Antibiotic resistance

Question 1

What are ways in which resistance can be acquired?

Answer 1

1. Single nucleotide base pair mutations
2. Cassettes of multiple resistance genes acquired through transposons.
3. Acquisition of resistant DNA from other bacteria:
   - conjugation
   - transduction
   - transformation (plasmid)

Question 2

What are mechanisms of resistance (4)

Answer 2

1. efflux pumps
2. target site change
3. decreased porins
4. inactivation of drug

Question 3

What is the only drug that GAS has developed resistance against?

Answer 3

Erythromycin

Question 4

How does S aureus develop resistance?

Answer 4

1. beta lactamase

2. altered PBPs

Question 5

How does strep pneumo develop resistance?

Answer 5

Altered PBP

Question 6

How do you treat strep pneumo?

Answer 6

1. Meningitis: ceftriaxone and vanco

2. pneumonia: ceftriaxone alone (take on the risk that resistance might occur cause a less emergent situation)

Question 7

How do you treat coag - staph and enterococcus?

Answer 7

Vancomycin. These can be HIGHLY resistant GPCs

Question 8

What is effective against pseudomonas?

Answer 8

Piperacillin
Ceftazzidine
Carbapenem + AG/quinolone

Question 9

A strain initially looks sensitive to an antibiotic in sensitivity testing. But when administered to pt, not effective. Why is that?

Answer 9

Inducible resistance.

Question 10

What covers the atypials?

Answer 10

macrolides (azithromycin)
Doxy
Quinolones

Question 11

What covers MRSA?

Answer 11

1. VANC/DAP/LINEZOLID

2. BACTRIM/DOXY/CLINDA

Question 12

What covers anaerobes?

Answer 12

1. Metronidazole
2. beta lactam ith a beta lactamase inhibitor
3. Clindamycin
4. Meropenem

Question 13

What covers GNR coverage?

Answer 13

1. Quinolone
2. Aminoglycoside
3. Aztreonam