Pathogens

Question 1

four main classes of microbes that cause disease in humans

Answer 1

1. bacteria 2, viruses 3, fungi 4. parasites (worms/protozoa)

Question 2

bacterial structure

Answer 2

prokaryote (think peptidoglycan walls, single chromosomes, and 70S ribosomes). can be rod, round, or spiral shaped. staining is gram positive (purple, NO LPS outer membrane), gram negative (pink, has LPS outer membrane - therefore staining does not detect the peptioglycan component of the cell membrane), or in rare cases no stain (TB, spirochetes)

Question 3

bacterial virulence factors: endotoxins

Answer 3

endotoxins (i.e. LPS outer membrane found in gram negative bacteria) - cause an inflammatory response. release of the endotoxin occurs when the bacteria dies. the endotoxin can signal to DNA and cause leaky blood vessels. endotoxin can stimulate macrophages to release IL1a and TNF (vasodilation, blah, blah, sepsis)

Question 4

bacterial virulence factors: capsules

Answer 4

found in gram positive cocci and consist of polysaccharide polymers. many are anti-phagocytic. can be effectively overridden by an active adaptive immune response (example of encapsulated bacteria - pneumonia)

Question 5

bacterial virulence factors: exotoxins

Answer 5

highly variable toxic secretion that often leads to the destruction of a barrier to infection

Question 6

pathogens whose virulence is dependent on toxin production

Answer 6

tetanus (wound based), cholera, diptheria (causes destruction of the epithelial cells in throat which leads to the creation of a graveyard of cells called the psuedomembrane)

Question 7

why the humoral (antibody) response is particularly necessary when dealing with virulent bacteria

Answer 7

needed to 1. target complement lytic components, 2. neutralize exotoxins 3. can enhance the phagocytosis of encapsulated bacteria

Question 8

4 fates of a cell infected by a virus

Answer 8

1. transformation (cancer) 2. lytic 3. latent/proviral 4. chronic/persistent

Question 9

immune response to viral cells

Answer 9

the humoral response is key in “mounting an extremely specific and efficient cell killing process to eliminate virally infected cells (via the CD8 T cell population)

Question 10

fungi structure

Answer 10

eukaryotes with mannans (mannoprotiens - important for recognition via Toll Like Receptors and mannose binding lectin, a scavenger receptor). fungi comes in two forms - yeast (single celled, budding) and moulds (complex filamentous forms). most fungi grow extracellularly within a host

Question 11

what is a dimorphic fungi

Answer 11

a fungi that can alternate between being a mould and a yeast. the change can be determined by temperature, and a major habitat of dimorphic fungi is soil (can exist as a mould in soil and then transition to a yeast in humans based on the local increase in temperature)

Question 12

candida

Answer 12

yeast, part of our normal microbial flora, opportunistic pathogens (when 1. antibiotic treatment reduces inhabiting bacteria, 2. cancer therapy reduces neutrophil count, 3. advanced AIDS, 4. specific immunodeficiency syndromes)

Question 13

yeast

Answer 13

can also have polysaccharide capsules to prevent phagocytosis from neutrophils and macrophages

Question 14

parasites

Answer 14

single celled protozoa and multicellular worms. complex life cycles that exist is more than one form when infecting humans

Question 15

single celled parasites

Answer 15

4 categories - amebas, ciliates, sporozoans, and flagellates (ex. malaria - 5 stages, matures in liver or RBC)

Question 16

multicellular parasites

Answer 16

helminths - invasive phases migrate through vertebrae hosts . complex life cycles that involve >1 host