3.2.2 Bacillus, Listeria and Corynebacterium

Question 1

What allows bacillus organisms to survive in the environment?

Answer 1

Spore-forming

Question 2

What’s wrong with Bob?

Answer 2

Bob has Bacillus anthrasis

Question 3

What are the symptoms associated with inhalational anthrax? What is the associated mortality rate?

Answer 3

Question 4

What is one of the key features of inhalational anthrax seen on imaging?

Answer 4

Mediastinal widening

Question 5

What are the two forms of GI anthrax?

Answer 5

Oropharyngeal: local ulceration leading to regional lymphadenopathy (tonsilitis), edema and fever

Intestinal: ulcer w/ initial symptoms of fever, nausea, vomiting, malaise, followed by bloody diarrhea or sepsis

Question 6

What is the key feature of cutaneous anthrax?

Answer 6

Painless pauple develops into a black necrotic ulcer (eschar) with edema

Question 7

What is the pathogenesis of bacillus?

Answer 7

Question 8

What is the unique feature of the antiphagocytic capsule of bacillus?

Answer 8

Poly-D-glutamic acid

Question 9

What are the two active subunits of the A₃-B₇ anthrax exotoxin?

Answer 9

Edema (EF): activates adenylate cyclase -> increased cAMP

Lethal factor (LF): inactivates MAP-kinase-kihase -> results in necrosis

Question 10

Draw a diagram of the bacillus A-B toxin pathogeneis.

Answer 10

Question 11

After a presumptive diagnosis of Bacillus is made, what confirmatory labs are conducted by the CDC?

Answer 11

Question 12

What is the DOC for Bacillus anthrasis?

Answer 12

Ciprofloxacin

Question 13

What preventive measure can be enacted if a patient is at risk for inhalation anthrax?

Answer 13

60 days of antibiotic prophylaxis

Question 14

What human mAb targets PA of Bacillus anthrasis?

Answer 14

Raxibacumab

Question 15

What are some of the defining characterstics of Bacillus cereus?

Answer 15

Gram pos, spore-forming, facultative anaerobe, motile, beta-hemolytic on SBA, ubiquitous in soil

Question 16

What causes the emetic form of GI dz caused by Bacillus cereus?

Answer 16

Heat-stable enterotoxin

Question 17

What causes the diarrheal form of GI dz caused by Bacillus cereus?

Answer 17

Heat-labile toxin

Question 18

What type of eye pathogy is associated with Bacillus cereus?

Answer 18

Question 19

What is the DOC for Bacillus cereus?

Answer 19

Vancomycin or Clindamycin

Proper refrigeration of food

Question 20

What diagnostic tests can help lock down a diagnosis of Bacillus cereus?

Answer 20

Contaminated food or infected patient specimen (eye, IV, site, etc)

Generally no fecal samples

Question 21

What are the general characteristics of Listeria?

Answer 21

Question 22

What type of hemolysis is Listeria?

Answer 22

Weak beta-hemolytic: zone of lysis is narrow

Question 23

What unique about Listeria and its growth?

Answer 23

Grows at 4 degrees Celcius, refrigeration of food is not sufficient

Question 24

What subgroup of the population is at most risk for a Listeria infection?

Answer 24

Pregnant Women (risk increased 20-fold)

Question 25

What are some characteristics of Early-onset Listeria dz?

Answer 25

Transplacentally acquired Granulomatosis infanticeptica: disseminated abscesses and granuloma in multiple organs 80% mortality rate

Question 26

What are some characteristics of Late-onset Listeria dz?

Answer 26

Acquired at birth or soon thereafter Meningoencephalitis, septicemia 70% mortality rate

Question 27

What are some of the dz's caused by Listeria in immunocompromised pts?

Answer 27

Meningitis, bacteremia, 50% fatality rate in severely immunocompromised pts and infants

Question 28

Where do Listeria infections typically initiate?

Answer 28

Enterocytes or M cells in Peyer's patches

Question 29

What type of immunity is essential for clearing a Listeria infection?

Answer 29

Cell-mediated immunity

Question 30

What are the 4 main virulence factors of Listeria?

Answer 30

Internalins (Inl): forced phagocytosis Listeriolysin O (LLO): pore-forming hemolysin 2 Phospholipases (PI-PLC, PC-PLC) Actin-binding protein (ActA): Mediates actin polymerization

Question 31

Draw a diagram of Listeria pathogenesis

Answer 31

Question 32

What are two unique features of Listeria when it comes to culturing?

Answer 32

Cold-enrichment and umbrella-like growth

Question 33

What allows for Listeria to acquire resistance so easily?

Answer 33

Conjugative plasmids from enterococci

Question 34

What are the DOC for Listeria?

Answer 34

Ampicillin (meningitis: IV) or TMP-SMX

Question 35

What are the characteristics of Corynebacterium diptheriae?

Answer 35

Question 36

What is the activity of the A-portion of the diptheria A-B exotoxin?

Answer 36

ADP-ribosylates elongation factor -\> shutting down protein synthesis

Question 37

What are the different toxoid vaccines?

Answer 37

DTaP, Td and Tdap

Question 38

What are the characteristics of respiratory diptheria?

Answer 38

Question 39

What are the unique cultures that can identify diptheria?

Answer 39

Tellurite-containing differential chocolate agar Elek test

Question 40

What is the rx of diptheria infection in pt who was not immunized?

Answer 40

Immediate administration of antitoxin DOC: erythromycin or penicillin

Question 41

What is not produced following diptheria infection?

Answer 41

Protective antibodies - immunization of convalescent patient

Question 42

What is the typical vaccination schedule for diptheria?

Answer 42