ANAEROBE ISOLATION AGAR

 

Designed to give optimum growth of demanding anaerobes.

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Code: CB1/1000

 

Typical formula g/l

 

Agar	15.0
Peptone mixture	23.0
Sodium chloride	5.0
Sodium bicarbonate	0.5
Dextrose	1.0
Sodium pyruvate	0.5
Amino acid factors	2.0
Soluble pyrophosphate	0.13
Vitamins	11.0mg

 

Final pH: 7.2 +/- 0.2

 

Description:

 

This medium has a high nutritive value due to its richness in peptones, extracts, haemin and amino acids.

This is a primary isolation medium capable of growing most clinically significant anaerobes. Starch and sodium bicarbonate act as detoxification agents. It contains promoting agents for Fusobacterium necrophorum, Propionibacterium acne, Bacteriodes fragilis, Eubacterium spp. and Veillionella spp. Pyruvate helps neutralise hydrogen peroxide.

 

Anaerobe Isolation agar + Kanamycin 75 (Code:CB/1000N) for the selective isolation of Clostridium spp. and other anaerobes. Kanamycin is more inhibitory to anaerobic cocci. Metronidazole  and Nalidixic acid for the isolation of actinomyces spp. from clinical material. The metronidazole will suppress the growth of most other anaerobes. Nalidixic acid for the isolation of non-sporing anaerobes from clinical material. Vancomycin for the isolation of Gram negative anaerobes from clinical material. When used with other blood agar bases, further enrichment of the medium with haemin and menadione is beneficial. When Neomycin 100 is added to egg yolk medium this supplement will allow the growth of clostridia whilst inhibiting other lecithinase producing organisms. When Neomycin 75 added to blood agar the resulting medium will allow the growth of clostridia, most bacteroides fragilis strains and some anaerobic cocci.

 

Media preparation:

Add 46 grams of dehydrated culture medium to 1 litre of distilled water. Allow to soak for 10 minutes, swirl to mix then sterilise by autoclaving at 121°C for 15 minutes.  Cool to 48ºC then aseptically add 5-10% of sterile defibrinated horse blood, mix well and pour into petri dishes.

 

Quality specification:

Dehydrated medium: homogeneous, straw colored fine powder.

Ready to use medium: red due to addition of blood. The blood will darken (reduce) because of the presence of reducing agents.

 

QC Organism Results:

Bacteroides fragilis ATCC 25285 Growth

Clostridium perfringens ATCC 13124 Growth

 

Storage:

Dehydrated medium should be stored between 10 to 25ºC. Once opened, place the

container in a dark, dry place. The dehydrated medium should not be used if there is lumps evident or if there is colour change.