PREPARATION OF CHOCOLATE AGAR MEDIUM This is prepared by heating 10% blood agar at 80°C for 5-10 minutes. It is easiest to use a blood agar plate that is placed in an oven or incubator set at this temperature for 5 - 10 minutes. Heating of the blood causes rupture of erythrocytes and the liberation of their contents into the medium. It is used to culture X and requiring bacteria (Haemophilus) and other fastidious bacteria such as Campylobacter. ACIDIC CULTURE MEDIA Acidic culture media whose pH value is below 5.0 should be prepared under conditions of low temperature, as agar is hydrolyzed when heated in an acidic medium and gel stability of the culture medium thus declines. POSSIBLE SOURCES OF ERROR DURING RECONSTITUTION AND HANDLING OF MEDIA Clumping of dehydrated culture media Humidity too high during storage. Container was left open for too long. Container not tightly sealed it had been opened. Dehydrated culture medium was too old. pH shift Water was not neutral. Container not tightly sealed after it had been opened. Culture medium was overheated during reconstitution. Dehydrated culture medium was too old. Turbidity, precipitation Water not adequately demineralised. Vessel used for reconstitution was not clean. pH value incorrect. Culture medium was overheated during reconstitution. In the case of self-mixed culture media, the basic components contained precipitating impurities. Caused by the sample material. Temperature of solidification too high Too much dehydrated culture medium was weighed out and used.
PREPARATION OF CHOCOLATE AGAR MEDIUM This is prepared by heating 10% blood agar at 80°C for 5-10 minutes. It is easiest to use a blood agar plate that is placed in an oven or incubator set at this temperature for 5 - 10 minutes. Heating of the blood causes rupture of erythrocytes and the liberation of their contents into the medium. It is used to culture X and requiring bacteria (Haemophilus) and other fastidious bacteria such as Campylobacter. ACIDIC CULTURE MEDIA Acidic culture media whose pH value is below 5.0 should be prepared under conditions of low temperature, as agar is hydrolyzed when heated in an acidic medium and gel stability of the culture medium thus declines. POSSIBLE SOURCES OF ERROR DURING RECONSTITUTION AND HANDLING OF MEDIA Clumping of dehydrated culture media Humidity too high during storage. Container was left open for too long. Container not tightly sealed it had been opened. Dehydrated culture medium was too old. pH shift Water was not neutral. Container not tightly sealed after it had been opened. Culture medium was overheated during reconstitution. Dehydrated culture medium was too old. Turbidity, precipitation Water not adequately demineralised. Vessel used for reconstitution was not clean. pH value incorrect. Culture medium was overheated during reconstitution. In the case of self-mixed culture media, the basic components contained precipitating impurities. Caused by the sample material. Temperature of solidification too high Too much dehydrated culture medium was weighed out and used.
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