Term
| What are 5 methods of avoiding the development of antibiotic resistance? |
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Definition
1) Use only when necessary
2) Choose appropriately
3) Narrowest effectivity (don't always treat broadly)
4) Dose control
5) Duration control |
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Term
| What is the generic "marker" of whether an antibiotic will be broadly effective against Gram (+) bacteria? What about Gram (-)? |
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Definition
MRSA for gram (+)
Pseudomones for gram (-) |
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Term
| What is the "Minimum Inhibitory Concentration"? How does it relate to a "zone of inhibition" on a Kirby Bauer Disc? |
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Definition
MIC is lowest conc. of antibiotic needs to cause NO VISIBLE GROWTH (turbidity).
The larger the "zone of inhibition" the lower the "MIC" |
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Term
| What are the 4 characteristics of Pharmacokinetics? |
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Definition
Bodily effects on drug= ADME
1) Absorption= (Level of drug orally/level given IV) X 100
ex) Vancomycin is poorly bioavailable.
2) Distribution= L/kg (indicates concentrations in sequestered sites)
ex) Tobramycin has poor CNS distribution, but Rifampin is good.
3) Metabolism
ex) