STEP 1 Gram Positive Bacteria 3

Question 1

Streptococcus agalactiae (GBS)
gram, shape, catalase, coagulase, *hemolysis, resistance (differs from GAS)

Answer 1

Gram positive cocci
Catalase and coagulase negative
B-hemolysis
Bacitracin resistant

Question 2

GBS colonizes (1)

Answer 2

GBS colonizes vagina

Question 3

GBS diseases (3)? Which population primarily (think of its colonization location)?

Answer 3

Pneumonia, meningitis, and sepsis

Mainly in babies

Question 4

GBS and pregnancy…screening and prophylaxis

Answer 4

Screen pregnant women at 35-37 weeks.

+ culture patients receive intrapartum PCN prophylaxis

Question 5

Two main Enterococci bacteria

Answer 5

Enterococcus faecalis

Enterococcus faecium

Question 6

Enterococci (group D strep) features

1. location
2. resistance
3. infection causes (3)

Answer 6

1. Normal colonic flora
2. Penicillin G resistant
3. Cause UTI, biliary tract infections, and subacute endocarditis

Question 7

Streptococcus bovis (non-enterococcus strep):

1. Colonizing location
2. Causes which infections (2) in which patient population (1)

Answer 7

1. Colonizes the gut

2. Causes bacteremia and subacute endocarditis in colon cancer patients

Question 8

Enterococcus algorithm findings:
Gram and shape
hemolysis
growth in which medium (2)

Answer 8

Gram + cocci
Catalase -
Gamma hemolysis
Growth in bile and 6.5% NaCl

Question 9

Non-enterococcus algorithm findings:
gram stain and shape
catalase
hemolysis
growth medium (compare to entercoccus)

Answer 9

Gram + cocci
Catalase -
Gamma hemolysis
Growth in bile, NOT in NaCl

Question 10

Corynebacterium diphtheriae algorithm findings

Answer 10

Gram + BACILLI (ROD)

Question 11

C. diphtheriae causes diphtheria via _____ encoded by _____

Answer 11

Causes diptheria via EXOTOXIN encoded by B-prophage

Question 12

C. diphtheriae exotoxin inhibits ______ via _____ of _____

Answer 12

Inhibits PROTEIN SYNTHESIS via ADP-ribophosphorylation of EF-2

Question 13

Symptoms of diphtheria (4)

Answer 13

1. PSEUDOMEMBRANOUS PHARYNGITIS (gray-white plaques/membrane)
2. lymphadenopathy
3. myocarditis
4. arrhythmias

Question 14

Lab diagnosis of diphtheria (3)

Answer 14

1. Algorithm findings
2. Elek test for toxin
3. Grows black colonies on cystine-tellurite

Question 15

What kind of vaccine is the diphtheria vaccine?

Answer 15

Toxoid vaccine

Question 16

ABCDEFG of diphtheria

Answer 16

ADP-ribophosphorylation
B-prophage
Corynebacterium
Diphtheriae
Elongation Factor 2
Granules

Question 17

Spore-forming gram + bacteria found in soil (3)

Other spore formers (3)

Answer 17

Bacillus anthracis
Clostridium perfringens
C. tetani

B. cereus
C. botulinum
Coxiella burnetii

Question 18

Lab algorithm findings of clostridia

Answer 18

Gram +
Spore-forming
Obligate anaerobic Bacilli

Question 19

C. tetani produces ______, an exotoxin causing _____

Answer 19

C tetani causes TETANOSPASMIN, an exotoxin causing tetanu

Question 20

How do the tetanus and botulinum toxins cause damage?

Answer 20

Both toxins are proteases that cleave releasing proteins for neurotransmitters

Question 21

Which neurotransmitters does tetanus block? Which cells do the NTs come from?

Answer 21

GABA and glycine (both are inhibitory NTs)

Renshaw cells in spinal cord

Question 22

Symptoms of tetanus (3)

Answer 22

Spastic paralysis
trismus (lockjaw)
risus sardonicus (grinning expression causes by spams of facial muscles)

Question 23

How does C. botulinum cause damage?

Answer 23

Produces a preformed, heat-labile toxin that inhibits ACh release at the NMJ causing botulism

Question 24

How do adults acquire botulism? Babies? which food is associated with babies and botulism

Answer 24

In adults, the disease is caused by ingestion of preformed TOXIN.
In babies, ingestion of SPORES in HONEY causes disease (floppy baby syndrome)

Question 25

How does C. perfringens cause damage? Produces which toxin? symptoms (2)

Answer 25

Produces ALPHA toxin that causes MYCONECROSIS and HEMOLYSIS

Question 26

What is the pathogenesis of the two C. diff toxins?

Answer 26

Toxin A, ENTEROTOXIN, binds to the brush border of the gut

Toxin B, CYTOTOXIN, causes cytoskeletal disruption via actin depolymerization–> pseudomembranous colitis –> diarrhea

Question 27

Use of which antibiotics (2) is associated with C. diff diarrhea?

Answer 27

Ampicillin and clindamycin

Question 28

How is C. diff detected?

Answer 28

Look for the toxins

Question 29

Treatment for C. diff (2)

Answer 29

Metronidazole or oral vancomycin

Question 30

Clostridium perfringens:

Name of the produced toxin? What is the cellular mechanism of this toxin

Answer 30

Produces ALPHA toxin (“lecithinase”)

It’s a phospholipase that cleaves the phospholipid bilayer of cells