Important Topics

Question 1

What is the MOA for Fluoroquinolones (be specific)

Answer 1

Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV

Question 2

MOA of aminoglycosides

Answer 2

Bind to both the 30s and 50s ribosomal subunits (aka 70s)
Requires O2 to enter cell and therefore ineffective against anaerobes

Question 3

Important methods for preventing renal toxicity with aminoglycosides

Answer 3

Check urine sediments frequently
Use SID if possible
Ensure adequate hydration
Make sure peak plasma conc >10 and trough <2
Use amikacin over gentamicin
Use gentamicin for staphylococcus
Use amikacin for pseudomonas
Use combinations of abx, especially when treating G+
NO furosemide or other nephrotoxic drugs
Give during periods of activity
Treat with NAC

Question 4

MOA Macrolides

Answer 4

Inhibits RNA protein synthesis by binding 50s ribosomal subunit

Question 5

MOA Lincosamides

Answer 5

Inhibits RNA protein synthesis by binding 50s ribosomal subunit

Question 6

MOA Chloramphenicol

Answer 6

Inhibits RNA protein synthesis by binding 50s ribosomal subunit

Question 7

MOA tetracyclines

Answer 7

Interferes with protein synthesis by binding 30s bacterial RNA, reversible

Question 8

Cephalosporin coverage changes with generation?

Answer 8

Increase G- and anaerobic coverage and decrease G+ coverage with increasing generations

Question 9

What is the antibiotic cause of MRSA?

Answer 9

Wide use of cephalosporins is causing increased resistance with E. coli and other G- organisms, just as it did with MRSA/MRSP

Question 10

What antibiotics concentrate in the bile?

Answer 10

Clindamycin, rifampin, erythromycin, and doxycycline
(CRED)

Question 11

What antibiotics have decreased efficacy with low pH environments?

Answer 11

Erythromycin: pH < 7
B-lactams, cefoxitin, imipenem: pH < 6
Clindamycin
Aminoglycosides and Fluoroquinolones

Question 12

Low tissue oxygen tension can prevent what antibiotic class from working?

Answer 12

Aminoglycosides

Question 13

What class of drugs is particularly ineffective in hyperosmolar environments?

Answer 13

B-lactams

Question 14

What antibiotics are best for acidic vs alkaline urine?

Answer 14

Acidic urine (E. coli): B lactams, TMS
Alkaline urine (Proteus, Klebsiella, Staph): Fluoroquinolones, aminoglycosides

Question 15

4 mechanisms that bacteria use to gain resistance to B lactams

Answer 15

1. Altered or different penicillin binding proteins (MRSA)
2. Efflux through specific pumps
3. Changes in porins (Pseudomonas)
4. Enzymatic destruction by B-lactamases* most common