Lecture 7 - Infectious Disease

Question 1

Bacteria

Answer 1

• prokaryotes (no nuclear membrane or membrane bound organelles)
• have cell/plasma membranes and cell walls
• staining differences due to differences in cell wall between bacteria = Gram stain
• body contains lots of normal flora ( slowly established in newborns)

Question 2

Chlamydiae / Rickettsias

Answer 2

• forms of bacteria that are obligate parasites (can only live/multiple in membrane bound cells).
  = infectious agents

Question 3

Fungi

Answer 3

• eukaryotes, but also have a cell wall
• can be hyphae (mold) or yeast
• produce spores
• Dimorphism = hyphae at room temp, yeast at body temp
• fungal infections predominantly in compromised immune systems

Question 4

Protozoan

Answer 4

• single-celled Eukaryotes
• commonly cause infections in developing countries
• Parasitic protozoans = entamoeba histolytica (causes gastroenteritis), trichonmonas vaginiolis (vaginitis), and malaria (endemic to tropical climates, attacks RBC).
• helminths = ascaris (round worm), flat worms (tapeworms), flukes

Question 5

Ascaris

Answer 5

• small intestinal roundworm; parasitic nematode worm
• most common helminth
• typically infects pigs

Question 6

Viruses

Answer 6

• acellular (neither prokaryote or eukaryote), obligate, intracellular organisms
• composed of nucleic acid genome surrounded by capsid
• sub microscopic but confluent (product aggregation) in a cell to form inclusions.
• can inhibit adaptive immunity
  Latency = viruses that aren’t replicating but can be turned on years later

Question 7

Capsid

Answer 7

protein coat/shell of virus that envelopes viral genetic material

Question 8

Prions

Answer 8

• “slow viruses”
• abnormal forms of host prion protein
• function of protein = unknown
• abnormal folding of proteins leads to propagation of the proteins in cells “infecting” them and causing damage
• extremely hard to disinfect though they don’t have DNA genome or capsid
• cause of transmissible spongiform encephalopathies: Creutz-Jacob disease (from BSE meat), Kuru, Bovine spongiform encephalopathy.

Question 9

Bacteriophages

Answer 9

• viruses that infect bacteria
• means for bacteria to share genetic information
• can confer additional characteristics on bacteria to promote human infection (susceptibility and resistance can be increased)

Question 10

Ectoparasties

Answer 10

• insects that attach to/live on the skin
• some can produce disease directly or be the vector of a disease
• ex: lice, bedbugs, fleas, mites, ticks (vector for lyme disease)

Question 11

Sepsis

Answer 11

• serious complication due to dissemination
• significant number of bacterial infections of the blood stream triggers chemical response that in turn leads to life-threatening inflammation cascade
• overpowers immune response

Question 12

Virulence

Answer 12

• ability of a microorganism to cause disease
• depends on strength of organism and state of host
• producing enzymes or having a capsule increases virulence
• the more virulent the more capable of causing disease