Walworth - Antibiotic Use

Question 1

Selective Toxicity

Answer 1

Bacteria have certain structures that we don’t so we target those differences for therapeutics.

Question 2

Susceptible vs resistant

Answer 2

S - concentration of drug can be achieved at site of infection that inhibits organism and is below level of toxicity for human cells. - this microbe will die
R - inhibitory or bacteriocidal concentration exceeds that which can be achieved safely. - this microbe will live

Question 3

Therapeutic index

Answer 3

Toxic Dose / Effective Dose

• So for instance a toxic dose might be the dose required to illicit a toxic affect whereas the effective dose is the dose required for a therapeutic affect. The therapeutic index is the ratio of these two, which basically tells us how many times you need to take the med to see a bad outcome due to overdose.

Question 4

Bacteriostatic vs bactericidal

Answer 4

Bacteriostatic - inhibits growth but does not kill bacteria

Bactericidal - reduces number of bacteria in the population by killing them.

Question 5

MIC vs. MBBC

Answer 5

MIC - minimal inhibitory concentration. It is the minimal amount of the drug that you must give in order for there not to be growth. We usually do a dilution test for this.

MBC - Minimal bactericidal concentration. It is the minimal dosage of the drug that you can give and still kill all of the bacteria. This is usually done it’s an agar test with no anti-bacteria on it, but we take the stuff from the dilution test.

Question 6

3. Main types of anti-microbial. Therapy

Answer 6

Prophylactic
Empiric
Definitive

Question 7

Prophylactic therapy

Answer 7

To prevent colonization or infection by any or all microorganism a in the environments of a patient.
- ex is rifampin to prevent meningococcal meningitis in people who were in close contact with infected people.

Question 8

Emperic therapy

Answer 8

Cover all likely pathogens because infecting organism has yet to be determined.

• use a single broad-spectrum agent or sometimes combination therapy.
• requires knowledge of most likely infecting organisms and their susceptibilities.

Question 9

Definitive therapy

Answer 9

Once infectious organism has been identified and susceptibility determined.

Question 10

when is combination therapy utilized?

Answer 10

• to prevent resistance to 1 drug.
• treatment of polymicrobial infections
• empirical therapy
• enhance antimicrobial activity for specific infection.
• reduce toxicity

Question 11

Different responses within combination therapy

Answer 11

Synergistic - one drug affects bug such that it is more sensitive to inhibitory action of another drug

Additive - drugs work independently of each other

Indifferent - combination is no better than just the individuals.

Antagonistic - combination less effective than individuals.