Host damage, Opportunistic and Nosocomial Infec (Gram - aerobes)

Question 1

membrane active exotoxins

Answer 1

• S. aureus hemolysin (pore former, lyses rbc)
• alpha toxin (C. perfiringens)
• listeriolysin (destroyed phagocyte membrane)

Question 2

MOA of botulinum/tetanus neurotoxins

Answer 2

protease

Question 3

MOA of shiga/shiga-like toxins

Answer 3

endonuclease

Question 4

MOA of cholera, pertussis, diptheria toxins

Answer 4

ADP-ribosyltransferase

Question 5

MOA of c. diff toxins A/B

Answer 5

glucosyltransferase

Question 6

staph features allowing long survival

Answer 6

desiccation tolerant
heat tolerant
high salt tolerant

Question 7

inhibitors of phagocytosis

Answer 7

• protein A
• polysaccharide capsule
• coagulase

Question 8

S. epidermidis Adhesins

Answer 8

fimbriae (pili)
AtlE
capsular polysaccharide

Question 9

tx for S. saphrophyticus UTI

Answer 9

same as other UTIs (Tmp-SMX)

Question 10

lancefield is based on

Answer 10

cell wall carbohydrate antigens

Question 11

erysipelas

Answer 11

infection of upper levels of dermis

red rash, slighty swollen with well-defined borders, warm and tender to touch

seen in GAS (pyogenes)

Question 12

GAS strep symptomatology can mimic

Answer 12

EBV or CMV

Question 13

major GAS virulence factor

Answer 13

M factor

• attachment
• resists phagocytosis
• resists complement

Question 14

GAS exotoxins in nec fasc

Answer 14

streptomycin O/S (beta-hemolysis)
streptokinase (activates plasminogen)
DNAse B

Question 15

strep bovis is common in bowel flora, but when in bloodstream correlates ~50% with

Answer 15

colon cancer

Question 16

subacute endocarditis

Answer 16

viridians

Question 17

encounter - pneumococcus

Answer 17

aerosols, mucus exchange, fomites?

Question 18

virulence fx pneumococcus

Answer 18

IgA protease
phosphoryl choline
pneumolycin (pre-forming toxin)
polysaccharide capsule

Question 19

pneumococcal vaccine

Answer 19

children/elderly –> conjugated vaccine (promotes T cell response)

or

non-conjugated (splenectomy pts, preexisting lung cond.)

Question 20

superantigen MOA

Answer 20

Superantigens couple the T cell receptor to MHC class II molecules on macrophages without a specific ligand in the T cell receptor.

This inappropriate coupling leads to a massive pro-inflammatory responses, due to elevated levels of TNFα, IFN-γ, etc and results in toxic shock.

Question 21

opportunistic infections

Answer 21

organisms multiply/spread when immune system is compromised

*pseudomonas aeroginosa is prototypic opportunistic pathogen

Question 22

pseudomonas pathogenicity factors

Answer 22

• pili/adhesions
• LPS, capsule, biofilm
• LPS, toxins, motility, chemotaxis
• sigma factors, two-component regulatory systems, quorum sensing

Question 23

pseudomonas colonies

Answer 23

mucoid
blue-green
fruity

Question 24

pseudomonas tx

Answer 24

b-lactams, fluroquinolones, aminoglycosides

Question 25

K. oxytoca

Answer 25

neonatal bacteremia

Question 26

EtOH, DM, chronic lung disease

Answer 26

susceptible to klebsiella

Question 27

currant jelly

Answer 27

klebsiella pneumoniae

Question 28

klebsiella pneumoniae resistance

Answer 28

ESBL

carbapenem resistant strains