Antibiotic Lecture Part 2

Question 1

Ampicillin:

• Bacteriostatic or Bactericidal
• Acid stable or incomplete
• Penicillinase-resistant?

Answer 1

Bactericidal
Acid stable
Penicillase-reistant

Question 2

Hos is Ampicillin administered?

Answer 2

Parenterally or injection

Question 3

T or F, Amoxicillin is one of the most commonly prescribed drugs in the U.S.?

Answer 3

True

Question 4

Which has better bioavailability: Ampicillin or Amoxicillin?

Answer 4

Amoxicillin

Question 5

What makes up Augmentin?

Answer 5

Amoxicillin is combined with clavulanic acid to broaden spectrum

Question 6

What is Clavulanic acid and how does it work?

Answer 6

An antibacterial agent (not an antibiotic)

- Synthetic = inhibits the penicillinase enzyme

Question 7

Why doesn’t the patient respond to penicillin V

Answer 7

1. Patient compliance
2. Microorganisms are producing penicillinase
3. Bacteria causing infection is outside of the narrow spectrum of kill

Question 8

Augmentin is prescribed in what 3 ways?

Answer 8

250 mg, 500 mg and 875 mg

- 875 mg is used for a severe infection every 12 hours

Question 9

Why is it better to prescribe 1- 500 mg capsule rather than 2- 250 mg capsules of Augmentin

Answer 9

Regardless of the size of the capsule, there is a consistent 125 mg of clavulanic acid. By prescribing 2 capsules instead of 1, the patient receives double the dose of clavulanic acid. This might produce side effects of diahrrhea

Question 10

T or F, 10% of population gets maculopapular rash. Rash responds to Benadryl and is considered an allergic reaction

Answer 10

False! It is NOT an allergic reaction. It is a Toxicity reaction

Question 11

T or F, if you are allergic to one penicillin, you are allergic to all penicillins

Answer 11

True

Question 12

Are cephalosporins broken down by penicillinase like penicillins?

Answer 12

No, destroyed by cephalosporinase. (very similar mechanism though)

Question 13

Cephalosporins are well absorbed through what medium?

Answer 13

Through GI tract

Question 14

What are some adverse reactions to Cephalosporins:

Answer 14

1. Hypersensitivity reactions
2. Gastrointestinal effects (NVDs)
3. Superinfection (fungal infection; oral or vaginal)
4. Nephrotoxicity

Question 15

What are some oral side effects to Cephalosporins?

Answer 15

Glossitis: inflamed tongue; smooth, shiny red
Stomatitis: inflammation, ulcerations on buccal mucosa

Question 16

T or F, Patients who are intolerant to penicillins may be intolerant to cephalosporins

Answer 16

True

Question 17

Is Cephalosporins the first choice for any orofacial infections?

Answer 17

Never the first choice

Question 18

Cephalosporins are active and effective in what indications

Answer 18

1. Active against many gram positive aerobic bacteria
2. Active against some anaerobic bacteria
3. Effective against gram negative organisms

Question 19

Describe how generations work on spectrum of kill

Answer 19

The higher the generation, the more broad the spectrum of kill

Question 20

What generation of cephalosporins are used most in dentistry

Answer 20

First generation = active against gram positive cocci; limited activity against gram negative bacteria

Question 21

What are common cephalosporin drugs in first generation

Answer 21

Cephalexin (Keflex)
Cefadroxil

• cephalosporin drugs begin with either “cef” or “ceph”

Question 22

Erythromycin is bacteriostatic or bacteriocidal

Answer 22

Bacteriostatic

- Bactericidal at high doses or when used against highly susceptible organisms

Question 23

What is the mechanism of action of Erythromycin

Answer 23

• Inhibits protein synthesis by binding to the ribosome at a site near peptidyltransferase to inhibit peptide bond formation. End result is suppressing bacterial growth due to the lack of protein production

Question 24

Erythromycin is more effective against what type of bacteria

Answer 24

Gram positive cocci (Staph and Strep)

Question 25

Erythromycin can cause bile to back up into the liver resulting in what?

Answer 25

Cholestatic hepatitis

Question 26

What about Erythromycin causes poor patient compliance

Answer 26

It causes diarrhea

Question 27

Which drug was formerly an alternate drug of choice for orofacial infections for patients who were allergic to penicillins?

Answer 27

Erythromycin

• No longer effective against oral organisms due to resistance
• No longer used in dentistry

Question 28

3 reasons why we don’t use erythromycin anymore in dentistry

Answer 28

1. Oral bugs are resistant to drug
2. GI side effects (poor patient compliance)
3. Dangerous drug interactions

Question 29

T or F, Erythromycin is a red flag drug in dentistry

Answer 29

True, interacts adversely with many commonly prescribed medications and outcome of interaction is often serious and potentially life-threatening