Micro 5 - Other Gram Positive Bacteria

Question 1

What type of bacteria is Corynebacterium diptheriae?

Answer 1

G(+) rod.

Question 2

What is the mechanism of the Diphtheria toxin?

Answer 2

ADP ribosylator of EF-2 (elongation factor).

Question 3

Which bacterial toxin have a similar toxin that inactivates EF-2?

Answer 3

Diphtheria toxin and Exotoxin A (pseudomonas).

Question 4

What does Diphtheria toxin target?

Answer 4

Damages nerve cells and heart cells. Causes pseudomembranouse pharyngitis (if scraped, bleeds profusely): spreads to respiratory system, causing the “bull neck” diphtheria.

Question 5

How is diagnosis of Diphtheria made?

Answer 5

Growth of G(+) rods on culture and proof of toxin production.

Question 6

What is the treatment for Diphtheria?

Answer 6

Antibiotic (Erythromycin, penicillin) to kill the bacteria and antitoxin to inactive the toxin. And vaccine because natural infection does not induce immunity.

Question 7

Which G(+) rods produces spores? Which G(-) produces spores?

Answer 7

Bacillus spp. And Clostridium spp. Coxiella burnetii is the G(-) that produces spores and causes Q fever.

Question 8

What is the mechanism of tetanospasmin (tetanus toxin)?

Answer 8

Blocks release of inhibitory neurotransmitters, increasing firing of motor neurons. Causes trismus (lockjaw).

Question 9

What is the mechanism of action of botulinum toxin?

Answer 9

Produces heat labile toxin that inhibits ACh at NMJ. Causes flaccid paralysis. Honey may contain spores.

Question 10

What is the mechanism of alpha toxin produced by Clostridium perfringens?

Answer 10

Alpha toxin is a phospholipase that causes gas gangrene and myonecrosis.

Question 11

What does Clostridium difficile cause?

Answer 11

Pseudomembranous colitis.

Question 12

What are the 4 main types of Clostridium?

Answer 12

Clostridium tetani, botulinum, difficile, perfringens.

Question 13

Which G(+) rod that produces spores is anaerobic? Which one is aerobic?

Answer 13

Anaerobic are the clostridium species, and the aerobic are bacillus.

Question 14

What are the three components of the anthrax toxin?

Answer 14

Edema factor, lethal factor, protective antigen.

Question 15

What are the three different presentations of anthrax? Which one is the most common?

Answer 15

Cutaneous, Inhalation and GI. Cutaneous is the most common.

Question 16

What is the clinical presentation of Cutaneous anthrax?

Answer 16

Occurs when spores enters skin. Starts with a small papule that evolves into a large, painless ulcer with central necrosis. There can be significant area of edema around the ulcer due to toxin production.

Question 17

What is the pathophysiology of inhalation anthrax?

Answer 17

AKA Wool sorter’s disease, aerosolized spores enter the respiratory system and are phagocytosed in alveoli then taken to mediastinal lymph nodes. Bacteria can then enter the bloodstream causing widespread infection, sepsis and death.

Question 18

What do we see in CXR in inhalation of anthrax?

Answer 18

Mediastinal widening.

Question 19

What are three obligate anaerobes?

Answer 19

Clostridium tetani, actinomyces, and bacteroides.

Question 20

What two antibiotics are effective for anaerobes?

Answer 20

Metronidazole, Clindamycin.

Question 21

What is the pathophysiology of Listeria monocytogenes infection?

Answer 21

It enters thru the GI tract and penetrates intestinal mucosa. It is then taken up by monocytes, and reside there (they are facultative intracellular organisms). If it infects a pregnant woman, it can cross the placenta, resulting in fetal loss or newborn sepsis.

Question 22

In what foods do we find Listeria monocytogenes?

Answer 22

Unpasteurized milk and cheese, and contaminated deli meats.

Question 23

What three bacteria are especially known for newborn sepsis?

Answer 23

Group B strep, E.coli, Listeria.

Question 24

What bacteria has branching filaments and can be stained with an acid fast Stain?

Answer 24

Nocardia.

Question 25

RFF: G(+) that causes scalded skin syndrome.

Answer 25

Staph aureus.

Question 26

RFF: G(+) causing gray-white membrane in the posterior pharynx of an unvaccinated child?

Answer 26

Corynebacterium diphtheriae.

Question 27

RFF: G(+) causing pharyngitis resulting glomerulonephritis.

Answer 27

Strep pyogenes.

Question 28

RFF: Most common cause of meningitis.

Answer 28

Strep pneumoniae.

Question 29

RFF: Most common cause of osteomyelitis.

Answer 29

Staph aureus.

Question 30

What bacteria would cause infant with poor muscle tone?

Answer 30

Clostridium botulinum.

Question 31

What bacteria would cause diarrhea after using antibiotics?

Answer 31

Clostridium difficile.

Question 32

What bacteria would cause respiratory distress in a postal worker?

Answer 32

Bacillus anthracis.

Question 33

What bacteria would cause otitis media in children?

Answer 33

Strep pneumoniae.

Question 34

What two bacteria would cause cellulitis?

Answer 34

Staph aureus and strep pyogenes.

Question 35

One hour after eating potato salad at a picnic, an entire family begins to vomit; after 10 hours, they are better. What would be the most likely organism to cause this?

Answer 35

Staph aureus.

Question 36

What patients are vulnerable to listeria monocytogenes?

Answer 36

Infants, elderly, immunocompromised, pregnant women.

Question 37

RFF: Branching, filamentous G(+) rods with sulfur granules.

Answer 37

Actinomyces israelii.