Module 16 Flashcards
What are the different virulence factors that bacteria use to cause infection?
Fimbriae and pilli
Flagella
Secretion of toxins and enzymes
Invasion (think TB)
Hair-like structures that project from the surface of bacterial cells.
Fimbriae and pilli
Allow bacteria to attach to certain sites in out body so they are not washed away.
Fimbriae/pilli
Describe how E. coli use virulence factors to cause infection.
Use fimbriae/pilli to attach to the urogenital tract to cause bladder infections
Virulence factor that bacteria use to swim in aqueous environments to a site where they may survive or cause infection.
Flagellum
Describe how toxins not produced by bacteria inside the body can cause toxic reactions.
In the case of food poisoning, toxins are left in food and, when ingested, cause toxic effects
How can bacterial enzymes work as virulence factors?
Can inactivate antibodies, breakdown tissues, etc.
Give examples of bacteria that use invasion as a virulence factor.
Salmonella - invade intestinal cells and cause diarrhea
TB - invade the lungs and hide inside our cells
Describe the major difference between gram positive and negative bacteria, and what colour each stains.
Gram positive - large peptidoglycan layer - stains purple
Gram negative - small peptidoglycan layer - stains pink
Differentiate gram negative and positive bacteria based on the following: Peptidoglycan/cell wall Major surface antigen Outer membrane Porins
Gram positive
- thick peptidoglycan layer (cell wall)
- Techoic acids are the major surface antigen - provide rigidity to cell wall
- No outer membrane
- No porins (few exceptions)
Gram negative
- thin peptidoglycan layer (cell wall)
- major surface antigen is LPS (structural component of outer membrane)
- outer membrane present
- has porins on outer surface - allow sugars, ions, and amino acids to enter
What are the typical signs of infection?
What groups may not show these? Why?
Typical signs of infection - local redness, fever, overall malaise, swelling
Newborns have poorly developed hypothalami, and the elderly may have decreased hypothalamic activity, and thus do not generate appreciable fever
Therapy is able to destroy the target without harming the host.
Selective toxicity
The major difference between mammalian cells and prokaryotic cells.
Mammalian cells do not have cell walls
What are the ways in which antibiotic therapy produces selective toxicity?
Disrupting the bacterial cell wall
Targeting bacterial enzymes (unique)
Disrupting bacterial protein synthesis (bacterial ribosomes are different than eukaryotic ones)
Ideally, bacteria are ________ prior to selection of the treatment.
identified
In general, ______ the bacteria to properly identify it will provide the best basis for selection of therapy.
culturing
In what cases would cultures not be able to be done?
Child ear infection - hard to obtain culture
LRT infections - too many bacteria to culture
Describe a bacteriostatic antibiotic.
Stops the growth and replication of bacteria
The immune system than attacks and remove the bacteria
Describe a bartericidal antibiotic.
Kill the bacteria
MIC
MBC
Minimum inhibitory concentration
Minimum bactericidal concentration