[an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive]

CLOSTRIDIUM DIFFICILE AGAR BASEo:p>

 

A medium base used for the isolation of Clostridium difficile.

 

Code: CB1/1024

 

Typical formula g/l

 

Peptone mix 40.0
Disodium phosphate 5.0
Monopotassium phosphate 1.0
Magnesium sulphate

0.1

Sodium chloride 2.0
 Fructose 6.0
Agar 15.0
Supplement with (vial contents for 500ml of medium)  
D-Cycloserine

250mg

Cefoxitin

 8 mg
Defribinated Horse Blood 50 ml

 

Final pH 7.4 +/- 0.1

      

Directions

Suspend 34.5g in 500 ml of cold distilled water; heat to boiling and autoclave at 1210C for is minutes. Reconstitute one vial of Clostridium Difficile Supplement with 5ml of sterile distilled water and add it to the pre-cooled base. Mix thoroughly and add 25ml of defibrinated hor­se blood, mix thoroughly and distribute into sterile Petri dishes.

 

Description

Clostridium difficile was first isolated from meconium and infant faeces in 1935 by Hall and O'Toole but only recently has been seen a clear correlation between the cytotoxin produced by Clostridium difficile and the illness characterised by pseudomembra­nous colitis with inflammatory plaques, serious diarrhoea, dehy­dration, fever and leucocytosis. The most suitable medium for the selective isolation of Clostri­dium difficile is that proposed by George et al. in 197B. The medium is a slightly modified version of the original for­mula. It contains fructose, cycloserine, cefoxitin and defibrinated horse blood as a substitute for the egg yolk emulsion, used by Geor­ge et al. Cycloserine and cefoxitin inhibit enterobacteria, faecal strep­tococci, anaerobic non spore-forming Gram-negative bacilli and Clostridium spp. except for Clostridium difticile.

 

In use technique

Streak the specimen directly onto the agar surface, to ob­tain well isolated colonies.

Incubate at 37°C for 48 hours in anae­robic conditions. After 48 hours Clostridium difticile colonies are visible with the following characteristics: circular, raised, opaque grey, sometimes with irregular borders, 4-6 mm in diameter.

 

User quality assurance (37°C-48 hrs, anaerobic incubation)

 

Productivity control

C. difficile ATCC 9689: growth

 

Selectivity control

E. coli ATCC 25922: inhibited

 

Storage

Dehydrated medium: 15-30°C

User prepared plates: 7 days at 2-8°C

 

References

Bartlett, J.G. et al. (1978) st1:place>N. Eng. J. Med., 298, 531.

Hall and E. O’Toole (1935) Am. J. Dis. Child. 49, 390.

Larson, H.E. et al. (1978) Lancet, i. 1063-6

[an error occurred while processing this directive]