EXAM 4 P4

Question 1

LD50

Answer 1

lethal dose 50
measure of virulence
is the number of pathogen cells required to kill 50% of infected organisms
is dependent on the pathogen species and strain, and the host species, age, sex, physical condition, and how it’s introduced

Question 2

streptococcus pneumoniae

Answer 2

highly virulent organism

Question 3

salmonella typhimurium

Answer 3

moderately virulent organism

Question 4

virulence factors

Answer 4

produced by the pathogen to increase its ability to cause disease

Question 5

capsule

Answer 5

extracellular polysaccharide that helps with adherence and invasion
inhibits phagocytosis by innate immune response

Question 6

fimbriae

Answer 6

help with adherence

Question 7

siderophores

Answer 7

help with iron activation

Question 8

toxins

Answer 8

either a protein or non-protein
only non-protein toxin is endotoxin
protein toxins include exotoxins and enterotoxins

Question 9

hemolysin

Answer 9

exotoxin (cytotoxin)
has the ability to lyse red blood cells
blackening reaction with the release of iron
cells can often lyse other host cells, causing tissue damage and disruption of blood flow, making it more hospitable for growth
some form pores in the mem

Question 10

lipase

Answer 10

exotoxin (cytotoxin)
breaks down lipids
if enough lipids are cleaved, the cell may break open

Question 11

neurotoxins

Answer 11

exotoxin (cytotoxin)

released by a pathogen that has side effects on neurons in the host body.

Question 12

C. botulinum toxin

Answer 12

blocks nerve stimulation of muscle contraction
botulism
extremely potent and deadly
first symptom is not being able to contract the muscles. they become flaccid, even the diaphragm, making you unable to breath.

Question 13

medical use of C. botulinum toxin

Answer 13

Botox injections

Question 14

C. tetani toxin

Answer 14

causes constant nerve stimulation of muscle contraction
tetanus (lockjaw)
all muscles start contracting and can’t move, so you’re unable to open your mouth
will essentially curl up in the fetal position
diaphragm contracts and kills you

Question 15

cholera toxin “AB-form toxin”

Answer 15

enterotoxin
causes extreme diarrhea where you essentially die of dehydration
in a normal body, the lumen is lined by epithelial cells where nutrients are passed through to the blood. they pick up sodium irons and transport them to the blood.
with cholera toxin, it binds to these cells and part of it enters the host cell, functioning as an adenylate cyclase (takes ATP and converts it). water follows and in the intestines you suddenly have water, aka DIARRHEA.

Question 16

what does AB-form toxin mean

Answer 16

it’s made of 2 proteins
the B protein binds to the host cell surface
the A protein enters the host cell and affects metabolism

Question 17

endotoxin

Answer 17

LPS in the gram negative outer membrane
it’s not intentionally produced to make the host sick. it’s just part of the cell
LPS is one of the things the immune system recognizes as infection.
it can cause fever, diarrhea, and inflammation

Question 18

characteristics of exotoxins

Answer 18

are excreted
have specific binding and effects on the cell
highly toxic, sometimes fatal
highly immunogenic; stimulate production of antitoxin
does not produce fever

Question 19

characteristics of endotoxins

Answer 19

LPS released on cell lysis
general effects (fever, diarrhea, vomiting)
weakly toxic, rarely fatal
poor immunogen; immune response not sufficient to neutralize toxin
no toxoid potential
pyrogenic; often induces fever in the host

Question 20

streptococcus

Answer 20

gram positive cocci in chains
common member of normal flora of the upper res tract
pathogenic strains produce capsules

Question 21

infections related to streptococcus

Answer 21

pharyngitis (strep throat)
otitis media (ear infection)
mastitis (mammary glands)
impetigo (sores common in small children)
erysipelas (very red skin)

Question 22

scarlet fever

Answer 22

redness over a wide area of the body
rarely, particularly virulent strains cause necrotizing fasciitis (flesh eating bacteria) that breaks down tissue
you lose blood flow and oxidation of the tissue, leading to skin grafts or amputation

Question 23

rheumatic fever

Answer 23

autoimmune reaction against heart valves due to similar antigens
shows up months after the initial infection
produce some protein similar to one in the heart valve, confusing recognition

Question 24

Neisseria meningitidis (B)

Answer 24

gram negative diplococci
bacteremia is invasion of the bloodstream. toxins cause coagulation and interrupted blood flow to extremities
tissue starts to die (necrosis)
often causes amputation of the limbs. once it’s dead it can’t be saved

Question 25

Neisseria meningitidis (M)

Answer 25

meningitis is the inflammation of the membranes around the central nervous system
caused by a variety of bacteria and viruses.
can get into the spinal cord and brainstem, leading to death
progresses rapidly with 10% death even with treatment
common in college student populations

Question 26

borrelia burgdorferi

Answer 26

gram negative spirochete
grows in many wild animal mammals (mice and deer) without clear disease
transferred from reservoir wild animals to humans by deer ticks. ticks must be on humans for over 24 hours to pass the bacteria.
Lyme disease

Question 27

Lyme disease

Answer 27

common in the northeast and upper mid-west
increasing incidence in the past 20 years
variety of factors contribute to this: increased deer populations, increased reporting, and increased human/tick contact
lone star tick

Question 28

progression of being bit by the lone star tick

Answer 28

no toxins, just inflammation (endotoxin).
initial symptom is erythema migrans (rash) spread form bite over several days.
headaches, chills, and fatigue are common. treated with antibiotics
if left untreated, chronic symptoms can progress
arthritis as bacteria invades the joints
invasion of the neural system (palsy, facial tics, weakness)
chronic symptoms are dye to residual peptidoglycan since BB has novel pg. structure.