(MT 2) Topic 1: Immunity to Bacterial Pathogens

Question 1

Human microbiome

Answer 1

all the microbes that call us home and mostly keep us healthy

“happy passengers”

very few are actually pathogens

Question 2

Pathogen

Answer 2

microbes that cause disease

Question 3

Infection

Answer 3

microbe replicates in/on host beyond its normal role

Question 4

Disease

Answer 4

microbial infection damages the host

Question 5

Difference between Infection and Disease

Answer 5

There’s host damage in disease

Question 6

Pathogenicity

Answer 6

ability of an organism to cause disease

whether to cause disease or not

Question 7

Virulence

Answer 7

the extent to which a microbe can cause disease

how quickly it can cause disease

Question 8

Virulence factors

Answer 8

the adaptations and traits that promote virulence in a pathogen

can be broader than some gene that they use or toxin; can be more subtle than that.

don’t have to be unique to that microbe (they can be but nor necessary)

Question 9

Two Main Types of Pathogens

Answer 9

• Opportunistic Pathogen
• True Pathogen

Question 10

Example of an opportunistic pathogen

Answer 10

S. aureus

Question 11

Opportunistic infections can result from opportunistic conditions such as: (2)

Answer 11

• compromised immune system
• disruption in the balance of normal microbes

Question 12

Two types of true pathogen

Answer 12

• Obligate pathogen
• Facultative pathogen

Question 13

Obligate pathogen
give an example of a disease

Answer 13

• pathogens must cause disease to be transmitted

ex: Herpes

Question 14

Facultative pathogen
give an example of a disease

Answer 14

• can cause disease but does not require a host to complete life cycle.

ex: Vibrio cholera

Question 15

Does the presence and even growth of microorganisms on the host always lead to disease?

Answer 15

No, The presence and even growth of microorganisms on the host does not always lead to disease.

Question 16

The interactions between the host and the microbe both contribute to the final outcome. This relationship is influenced by __________________ and ___________________.

Answer 16

• virulence of the microbe
• the defense mechanisms of the host

Question 17

There are many steps to establishment of infection that start with: colonization, persistence and spread.
These can be subdivided into: (5)

Answer 17

• exposure to pathogens
• adherence to skin or mucosa
• invade host tissue through epithelium
• immune evasion
• host damage

Question 18

How does bacteria access your nutrients?

Answer 18

It’s gonna damage you to access your nutrients

Question 19

Do you get sick right away by getting exposed to a bacterium that is pathogenic?

Answer 19

No. Just because you’re exposed to a bacterium that is pathogenic doe snot mean you’re getting sick. The bacteria has to stick to you and penetrate into you.

Question 20

Each step in the establishment of infection requires unique _____________ strategies for the pathogen

Answer 20

evasion

Question 21

Pathogen Profile

Staphylococcus epidermidis (S. epidermidis)

Answer 21

• gram positive
• example of an opportunistic pathogen
• normal component of the skin microbiome and important in protecting skin form unwanted pathogens

1. Encounter/Exposure -ubiquitous component of skin microbiome.
2. Host entry -noscomial (hospital-borne); particularly it adheres to plastic catheters, pacemakers, implants as a biofilm.
3. Adhesion and Invasion -tolerates changing osmolarity
   -adheres via teichoic acid association to the plasmid
   -binds extracellular matrix components of the host.
4. Immune system evasion -biofilms provide resistance to AMPs and antibodies and mechanical removal.
   -extensive efflux pumps -provides AMP resistance; if you can get your host defenses into the bacterium, bacterium spits them out-efflux pumps pump them out.
5. Host damage -PSM=phenol-soluble modulins -damages membrane to allow access to host resources

Question 22

PSM (phenol-soluble modulins)

Answer 22

damages membrane to allow access to host resources.

found in S. epidermidis

Question 23

He developed the Germ Theory of Infectious Disease and disproved the notion of spontaneous generation of microbes and miasma (“spirits”) theory for the spread of disease.
He also explained why so many people died of infection after surgeries where handwashing and antiseptic technique was not practiced.

Answer 23

Louis Pasteur

Question 24

How did Pasteur show that microbial cells arise from preexisting cells?

Answer 24

1. Put beef broth into flash
2. Heated neck of flask to introduce bend
3. Boiled broth to sterilize
4. Air could enter flash through bent neck, but microbes got stuck in the bend- bend in flask removed the route of entry of new microbes.
5. Broth stayed sterile

Question 25

He studied the theory that microorganisms cause human disease. He showed a cause and effect relationship between pathogen and disease.

Answer 25

Robert Koch

Question 26

Koch’s postulates

Answer 26

• pathogen must be present in all cases of the disease.
• pathogen must be grown in pure culture.
• pathogen must cause disease from pure culture.
• pathogen must be reisolated from the organism where you induce the disease.

Question 27

Pathogen Profile

Treponema pallidum

Example of Koch’s postulate in action

Answer 27

• believed to be the causative agent of STI syphilis
• spirochete
• has endoflagella where two or more flagella originate from opposite poles of the bacterium and are located in the periplasmic space.
• avoids recognition by the innate immune system and TLR5
• bacterium has never been grown in the lab and doe snot have an animal model.

Question 28

What can treat syphilis and how many % is it asymptomatic?

Answer 28

Antibiotics, 43%

Question 29

In 2017,
CDC- ___-____% of American population had previous syphilis infection.

Answer 29

15-20%

Question 30

Case study
Clinical case of a woman with a year-long mouth ulcer in rural Uganda

Answer 30

• was about to go in for surgery to remove a presumptive tumor
• did ELISA and pathological analysis- T. pallidum spirochetes were detected
• Penicillin G managed the infection and it resolves in 2 months.

Question 31

TRUE or FALSE
Alternative methods can be used to satisfy Koch’s postulates

Answer 31

TRUE