Antimicrobial adaptations

Question 1

Why did smallpox spread so widely?

Answer 1

Had a very long incubation period, infectious before symptoms began

Question 2

Why is herd immunity so important?

Answer 2

Protects those who cannot be vaccinated i.e; too young, health problems, pregnant, etc

Question 3

Define microbial adaptation

Answer 3

Ability of the microbe to endure the selective pressure of their environment

Question 4

Which component of bacteria is key to microbial adaptations?

Answer 4

Their plasmid

Question 5

Describe the three types of horizontal transmission for the transfer of genetic information

Answer 5

1. Conjugation; bacteria-bacteria transfer
2. Transduction; viral-mediated transfer (of genetic info between bacterium)
3. Transformation; free DNA transfer (involves changing the permeability of the bacterial cell capsule/wall to share free DNA)

Question 6

Describe how a plasmid is shared between two bacterium in conjugation

Answer 6

1. A bacterium produces proteins that break the circular plasmid into a single length of extracellular DNA
2. This is then replicated and transferred to the recipient with the help of its pili (helps connect the bacterium with the recipient).
3. That recipient now contains DNA that allows it to express the pili and conjugate with other bacteria.

Question 7

Describe the lytic stage of a bacteriophage

Answer 7

1. Bacteriophage attaches to the surface and injects its genetic material into the host.
2. It digests the DNA of the bacteria

Question 8

How does the Lysogenic cycle differ from the lytic cycle in a bacteriophage? Describe the Ly’s organic cycle of a bacteriophage

Answer 8

Both begin with the bacteriophage attaching to the surface and injecting its genetic material into the host

In the lytic stage:

1. The bacteriophage digests the host’s DNA and takes over the bacteria’s cellular processes to replicate its own proteins and parts
2. Once made, the parts reassemble into a new phage, lyse open the cell and begin the cycle again

In the lysogenic stage:

1. Bacteriophage will have integrase enzyme, where it can integrate it’s own genetic into the host’s
2. The bacterium can lay dormant in the host while the host continues replicating its genetic info

Question 9

What is generalized transduction and which cycle is it more associated with?

Answer 9

Lysogenic cycle; when the virus finally lyses from the cell it may take some of the host bacteria’s genetic material

Question 10

What is specialized transduction?

Answer 10

As the bacteriophage integrates its genetic material into the bacteria, it can bring with it genetic elements that impart particular characteristics onto the bacteria

Question 11

Why would bacteria produce antibiotics?

Answer 11

To compete with other bacteria in the environment

Question 12

Name the three methods bacteria can use to resist antibiotics

Answer 12

If their genetic info allows the bacteria to encode for certain proteins they may develop the ability to undergo ___ so the antibiotic no longer works
1. Enzymatic degradation; degrades the antibiotic

2. Express efflux pumps; transmembrane structures that pump out metabolites the bacteria naturally generates. If they develop genetic info that has efflux pumps particular to specific antibiotics they could pump the antibiotics out.
3. Target resistance: the bacteria may obtain characteristics that the antibiotic doesn’t target, and therefore the antibiotic becomes ineffective
   a) prevent penetration to the target site
   b) Alters the drug target site

Question 13

Briefly describe the WHO’s 5 step action plan to target antibiotic resistance

Answer 13

1. Improve awareness of the issue
2. Strengthen knowledge through surveillance and research
3. Reduce incidence of infection
4. Optimize use of antimicrobial agents
5. Develop the right economic case for a sustainable investment that takes into account the needs of all countries and increases investment in new medical interventions/tools

Question 14

What is the difference between antibiotic and antimicrobial resistance

Answer 14

Antibiotic resistance refers specifically to resistance to antibiotics occurring in common bacteria, antimicrobial is much broader and includes resistance to drugs to treat infections caused by other microbes as well

Question 15

Name three ways bacteria can become resistant to antibiotics molecularly

Answer 15

1. Develop point mutations in one of the target genes
2. Acquir plasmids or transposons through macro-evolutionary changes
3. Acquir DNA from an exogenous source (i.e Neisseria can acquire DNA from the environment)

Question 16

Define cross-resistance, when does it occur?

Answer 16

When a single resistance mechanism confers resistance to an entire class of antibiotics. It can also occur across different classes of agents as a result of either overlapping drug targets or if there is a drug efflux pump with a broad range of activity

Question 17

Define co-resistance

Answer 17

Refers to resistance to more than one class of antibiotics in the same bacterial strain

Question 18

Define co-selection

Answer 18

The selection of multiple antibiotic resistance genes when one of these genes is selected (since all the antibiotic-resistant mechanisms are linked together on a plasmid)

Question 19

Name four methods that antimicrobial resistance genes can be widely spread

Answer 19

1. Clonal spread of the resistant strain; under selective pressure of antibiotics a strain carrying antimicrobial resistance genes may be selected and transferred within a population
2. Plasmid transfer: can be transferred among different bacterial strains or species by conjugation or transduction
3. Free DNA: naturally transformable species can acquire native DNA from the environment and integrate this genetic info into the chromosome
4. Bacteriophage transduction

Question 20

List three key protective features of the respiratory tract against microbes

Answer 20

1. Mucous membranes line the trachea, bronchi and bronchioles and are lined with IgA
2. Microbes trapped in the mucous are beaten up to the pharynx (mucociliary escalator) to prevent them from entering the body
3. Alveolar macrophages enter alveoli from blood capillaries to fight microbes