50°C, mix well and pour into sterile Petri dishes.

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 6 weeks at 2-8°C.

• Oxoid Clostridium Difficile Selective Supplement is added to Clostridium Difficile Agar Base, Part No. CM0601B.
• Each vial supplements 500mL of medium.

Clostridium Difficile Selective Supplement, Oxoid Composition

Clostridium Difficile Agar, Oxoid Preparation:
Suspend 34.5g in 500ml of distilled water and bring gently to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Allow to cool to 50°C and add aseptically the contents of 1 vial of Oxoid Clostridium Difficile Supplement (SR0096) reconstituted as directed, together with 7% (v/v) Defibrinated Horse Blood (SR0050). Sheep Blood (SR0051) may be used in place of Horse Blood but some strains of the organism will show a slightly reduced growth recovery. Mix well and pour into sterile Petri dishes.

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 at 2-8°C no longer than 5-7 days.

• Oxoid Clostridium Difficile Agar Base is used for the isolation of Clostridium difficile.
• Also available Clostridium Difficile Selective Supplement, Part No. SR0096E.

lostridium Difficile Agar Base, Oxoid Composition

Clostridium Difficile Agar, Oxoid Preparation:
Suspend 34.5g in 500ml of distilled water and bring gently to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Allow to cool to 50°C and add aseptically the contents of 1 vial of Oxoid Clostridium Difficile Supplement (SR0096) reconstituted as directed, together with 7% (v/v) Defibrinated Horse Blood (SR0050). Sheep Blood (SR0051) may be used in place of Horse Blood but some strains of the organism will show a slightly reduced growth recovery. Mix well and pour into sterile Petri dishes.

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 at 2-8°C no longer than 5-7 days.

Precautions
Colonies of Clostridium difficile from faecal cultures are smaller when egg yolk is used in place of horse blood.

The Oxoid formula does not contain the neutral red indicator proposed by George et al. because it is designed for use with horse blood. On this medium the typical colour of the colony of Clostridium difficile will not appear however there will be a fluorescent reaction.

Typical Gram stain morphology of Clostridium difficile may not be evident in colonies picked from this medium because of the antibiotics present. Subculture to blood agar to obtain characteristic morphology.