Antibiotic Overview - Antibacterial

Question 1

What are the 4 mechanisms of action of antibacterials?

Answer 1

1. Inhibit of cell wall synthesis
2. Inhibit translation & transcription
3. Inhibit DNA synthesis & integrity
4. Inhibit folate synthesis & fxn

Question 2

What is the MOA of bactericidal drugs?

Answer 2

Inhibit cell wall synthesis

• Time-dependent killing
• Concentration-dependent killing

Question 3

What is the MOA of bacteriostatic drugs?

Answer 3

Inhibition of protein synthesis

Question 4

Describe the post-antibiotic effect

Answer 4

Persistent suppression of bacterial growth after limited exposure to an antimicrobial agent

Question 5

What is the mechanism of the post-antibiotic effect?

Answer 5

• Slow recovery after non lethal damage to cell
• Persistence of the drug at the binding site
• Need to synthesize new enzymes before microorganism growth can resume

Question 6

What are examples of narrow spectrum penicillin?

Answer 6

• Penicilinase- susceptible: Penicillin VK

- Penicillinase-resistant: Nafcillin

Question 7

What is an example of a wider spectrum penicillin?

Answer 7

• +/- penicillinase inhibitor:

Amoxicillin

Question 8

What is narrow spectrum penicillin used for? (What organisms?)

Answer 8

Staph & strep

Question 9

What is wider spectrum penicillin used for?

Answer 9

Greater activity vs. gram-negative bacteria

Question 10

What is 1st generation cephalosporin used for? (Cephalexin)

Answer 10

Skin, soft tissue, UTI

Question 11

What is 2nd generation cephalosporin used for? (Cefuroxine)

Answer 11

• S. pneumoniae & H. influenza

- B. fragilis

Question 12

What is 3rd generation cephalosporin used for? (Ceftriaxone, cefixime)

Answer 12

• Pneumonia, meningitis, & gonorrhea

* Beta-lactamase stable

Question 13

What is 4th generation cephalosporin used for? (Cefipime)

Answer 13

Pseudomonas

Question 14

What is 5th generation cephalosporin used for? (Ceftaroline)

Answer 14

• Skin, soft tissue

- CAP

Question 15

What is unique about 1st generation cephalosporin?

Answer 15

• Cross sensitivity w/ PCN

- Contaminated w/ PCN in the past –> cross-reactivity in PCN-allergic pts

Question 16

When is 2nd, 3rd, 4th, & 5th generation withheld?

Answer 16

If pt suffered TRUE penicillin-induced anaphylaxis

- But they can usually be given safely to penicillin-allergic pts

Question 17

Describe synergism.

Answer 17

Inhibitory or killing effects of 2 or more antimicrobials used together are greater than expected when used individually

Question 18

What is synergism marked by?

Answer 18

Fourfold or greater reduction in MIC or MBC of each drug when used in combo vs. alone

Question 19

Describe empiric tx.

Answer 19

Antimicrobial agent is used before pathogen is identified for particular illness or susceptibility is known

Question 20

Describe guided tx.

Answer 20

Antimicrobial agent identified by susceptibility testing

Question 21

What is an antibiogram?

Answer 21

Report of susceptibility/resistance of pathogens to antibiotics

Question 22

What does an antibiogram provide info about?

Answer 22

Local resistance patterns

Question 23

What is an antibiogram used to determine?

Answer 23

Empiric tx options

Question 24

Which meds require dosa adjustment in renal impairment?

Answer 24

• Aminoglycosides
• Carbapenems
• Cephalosporins
• PCNs
• Trimethoprim-sulfamethoxazole
• Vanco

Question 25

Which meds are contraindicated in renal impairment?

Answer 25

• Nitrofurantoin
• Sulfamides (long-acting)
• Tetracyclines

Question 26

Which meds require dose adjustment in hepatic impairment?

Answer 26

• Chloramphenicol
• Clindamycin
• Erythromycin
• Metronidazole

Question 27

What is in common btwn PCN & cephalosporin?

Answer 27

Linked to a side chain