GI Specimen Processing

Order for Inoculating GIT tubes

1. MAC (small line)

2. BA (small line)

3. TSI (down to 1/4" from bottom in straight line, then streak surface)

4. ONPG-PAM (down to 1/4" from bottom in straight line)

5. TSB (swish around)

Then return to MAC and BA to streak out the quadrants.

Spot Oxidase

1. put filter paper on microscope slide

2. add drop of oxidase reagent to filter paper

3. Let dry at least 1 min (IMPORTANT: will get false neg otherwise)

4. Get colony on applicator stick and press and hold onto paper for 5 sec

5. read results (positive blue)

Other Notes

Serology: perform from TSI or BApp (cannot use anything that's selective)

• Serology may take a while to show agglutination - use a thick/milky suspension and rock card back and forth for 1-2 minutes (may need to wait the full 2 minutes)

Indole: use TSB tube (make sure you're using correct reagent - Kovacs!) or spot indole from BApp. If doing motility, take drop before adding reagent.

Motility darkfield: use TSB sample or colony from BApp with saline drop

ONPG: Check ONPG and motility first, then add ferric chloride.

Check for purity from MAC plate.

Organisms

very tiny clear things on plate - bile salts precipitating out (likely that your plate has been refrigerated)

Edwardsiella are always indole + but otherwise appear to be Salmonella (which is indole -)

Shigella may appear similar to Salmonella, but is non-motile.

Proteus is PPD + (organisms of interest are all PPD -)