||To study some biochemical reactions of Salmonella and Shigella
Simmons citrate slants
Urea broth tubes
Phenylalanine agar slants
Lysine and ornithine decarboxylase broths
Mineral oil in dropper bottle
Sterile 1.0-ml pipettes
Pipette bulb or other aspiration device
Sterile empty tubes
Methyl red indicator
40% sodium or potassium hydroxide
10% ferric chloride
Agar slant cultures of Salmonella and Shigella species
- You will be assigned a culture of either Salmonella or Shigella. Inoculate one tube of each medium provided (i.e.:TSI; SIM;
MR-VP broth; citrate slant; urea, lysine, and ornithine broths; and phenylalanine agar).
- Incubate all tubes at 35°C for 24 hours.
- Complete the IMViC and PD tests (see Experiment 24.1). Read and record all biochemical reactions under Results.
Observe your neighbors’ results and record all information for both organisms.
||To illustrate identification of a microorganism by the slide agglutination technique
Heat-killed suspension of E. coli or Salmonella
E. coli or Salmonella antiserum
- Carefully wash a slide in 70% alcohol and let it air dry..
- Using a glass-marking pen or pencil, draw two circles at opposite ends of the slide..
- Using a capillary pipette, place a drop of saline in one circle. Mark this circle “C,” for control..
- With a fresh capillary pipette, place a drop of antiserum in the other circle..
- Use another pipette to add a drop of heat-killed bacterial suspension (this is the antigen) to the material in each circle..
- Pick up the slide by its edges, with your thumb and forefinger, and rock it gently back and forth for a few seconds..
- Hold the slide over a good light and observe closely for any change in the appearance of the suspension in the two circles.
- In the following diagram indicate any visible difference you observed in the suspensions at each end of the slide.
192 Diagnostic Microbiology in Action
- State your interpretation of the result.