Common Bacterial Pathogens

Question 1

Staph. aureus: gram stain, carrier location, catalase?

Answer 1

gram positive cocci in clusters; carried in anterior nares and perineum; catalase positive

Question 2

Staph. epidermidis: gram stain, carrier location, catalase?

Answer 2

gram positive cocci in chains or pairs; normal skin flora; catalase negative

Question 3

Strep. pyogenes: gram stain, carrier location, catalase?

Answer 3

gram positive cocci in chains or pairs; strep throat; catalase negative

Question 4

Strep. pneumoniae: gram stain, carrier location, catalase?

Answer 4

gram positive diplococci; normal UR flora; catalase negative

Question 5

Staph. aureus pathogenicity?

Answer 5

pathogenic; cutaneous infections (folliculitis, boils, wound infections); foreign bodies and splinters; TSS; pneumonia; bacteremia/endocarditis

Question 6

How does Staph. aureus persist in cutaneous infections? What is the treatment?

Answer 6

formation of a fibrinous capsule; drainage of the abscess

Question 7

____ is an essential virulence factor that is assoc. with the formation of the fibrin capsule.

Answer 7

Coagulase

Question 8

What is the major cytotoxic agent released by Staph. aureus?

Answer 8

Alpha-toxin

Question 9

How does Alpha-toxin work?

Answer 9

it forms a beta-barrel pore

Question 10

Why does Staph. aureus like foreign bodies?

Answer 10

they provide a surface for colonization and interferes w/ phagocytosis

Question 11

What is a superantigen toxin?

Answer 11

antigens that cause non-specific activation of T-cells, leading to massive cytokine release

Question 12

Superantigens can cause up to _____ of all T-cells to become activated, as compared to a normal antigen-induced T-cell response of _____.

Answer 12

25%; .0001-.001%

Question 13

Name 3 staph toxin mediated diseases.

Answer 13

1. TSS
2. staph food poisoning
3. scalded skin syndrome

Question 14

What are the s/s of TSS?

Answer 14

high fever, low BP, malaise, confusion, rash resembling a sunburn

Question 15

What can TSS lead to?

Answer 15

stupor, coma, multiple organ failure

Question 16

What is the causative factor of TSS?

Answer 16

local Staph. aureus infection that produces toxin that circulates

Question 17

What does the TSS rash look like, and what happens with it?

Answer 17

a sunburn over any part of the body, including lips, mouth, soles, and palms; it desquamates (peels off) after 10-14 days

Question 18

What is Staph. food poisoning?

Answer 18

ingestion of preformed toxin in contaminated/improperly stored food

Question 19

Staph. aureus pneumonia is common in _____.

Answer 19

health care acquired settings

Question 20

What is the mortality of Staph. aureus pneumonia?

Answer 20

about 50%

Question 21

Name one of the most common pathogens causing endocarditis/bacteremia.

Answer 21

Staph. aureus

Question 22

What drugs can Staph. aureus be resistant to?

Answer 22

penicillin, methicillin, and vancomycin

Question 23

What is an SSNA?

Answer 23

staph species, not aureus

Question 24

Where do Staph. epidermidis normally live?

Answer 24

skin

Question 25

Staph. epidermidis is usually a ____ infection involving _____.

Answer 25

localized; foreign body

Question 26

What organism is assoc. with slime production?

Answer 26

Staph. epidermidis

Question 27

What is the slime of Staph. epidermidis?

Answer 27

an extracellular glycocalyx allowing for adhesion and protective biofilm

Question 28

What is Staph. epidermidis resistant to?

Answer 28

methicillin

Question 29

Why is Staph. epidermidis hard to treat?

Answer 29

the biofilm is hard to penetrate and it's resistant to methicillin

Question 30

What diseases does Strep. pyogenes cause?

Answer 30

pharyngitis/strep throat, skin and wound infections

Question 31

Name 2 post-streptococcal diseases.

Answer 31

1. glomerulonephritis | 2. Rheumatic fever

Question 32

What is glomerulonephritis?

