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Cology 2 Exam 2 > "And the rest" of the Protein synthesis inhibitors > Flashcards

"And the rest" of the Protein synthesis inhibitors Flashcards

1
Q

How does Chloramphenicol work?

A

Binds 50s subunit

Inhibits bond formation between peptide and new amino acids (Inhibits peptidyltransferase)

Binding is reversible!

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2
Q

What is the first synthetic antibiotic?

A

Chloramphenicol

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3
Q

Is chloramphenicol bacteriocidal or bacteriostatic?

A

Mostly bacteriostatic

It’s bacteriocidal in H influenzae, strep pneumoniae, and neisseria meningitidis

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4
Q

Use of chloramphenicol is limited to what? Why

A

Use is limited due to toxicity

Use is limited to meningitis and rickettsial infections in patients who can’t take safer drugs because of reisstance or allergies

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5
Q

What causes chloramphenicol resistance?

A

Plasmid encoded acetyltransferase prevents binding to the ribosome

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6
Q

True or False: Chloramphenicol enters the CNS

A

True

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7
Q

True or False: Chloramphenicol is safe in pregnancy

A

False

Enters both breast milk and placenta

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8
Q

What toxicities are associated with chloramphenicol?

A 
Lots!
Bone marrow suppression (can be fatal) - aplastic anemia, leukopenia, thrombocytopenia
Altered red blood cell maturation
Peripheral neuropathy
Inhibits microsomal enzymes
Hypersensitivity reactions
Inhibits CYP enzymes
nausea, vomiting, diarrhea, blurring of vision
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9
Q

How do Streptogramins work?

A

Bind the 50S subunit

Dalfopristin prevents peptide bond formation (inhibits peptidyltransferase, causes early termination)
This changes the 50s subunit to enhance quinupristin binding
Quinupristin inhibits t-RNA synthesis (inhibiting elongation, causing early termination)

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10
Q

What is streptogramins?

A

Combination product of Dalfopristin (group A) and Quinupristin (Group B)

30 Dalf
70 Quin

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11
Q

Is streptogramins bacteriostatic or bacteriocidal?

A

The individual agents are bacteriostatic

When given in combination, they’re bacteriocidal

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12
Q

What causes resistance in streptogramins?

A

Quinupristin: Altered ribosomal binding
Dalfopristin: Increased metabolism

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13
Q

What is streptogramins used for?

A

vancomycin resistant e. faecium

NOT active against faecalis

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14
Q

How is streptogramins administered?

A

IV infusion

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15
Q

What toxicities are associated with streptogramins

A 
Inflammation of the veins
Muscle aches
Diarrhea, nausea
Inhibits CYP3A4
Elevates serum transaminase
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16
Q

Which drug elevates serum transaminase

A

Streptogramins

17
Q

Which drug causes veinflammation

A

Streptogramins

18
Q

What drugs are replacing Streptogramins?

A

Linezolid and Daptomycin

19
Q

What is linezolid?

A

An oxazolidinone

20
Q

How does Linezolid work?

A

Binds the P site of the 50s subunit, preventing formation of the 70s unit

Inhibits binding of the met-tRNA

21
Q

What is Linezolid used for?

A

Nosocomial pneumonia by:
MRSA
S Aureus
S Pneumoniae

Also skin and skin structure infections (MRSA resistant and sensitive)

Reserved for MULTIPLE-DRUG-RESISTANT strains

22
Q

How is Linezolid administered?

A

Oral and IV formulations

23
Q

How is Linezolid excreted?

A

Metabolized by non-enzymatic oxidation

24
Q

True or False: There is no resistance to linezolid

A

False, thought to have no resistance but has started showing resistance

25
Q

What toxicities are associated with Linezolid

A 
Nausea
Thrombocytopenia, anemia, leukopenia
Itching
Non-selective MAO inhibitor
Peripheral neuropathy
26
Q

What is Mupirocin?

A

Topical cream/ointment

27
Q

How does Mupirocin work?

A

Inhibits Isoleucyl-tRNA synthase only

Prevents incorporation of isoleucine into proteins only

No cross tolerance with other antibiotics

Can still make peptides that don’t have isoleucine!

28
Q

True or false: Mupirocin shows no cross tolerance with other antibiotics

A

True

29
Q

Is mupirocin bacteriocidal or bacteriostatic?

A

Bacteriostatic at low concentrations

Cidal at higher

30
Q

What is Mupirocin used for?

A

Traumatic skin lesions (Impetigo, s aureus, streptococcus pyrogens)

or nasal colonization with Methicillin resistant s. aureus

31
Q

What drug is used to treat nasal colonies of MRSA?

A

Mupirocin

Cology 2 Exam 2 (18 decks)

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