Lecture 1 Flashcards
What is an infection?
Invasion of the body by a microbe (i.e., bacterium, virus, fungus, or parasite) that causes damage either directly or indirectly.
What are the six steps of the infectious disease process?
1.encounter; 2.entry; 3.colonization and/or invasion; 4.multiplication and/or spread; 5.damage; 6.outcome
Describe nonspecific adherence.
Involves nonspecific attractive forces which allow approach of the bacterium to the eukaryotic cell surface
Is nonspecific adherence a reversible attachment?
Yes
Is specific adherence a reversible attachment?
No
What are the three ways that bacteria “take-up” nutrients?
1.carrier-mediated diffusion (facilitated); 2.phosphorylation-linked transport (group translocation); 3.active transport (energy dependent)
To invade pathogens must have specific ________ factors that allow them to invade the host. These are generally referred to as what?
Virulence; invasins
Spread of microbes can occur through what two mechanisms?
Lateral propagation to contiguous tissues (multiply then spread) and dissemination to distant sites (spread then multiply)
What are the two types of toxins?
Exotoxins and endotoxins
Is exotoxin or endotoxin a part of the cell wall?
Exotoxin; the term is generally reserved for lipopolysaccharide
What do cytotoxins do?
Lyse cells
What do enterotoxins do?
Affect intestinal cells
What do neurotoxins do?
Affect neurons
What are the four factors that make a microbe a pathogen?
Ability to adhere to a host; ability to colonize a host; ability to replicate within a given niche; ability to cause damage
Describe a strict aerobe.
Must have oxygen to grow
Describe an obligate anaerobe.
Cannot tolerate oxygen
Describe a facultative anaerobe.
Can grow with or without oxygen (most medically important bacteria)
Describe oligotrophs.
Can grow with limited nutrients
Describe a microaerophile.
Require some oxygen but lower levels of oxygen
Describe a mesophile.
Grow well in mild temperatures (15-45 degrees celsius)
Gram positive bacteria stain what color?
Purple
Gram negative bacteria stain what color?
Red/pink
In gram-positive murine the terminal D-ala of the crosslinking chain will bind with what?
Glycine
In gram-negative murine the terminal D-ala of the crosslinking chain will bind with what?
DAP = diaminopimelic acid
