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First Semester: Principles of Infectious Disease > Lecture 3: Antiboitics > Flashcards

Lecture 3: Antiboitics Flashcards

1
Q

Definition of an antibiotic according to Waksmann

A

A chemical substance that is produced by microorganisms and that has the capacity in dilute solution to selectively inhibit the growth or kill other microorganisms

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2
Q

Modern definition of an antibiotic

A

any substance of natural, semisynthetic or synthetic origin that kills or inhibits the growth of microorganisms/bacteria but causes little or no damage to the host

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3
Q

Relationship between antibiotics and antimicrobials

A

All antibiotics are antimicrobials but not all antimicrobials are antibiotics

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4
Q

4 types of usage of antimicrobials in animals

A

Therapeutic
Prophylactic
Metaphylactic
Growth promotion

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5
Q

Therapeutic use

A

when diseased animals are treated to cure infection

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6
Q

Prophylactic use

A

when healthy herds or animals are treated to prevent infection

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7
Q

Metaphylactic use

A

when diseased herds are treated to cure infection in some individuals and prevent infection in others

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8
Q

Growth promotion use

A

when healthy animals are treated with low (sub-therapeutic) concentrations in feed to improve growth rate and efficiency of feed utilization, and improve reproductive performance

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9
Q

Most of the antimicrobial use in the US is for

A

Growth promotion use in livestock

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10
Q

6 Ways to Classify antibacterial agents

A
  1. Chemical structure
  2. Origin
  3. Effect on bacteria
  4. Spectrum of activity
  5. Mode of action
  6. PK/PD index
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11
Q

Three kinds of beta lactams

A
  • Penicillins
  • Cephalosporins
  • Carbapenems
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12
Q

Three origins

A

Natural
Semi-synthetic
Synthetic

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13
Q

Natural

A
  • Produced by fungi and bacteria

- Most common

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14
Q

Semi-synthetic

A
  • Chemically altered natural compounds
  • Modified to enhance activity of the drug
  • Either to increase or decrease toxicity
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15
Q

Synthetic

A

Chemically designed by man

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16
Q

Bactericidal

A

kills bacteria

17
Q

Bacteriostatic

A

inhibits growth of colonies but does not kill the cells

18
Q

Three determinants of whether a drug may be bacteriostatic or bactericidal

A
  • Drug concentration
  • Presence of other drugs
  • Bacterial species
19
Q

Narrow spectrum durgs

A

have activity restricted to few bacterial groups

20
Q

Broad spectrum drugs

A

have activity against a wide range of different bacterial organisms

21
Q

Spectrum assessment

A
  • Assessed before drug marketing in the Summary of Product Characteristics (SPC)
  • May change over time as a consequence of drug use and resistance development
22
Q

Three main ways to classify according to mode of action

A
  • Cell wall synthesis
  • Folic acid metabolism
  • Protein synthesis inhibitors
23
Q

Three PK/PD indices

A
  1. Time over MIC
  2. Cmax/MIC
  3. AUC/MIC
24
Q

Time over MIC

A

The time that the drug concentration at the site of infection is higher than the minimal inhibitory concentration

25
Q

Cmax/MIC

A

The ratio of the peak drug concentration at the site of infection to the MIC

26
Q

AUC/MIC

A

The ratio of the “area under the (concentration-time) curve” over 24 hours to the MIC

27
Q

MIC

A

The lowest concentration of the drug that inhibits the bacteria completely

28
Q

Time dependent antibiotics

A
  • Index: Time over MIC
  • Most effective if their concentration is maintained above the MIC as long as possible (at least 50% of dosing interval for beta-lactams).
  • An increase in concentration more than 4 times MIC does not influence efficacy
29
Q

Concentration-dependent antibiotics

A

Most effective if they reach a high concentration compared to the MIC at the site of infection, while the time they maintain this concentration is less important

30
Q

In order to maximize clinical efficacy, what dose do you use for concentration-dependent drugs?

A

High

31
Q

In order to maximize clinical efficacy, what dose do you use for time-dependent drugs?

A

Regular dose intervals

First Semester: Principles of Infectious Disease (22 decks)

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