Antibiotics Flashcards

0
Q

50S inhibitors

A

Linezolid, macrolides, chloramphenicol, clindamycin, quinupristin/dalfopristin

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1
Q

30S inhibitors

A

Amino glycosides and tetracycline

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2
Q

Blocks initiation

A

Linezolid, amino glycoside

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3
Q

Blocks elongation

A

Amino glycosides, tetracycline, macrolides, chloramphenicol, clindamycin, quinupristin/dalfopristin

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4
Q

Blocks termination

A

Amino glycoside

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5
Q

Mitochondrial ribosomes

A

Linezolid, tetracycline, chloramphenicol

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6
Q

Linezolid binds what part of ribosome

A

P site on 50S

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7
Q

Oxazolidinones

A

Mech: binds 23S RNA on 50S unit prevents forming of initiation com
Spec: gram+, MRSA and vanco resistant enterococci
Resis: alterations in 23 rRNA
AdvE: bone marrow suppression, serotonin syndrome if taken with SSRI, hallucinations, increased heart beat, nausea. Linezolid

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8
Q

Gentamicin amikacin tobramycin

A

Amino glycosides - bactericidal mech: prevents formation of initiation complex, causes misread mRNA, induces early termination
Spec: gram neg aerobes (in combo)…intrinsic resis- can’t enter cell = treat with cell wall inhibitor, acquire resis - enzymes that inactivate drugs…amikacin is special to pseudomonas

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9
Q

Mechanisms of amino glycosides

A

Blocks initiation of synthesis
Blocks further translation and elicits premature termination
Incorporates incorrect amino acid
Creates fissures in cell membrane

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10
Q

Side effects of amino glycosides

A
Tubular necrosis: nephrotoxicity- drug held in renal cortex (reversible)
Ototoxicity - vestibular and auditory dysfunction (irreversible)
Pregnancy class D  - hearing loss in fetus
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11
Q

Important facts of amino glycosides

A

Poor absorption - usually administered through IV

Polar and excluded from CSF

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12
Q

Concentration dependent killers

A

Amino glycosides and fluoroquinolones

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13
Q

Time dependent killers

A

Vancomycin and beta lactams

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14
Q

Tetracycline mechanism

A

Prevents attachment of tRNA to A site bacteriostatic

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15
Q

Chloramphenicol mechanism

A

Inhibits peptide bond formation

16
Q

Mechanism of macrolides streptotagims and clindamycin

A

Inhibit translocation (tRNA moving from A site to P site)

17
Q

The tetracyclines

A

Tetracycline doxycycline and minocycline

18
Q

Spectrum of tetracycline

A

Broad at first but due to resistance

B. burgdorferi, h. Pylori, mycoplasma pneumoniae

19
Q

Resistance of tetracycline

A

Intrinsic - decreased uptake

Acquired - increased efflux, alteration of ribosome target, rarely enzymatic inactivation of drug

20
Q

Adverse effects of tetracycline

A

Chelates with metal ions decreases absorption
GI irritation and photosensitive
Discoloration of teeth and inhibits bone growth in children
Don’t use during pregnancy class D

21
Q

What is drug persistence? And what bacteria displays this?

A

Shifts between different genetically homogenous forms depending on presence of drug
Borrelia burgdorferi

22
Q

Spectrum of chloramphenicol

A

Extended but limited due to severe side effects

23
Q

Resistance to chloramphenicol

A

Acetyltransferase modifies drug to prevent binding to ribosome

24
Q

Adverse effects of chloramphenicol

A

TOXIC. Bone marrow depression. Aplastic anemia. Gray baby syndrome

25
Q

Gray baby syndrome

A

Premature infants lack enzyme UDP-glucuronyl transferase and have decreased renal function so high levels of the drug accumulate which can lead to cardiovascular and respiratory collapse

26
Q

Macrolides, what are they and the mechanism?

A

Erythromycin, azithromycin and clarithromycin
Bacteriostatic
Inhibit translocation by binding 23S rRNA of the the 50S subunit

27
Q

Spectrum of macrolides

A

Broad coverage of respiratory pathogens

Chlamydia (single dose)

28
Q

Atypical pneumonia - what causes it and treatment?

A

Mycoplasma pneumonia
Treat with doxycycline, azithromycin, levofloxacin
Beta lactams are not effective

29
Q

Resistance to macrolides

A

Methylation of 23S rRNA binding site (associated with clindamycin and quinupristin/dalfopristin resistance)
Increased efflux
Hydrolysis of macrolides by esterases

30
Q

Adverse effects of macrolides

A

GI
Liver failure, prolonged QT interval
Inhibitors of cyp450 enzymes
Clarithromycin is not safe during pregnancy

31
Q

Mechanism and spectrum of clindamycin

A

Bacteriostatic - blocks translocation of at 50S ribosomal subunit

Gram positive anaerobic….treat ance

32
Q

Resistance and adverse effects of clindamycin

A

Mutation of ribosome, methylation of rRNA…cross resistance with macrolides and inactivation by adenylation
Hypersensitivity - rash and fever
Diarrhea, abdominal pain, mucus and blood in stool
Superinfection with C. difficile

33
Q

Streptogramins - what are they and what is their mechanism

A

Quinupristin/dalfopristin

Combined action can be bactericidal
Bind 50S to inhibit translocation

34
Q

Spectrum of quinupristin/dalfopristin

A

For infections of multiple drug resistant gram positive bacteria

35
Q

Resistance of quinupristin/dalfopristin

A

Ribosomal methylase prevents binding of drug to its target
Enzymes can inactivate the drugs
Efflux of proteins that put them out of the cells
Cross resistance with macrolides and clindamycin

36
Q

Adverse effects of quinupristin/dalfopristin

A

High incidence including arthralgias, myalgias

Inhibits cyp450 enzymes and likely to have significant drug-drug interaction