LECTURE - Bacilli

Question 1

when do endospores form?

Answer 1

when nutrients are depleted or conditions are unfavorable for growth
- can last in soil for hundreds of years

Question 2

Bacillus anthracis capsule

Answer 2

• Poly D-glutamic acid
• protein capsule (unique!)
• antiphagocytic
• Abs to capsule is not protective

Question 3

T or F. Bacillus anthracis disease is more common in wild and domesticated animals, than in humans

Answer 3

T

Question 4

Three types of anthrax

Answer 4

• cutaneous (spores enter cut; eschar; necrosis of tissue so black; death rare)
• gastrointestinal (spores ingested; undercooked meat; death rate high even with antibiotics)
• systemic (spores inhaled; germinate in lung phagocytes; septic shock)

Question 5

Toxins of anthrax

Answer 5

• edema toxin

- lethal toxin

Question 6

edema toxin

Answer 6

• B = Protective Antigen

- A = adenylate cyclase - calmodulin …

Question 7

lethal toxin

Answer 7

• B = PA

- A = zinc-dependent protease that cleaves MAP-kinase = cytokine release = shock for macrophages

Question 8

T or F. B. anthracis is resistant to many broad-spectrum antibiotics, including penicillin

Answer 8

F! susceptible

= CDC = ciproflaxin or doxycycline IV until antibiotic sensitivity tests are done

Question 9

Process of forming an endospore

Answer 9

1. DNA aligned into long filament
2. DNA duplicated then divided into individual chromosomes; cytoplasmic membrane begins to invaginate
3. DNA becomes completely surrounded by cytoplasmic membrane
4. cortex formed and some of the spore coat beginning to form
5. several layers surround internal contents; mature spore
6. cell wall lyse = releases endospore

Question 10

coonies on BAP look like medusa heads

Answer 10

B. anthracis

- also edges lift with loop like beaten egg white

Question 11

chest radiograph og someone with inhalation anthrax

Answer 11

shows mediastinal thickening

- lymph nodes swollen in mediastinum = edema

Question 12

second most common cause of anthrax

Answer 12

systemic anthrax

- lethal if successful spread from lungs to bloodstream

Question 13

Exposure to anthrax

Answer 13

high density of spores inhaled from infected animal fur, hide, or wool

Question 14

confirmed case of anthrax

Answer 14

compatible clinical illness plus positive culture or 2 other tests (PCR, immunohistochemistry, serology)

Question 15

suspected case of anthrax

Answer 15

compatible illness plus one non-culture test OR epidemiological link

Question 16

Main component of anthrax vaccine

Answer 16

B = protective antigen

Question 17

Protective antigens of B. anthracis assembly

Answer 17

assemble into heptameric ‘prepores’ when bound to their ligands on the cell surface

Question 18

Anthrax toxin entry into cells

Answer 18

1. binding of PA to receptor
2. proteolytic activation; dissociation of PA20
3. self-association of PA63 to form heptameric prepore
4. binding of either EF or LF to prepore
5. endocytosis of complex
6. pH-dependent conversion of prepore to pore, translocation of lifand to cytosol

Question 19

B. anthracis virulence plasmids

Answer 19

pXO1 and pXO2

Question 20

Bacillus cereus

Answer 20

• motile unlike B. anthracis
• diseases are toxicoses (food poisonings); fried rice
• two different enterotoxins = vomiting and diarrhea

Question 21

T or F. There are three different types of toxins implicated in emetic disease of B. cereus

Answer 21

F! for diarrheal = Hbl, Nhe, CytK

Question 22

toxins are preformed in food

Answer 22

emetic toxins

Question 23

Foodborne illness due to B. ereus w rice as th vehicle is most likely associated with

Answer 23

diarrheal-type syndrome

Question 24

Certhrax

Answer 24

• first anthrax-like mART toxin from B. cereus strain
• shares 31% sequence identity with anthrax lethal factor
• like LF, requires PA for host cell entry
• 60-fold more toxic to mammalian cells than anthrax LF

Question 25

B. subtilis

Answer 25

• common contaminant of lab media
• killing of spores to check if autoclaving was good
• effective = 121 degrees C for at least thirty mins by using saturated steam under at least 15 psi