Answer 32

type 3 immunopathology: strep antigen-antibody complexes deposited in the kidney and accumulate in the BM

Question 33

What is Rheumatic Fever?

Answer 33

autoimmune inflammatory disease; antigens cross react to myocardium and heart valves--NOT a colonization of bacteria

Question 34

What is unique about Group A Strep skin infections?

Answer 34

they spread

Question 35

What is the primary virulence factor in Strep. pyogenes?

Answer 35

M-protein

Question 36

What is M-protein?

Answer 36

a surface protein on Strep. pyogenes that inhibits phagocytosis, kills PMNs, and enhances adherence to epi

Question 37

What protects against M-protein?

Answer 37

antibodies

Question 38

Where is Strep. pyogenes normally found?

Answer 38

in the pharynx

Question 39

How does Strep. pneumoniae evade host defenses?

Answer 39

it has an antiphagocytic polysaccharide capsule

Question 40

What is PPSV23?

Answer 40

pneumovax; protects against invasive Strep. pneumoniae

Question 41

What diseases are invasive Strep. pneumoniae?

Answer 41

meningitis, bacteremia/septicemia, pneumonia

Question 42

What diseases are noninvasive Strep. pneumoniae?

Answer 42

pneumonia, sinusitis, otitis media, bronchitis

Question 43

What are the predisposing factors for Strep. pneumoniae?

Answer 43

young or old age, alcoholism, respiratory viral infections

Question 44

Why is alcoholism a predisposing factor for Strep. pneumoniae?

Answer 44

it negatively affects the mucocilliary escalator

Question 45

What is Prevnar?

Answer 45

the children's pneumonia vaccine

Question 46

What is Strep. pneumoniae resistant to?

Answer 46

penicillin

Question 47

What does Viridans streptococci cause?

Answer 47

infective endocarditis and dental caries

Question 48

Viridans streptococci are either ____ and turn green on blood agar plates, or are _____ and do not.

Answer 48

alpha-hemolytic; nonhemolytic

Question 49

Where is Viridans streptococci normally found?

Answer 49

in the mouth

Question 50

What does Viridans streptococci produce that allows it to adhere to teeth and heart valves?

Answer 50

dextrans

Question 51

What do dextrans allow Viridans streptococci to do?

Answer 51

adhere to teeth and fibrin/platelets in damaged heart valves

Question 52

What do Enterococcus faecalis/faecium cause?

Answer 52

UTIs, infections of surgical wounds, biliary tract infections, endocarditis

Question 53

Where is Enterococcus faecalis/faecium normally found?

Answer 53

GI flora

Question 54

What is Enterococcus faecalis/faecium resistant to?

Answer 54

vancomycin

Question 55

What is a hospital-acquired infection called?

Answer 55

nosocomial infection

Question 56

What is a nosocomial infection?

Answer 56

a hospital-acquired infection

Question 57

The most common ____ in human disease are members of the genus Clostridium.

Answer 57

gram + rods

Question 58

The most common gram + rods in human disease are members of the genus ____.

Answer 58

Clostridium

Question 59

Clostridum are strict ____ and form ____, which are extremely resilient.

Answer 59

anaerobes; endospores

Question 60

What diseases does Clostridium difficile cause?

Answer 60

hospital-acquired diarrhea and pseudomembranous colitis

Question 61

What diseases does Clostridium tetani cause?

Answer 61

tetanus

Question 62

What diseases does Clostridium botulinum cause?

Answer 62

botulism

Question 63

What diseases does Clostridium perfringens cause?

Answer 63

gangrene and other tissue infections

Question 64

What kind of toxin does C. diff produce?

Answer 64

an entertoxin and a cytotoxin

Question 65

How is C. diff diagnosed?

Answer 65

ELISA or PCR of stool sample

Question 66

Name 2 gram negative rods.

Answer 66

1. E. coli | 2. Pseudomonas aeruginosa

Question 67

Name a gram negative cocci.

Answer 67

Neisseria gonorrhoeae

Question 68

What bacteria family lack cell walls?

Answer 68

Mycoplasma and ureaplasma