||To study some enteric bacilli normally found in the bowel
||A stool specimen
Tubed sterile saline (0.5 ml)
EMB or MacConkey agar plate
Hektoen enteric (HE) agar plate
Blood agar plate
- 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.
- 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.