Culturing a Fecal Sample
| Purpose | To study some enteric bacilli normally found in the bowel |
| Materials | A stool specimen Swab Tubed sterile saline (0.5 ml) EMB or MacConkey agar plate Hektoen enteric (HE) agar plate Blood agar plate |
Procedures
- Bring a fresh sample of your feces to the laboratory session. Collect it in a clean container fitted with a tight lid (a screwcap jar;waxed, cardboard cup; or plastic vessel).
- Using a swab, take up about 1 gm of feces (a piece the size of a large pea) and emulsify this in the tube of saline.
- Inoculate the fecal suspension, with the swab, on a blood agar, EMB or MacConkey agar plate, and a Hektoen enteric (HE) plate. Discard the swab in disinfectant solution. Streak for isolation, using a loop.
- Incubate the plates at 35°C for 24 hours.
Results
- Describe the appearance of growth on your plate cultures.
- Interpret any difference in numbers of colonies on these plates.
- Interpret the color of colonies on EMB or MacConkey agar.
- Interpret the appearance of colonies on the HE plate.
- Were any lactose-negative colonies present? If so, name the genera to which they might belong and indicate the key procedures that would identify each.
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