Page 137 - 2013 ISPAM Mid-Year Mtg Book

incubated for the same time with incubation temperatures within a degree of 42 ºC. For the ISO,
BAM and AOAC method the MKTTn broth and the TT broth are incubated at a different
temperature (37 and 35 ºC respectively).
Overall the selective enrichment media and incubation conditions are equivalent to
MFHPB 20.
Selective plating:
All methods are using a combination of different plating media; however there is a great
deal of overlap between each type of media that is used in each method (i.e. BGS plates are
used in 2 of the methods and XLD is used in 3 of the methods). MLG 4.04 has the selective agar
BGS in common with MFHPB 20 where as FDA BAM and AOAC have Bismuth Sulfite agar in
common with MFHPB 20. The ISO method uses XLD as the selective agar and requires the use
of a second selective agar. The method does not specify the type of agar, but states that any
agar suitable for the isolation of Salmonella can be used. Since the ISO method does not specify
which selective agar to use it is possible to use plating media in MFHPB 20.
Biochemical Tests:
All methods use the same principals for their biochemical and serological confirmation
testing and as such are deemed equivalent.
Conclusions:
Over all the FISIS MLG 4.04 method and the ISO 6579 method are similar to MFHPB 20
method up to the selective plating step. In order for the two methods to be deemed equivalent,
there must be agreement that the agars used for the isolation of Salmonella in the two methods
are equivalent to those used in MFHPB 20.
The FDA BAM method and all of the AOAC Methods (2000.6, 995.2, and 967.26) cannot be
deemed equivalent at this time. The use of Lactose broth and the lack of data comparing Lactose
broth and TSB to BPW or Nutrient broth limit the comparison of BAM and AOAC methods to
MFHPB 20. To prove equivalency, more data must be presented before a final ruling can be
made.
Reference:
D'Aoust JY, Sewell AM, Warburton DW. A comparison of standard cultural methods for the
detection of foodborne Salmonella. Int. J. Food Microbiol. 1992;16 (1): 41-50
van Schothorst M, van Leusden FM. Comparison of several methods for the isolation of
salmonellae from egg products. Can. J. Microbiol. 1975;21 (7): 1041-5.