Gram Pos Aerobic Rods

Question 1

What are the G+ aerobic rods that form spores and doent (2 + 3)

Answer 1

Spores

• Bacillus anthracis
• Bacillus cereus

No

• Listeria monocytogenes
• Corynebacterium diptheriae
• Lactobacillus spp.

Question 2

What are bacterial spores and when do they form

Answer 2

Protective structure that some bacteria produce to increase its likihood of surviving in unfavourable env.

Question 3

What is the process of sporalation up to when it pinches off

Answer 3

1. signal is recieved and spore septum forms near one pole (becomes forespore)
2. Plasma membrane surounds spore septum and pinches it off with double membrane

Question 4

What is added to the forspore after pinching off

Answer 4

3. Calcium, dipicolinic acid and loosely linked PG form a cortex around forespore (stablaize)
4. bacterium addes spore coat more of pros and sugars

then released from mother cell

Question 5

What is the cross section of endospore from out to in

Answer 5

Coat- proteins/sugars
Outer membrane- mother cell
Cortex- dipicholincic acid/calcium
Germ cell wall- normal PG
inner- spore septum

Question 6

Bacillus anthracis- causes what, what it looks like on blood agar, does it move

Answer 6

• Causes anthrax
• Forms white/gray colonies on blood agar (medusa head, y hemolytic)
• Atrichous (doesnt move flagela)

Question 7

What two plasmids in the capsul do you need for full virulence in bacillus anthracis

Answer 7

pXO1- anthrax toxins

pXO2- antiphagocytic capsul

Question 8

What is the 3 subunits of pXO1 (anthrax toxins) that produce the affects

Answer 8

1. Edema factor- contverts ATP to cAMP, ion influx (build up of water in tissue
2. Lethal factor disrupts cell signaling pathways
3. Protective antigen mediates cell entry of edema factor + lethal factor (mediates cell entry)

Question 9

How can bacillus anthracis be transmitted (3) and who is at risk

Answer 9

-Primarly occupational hazard of vegterians, agriculture

1. Cutaneous
2. Inhalation
3. Gastrointestinal

Question 10

Cutaneous anthrax- transmission, symptoms, how common

Answer 10

• Entry of bacilli into wounds/abrasions
• Painless ulcer with a black necrotic center w/ inflamed tissue
• 95% of all anthrax cases

Question 11

Pulmonary anthrax- transmission, symptoms, lethality

Answer 11

• Spores inhaled and enter respiratoryy tract
• Causes pulmonary edema + severe respiratory distress
• 70-95% fatality

Question 12

Gastrointestinal anthral- transmission, symptoms

Answer 12

• Ingestion of undercooked meat from animal contaminated with spores
• Neusea, vomitting severe abdominal pain, dysentery

Question 13

what bacteria is used as a bacterial pesticide

Answer 13

Bacillus thuringiensis- produces crystal proteins that have insecticidal action

Question 14

What does bacillus cereus cause and why

Answer 14

associated with 2-5% of food poisoning

• if food is not prepared or stored properly (endospores may survive, toxigenic strains germinate in gut)

Question 15

What are the 2 types of bacillus cerus

Answer 15

1. Emetic variety

2. Diarrheal variety

Question 16

What foods is the emetic variety of bacillus cerus due to, symptoms, incubation time

Answer 16

foods- Rice, couscous, bulgar wheat dishes

Symptoms- nausea, vommiting, cramps

incubatuon- <6hrs

Question 17

What foods in the diarrheal variety of bacillus cereus due to, symptoms, incubation time

Answer 17

• improperly cooked/reheated meat, soups, sauces (inactivated in heat tho)
• non dysenteric diarrhea + cramping

incubatuon- 8-16 hrs

Question 18

Listeria monocytogenes- blood agar type, can it survive in/out of cells, was illness is it associated w

Answer 18

B hemolytic
facultative intracellular

Associated with lethal type of foodborne illness called listeriosis

Question 19

foods that cause listeriosis, incubation, symptoms

Answer 19

Consumption of deli meats, unclean raw vegs/fruit, unpasturized milks

incubation- 21 days

May cause self limiting gastroenteritis + fever (can also cross blood brain barrier causing more severe symptoms)

Question 20

what is the risk of listeriosis during pregnancy

Answer 20

listeria can spread to placenta and may lead to spontaneous abrotion, still birth etc

Question 21

How does liseria invade into cells (2)

Answer 21

express surface pros called internalins which allow them to be internalized into cells

when in cells they induce host actin polymerization which facilitates their invasion into neighbouring cells

Question 22

How does listera evade hose immunity (1)

Answer 22

Listeriolysin O is used to escapse phagosomes

Question 23

What does corynebacterium diptheriae cause + how it spreads

Answer 23

Causative agent of diphtheria, an acute upper respiratory tract infection

Repiratory droplets

Question 24

what is the pathogenisis of diptheria

Answer 24

Toxigenic strains adhere to respiratory epithelium and secrete diphtheria toxin which attenuates protein translation

Question 25

What does diptheria cause in the respiratory epithelium + systematically

Answer 25

pseudomembrane composed of fibrin, WBCs, RBCs, dead epithelial cells and microbes- white/grey lesion in back of throat

• also causes fever, malaise, sore throat etc

Question 26

why dont commensal bac make us sick

Answer 26

Genetics
not all strains toxic
colony size
where is colony 
immune system
barriers