test 4 notes

I. Clostridium botulinum—botulism
a. Strict anaerobes
b. Spore forming
i. Spores: very durable, suspended-animation state of bacteria
c. Reservoir=soil so almost certainly botulism toxin for improving bacterial survival in soil not for killing people
d. C. botulinum: Reservoir= soil
i. Since reservoir is soil, almost certainly botulism toxin for improving bacterial survival in soil, not for killing people
e. Botulism toxin—actively growing C. botulinum express this
i. Deadly dose: 1ng/kg weight of person—most toxic chemical known
ii. Death from suffocation: botox disables motor neurons, including those that control diphragm
1. Can’t breathe
f. Botulism and normal flora—anaerobic environment created by canning food from home→ germination of C. botulinum spores→expression of botox genes→lots of botox in jar (then person
g. Infant botulism and normal flora—human gut is non-sterile, anaerobic
i. C. botulinum spores in soil elsewhere
ii. Gut is a good pace for C. botulinum to grow—except that in healthy adult, normal flora fills spots for C. botulinum to grow
iii. Infants, very little normal flora to displace C. botulinum bacteria (floppy baby syndrome)
II. Vibrio cholerae: gram negative rod that can live in salt or freshwater
a. Sensitive to acids
i. Humans must ingest 10E9 at once to get sick
b. Cholera symptoms: loss of up to 2 gallons/day
i. Watery diarrhea
c. Produce cholera toxin when growing
i. Cholera toxin makes epithelial cells pump NaCl out, because of osmosis, water follow
III. Cystic fibrosis
a. Super sticky mucus in lungs because they cant ship NaCl out of epithelial cells
b. Heterozygote advantage
i. If you have 1 cystic fibrosis allele, 1 normal allele, protected against cholera, and don’t have CF
IV. Copepods—arthropods that travel from salt→fresh water
a. Reservoir for cholera
b. Cholera= necessary normal flora for copepods—copepods would die without cholera
V. S. pyogenes: Gram positive streptococci→ “Strep throat”
a. Used to cause scarlet fever
VI. Ewalds hypothesis
a. Over time, pathogens evolve towards reduced virulence in reservoir host, over time, pathogens→necessary normal flora