Streptogramin Antibiotics and Oxazolidinone Antimicrobial Agents Flashcards Preview

Pharmacology Test #2 > Streptogramin Antibiotics and Oxazolidinone Antimicrobial Agents > Flashcards

Flashcards in Streptogramin Antibiotics and Oxazolidinone Antimicrobial Agents Deck (28)
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1
Q

Synercid is a mixture containing?

A

30% quinupristin and 70% dalfopristin

2
Q

Are quinupristin and dalfopristin useful on their own?

A

No, each of these compounds is bacteriostatic alone, but bactericidal in combination

3
Q

Dalfopristin MOA

A

directly interferes with the peptidyl transferase-catalyzed step

4
Q

What reaction does peptidyl transferase (ribosomal RNA) catalyze?

A

catalyzes the formation of a peptide bond between the two amino acids present in the ribosome

5
Q

Quinupristin MOA

A

binds in the ribosomal tunnel and causes blockage of the tunnel

6
Q

Syncercid is used IV for treatment of:

A
  1. Vancomycin-resistant Enterococcus faecium bacteremia
  2. Skin infections caused by MRSA
  3. Vancomycin-resistant Enterococcus faecium urinary tract infections
7
Q

Most common resistance to quinupristin is due to?

A

adenine methylation of A2058 in the 23S rRNA as in the case of erythromycin and clindamycin

8
Q

What can resistance to Streptogramin also be caused by?

A

resistance can also be due to efflux and enzymatic inactivation (metabolism) by resistant bacteria

9
Q

What is Streptogramin likely to be reserved for?

A

reserved for serious life-threatening infections caused by gram (+) organisms

10
Q

Mild side effects of synercid?

A

inflammation and pain at the site of injection, nausea, diarrhea, muscle weakness and rash

11
Q

Drug interactions of Streptogramins

A

Streptogramins inhibit cytochrome CYP3A4

12
Q

CYP3A4 metabolizes

A

warfarin, diazepam, astemizole, terfenadine, cisapride, non-nucleoside reverse transcriptase inhibitors and cyclosporine

13
Q

Oxazolidinones are a novel class of antimicrobials that act by

A

inhibiting protein synthesis

14
Q

MOA of linezolid?

A

acts early by potent interaction with 50S ribosomal subunit

15
Q

In the initiation step of bacterial translation, the 50S subunit associates with?

A

associates with fMet-tRNA and a complex composed of the 30S ribosomal subunit and mRNA to form the functional 70S initiation complex

16
Q

What does linezolid have affinity for?

A

the 50S subunit - no affinity to the 30S subunit

17
Q

Linezolid interaction with the 50S subunit does what?

A

prevents the formation of the 70S initiation complex

18
Q

Which rRNA does linezolid specifically interact with?

A

the 23S rRNA

19
Q

Linezolid is used to treat:

A
  1. Vancomycin-resistant Enterococcus faecium
  2. Nosocomial pneumonia caused by methacillin - resistant strains of Staphylococcus aureus
  3. Skin infections caused by methicillin-resistant strains of Staphylococcus aureus
20
Q

Emergence of linezolid resistant has been reported in which species?

A

Enterococcus species, MRSA, and E. coli

21
Q

Other mild reported side effects of linezolid?

A

headache, tongue discoloration and oral Monilia (Candida) infections

22
Q

More serious side effects of linezolid?

A

thrombocytopenia, GI bleeding and anemia

23
Q

Long-term treatment of linezolid resulted in?

A

fully reversible myelosuppression and linezolid-induced neuropathy

24
Q

What should be monitored weekly in patients receiving linezolid?

A

complete blood counts

25
Q

Linezolid is a reversible, nonselective inhibitor of

A

monoamine oxidase

26
Q

Patients taking linezolid should not consume large quantities of?

A

food or beverages that are rich in tyramine (cheese, red wine) in order to avoid a significant pressor response

27
Q

Because of drug interactions, linezolid has the potential for interaction with?

A

adrenergic and serotonergic agents

28
Q

What has been observed when linezolid is administered to normotensive subjects?

A

a reversible potentiation of pressor response to pseudoepherine