Rapid detection of E.Coli and Salmonella

[Lisa Demczuk]

Steen Ostergaard (klasteos at kbar.dtu.dk) wrote:
: I am in the preliminary manoeuvres of implementing an assay for detec-
: tion of bacterias as E. Coli and Samonella. My intention is to avoid 
: long incubation times and make the assay as quick and sensitive as 
: possible.
: ...would appreciate it very much if you could help me out. Even informa-
: tion that seems simple and wellknown to you may turn out to be valuab-
: le.

We here at Agriculture Canada use Modified Semi-Solid Rapport-Valliatus 
(MSRV) medium for the isolation of Salmonella from food.  Where the standard 
method of pre-enrichment, selective enrichment, selective plating, and 
then finally non-selective plateing takes about 4 days, the MSRV method 
requires only pre-enrichment then inoculation of an MSRV plate, therefore 
about 2 days. We have conducted many comparison studies have found that 
the MSRV isolation rate far exceeds that of the standard method.  The 
isolation is based on a very selective medium containing novobiocin and 
brilliant green. Also being semi-solid, it selects for only motile 
organisms.  Incubation is at 42 Celcius and is selective also.  One hitch 
however, non-motile salmonella will not be isolated, i.e. S.pullorum and 
S.gallinarum, but these are very rare. 
Hope this helps.