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Flashcards in Abx vs. gram-pos organisms Deck (41)
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1
Q

What are the 3 phenotypes of vancomycin resistance?

A

vanA, vanB, vanC

2
Q

What group of organisms is vancomycin capable of killing? (name the class and the 5 major targets)

A

Gram-pos ONLY - *MRSA, *MSSA, *coag-negative staph, *PRSP, *c-dif (clostridium spp.) - Also targets other strep pneumoniae, viridians strep, group strep, enterococcus, corynebacterium, bacillus, listeria, actinomyces, clostridium spp., peptococcus, peptostreptococcus.

3
Q

Since vanc is distributed widely in the tissues, you should use ________________ for dosing.

A

TBW (total body weight?)

4
Q

How long does it take for vanc to distribute into the tissues?

A

1 hour - Peak should be drawn 1 hr post-infusion

5
Q

For vancomycin, elimination T1/2 depends on _______ function.

A

renal function

6
Q

Can pts who are allergic to PCNs be given vancomycin?

A

Yes! (different structure)

7
Q

What’s an e.g. of a target of vancomycin that is a multi-drug-resistant bacterium?

A

PCN-resistant streptococcus pneumoniae (PRSP)

8
Q

Vanc treats ______-______ c-dif colitis.

A

moderate-severe

9
Q

Recall: what drug is used to treat mild-mod c-diff?

A

Metronidazole

10
Q

How does Red Man Syndrome occur? - Which drug is it a/w?

A

Infusion of vancomycin at too high a RATE - Also a/w other glycopeptides

11
Q

In what specific type of infection would you prefer the 2nd gen glycopeptide dalbavancin to vancomycin? - Which genes must be present?

A

VRE (must have vanB or vanC gene, not vanA.)

12
Q

What is the MoA of vancomycin?

A

Binds D-ala-D-ala to inhibit cell wall synthesis

13
Q

What is the MoA of linezolid? (is resistance common or uncommon?)

A

Binds 50S ribosomal binding site (resistance rare)

14
Q

What is the major class that linezolid can inhibit? List the main targets. - What is the other class?

A

Gram-pos: - *MSSA - *MRSA - *VRSA, - strep-pneumoniae (including *PRSP), - **enterococcus faecium and faecalis (including *VRE) Also: viridian streptococci, group streptococci, coag-neg staph, bacillis, listeria, clostridium spp (except c-diff), peptostreptococcus, c. acnes. Atypical bacteria: mycobacteria

15
Q

What is unique about the pharmacology of linezolid?

A

100% bioavailable

16
Q

What major category of pathogens is linezolid generally used for? What body area category is it NOT used for?

A

* Serious/complicated infections caused by resistant gram-positive bacteria: - Not used for UTIs

17
Q

What is linezolid contraindicated with and what condition does it cause?

A
  • SSRIs, MAOIs - Serotonin syndrome
18
Q

What are the major side effects a/w linezolid?

A

* Thrombocytopenia/anemia - SSRIs/MAOIs: serotonin syndrome. - Lactic acidosis - BM suppression - Neuropathy

19
Q

What category of drugs are linezolid and tedizolid?

A

Oxazolinidones

20
Q

What’s the advantage of tedizolid over linezolid? Why isn’t tedizolid prescribed more often?

A
  • Doesn’t cause serotonin syndrome - It’s even more expensive than linezolid
21
Q

What class of drugs does daptomycin belong in?

A

Lipopeptide

22
Q

What class of bacteria is daptomycin active against? Name the bacteria. (*or at least the targeted ones).

A

Gram-pos: *MRSA *MSSA *VRSA coag-neg staph strep pneumoniae (including *PRSP) viridians streptococi group streptococci *Enterococcus faecium and farcalis (including *VRE)

23
Q

*Daptomycin should NOT be used in the treatment of _____________.

A

*Pneumonia

24
Q

*What is the major adverse effect a/w daptomycin?

A

Myopathy and CPK elevation (must continually monitor them)

25
Q

Glycopeptides: mech of action (be specific)? - Time or conc-dependent? - Static or cidal?

A

Inhibits cell wall synth at a site different than beta-lactams, binding to D-alanyl-D-alanine portion of cell wall, preventing cross-linking. - Time-dependent - Bacteriocidal

26
Q

Vancomycin: mech of resistance? - In what 2 organisms, specifically, is this an issue?

A

Resistant in VRE/VRSA due to change in D-alanyl-D-alanine binding site of PG.

27
Q

Which glycopeptide is more potent than vanc?

A

Dalbavancin

28
Q

How can linezolid be administered?

A

PO or IV

29
Q

What class of drug is the quinupristin-dalfopristin combo? - MoA? - Static or cidal?

A

Synercid - Streptogramins - Protein synthesis inhibitor (50S ribosomal subunits; late stages) - Bacteriostatic, but syngeristic together to be bacteriocidal.

30
Q

What organism class are quinupristin-dalfopristin effective against? - What is the main target organism? What others are its targets?

A

Gram-positives, namely VRE. Gram-positive organisms (developed for VRE) - Enterococcus faecium (including VRE)* - MSSA, MRSA - Coagulase-negative staphylococci* - PRSP*, and many more. Also coverage vs. gram-neg aerobes and atypical bacteria (in vitro).

31
Q

How is quinupristin-dalfopristin cleared?

A

Hepatically/biliary

32
Q

What are the glycopeptides we need to know?

A

VDTO - Vancomycin - Dalbavancin - Telavancin - Oritavancin

33
Q

Name the 3 major side effects a/w vancomycin.

A
  • Red man syndrome - Nephrotoxicity - Ototoxicity
34
Q

Name the major side effects a/w dalbavancin.

A

GI s/s, skin rxns + flushing - Can also get red man syndrome

35
Q

Name drugs that are highly active/focused towards vs. resistant gram-pos organisms.

A

Vancomycin Dalbavancin Telavancin Oritavancin Linezolid Tedizolid Daptomycin Quinupristin-dalfopristin

36
Q

Quinupristin-dalfopristin: mech of resistance?

A
  • Alterations in ribosomal binding sites (erm) - Enzymatic inactivation - Active transport out of the cell
37
Q

Via what route is quinupristin-dalfopristin absorbed? - Does it penetrate CSF?

A

Parenterally - Minimally

38
Q

How is quinupristin-dalfopristin eliminated?

A

Both via hepatic and biliary

39
Q

What are the main clinical uses for Synercid (quinupristin-dalfopristin)? (2)

A
  • VRE bacteremia - Complicated skin and soft tissue infections due to MSSA or Streptococcus pyogenes
40
Q

Does quinupristin-dalfopristin affect CYP450?

A

P450 3A4 Inhibitor

41
Q

Adverse effects of quinupristin-dalfopristin?

A
  • Sever GI intolerance (N/V/D) - Venous irritation