Antibiotic Lecture Part 1

Question 1

Define Narrow Spectrum

Answer 1

Antibiotics that are only effective against a SMALL number of bacteria

Question 2

Define Broad Spectrum

Answer 2

Effective against MANY bacteria

Question 3

Give examples of both a narrow spectrum and broad spectrum antibiotic

Answer 3

Narrow: Penicillin
Broad: Tetracycline

Question 4

Define Bactericidal:

Answer 4

Antibiotic has the ability to KILL bacteria

Question 5

Define Bacteriostatic:

Answer 5

Antibiotic inhibits bacterial growth or slows the growth

Question 6

What is Antibiotic Antagonism:

Answer 6

When 2 antibiotics are used together, one antagonizes the effect of the other

Question 7

T or F, Never combine a bactericidal antibiotic with a bacteriostatic antibiotic in the same person

Answer 7

True

Question 8

T or F, Bactericidal antibiotic will inhibit or diminish the effects of Bacteriostatic antibiotic

Answer 8

False, Bacteriostatic will inhibit effects of Bactericidal

Question 9

If tetracycline and penicillin are given together, which will NOT be effective?

Answer 9

Penicillin will NOT be effective. This is because it is a bactericidal antibiotic

Question 10

T or F, Not all antibiotics are bacteriostatic

Answer 10

False, ALL are bacteriostatic (depending on dose)

Question 11

T or F, All antibiotics are bactericidal at therapeutic doses

Answer 11

False, NOT all

Question 12

What is Minimum Inhibitory Concentration

Answer 12

A test used to determine bactericidal concentration of an antibiotic

Question 13

T or F, Theoretically, all antibiotics are bactericidal, but the dose to achieve bactericidal effects would be so high that it would kill the patient

Answer 13

True

Question 14

Define Antibiotic Synergism:

Answer 14

Occurs when 2 antibiotics work together for a more positive effect when given to the same patient

Question 15

What five steps are used to choose an antibiotic

Answer 15

1. Identify the microorganism
2. Determine the most effective antibiotic against that organism
3. Choose an antibiotic with low host toxicity
4. Choose a bactericidal antibiotic
5. Choose an antibiotic with low resistance potential

Question 16

Is it a good thing to try and identify the microorganism in the mouth?

Answer 16

Not really efficient clinically, in normal healthy ambulatory population, the predominant microorganism in the oral cavity is going to be gram positive strep or staph. 90-95% of the time. Without even taking a culture, we know that the oral infection is most likely a gram positive strep or staph

Question 17

What is the most effective antibiotic against gram positive strep or staph?

Answer 17

Penicillin

Question 18

What is the least toxic antibiotic

Answer 18

Penicillin

- Cannot kill the host at ANY concentration

Question 19

T or F, 10% of the population is allergic to penicillin but it is not toxic to them.

Answer 19

True

Question 20

Why do we try to choose a bactericidal antibiotic?

Answer 20

If a patient has an infection, it drains their resistance and disability to fight off other infections. An antibiotic kills bacteria so we don’t have to rely on the patient’s defense mechanisms.

Question 21

When choosing antibiotic with low resistance potential, what are 4 ways that we minimize resistance:

Answer 21

1. Give an adequate dose
2. Take for an adequate duration
3. Avoid repeated administration
4. Avoid topical administration

Question 22

T or F, Is it ok to give patients a lower dose of antibiotics just in case they are allergic to prevent the patient from going into anaphylactic shock

Answer 22

False, Remember that allergic reactions are NOT dose dependent

Question 23

T or F, Do not give patients same antibiotic week after week

Answer 23

True, Bacteria develop mechanisms to become resistant

Question 24

Sulfa Drugs are indicated for what use?

Answer 24

Used primarily for urinary tract infections (UTI)

• No indications for use in dentistry

Question 25

What was the first antibacterial agent?

Answer 25

Sulfanilamide

Question 26

Mechanism of action of penicillins

Answer 26

Blocks bacterial cell wall synthesis by interfering with structural glycopeptides - Bacterial cell death results from lysis

Question 27

What is penicillinase?

