Lecture 24 --Bacterial infections of skin/soft tissue

Question 1

infections of skin/soft tissues happen in these 2 ways:

Answer 1

1) access deeper skin layers via wounds, hair follicles, pores 2) use another point of entry and spread to skin

Question 2

infection of skin mostly ____ spp.

Answer 2

strep and staph

Question 3

gram + cocci in clusters, part of normal fora of skin/nasal, bacteria migrate down hair follicles into sebaceous glands, involve lots virulence factors

Answer 3

staphylococcus aureus

Question 4

typical clin. presentations of aureus infection?

Answer 4

folliculitis (small red bumps), furuncles (boils), carbuncles (merged furuncles)

Question 5

transmission aureus?

Answer 5

fomites, contact, resp drops

Question 6

prevention?

Answer 6

hand hygiene and chlorhexidine wash to decolonize patients

Question 7

treat aureus?

Answer 7

drainage of pus , antibiotics

Question 8

some strains of S aureus produce ___ toxin that destroys material holding epidermis to dermis, which leads to ____ syndrome in kids < __ yrs

Answer 8

exfoliatin ; scalded skin; 2

Question 9

s aureus cause these varieties of diseases:

Answer 9

endocarditis, bacteremia, pneumonia, osteomyelitis, toxic shock syndrome, GI (following primary staph infection at another site)

Question 10

leukocidin exotoxin usually ___ in CA and usually ___ in HA

Answer 10

present; absent

Question 11

population at high risk for CA?

Answer 11

children, homeless, athletes, soldiers, prisoners, drug users, adult ER patients

Question 12

bacteria which cause GI infection by using food or water as means to enter

Answer 12

enteric

Question 13

toxin consumed with food/water, rapid onset of symptoms

Answer 13

poison

Question 14

live bacteria consumed w/ food/water, slower onset symptoms

Answer 14

infection

Question 15

___ foods favour growth of s. aureus

Answer 15

high sugar/high salt

Question 16

whill heating foods to 100 degrees destroy toxin?

Answer 16

nooooo

Question 17

room temp storage allows growth of staph in food, releases ____ during growth

Answer 17

exotoxin (Enterotoxin A)

Question 18

E coli O157:H7 is _____ strain

Answer 18

enterohemorragic strain

Question 19

O means ___, H means __

Answer 19

type of LPS side chain; type of flagella antigen

Question 20

reservoir for e.coli

Answer 20

intestinal tract of cows

Question 21

pathogenesis of e.coli

Answer 21

attach to gut wall w/ pilli, then grow/multiply, secrete verotoxin when growing

Question 22

what does verotoxin do?

Answer 22

killl gut epithelial cells and damage lining of intestinal tract

Question 23

symptoms of e.coli?

Answer 23

nausea, cramping, bloody diarrhea

Question 24

diagnose e.coli from:

Answer 24

stool culture

Question 25

treatment of e.coli

Answer 25

fluid replacement

Question 26

not recommended for e.coli?

Answer 26

anti diarrhea or antibiotics

Question 27

possible complications of e.coli?

Answer 27

hemolytic uremic syndrome–>kidney damage

Question 28

what makes O157 pathogenic?

Answer 28

extra 200 genes that encode virulence factors

Question 29

water borne transmission, causative agent of cholera, gram neg. curved rod transmit fecal-oral (need large amounts to have disease)

Answer 29

vibrio cholerae

Question 30

___ stims enzyme in gut epithelial cells that convert ATP to cyclic AMP–>this cause hypersecretion of fluids/ions from gut into intestinal lumen, resulting in ____

Answer 30

cholera toxin; severe diarrhea, dehydration

Question 31

what is rice water stool?

Answer 31

mix of mucus, water, and live vibrio

Question 32

treatment cholera?

Answer 32

oral rehydration therapy

Question 33

periodic outbreaks of cholera cuz?

Answer 33

natural disaster, war, famine

Question 34

how prevent cholera?

Answer 34

Dukoral vaccine (60-80% protection for 2 years, killed whole vibrio cells and inactivated toxin), purify drinking water, avoid raw foods washed in contaminated water

Question 35

natural reservoir for vibrio?

Answer 35

maybe marine plankton

Question 36

most common virulence factor in GI infections

Answer 36

exotoxins

Question 37

stomach ulcers by ____ spp., gram neg. and motile rod

Answer 37

helicobacter pylori

Question 38

pathogenesis of helicobacter:

Answer 38

in mucus layer of GI, produce urease (allow H pylori survive by neutralize stomach acid), penetrate mucus and attach to epithelial cells of stomach, cause inflammation, destruction from exotoxins–>ulcers cuz expose stomach lining to acids

Question 39

how diagnosis helicobacter prob?

Answer 39

invasive: endoscopic biopsy of gastric mucosa–>culture; non-invasive: urea breath test

Question 40

what is urea breath test?

Answer 40

ingest urea labelled w/ carbon isotope, urea convert to CO2 and ammonia by H pylori urease, detect labelled CO2

Question 41

old ulcer therapy was ____, now is ___

Answer 41

bland diet and reduce stomach acid; antibiotics and acid suppressing drugs (eliminates bacteria so no recurrence)

Question 42

helicobacter pylori is example of ____

Answer 42

ancestral flora (human adapted microbe!)

Question 43

H pylori might protect against

Answer 43

asthma and allergy