Refrigeration of Broths and Agars

The following are acceptable alterations of compendial methods: 1. use of incubators that become refrigerators (i.e., after the recommended incubation time and temperature the incubator can automatically revert to a refrigerator); 2. refrigeration of broths and/or agar plates after the appropriate incubation but prior to the next step in the method (i.e., the broth is plated on the selective agar, incubated under the appropriate conditions, and then refrigerated for 24-72 h prior to picking of the presumptive colonies); and 3. refrigeration of inoculated broths (or aliquots thereof) while plating and confirmation is completed and refrigeration of selective agar plates while confirmation is completed. Appropriate controls must be used throughout these alterations.

Reincubation of Agar Plates

It is common practice to reincubate agar plates (beyond that recommended in the method) to allow colonies to reach suitable size for counting or picking. It is recognized that some serotypes of the target microorganism may be considered "slow growers" and may need extra incubation time. It is also common practice to reincubate negative or "No growth" agar plates to ensure that no "slow growers" were present before releasing results. Appropriate controls must be used throughout these alterations.

Use of Helpful Hints from Kit Inserts, not in the Compendial Method

Unless specified in the method, helpful hints provided by manufacturers either in kits or in correspondence may be used in a method.

Reanalysis of a Sample

If the initial analysis of a sample cannot be completed, then reanalysis may be considered when requested by the inspector/client to do so.

A new analytical unit may be obtained from the original sample unit, if it has been maintained under suitable conditions that prevent any alteration of it's original state.

Reincubation of Biochemicals

It is acceptable to reincubate biochemicals (for example, carbohydrates as agars, broths or in rapid identification kits) when the colour reaction is not definitive. This may happen when the isolate is a "slow grower" and needs extra time to reach suitable numbers for a definitive reaction. The analyst may reincubate up to an additional 24 h but should reexamine the test every few hours until the reaction is suitable. The analyst should also check with the manufacturer of the kit or test if problems occur.

Recording Results

Various clients may have their own microbiological specifications for raw materials, environmental samples, and intermediate/finished products that complement and augment those established by the Government of Canada. The examples given in the Section "Recording Results" reflect the regulations, standards and guidelines set in The Food and Drugs Act and Regulations and other Government policies. It is recognized that the analyst may record and report the test results to reflect the needs of the client, and that this may be determined by any alteration in the "Limits of Detection" and use of alternate dilutions , as described above.