Micro 12/13

Question 1

describe the stages on the sepsis continuum

Answer 1

infection or trauma, SIRS, sepsis, septic shock, multi organ failure

Question 2

clinical signs of SIRS

Answer 2

“systemic inflammatory response syndrome”

high fever (or hypothermia), leukocytosis or leukopenia or bandemia, tachycardia, tachypnea

Question 3

how does SIRS become sepsis?

Answer 3

requires an infection

Question 4

progression of sepsis

Answer 4

w/ low BP it is severe sepsis, w/ persistent hypotension it is septic shock (need pressor drugs)

Question 5

what is MODS

Answer 5

multi organ dysfn sydnrome- SIRS + persistent hypotension causes lots of problems: clotting, organ failure, cognitive impairment, metabolite accumulation

Question 6

what are some microbial triggers of SIRS

Answer 6

lipid A component of LPS in G- outer membrane

lipoteichoic acid in G+ and peptidoglycan

bacterial toxins

Question 7

what are some bacteria associated w/ hospital sepsis

Answer 7

G+ cocci- staph, strep, enterococcus

G- rods- E coli, pseudomonas, acinetobacter, klebsiella

Question 8

describe pseudomonas aeruginosa

Answer 8

common in water and soil, forms blue green colonies, fruity smell w/ infected wounds

Question 9

p aeruginosa and CF

Answer 9

chronic lung mucoid colonization w/ overproduction of polysaccharide

they have LPS defects making them more sensitve to complement

Question 10

3 opportunistic G- rods that cause sepsis in hospitals

Answer 10

klebsiella pneumoniae, pseudomonas aeruginosa, acinetobacter baumannii

Question 11

describe acinetobacter baumannii

Answer 11

common in soil and water, coccobacilli or cocci, similar risk factors to pseudomonas

Question 12

aceinetobacter resistance

Answer 12

some are resistant to all known antibiotics

Question 13

describe klebsiella pneumoniae

4 characteristics

Answer 13

enterobacteriacea family, colonizers of the GI tract, collector of drug resistant plasmids, large capsule

Question 14

klebsiella resistance mechanism

Answer 14

have a klebsiella pneumoniae carbapenemase

Question 15

catalase neg bacteria

Answer 15

strep and enterococcus

Question 16

catalase pos bacteria

Answer 16

staph- either S. aureus or the coag neg S. epidermidis

Question 17

give examples of beta, alpha, and gamma hemolytic bacteria

Answer 17

all catalase positive
beta: Group A- S. pyogenes, Group B- S. agalactiae

alpha: S. pneumoniae and S. viridans
gamma: entero

Question 18

acute and sequelae effects of strep pyogenes

Answer 18

leading cause of pharyngitis and cellulitis, impetigo, strep toxic shock

sequelae: glomerulonephritis, rheumatic fever

Question 19

fn of S. pyogenes M protein

Answer 19

binds Ab and complement, antiphagocytic

Question 20

cause of rheumatic fever

Answer 20

molecular mimicry of M proteins- Abs attack host antigens that are similar and cause inflammation/ tissue damage to heart valves, joints, and basal ganglia (st vitus dance)

Question 21

IE etiology

Answer 21

G+ cocci, G- HACEK, candida, blood culture neg

Question 22

cases where staph aureus is even more likely to cause IE

Answer 22

in hospital, IV drug users, w/ diabetes

S. aureus is most common w/ native valves

Question 23

location of IE causing colonies

Answer 23

Staph and strep on skin, viridans strep in mouth, enterococci in GI

Question 24

compare strep viridans and staph aureus in IE

Answer 24

viridans are lower virulence, cause slow progression IE to previously damaged valves

aureus is higher virulence, affects normal valves, and has rapid onset of fever/sepsis

Question 25

purpose of pili/fimbriae

Answer 25

adhesion organelles, found in G- and G+

Question 26

staph aureus and complement

Answer 26

the microbes can bind C4BP regulatory protein and inactivate C4b

Question 27

capsules in GAS and staph aureus

Answer 27

hyaluronic acid in GAS and S aureus have polysaccharide

Question 28

fn of staph protein A

Answer 28

binds to Fc portion of Abs, inhibiting their interatction w/ complement and prevents phagocytosis

Question 29

manifestations of staph and strep superantigens

Answer 29

can cause cytokine storm

toxic shock syndrome and food poisoning from staph and scarlet fever from strep

Question 30

enterococci drug resistance

Answer 30

low affinity for beta lactams, resistant to clindamycin, can absorb folate from host (no Tmp-Smx), resistant to aminoglycosides at relevant doses, resistance to vanc is growing