Exam 3 (Clostridium & Bacillus)

Question 1

Clostridium bacteria
Gram:
O2 req:
Endospores:
Environment:

Answer 1

Gram: G+
O2 Req: obligate anaerobes
Endospores: yes (stains green)
Environment: soil and intestinal mucus

Question 2

Virulence factor associated with Clostridium botulinum? How does it work?

Answer 2

Botulinum neurotoxin (blocks acetylcholine release) 
-AB-exotoxin

Question 3

A pt has flaccid muscle paralysis that has taken weeks to months to neutralize with anti-toxin and has no evidence of tissue invasion by pathogen. What was the pt infected with?

Answer 3

Clostridium botulinum (or botulinum neurotoxin)

Question 4

What is the main virulence factor of Clostridium tetani?

Answer 4

tetanospasmin

Question 5

C. tetani

What is the mechanism of tetanospasmin?

Answer 5

the AB-exotoxin neurotoxin blocks GABA and glycine release which are both inhibitory controls for motor neurons. Uncontrolled muscle contraction. Opposite effect of botulinum toxin

Question 6

Method to prevent tetanus in neonates?

Answer 6

passive immunization of IgG of pregnant women can prevent tetanus death by umbilical infection

Question 7

What is the only Clostridial species with tissue invasion?

Answer 7

Clostridium perfringens

Question 8

What are the three main virulence factors of C. perfringens?

Answer 8

1. alpha toxin: lecithinase-phospholipase destroys membranes and causes alpha hemolysis
2. theta toxin: cytolytic toxin causes beta hemolysis
3. collagenase/hyaluronidase help tissue invasion from edges of dying tissues

Question 9

What are two forms of gangrene? What pathogen can cause it?

Answer 9

1. gas gangrene: anaerobic fermentation of amino acids
2. uterine gangrene: puerperal fever

-clostridium perfringens

Question 10

What is the only treatment for gangrene?

Answer 10

amputation

Question 11

2 virulence factors of Clostridium difficile?

Answer 11

1. Toxin A: enterotoxin inhibits intestinal tight junctions, fluid leak
2. Toxin B: cytotoxin depolymerizes actin and epithelial cells round and leak

both cause diarrhea

Question 12

How can clostridium difficile benefit from antibiotics?

Answer 12

-antibiotic-associated pseudomembranous colitis (PMC) caused by broad spectrum antibiotics that kill normal intestinal flora and allow resistant species to take over like toxin producing C. difficile

Question 13

What are sources/causes of C. difficile infection?

Answer 13

• colonized intestines/genital tracts
• hospital environment
• prior antibiotics

Question 14

Bacillus anthracis
Gram: 
Shape:
O2 req:
Epidemiology:

Answer 14

Gram: G+
Shape: rods
O2 req: facultative anaerobe
Epidemiology: zoonotic infection “woolsorter’s disease”

Question 15

What are the two virulence factors of Bacillus anthracis and what are their mechanisms?

Answer 15

1. Edema factor: is an adenylate cyclase that incr cAMP and causes edema
2. Lethal factor: metallo-protease that causes cell death with pulmonary edema

Question 16

Are LF and EF of anthrax endo or exotoxins? Are they A or B portions?

Answer 16

A portions of exotoxins

Question 17

Disease mechanism of inhalation anthrax?

Answer 17

1. enters lungs, phagocytes take up (latency up to 2 months)
2. to lymph nodes where spores germinate and cause pneumonial and meningitis type symptoms
3. bloodstream: powerful toxins stim macrophage TNF-alpha and cause toxic shock death in 1-2 days

Question 18

Symptoms of gastrointestinal anthrax?

Answer 18

• ulcers in mouth and esophagus (edema and sepsis)

- lethality of 100% if in lower intestines

Question 19

Symptoms of skin anthrax? Lethality %?

Answer 19

• redness
• edema and vesicle rupture
• lethality of 20%

Question 20

Epidemiology of bacillus anthracis?

Answer 20

• animal workers
• microbiological accidents
• bioterrorism
• contaminated meat