Test Two: Orofacial Infections

Question 0

Two most common causes of orofacial infections

Answer 0

Strep viridans and staph aureus

Question 1

What are the common oral infections?

Answer 1

acute orofacial abscesses, pulpal/periapical infections, and acute necrotizing ulcerative gingivitis

Question 2

What makes up the basic structure of penicillin?

Answer 2

Thiazolidine ring, beta lactam ring, and side group

Question 3

What are the two sites for enzyme degradation of penicillin?

Answer 3

Beta lactamase acts at penicilloic acid

Amidase acts at 6-aminopenicllanic acid to remove the R side group

Question 4

What is the site that causes penicillin allergies?

Answer 4

6-aminopenicillanic acid–>penicilloyl antigen

Question 5

What enzyme does penicillin bind to in order to block cell wall synthesis?

Answer 5

Transpeptidase

Question 6

Class 1 penicillins

Answer 6

High gram + activity with little gram - and beta lactamase susceptibility (pen G)

Question 7

Class 2 penicillins

Answer 7

Lower gram+ activity with no gram- activity. Some resistance to staph beta lactamase (methicillin)

Question 8

Class 3 penicillins

Answer 8

Broad spectrum (activity against gram+/-) but beta lactamase susceptible (carbenicillin and ticarcillin)

Question 9

Class 4 penicillins

Answer 9

Mainly active against gram+ with some gram - activity. Susceptible to b-lactamase, basically same as class one except ACID STABLE- can be taken orally unlike class 1. (Pen VK, amoxicillin, ampicillin)

Question 10

Groups of beta lactamases

Answer 10

Group 1) Cephalosporinases not well inhibited by clavulonic acid
Group 2) Penicillinases, cephalosporinases
and broad spectrum β-lactamases inhibited by some β-lactamase
inhibitors
Group 3) Metallo β-lactamases that are poorly inhibited by almost
all enzyme inhibitors
Group 4) Penicillinases not inhibited by clavulonic acid

Question 11

What can cause Amidase inhibition?

Answer 11

A bulky side chain that causes steric hinderance

Question 12

Penicillin G

Answer 12

Only one that can be taken via IV
Cannot be taken orally bc of poor absorption
Widely distributed in tissue
Peak plasma level in 30-60 min
T1/2 is 30 min, excreted via kidney

Question 13

Penicillin V

Answer 13

Same as pen G except good oral absorption and acid stable

Question 14

How are long acting penicillins given?

Answer 14

Procaine and benzathine penicillin given IM to delay absorption for longer duration (constant blood level over 28 days)

Question 15

When are long acting penicillins given?

Answer 15

Given to children as a prophylaxis for rheumatic fever and bacterial endocarditis

Question 16

Examples of semisynthetic penicillins and how they are diff from classic penicillin

Answer 16

Methicillin, oxacillin, cloxacillin; have bulky side chains that help with penicillinase resistance but aren’t used frequently bc the side chain can decrease bactericidal effect

Question 17

Ampicillin

Answer 17

Spectrum can include some gram- and enterococci
Acid stable and good oral absorption
Peak blood level in 2 hrs
T1/2 is 60 min
Can upset GIT

Question 18

How is amoxicillin diff from ampicillin?

Answer 18

Broad spectrum
Better absorption, so effective levels last longer
Less GI problems bc of greater absorption

Question 19

What is the most frequently used antibiotic for dental infection?

Answer 19

Penicillin V

Question 20

How is amoxicillin better than penicillin V?

Answer 20

Better pharmacokinetics and broader spectrum

Question 21

Alternatives in case of allergy to penicillin

Answer 21

Erythromycin or clindamycin

Question 22

How do NSAIDs and probenecid affect penicillin?

Answer 22

Increase serum half life by decreasing renal excretion