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Host and Defense San-D > Antimicrobials > Flashcards

Antimicrobials Flashcards

1
Q

microbobes in human body

A

100 trillion

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2
Q

weight of microbes in human body

A

1-3 lbs

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3
Q

bacterial genes and # human genes

A

3.3 million and

22,000

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4
Q

Antibiotic

A

low molecular substance produced by a
microorganism that inhibits or kills other microorganisms
while (ideally) causing little or no damage to itself.

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5
Q

Antimicrobial

A

any substance of natural (i.e.,
penicillin and alkaloids), semisynthetic (i.e., methicillin and
amoxicillin) or synthetic (i.e., sulfonamides and quinolones)
origin that kills or inhibits the growth of microorganisms while
(ideally) causing little or no damage to the host.

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6
Q

All antibiotics are antimicrobials

A

but not all antimicrobials are antibiotics

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7
Q

microorganisms drugs are active against

A

viruses, bacteria, fungal (antifungal/mycotic), protozoans (antiprotozoal), helminths (antihelmintic)

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8
Q

Classification

A

class and spectrum of microorganisms it effects

the biochemical pathway or target

chemical structure

***pattern of activity (type I,II,III)

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9
Q

Broad specturm

A

drugs are active against wide range * not the same as its useful therapeutic range

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10
Q

Narrow specturm

A

limited activity and primary only useful against particular species

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11
Q

Spectrum of activity

A

no antimicrobial is effective against all microbes, tetracycline have very broad spectrum, isoniazid has narrow specture

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12
Q

Clinical considerations before prescribing antimicrobial therapy (AMT)

A

be very careful, don’t guess! Culture and test, consider drug route and if effective

most effective, least toxic, narrowest spectrum, least expensive, patients immune status

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13
Q

ID the pathogen

A

collect and culture specimens, treatment should be ASAP for serious infections (Handbook of Antimicrobial Therapy HATs)

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14
Q

Disc diffusion test

A

Estimates minimal inhibitory conc (MIC) of antimicrobials

MIC is lowest conc of an antibiotic that will inhibit the growth of a bacterial stain

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15
Q

Broth dilution test

A

determines both MIC (no more turbidity) and MBC (minimum bactericidal conc) no more bacterial growth

Bactericidal antibiotics usually have very similar MIC and MBC values

Bacteristatic antibiotics have much higher (if any) MBC than MIC values.

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16
Q

Prophylactic

A

no infection

17
Q

Definitive

A

pathogen isolated

18
Q

Pharmacokinetics

A

absorption, distribution, metabolism, and excretion of drug

dosing regimen
serum conc

19
Q

Pharmacodynamics

A

he relationship of the drug concentration at the site of action and the resulting effects, including the time course and intensity of therapeutic and adverse effects.

conc in tissues and body fluids
- pharm and toxic effects

conc at infection site
- antimicrobial effect

20
Q

choosing a dose regimen

A

Must keep in mind that although MIC is compared to plasma
concentrations, these concentrations may or may not reflect drug concentration at site of infection.

want OVERKILL without causing toxicity

21
Q

Goals in dose regimen

A

GOAL #1: achieve a bactericidal concentration at the site.

GOAL #2: discourage emergence of resistant bacteria.

22
Q

Growth curve

A

log phase of bacterial growth is the most sensitive to antimicrobial intervention, want to target this

23
Q

Bacteriacidal vs Bacteriostatic drug growth curve

A

bacteriostatic plateaus and will increase if Rx stopped

bactericidal decreases log # of bacteria

Bactericidal antibiotics kill bacteria, while bacteriostatic antibiotics stop bacteria from growing or reproducing.

body still plays a role in removing last bit

24
Q

Antimicrobial Patterns

A

pharmacodynamic properties:
conc-dependence (I)
time-dependence (II)
time-dependence with persistent effects (III)

Rate of effect determined by II and III

25
Q

Persistant Post Antibiotic Effect (PAE)

A

provide suppression of bacterial growth following
antibiotic exposure. (Delayed regrowth of the bacteria after complete removal of an
antibiotic allowing less frequent dosing than with agents with no PAE )

26
Q

Drug conc v time graph

A

use area under cruve

27
Q

Treating Serious infections

A 
treat ASAP but still culture
use safest drug
Give max non-toxic dose
monitor plasma conc of drug
continue treatment for at least 2 days past apparent cure

ex. CNS infections, malaria, TB

28
Q

Selectivity

A

select for pathogen not host

When selectivity is high, the risk of adverse effects are reduced. However,
even highly selective antibiotics can have side effects.

The “ideal” AMT is defined by its specificity of action in host vs. bacteria.

29
Q

Therapeutic Index (TI)

A

ratio of dose toxic to the host to the effective therapeutic dose

the higher or wider the TI the better and safer

30
Q

Adverse Effects of AMT

A

Analogous to drug action: same effect on human cells as bacteria

Independent to drug action: irritation, allergy

31
Q

Absorbtion

A

Absorption critically determines the compound’s bioavailability. -  Route of administration is an important consideration (i.e., PO, IV, IM, IT)

32
Q

Distribution

A

lipid, water solubility, cross BBB?

Some antibiotics leave the brain by active transport via choroid
plexus (e.g., penicillin)

inflammation? can increase BBB leaky and things go out and in more easily

33
Q

Metabolism

A

usual clearance through liver and kidneys

immediately begin to metabolize by redox cytochrome p450 enzymes

can become more active after broken down to metabolites

inactivation by bacterial enzymes give one drug with another to prevent enzymes to break down

34
Q

Excretion

A

low potency for UTIs because they get more conc as they transport to urine

35
Q

Mechanisms of action of drugs

A

inhibit microbes

cell wall synthesis/permeability/function
protein synthesis
metabolic pathways
nuclei acid synthesis

36
Q

Combination therapy

A

Okay as long as not antagonistic

Too improve efficacy

For initial empiric therapy of uncharacterized serious infection.

To enable use of lower (i.e., less toxic) drug concentrations.

To delay emergence of resistance by avoiding the selection of naturally
occurring drug-resistant mutants

37
Q

Superinfections

A

Antimicrobial use can cause a wide-spread alteration of the microbial ecosystem

The current view is that nonpathogenic microbes interact with other bacteria to
control growth of pathogens as well as of harmless bacteria in our ecosystem

reducing the number of harmless microbes opens niches in the ecosystem

reducing the number of harmless microbes opens niches in the ecosystem

Host and Defense San-D (11 decks)

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