Bacterial Pathogenesis Final Part 2

Question 1

What is the microbiota?

Answer 1

• hundreds of organisms that colonize a host

- bacteria are the most abundant, then fungi and archaea

Question 2

Is there a a single healthy adult human microbiota?

Answer 2

No

Question 3

What is the difference in the microbiota of c-section babies vs natural birth babies?

Answer 3

C-section: disrupted transmission of maternal bacteroides, high level of colonization by opportunistic pathogens (enterococcus, enterbacter)

Question 4

What is the difference between resident and transient microbiota?

Answer 4

Resident: life-long
Transient: just passing through, can’t stay because of competition, or elimination by immune system

Question 5

What are the types of relationships between bacteria and host?

Answer 5

Mutualism, commensalism, parasitism

Question 6

What is microbial antagonism?

Answer 6

The inhibition of one bacterial organism by another

Question 7

What are some nutritional benefits of bacteria?

Answer 7

Synthesize vitamin K, converts steroids into the active form or a form that can be absorbed by the host, break down food that is normally indigestible

Question 8

Where is the microbiota located?

Answer 8

Any body part exposed to the environment (mostly skin, resp, GI tract, urogenital tract)

Question 9

What are common bacteria found on the skin?

Answer 9

Propionibacterium acnes, staphylococcus aureus, staphylococcus epidermidis

Question 10

What bacteria are commonly found in the oral cavity?

Answer 10

Streptococcus mutants

Question 11

What bacteria are commonly found in the GI tract?

Answer 11

Helicobacter pylori, clostridium difficile

Question 12

Why is the skin a good place for bacteria to grow?

Answer 12

Acidic, salty, dry. Sebum contains lipids, amino acids, lactic acid and is used as nutrients

Question 13

Is Propionibacterium acne’s gram pos or neg? Is it aerobic or anaerobic? Where does it live? How does it cause inflammation?

Answer 13

• gram pos
• aerotolerant anaerobe
• lives at the base of a hair follicle
• fermentation products lead to skin inflammation

Question 14

What phylum does staph belong to?

Answer 14

Firmicutes

Question 15

Is S. aureus found in all people? How about S. epidermis? What kind of infections do they cause?

Answer 15

S. Aureus: some people, can cause skin infections, pneumonia or sepsis
S. Epidermis: all people, forms a biofilm and can cause catheter infections and introduced into blood

Question 16

What do Streptococcus mutants synthesize? What promotes this?

Answer 16

Dextran, sucrose

Question 17

What is the purpose of glucan binding proteins?

Answer 17

Dextran binds and forms a biofilm

Question 18

Which parts of the respiratory tract are sterile?

Answer 18

The sinuses and lower resp tract

Question 19

Where is most of the bacteria in the GI tract?

Answer 19

The large intestine

Question 20

What kind of bacteria live in the stomach? How do they move?

Answer 20

Fermentitive bacteria live in gastric epithelium mucus; spiral flagella propels into the stomach lining

Question 21

What are the virulence factors of H. Pylori?

Answer 21

• flagella
• urease: gastric mucosal injury and gastric acid neutralization
• LPS: adheres to host
• T4SS: injects effectors
• exotoxins/enzymes: gastric mucosal injury

Question 22

What is an endospore?

Answer 22

Some of the bacteria go from vegetative state into a resting state, to protect the genome until there are more favourable conditions

Question 23

What are the virulence factors for C. Diff?

Answer 23

• Bile-tolerance
• flagella
• cell-wall proteins
• Cathelicidin resistance
• O-nitrosylation

Question 24

What bacteria is in the vagina?

Answer 24

Lactobacillus

Question 25

What is a biofilm?

Answer 25

Bacteria stuck to a surface and enmeshed by slimy EPS matrix

Question 26

What is EPS made out of?

Answer 26

Polysaccharides, proteins, DNA

Question 27

How many species are biofilms made out of?

Answer 27

Sometimes 1, sometimes more than 1

Question 28

What are the requirements for biofilm formation?

Answer 28

• flagella
• be able to attach to a solid substrate
• be able to move on the substrate
• have cell density signals

Question 29

How are biofilms resistant to treatment?

Answer 29

• EPS forms a mesh barrier
• the inside cells are hard to access by drugs and immune cells
• inside cells have no access to nutrients so they are resistant to antibiotics
• the inside cells persist and repopulate

Question 30

What are the infections caused by P. Aeruginosa?

Answer 30

Skin infections in burn patients and lung infections in cystic fibrosis patients