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Microbiology > Unit 8 Antimicrobial Chemotherapy > Flashcards

Unit 8 Antimicrobial Chemotherapy Flashcards

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Biology 101 flashcards
1
Q

Antimicrobial activity is the ability to

A

Produce the death of the organism
Or
Prevent the development and multiplication of microorganisms

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2
Q

Antimicrobial

A

Substance with Antimicrobial activity that can be used for the treatment of infectious diseases because of its effectiveness and lack of toxicity

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3
Q

Categories Antimicrobial

A

Antibacterial
Antiviral
Antifungal
Antiparasitic

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4
Q

Selective toxicity

A

Harms the microorganisms but not the human cells

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5
Q

Therapeutic target

A

The structures we target in order to kill a microorganism like it’s fundamental structures

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6
Q

Characteristics we aim for Antimicrobial

A

Minimum toxicity for the host
Active at low concentration
Antimicrobial activity

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7
Q

Narrow spectrum

A

Selectively active on some species

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8
Q

Broad spectrum

A

Active against large number of microorganisms

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9
Q

Bacteriostatic

A

Inhibit the growth of microorganisms

The performance of the patient’s defense mechanisms in essential here

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10
Q

Bactericidal

A

Kills the microorganisms
Depends on the concentration, if it’s low it could be static

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11
Q

Mechanism of action

A

The specific biochemical interaction through which an antimicrobial produces its pharmacological effect.

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12
Q

Why an antibiotic might not work against a bacteria

A

Depends on the structure of the bacteria and the mechanism of action

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13
Q

Mode of action of B-lactam

A

Bind to the proteins PBP involved in cell wall synthesis

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14
Q

Efficacy of antibiotics depends on

A

A target for the antibiotic must exist

Antibiotic shouldn’t be inactivated or modified

Sufficient amount of antibiotic must reach the target

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15
Q

Two types of antibiotic resistance

A

Intrinsic : possessed by all the bacteria of a specie by innate genetic characters.

Acquired : by certain individuals of a specie due to chromosomal mutations, selective pressure or horizontal transmission

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16
Q

How is the resistance of an antibiotic passed to the whole population

A

-Horizontal transmission
-selective pressure
-mutation
and selection by the use of antibiotics by killing the sensitive population and leaving the mutant

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17
Q

Antibiotic resistance by inactivation : 3 mechanisms

A

Hydrolysis
Transference of a chemical group
Reduction/oxidation

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18
Q

Resistance by modification of the target exemples

A

Alteration of peptidoglycan structure
Modification of PBPs

Interference with protein synthesis
Mutation in rRNA

Interference with DNA synthesis (mutation in gyrase and topoisomerase)

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19
Q

Resistance by active efflux pump

A

Expel antibiotics outside of the cell
Different level of specificity
Can affect all classes of antibiotics
Produce a low level resistance

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20
Q

Reduction of permeability
Can generate resistance to what

A

Affects the transport through the outer membrane

Due to changes in the number, size or specificity of the porins

Can generate resistance to hydrophilic b-lactam and fluoroquinolone

Low level resistance

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21
Q

Mechanisms of bacterial resistance

A

Modification of the target
Reduced permeability to antibiotics
Active efflux pump
New metabolic pathways
Enzymatic inactivation

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22
Q

The mechanisms of resistance to b-lactam antibiotics are

A

Destruction by b-lactamase
Modification of the target PBPs, no recognition
Reduction of permeability
Efflux pumps

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23
Q

How do b-lactamase works
When is it the most effective

A

Break the b-lactam ring. More effective in gram- because Periplasmic space is bigger

24
Q

Enterobacteriaceae (type of b-lactamase)

A

TEM 1
Extended spectrum b-lactamase
Carbapenemase

25
Q

TEM 1

A

Resistance to penicillin only

26
Q

Extended spectrum b-lactamase ESBL

A

Resistance to penicillin and cephalosporin of all generations

27
Q

Carbapenemase

A

Against all b-lactam including carbapeneme

28
Q

B-lactamase inhibitors

A

Irreversible binding to b-lactamase.
Combined with some penicillin

Exemple:
Clavulanic acid
Sulbactam
Tazobactam

29
Q

Resistance to macrolides

A

Target modification (ribosomes)
Active efflux pumps
Enzyme inactivation

30
Q

Ribosomes modification

A

Methylation of 23S ribosomal RNA fraction

Change in ribosomal proteins

31
Q

Resistance to quinolone

A

Modification of targets : gyrase and topoisomerase
Pumps

32
Q

Antibiogram/sensitivity test function

A

Determine the resistance of a bacteria to a type and a quantity of antibiotic

33
Q

Two types of antibiograms

A

Disk plate diffusion
Dilution technique

34
Q

Disk plate diffusion

A

Bacteria classified resistance according to the inhibition area measured in mm

35
Q

Dilution techniques

A

In a liquid medium, specific concentration of bacteria and drug.
To determine the minimum concentration of antibiotic required to inhibit growth MIC

36
Q

Agar diffusion

A

In a plate, band with progressive concentration of antibiotics

37
Q

Types of dilution techniques

A

Agar diffusion
Micro broth dilution
⚪️⚪️⚪️⚪️
⚪️⚪️⚪️⚪️

38
Q

Classification resistance bacteria

A

Susceptible ( using standard dosing regimen )
Susceptible when exposure is increased/ intermediate (dosing regimen is increased )
Resistant

39
Q

Dosing regimen

A

Frequency and dose at which a drug is administered

40
Q

Exposure depends on

A

Dose, dosing intervals, infusion time, mode of administration, excretion of the drug

41
Q

MIC

A

Minimum inhibitory concentration

42
Q

To set the susceptibility of an antibiotic, 3 data are collected

A

The range ( lowest MIC- highest MIC)
MIC50 : MIC that inhibits at least half of the bacteria

MIC90 : MIC that inhibits at least 90%

43
Q

Undesirable effects of antibiotics in the patient

A

Target also exists in the host
Toxic side effect unrelated to the mechanism of action
Hypersensitivity
Kills normal microbiota

44
Q

Association of antibiotics function

A

Increase intensity of action
Extension of spectrum
Systemic infections
Prevent emergence of resistance ( some microorganisms have several mechanisms of resistance)

45
Q

Interaction between antibiotics

A

Additive effect
Synergistic effect
Antagonistic effect

46
Q

Disadvantages of association of antibiotics

A

Possible increase of toxicity
Possible antagonism

47
Q

Addition

A

Actions are added with no increase in the sum effect
Independent

48
Q

Synergy

A

Action of antibiotic together is better than separately

49
Q

Antagonism

A

The association in less effective

50
Q

Prophylaxis

A

Treatment given in advance to prevent disease

51
Q

When to prescribe antibiotics

A

Prophylaxis
Treatment of bacterial infections

52
Q

What are the criteria to consider when prescribing antibiotics

A

Bacteria involved
Patient
Antibiotic dosage, administration route…

53
Q

What to keep in mind when prescribing antibiotics

A

Side effects
Respect treatment dose and duration
Associations

54
Q

Antibiotics in dentistry

A

Oral flora in abundance
Most dental infections are polymicrobial
Involvement of anaerobes

55
Q

Microorganism has several mechanism of resistance

A

Emergence of resistance

Microbiology (12 decks)

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