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Salmonella sp. vs. Proteus

A. Seoane seoaneb at yahoo.com
Fri Jan 28 06:23:13 EST 2000

--- hec <helle_christensen at mail.tele.dk> wrote:
> Hi does anyone know a good quick method, how to
> identify eg, Proteus
> Mirabilis and Citrobacter without any fancy
> equipment. I make Salmonella
> samples ( from poultry) every day, but often I get
> false results in Triple
> Sugar Iron. It would help me if I could identify
> Proteus M in the lab,
> instead of spending a lot of money in sending the
> samples in for futher
> identification. ( The danish law says that every
> Salmonella suspect sample
> should be sent in for identification.)
> Thanks
> Helle Christensen
> helle_christensen at mail.tele.dk
I use this method on SH2+ colonies:

1st STEP: Slide agglutination with polyvalent
Salmonella antiserum (you can obtain it from
DIFCO).CAUTION: Sometimes Citrobacter shows
auto-agglutination, that is, it will agglutinate using
0.9% saline as well as using salmonella antiserum.

2nd STEP: If positive agglutination, proceed to more
complete biochemical / serological identification.
If negative agglutination, to avoid false negative
results, perform Urea and ONPG tests on your isolate.
Salmonella are mainly both Urea/ONPG negative, except
for ONPG positivity in groups II, III, V and VI.(These
groups are easily missed since lactose fermentation
can lead to false SH2-negative colonies or very small
black centers).

3rd STEP: If Urea and/or ONPG positive, consider
isolate as being Proteus or Citrobacter. No further
tests. If both tests negative, proceed to complete
biochemical identification.

WARNING: This working scheme SHOULD NOT BE USED if you
must screen for lactose-fermenting salmonella ( groups
II, III, IV, VI, usually isolated from cold-blooded
animals and the environment ).

Best wishes!. If in doubt, you should only eat
autoclaved poultry :)

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