Anaerobic Bacteria Flashcards
(23 cards)
How are anaerobic bacterial pathogens aquired?
Normal flora gone bad. They have escaped from their normal compartment.
From the soil. Spores enter wound and germinate the tissue. OR contaminate food
An infection of anaerobic bacteria causes what symptom?
an abcess
How are anaerobic bacterial infections treated?
surgical treatment of the abcess and antibiotics
What is the problem with food contamination of anaerobic bacteria?
the bacteria do not cause the problem directly. the bacteria release exotoxins which cause disease.
How are anaerobic bacteria cultured in liquid media?
1- add reducing agent
2- fill tube completely (so there is no air)
3- stopper tightly
4- incubate without shaking
How are anaerobic bacteria cultured on ager plates?
1- streak promptly 2- place in anaerobic culture jar 3- add a chemical system to ind oxygen 4- incubate open jar in anaerobic glovebox
Why is gas chromatography beneficial for anaerobic bacteria?
It allows for analysis of the organic acids being produced by the bacteria and thus specific identification of the bacteria
How are the toxigeic effects of anaerobic bacterial infections?
antitoxin and antibiotics
What are examples of anaerobic bacteria?
C. tetani and C. dificil
Do C. tetani and C. dificil have spores?
yes!
What is the pathogenesis of C. tetani?
1- Insertion beneath the skin
2- spores germinate
3- vegetative cellls release exotoxin
4- loss of central inhibitory activity on motor and autonomic neurons
What is the structure of the tetanus toxin?
2 subunits
What is the function of the large tetanus toxin subunit?
bind presynaptic motor nerons and opens a pore
What is the function of the small subunit?
cleaves synaptobrevin in inhibitory motor nerves of the central nervous system
What does C. difficile cause?
severe colitis
How is C. difficile acquired?
fecal-oral transmission. major problem in a hospital setting
What are two virulence factors of C. difficile?
Exotoxin A and Exotoxin B
What is the major toxin for C. difficile?
Toxin B
What is the mechanism of action of Exotoxin A?
it disrupts tight junctions and causes intestinal swelling and inflammation
What is the mechanism of action of Exotoxin B?
disrupts the cytockeleton by depolymerizing actin and kills the surrounding cells
What is diagnostic of C. dificile?
Pseudomembranes: patches of dead any dying cells that appear as plaques in the affected area
When a person is diagnosed with C. difficile what is the first action for treatment?
Withdraw their antibiotics
Which drugs are used to treat C. diff?
metronidazole and vancomycin
