Infectious Diseases Part II: Vaccinations, Bacterial Diseases and Antibiotics

Question 1

State the 4 types of immunity.

Answer 1

• Natural active immunity
• Natural passive immunity
• Artificial active immunity
• Artifical passive immunity

Question 2

What is natural active immunity?

Answer 2

Antibodies made after exposure to an infection.

Question 3

What is natural passive immunity?

Answer 3

Antibodies transmitted from mother to baby.

Question 4

What is artificial active immunity?

Answer 4

Antibodies made after getting a vaccination.

Question 5

What is artificial passive immunity?

Answer 5

Antibodies acquired from an immune serum medicine.

Question 6

What is a vaccine?

Answer 6

Vaccines stimulate a real infection and induce the host to mount an immunological response to render immunity against the pathogen without causing the disease.

Question 7

How do vaccines work?

Question 8

What is herd immunity?

Question 9

State the types of vaccines.

Answer 9

• Live attenuated vaccines (variants of pathogen that are less pathogenic)
• Inactivated or killed pathogen (contains destroyed pathogens)
• Subunit vaccine (contains only pathogenic antigens, not whole pathogen)
• Toxoids (contains bacterial toxins)
• Nucleic acid vaccine (contains DNA or mRNA that code for pathogenic antigens)

Question 10

What is the implication of live attenuated vaccines?

Question 11

What is the implication of inactivated or killed pathogen vaccines, subunit vaccines and toxoids?

Question 12

What is the implication of nucleic acid vaccines?

Question 13

What is Tuberculosis?

Answer 13

TB is a respiratory infectious diseased caused by Mycobacterium tuberculosis.

TB is a bacterial disease.

Question 14

How does TB spread?

Answer 14

Via airborne transmission via small respiratory droplets in coughs or sneezes

Question 15

How does TB enter the body?

Answer 15

Inhaled into lungs of individual

Question 16

How does TB infect the body cells?

Answer 16

• Bacteria taken up by alveolar macrophages and dendritic cells via phagocytosis.
• M. tuberculosis can block fusion of lysosome to phagosome in macrophages –> replicate in macrophages
• Macrophages undergo macrophage necrosis –> release M tuberculosis to multiply extracellularly

Question 17

How does the body respond to tuberculosis?

Answer 17

• Infected alveolar macrophages produce inflammatory cytokines –> recruit more immune cells to site of infection
• Dendritic cells with engulfed M. tuberculosis migrate to regional lymph node –> activate T cells that migrate to site of infection
• Accumulated macrophages, T cells form the granuloma –> limits spread of bacterial infection

Question 18

Describe the reactivation of TB infection.

Answer 18

When the immune system is weakened, M. tuberculosis cells exit dormancy and escape from granuloma to spread throughout lungs and body –> active TB

Question 19

What are antibiotics?

Answer 19

It is used to treat bacterial infection by killing the bacteria or inhibiting their growth.

Question 20

How does penicillin (antibiotic) treat bacterial infection?

Answer 20

• Penicillin binds to and inhibits DD-transpeptidase, an enzyme that catalyses formation of cross-links in peptidoglycan
• Newly formed bacterial peptidoglycan cell wall to be weakened
• Daughter bacterial cell walls have weaker peptidoglycan cell wall are not able to withstand osmotic pressure –> cell lysis and death