Answer 27

Is a beta lactamase that breaks down the beta lactic ring of the penicillin molecule. Without an intact beta lactic ring, penicillin is ineffective: drug cannot inhibit bacterial cell wall synthesis

Question 28

T or F, 99% of the normal, healthy ambulatory population does not have penicillinase-producing microorganisms

Answer 28

True

Question 29

How are natural pencillins (penicillin G) administered?

Answer 29

Given parenterally | - They are incomplete and variable due to destruction by gastric juices when given orally

Question 30

How are semi-synthetic (penicillin V) administered?

Answer 30

Orally | - More acid stable, therefor more uniform absorption

Question 31

How much of an oral dose of penicillin is secreted within the first 4 hours?

Answer 31

70% of an oral dose

Question 32

T or F, Penicillin molecule excreted unchanged?

Answer 32

True

Question 33

How much of penicillin is excreted from the body via active transport?

Answer 33

90% | -10% passive transport

Question 34

What is probenecid?

Answer 34

A medication used to treat gout | - Also called Benemid

Question 35

How is probenecid used with penicillin?

Answer 35

It is used to slow the excretion of penicillin. It competes with the penicillin molecule for the active transport mechanism. probenecid has a greater affinity for the carrier than penicillin does. So if probenecid is given before penicillin is given, the penicillin is not excreted as rapidly

Question 36

probenecid elevates the blood level of penicillin how much?

Answer 36

3-4 times; prolongs the effect of the penicillin

Question 37

What are the two indications of Penicillins?

Answer 37

1. Orofacial infections - penicillin is drug of choice | 2. Prophylactic use - prevention of bacterial endocarditis and of infections around prosthetic joints and devices

Question 38

What was the first penicillin produced?

Answer 38

Penicillin G - Only natural penicillin available commercially Narrow spectrum

Question 39

What is the indication of penicillin G

Answer 39

in Treatment of STDs

Question 40

What is the advantage of Procaine Penicillin G = repository form

Answer 40

The penicillin escapes at a slower rate out of the oil after injection It is released over a 12-24 hour period

Question 41

What is the indication for Procaine penicillin G = respiratory form

Answer 41

- Infections with Treponema palladium | - Anthrax

Question 42

What is the advantage of Benzathine Penicillin G = repository form

Answer 42

Produces therapeutic blood levels that last for 3 weeks. | - Doesn't reach the peak level that is obtained with the aqueous form of penicillin G

Question 43

What is the brand name for Benzathine Penicillin G?

Answer 43

Bicillin

Question 44

Primary indication for Bicilin or Benzathine penicillin G?

Answer 44

STDs

Question 45

What was the first semi-synthetic penicillin

Answer 45

Penicillin V

Question 46

Sodium penicillin V is an improved version of penicillin G why?

Answer 46

Because it is acid stabile | - It can be taken orally

Question 47

How is Penicillin V best bioavailable?

Answer 47

It was first combined with sodium but later was determined that it has better bioavailability when it was in the potassium form - Now, all forms of penicillin V are going to be in potassium form

Question 48

T or F, Never write a prescription for penicillin VK

Answer 48

True, Just write it for penicillin V | - If you write the prescription for penicillin VK, the pharmacist has to fill the prescription with that brand name drug

Question 49

``` Penicillin V: Bactericidal or Bacteriostatic Broad spectrum or Narrow spectrum Acid stabile or incomplete Penicillinase labile? ```

Answer 49

- Bactericidal - Narrow spectrum - Acid stabile - Penicillinase labile

Question 50

T or F, CDC says that when you are treating an infection, you must use the most broad spectrum antibiotic so that all bacteria will be killed

Answer 50

False, Narrow spectrum that is available for that particular infection

Question 51

When are penicillinase-resistant penicillins used?

Answer 51

Only used if the patient has an infection caused by penicillinase-resistant microorganisms

Question 52

What 4 reasons must you consider in not using penicillinase-resistant drugs

Answer 52

1. Promotes resistant microorganisms 2. More expensive 3. More toxic 4. Not as effective as penicillin V