If you're using conventional media, as we used to do a long time ago, to screen
lactose negative colonies from stool cultures, adding a urea slant and SIM
deep (indole, motility, and H2S) to a TSI and LIA slant can eliminate false
positive Salmonella's. Are you serotyping your isolate before you call it a
Salmonella? When Vitek (automated system) identifies a Salmonella, it is
always understood that this result is subject to serotyping. If you're merely
using TSI, you probably should add at least a urea to your screen. When we got
a positive screening with the TSI, LIA, Urea, and SIM, then we performed
serotyping, sensitivity, and a full lactose negative biochemical panel.
(Likewise, if the screening with the four media came up with a Shigella
species, we went on to perform serotyping, sensitivity, and full panel).
Hope this helps.
Judy Dilworth, M.T. (ASCP)
> Hi group
> How do I identify Proteus ? They make a false positive Salmonella, ........