Exercise 5-29 Micro Lab: API 20 E Identification System for Enterobacteriaceae and Other Gram Negative Rods
multiple test systems
systems designed to run an entire battery of tests simultaneously
API 20 E system
A plastic strip of 20 microtubes and cupules, partially filed with different dehydrated substrates. Bacterial suspension is added to the microtubes, rehydrating the media and inoculating them at the same time. Color changes take place and reveal the presence or absence of chemical action and thus, a positive or negative result.
Which API tests are evaluated first?
spontaneous reactions - those that do not require addition of reagents
What constitutes the 21st test?
an oxidase test
What happens in the rare instances when the 21 tests are not discriminatory enough to identify an organism?
the organism is grown and examined on MacConkey Agar and supplemental tests are performed for nitrate reduction, oxidation/reduction of glucose and motility.
The API test divides the test into _____, assigning each member a numerical value ______.
groups of three
1, 2, or 4
Why do you add water to the honeycombed wells?
to humidify the strip during incubation