Final: Enteribacteriaceae And Biochemical Testing Flashcards
What are the shape and gram-reaction-type of enterobacteriaceae?
They are gram-negative rods
Where are enterobacteriaceae commonly found?
In water, soil, and vegetation
How do humans commonly spread enterobacteriaceae?
Improper hand washing and poor sanitary practices
Why are fimbriae needed by bacteria?
They allow bacteria to attach themselves to host cells and tissue
What diseases are enteric bacteria known to commonly cause?
30% of all septicemias
70% of all UTI’s
Pneumonia
Intestinal infections
How do endotoxins, such as lipid A, cause harm to the human body during infection?
They stimulate and immune reaction in the host when released from the bacterial cell wall through lyses or death of bacteria. If released in a short time the immune system can become overwhelmed and go into anaphylactic shock
How do capsules protect bacteria?
The prevent phagocytosis by the host’s white blood cells
What is the most common symptom of an acquired enteric infection?
Diarrhea
How are enteric bacteria differentiated (considering they all look mostly identical under the microscope)?
They are run through a series of test groups called IMVC (Índole, Mehtyl red, Voges-Proskauer, and Citrate)
What is the basis for the majority of biochemical tests?
The presence of absence of certain metabolic products
What is indole? How would one test for the presence of indole?
Indole is a molecule produced as a by-product during the breakdown of tryptophan by triptophase while bacteria are caatobolizing protein.
One would test for it by adding Kovac’s regent to an actively growing culture
Generally speaking, what is the Methyl Red and Voges-Proskar media designed to test for?
To see which metabolic pathways are used to break down glucose
What is citrate media designed to test for and what does a positive test look like?
Designed to place microbes under nutritional stress and see how much they respond
Blue color= positive
Why is SIM media considered a different combination media?
It has multiple tests within one media
What three things does the SIM media test for?
Sulfur reduction
Indole production
Motility
