P: Inhib Of Pro Synth

Front 1

Label the following as bactericidal or bacteriostatic:

Linezolid
Clindamycin
Streptogramins
Chloramphenicol
Erythromycins
Tetracyclines
Aminoglycosides (except spectinomycin)

Which two interfere w/ initiation of protein synth? Which step do they mess w/?

What do the others interfere with? Which three block binding? Translocation?

Back 1

- Bactericidal
Aminoglycosides (except spectinomycin)
Streptogramins

- Bacteriostatic
Tetracyclines
Chloramphenicol
Erythromycins
Clindamycin
Linezolid

Aminoglycosides, Linezolid
- mess with initiation complex formation

Elongation
- chloramphenicol, tetracyclines, clindamycin
- erythromycin, streptogramins

Front 2

Aminoglycosides are active as a single agent only against gram __ bacteria, with the exception of ____.

How do they work? What inhibits them?
Need what to be effective on gram + bacteria?
Are they effective against strict anerobes?

Do they display activity in vivo even below MIC?

Back 2

gram - ; exception = staphylococci

- penetrate outer membrane thru an O2 dependent mechanism --> b/ sites on the cytoplasmic membrane
- divalent cations
- B-lactam co-admin
- no, they are not.

Yes = post-antibiotic effect

Front 3

When are aminoglycosides used? If they're used against enterococcus faecium, what is used in combo?

Back 3

moderate to severe aerobic gram - infections; almost always in combo w/ B-lactam antiB.

a penicillin.

Front 4

How are aminoglycosides administered?
- get into the CNS?
- primary excretion?
- toxicities?
- mechanisms of resistance?
+ transmissable?
+ which is the least susceptible?
Should they be premixed with B-lactams?

Back 4

Parenteral admin (usually IM)
- no, largely excluded from CNS and ocular fluids
- by the kidneys
- ototoxicity, and nephrotoxicity; both usually dose-limiting.
- degredation by enzymes; also mut of b/ site on ribosome less freq.
+ yes, usually plasmid mediated.
+ Amikacin

No, just co-administered.

Front 5

Tetracycline, doxycycline, minocycline
- broad or narrow?
- used often?
- therapeutic uses?
- Admin?
+ inhibitied by?
- toxicities?
+associated syndromes?
- contraindications?
- Resistances?

Back 5

- broad
- decline due to widespread resistance and sig. toxicities
- Rickettsia, cholera, lyme dz, brucellosis
- orally / IV, don't go to CNS very well.
+ by di/trivalent cations (milk, antiacids, etc.)
- GI irritation, Phototoxcitiy, hepatic and renal toxicities; deposition in bones and teeth.
+ Fanconi syndrome
- Preg women, children <8yo
- tetracycline pump; TetM --> protects ribosome from the antiB.

Front 6

What is Fanconi syndrome caused by? Effects?

Back 6

Fanconi syndrome
Caused by ingestion of outdated and degraded tetracycline
Effects include nausea, vomiting, polyuria and proteinuria

Front 7

What can be used to tx the following?
- Bacterial meningitis caused by h.influenzae or N. meningitidis in pts with penicillin analphylaxis.
- alternative for Rocky mtn spotted fever when tetracyclines are contraindicated

Back 7

Chloramphenicol

Front 8

Chloramphenicol
- broad or narrow?
- uses?
- distribution/CNS penetration?
- toxicities?
- resistance?

Back 8

- broad
- used for tx of serious infections when other antiBs are contraindicated
- well spread out, penetrates the CNS

- Aplastic anemia: rare but irreversible & fatal
- dose-related reversible BM depression
- Gray-baby syndrome due to circ collapse of newborn.

Chloramphenicol Acetyl Transferase: inactivates the antiB; found in MDR plasmids

Front 9

Macrolides include which drugs?
- broad or narrow?
- interactions?
- Uses?
- toxcities?
- resistances?

Back 9

Erythromycine, clarithromycin, azithromycin
- broad

- antagonistic with chloramphenicol and clindamycin.
- Erythromycin and clarithromycin (NOT azith) potentiate the effects of corticosteroids, cyclosporin, digoxin, warfarin b/c it inhibits P450.

- Legionnaire's dz
- Mycoplasma pneumoniae
- chlamydia trachomatis
- whooping cough

- GI distress, hepatotoxcity for one form.

- \perm, efflux, mut target, hydrolysis by esterase.... most are plasmid mediated & transferable.

Front 10

Clindamycin
- usage?
- admin?
- pharmK?
- toxicities?
- resistances?

Back 10

- limited due to toxicities, but used for opportunistic infections assoc. w/AIDs.
- oral admin
- met i/liv, excre i/bile. Small quantities found in feces for weeks.
- GI distress, skin rashes, hepatotoxicity
+ superinfection by clostridium difficile --> pseudomembraneous colitis.
- methylase mods b/ site (most common)..... inactivation of drug ...... decreases in mem. permeability.

Front 11

What is useful for tx'ing of severe anaerobic infections caused by bacteroides fragilis and other anaerobes, as well as being an alternative for toxoplasmosis and PCP tx?

Back 11

Clindamycin

Front 12

What is NAP1/027?

Back 12

Strain of C. difficile that has a 20x production of toxins and is resistant to all fluoroquinolones

Front 13

Streptogramins (Dalfopristin/Quinupristin)
- mechanism?
- are the two drugs more effective together?
- toxicities?
- interactions?
- resistances?

Back 13

- b/50s subunit and constrict exit channel --> loss of free tRNA --> protein synth inhib --> cell death
- yes, 16x more effective.
- hyperS, antiB-associated pseudomem. colitis
- inhibits P450 (warfarin, cyclosporine, CCBs, etc)
- mutations in rRNA that decrease affinity for ribosome

Front 14

What can be used for the following dz constellation?
- vancomycin-resistant E. Faecium (NOT E. Faecalis)
- Pen-r Strep pneumo
- MRSA

Back 14

Streptogramins (Dalfopristin/Quinupristin)

Front 15

What is used for:
VRE
Pen-r Strep Pneumo
MRSA
GAS & GBS

Back 15

Oxazolidinones (Linezolid)

Front 16

Oxazolidinones (Linezolid)
- mech
- origin
- resistances?
- toxicities?
- interactions?

Back 16

- b/50s and prevents 70s formation.
- completely synthetic
- mut i/ rRNA that decrease affinity of the drug.
- bradycardia in those taking B-blockers; Thrombocytopenia, Risk of superinfections
- Linezolid is a reversible MAOI

Front 17

Which drug is a reversible MAOI? What precautions must be taken as a result?

Back 17

Oxazolidinones (Linezolid)

Patient must avoid food high in tyramine
Must not be given concurrently with MAOIs, bupropion, tricyclic antidepressants, SSRIs or St. John’s Wort

Front 18

What is used to tx the following:
- Pseudomembraneous colitis caused by C. Difficile
- Bacteroides fragilis
- Three parasitic infections:
+ trichomoniasis
+ giardia
+ amebiasis

Back 18

Metronidazole

Front 19

Metronidazole:
- mechanism of action?
- toxicities/contraIndications?
- resistances?

Back 19

- taken up only in anaerobic bacteria and parasites --> converted to active metabolite --> cell death

- nausea, HA, dry mouth
- disulfiram-like rxn w/alcohol
- potentially carcinogenic in preg women

- due to a decrease or loss of enzymes involved in activation of the antiB