Enumeration of Clostridium perfringens in Foods

2) Nitrate-motility (NM) agar

3) Nitrate reagents

4) 2% sodium citrate (tempered to 45^oC) (may be used for cheese samples)

5) Peptone water diluent (PW) (0.1%)

6) Lactose gelatin (LG)

7) Stomacher, blender or equivalent

8) pH meter or paper capable of distinguishing to within 0.3 to 0.5 pH units within a range of 5.0 to 8.0

9) 1N HCl and 1N NaOH

10) A system capable of generating anaerobic conditions, such as, anaerobic jars (with a venting system or disposable H₂/CO₂ gas generator envelopes and a desiccant, such as anhydrous CaSO₄); the AnaeroGen^TM anaerobic atmosphere generation system (Oxoid) or an anaerobic incubator capable of maintaining 35^oC.

11) 5% C0₂, 10% H₂ and 85% N₂ (if anaerobic incubator or jars with venting system are used)

12) Anaerobic indicator

13) Aerobic incubator capable of maintaining 35^o

14) 45^oC waterbath (if sodium citrate is to be used)

Note: It is the responsibility of each laboratory to ensure that the temperature of the incubators or waterbaths is maintained at the recommended temperatures. Where 35^oC is recommended in the text of the method, the incubator may be 35 +/-1.0^oC. Similarly, lower temperatures of 30 or 25^oC may be +/- 1.0^oC. However, where higher temperatures are recommended, such as 43 or 45.5^oC, it is imperative that the incubators or waterbaths be maintained within 0.5^oC due to potential lethality of higher temperatures on the microorganism being isolated.

15) Colony counting device

7. PROCEDURE

Each sample unit should be analyzed individually. Carry out the test in accordance with the following instructions:

7.1 Handling of Samples Units