.3

Question 1

An adaptive response in which microorganisms begin to tolerate an amount of drug that would normally be inhibitory.
Due to the genetic versatility and adaptability of microbial populations
Can be intrinsic as well as acquired

Answer 1

drug resistance

Question 2

Microbes become newly resistant to a drug after one of the following occurs:
Resistance occurs due to what?

Answer 2

Spontaneous mutations in critical chromosomal genes
Acquisition of entire new genes or sets of genes via horizontal transfer from another species

Question 3

What does chromosomal drug resistance results from what? How can drug sensitivity be overcome? What are persisters?

Answer 3

Usually results from spontaneous random mutation

Slight changes in drug sensitivity can be overcome with larger doses of drug.

“Persisters”: slowing or stopping of metabolism so that the microbe can’t be harmed by the antibiotic

Question 4

What are the 4 ways to use the resistance form horizontal transfer?

Answer 4

Resistance (R) factors
Plasmids encoded in drug resistance
Transporons
Sharing of resistance genes

Question 5

What are resistance (R) factors?

Answer 5

plasmids containing antibiotic resistance genes
Can be transferred through conjugation, transformation, or transduction

Question 6

Plasmids encoded with drug resistance are naturally present in micrbes before they have been

Answer 6

exposed to an antibiotic

Question 7

How do transporons participate in horizontal transfer?

Answer 7

Transposons also duplicate and insert genes for drug resistance into plasmids

Question 8

Sharing of resistance genes accounts for the rapid proliferation of drug-resistant species

Answer 8

horizontal transfer

Question 9

What are the new approaches to antimicrobial therapy?

Answer 9

RNA interference
defense peptide
bacteriophages:

Question 10

Describe Using RNA interference strategies

Answer 10

Small pieces of RNA that regulate the expression of genes

Used to shut down the metabolism of pathogenic microbes

Drug trials have begun to evaluate the effectiveness of synthetic RNAs in treating hepatitis C and respiratory syncytial virus.

Question 11

How are mimicking defense peptide molecules helpful in antimicrobial therapy?

Answer 11

Peptides of 20 – 50 amino acids secreted as part of the mammalian innate immune system called defensin, magainins, and protegrins

Bacteria also produce defense peptides called bacteriocins and antibiotics.

Insert into membranes and target other structures in cells

May be more effective than narrowly targeted drugs and less likely to foster resistance.

Question 12

Using bacteriophages as a new approach to antimicrobial therapy. Provide examples.

Answer 12

Eastern European countries use mixtures of bacteriophages as medicine, but these drugs have never been approved for use in the West.

Biophage-PA used to treat ear infections caused by Pseudomonas aeruginosa biofilms

Other researchers are incorporating bacteriophages into wound dressings.

Advantage to bacteriophage is their narrow specificity; only infect one species of bacterium

Question 13

Describe probiotics, prebiotics, and fecal transplants

Answer 13

Probiotics:
Preparations of live microorganisms fed to animals and humans to improve intestinal biota
Can replace microbes lost during antimicrobial therapy
Augment biota already there
Safe and effective
Useful in the management of food allergies

Prebiotics:
Nutrients that encourage the growth of beneficial microbes
Fructans encourage the growth of Bifidobacterium in the large intestine and discourage the growth of pathogens.

Fecal transplants:
Used to treat recurrent Clostridium difficile infection and ulcerative colitis.
Transfer of feces from a healthy patient via colonoscopy
Work is underway to develop a pill containing the species to re-colonize the colon.