This exercise provides you with an opportunity to apply your knowledge of the Enterobacteriaceae to making a laboratory diagnosis of an intestinal infection. In Experiment 25.1 you will prepare a
culture of your own feces and observe the normal intestinal flora on primary isolation plates. In
Experiment 25.2 you will be given a pure culture of one of the Enterobacteriaceae as an “unknown”
to be identified. Experiment 25.3 is an antimicrobial susceptibility test of your pure unknown culture.
Here you should observe the differences in response of gram-negative enteric bacilli, as compared
with streptococci and staphylococci studied earlier, to the most clinically useful antimicrobial