Chapter 13- Antibiotic therapy Flashcards

1
Q

Antibiotics (antibacterial) are a).. to bacteria without toxicity to eukaryotic organisms

A

Selectively toxic

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2
Q

What types of organisms do antibiotics effect?

A

antibacterial, antiprotozoal. antifungal and antiviral

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3
Q

spectrum of activity.

Penicillin has a a)… spectrum

A

narrow (GRAM + bacteria)

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4
Q

spectrum of activity.

Ampicillin has a a).. spectrum

A

broad (GRAM - and GRAM + bacteria)

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5
Q

What is the magic bullet concept?

A

an antimicrobial agent capable of selective destruction of pathogenic microorganisms.

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6
Q

spectrum of activity.

Isoniazid has a a)… spectrum.

Isoniazid aims at what type of bacteria?

A

a) very narrow
b) Mycobacterium tuberculosis. (mycolic acid)

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7
Q

bactericidal antibiotics do what

A

kill pathogens

good for immunocompromised

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8
Q

bacteriostatic do what

A

prevent or slow bacterial growth, which enables immune response to get rid of pathogen.

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9
Q

selective toxicity

A

The ability of a drug, at a given dose, to harm a pathogen without harming its host.

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10
Q

despite bacteria selectivity, abx’s still a)..

A

a) have unintended side effects

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11
Q

four unintended side effects of selective toxic antibacterials

A

-age dependent (toxicity depending on age)
-cell development (interferes with RBC in bone marrow)
-metabolism dependant (excreted/metablolized by kidney and liver)
-allergy (sensitivity)

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12
Q

The in vitro effectiveness of an antibiotic is determined by measuring what?

A

how little of it is needed to stop growth

minimum inhibitory concentration (MIC),

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13
Q

minimum inhibitory concentration (MIC), is defined as the?

A

lowest concentration of the drug that will prevent the growth of an organism

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14
Q

Kirby-Bauer assay

A

A method for determining antibiotic susceptibility.

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15
Q

zone of inhibition

A

A region of no bacterial growth on an agar plate owing to the diffusion of a test antibiotic

correlates to MIC

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16
Q

What is the flaw with Kirby-Bauer assay and tube dilution?

A

You can not tell if a drug is bactericidal because you can not tell if the cells within the zone of inhibition are dead or remain viable and just stopped growing.

17
Q

minimum bactericidal concentration (MBC) is defined as a)..

A

a) The lowest concentration of a abx that kills bacteria

requires futher plating to determine if any cells survived.

18
Q

For an antibiotic to stop bacterial growth in the patient, the drug’s concentration in tissue must a)..

A

remain higher than the MIC at all times.

19
Q

The half life of a drug tells us what?

A

How long a drug will remain in the tissues.

20
Q

To keep a drug level within the sufficient range, the clinician can do what?

A

Administer a higher dose (risk of SE)
or
Schedule mutiple doses to keep drug levels above lab determined MIC

21
Q

therapeutic dose

A

Minimum dose per kg of body weight that stops growth

22
Q

Toxic dose

A

Maximum dose tolerated by the patient

23
Q

The ratio of the toxic dose to the therapeutic dose

A

chemotherapeutic index

24
Q

The higher the chemotherapeutic index

A

the safer the drug

25
synergisitic drugs
have greater effectiveness when used together (1+1=3) | example: aminoglycoside and vancomycin
26
Antagonist drugs
intere with each other and decrease effectiveness | example: penicillin and macrolides
27
What are the three ways of classifiying antibacterial agents?
1. bactericidal or bacteriostatic 2. target site 3. chemical structure
28
What antibiotics are metabolic inhibitors? | intermediary metabolism
Sulfonamides Trimethoprim Metronidazole
29
What abx are protein synthesis inhibitors Larger subunit (50S) and Small subunit (30s)
50s= macrolides (erythromycin) 30s= aminoglycosides (gentamicin)
30
what abx affects cell membrane integrity?
Polymyxins
31
What abx affect cell wall synthesis | cell wall inhibitor
penicillins, cephalosporins, vancoymycin, bacitracin, monobactams.
32
what abx effects mycolic acid synthesis?
Isoniazid
33
what abx effects DNA replication
Quinolones
34
What abx affects transcription? | RNA polymerase inhibitors
Rifampin and myxopyronins, fidaxomicin
35
Antibiotics targeting the cell wall biosynthesis generally only kill
growing cells
36
enzymes that produce peptide cross links in peptidoglycan
penicillin-binding proteins,
37
beta-lactam abx
penicillin and related abx bind to them
38