L20 Emerging Infections

Question 1

What are the three concepts of an emerging pathogen?

Answer 1

1. Previously unknown organism that causes disease
2. Previously identified organism that has recently acquired the capacity to cause disease
3. Previously identified pathogen that has recently acquired the capacity to resist antibiotic treatment

Question 2

What are the 6 major factors contributing to the emergence of infectious diseases?

Answer 2

1. Human demographics and behavior
2. Technology and industry
3. Economic development and land use
4. International travel and commerce
5. Microbial adaptation and change
6. Breakdown of public health measures

Question 3

What is one technology/industry-related issue leading to emergence of infectious diseases?

Answer 3

Overuse of antibiotics in agriculture to increase their growth rate

Question 4

Correct drug therapy involves both the proper ___ and ___.

Answer 4

Dose; duration

Question 5

When the drug dose or duration is too low, what happens?

Answer 5

This permits bacterial replication and modest levels of selection which result in evolution of drug resistance.

Question 6

In the absence of selection, appearance of mutations is ___.

Answer 6

Stochastic

Question 7

Any given mutant need not be a ___ in the absence of selection.

Answer 7

Founder

Question 8

Describe the evolution of antimicrobial resistance in the presence of selection.

Answer 8

Selection must be strong enough to enforce selection but weak enough so that bacteria can survive long enough for advantageous mutations to arise and contribute to survival

Question 9

Evolution of antimicrobial resistance would be faster if cells mutated at a ___ rate.

Answer 9

Higher

Question 10

What is combination therapy?

Answer 10

Use of two types of drugs to combat resistance; the probability of appearance of resistance is much lower when bacteria need to resist 2 drugs.

Question 11

___ can compromise transmission. Evolution balances these two factors.

Answer 11

Lethality

Question 12

As virulence increases, lethality ___ and transmission ___.

Answer 12

Increases; decreases

Question 13

Introduction of a ___ alters the balance between lethality and transmission, permitting greater virulence.

Answer 13

Non-living vector

Question 14

Elimination of vectors has what effect?

Answer 14

Reduction of virulence

Question 15

What are the 2 current paradigms of drug discovery?

Answer 15

1. Reductionist approach (identify virulence factors, design drugs to target virulence factors)
2. Genomic approach (sequence genome of the pathogen, design drugs to target all potential VFs)

Question 16

What is a new paradigm of drug discovery and what are the steps?

Answer 16

Attack intrinsic resistance

1. Identify and analyze mechanisms of resistance
2. Ensure that drug works in spite of these mechanisms before the compound is considered for R&D
3. Design drugs to attack the resistance mechanism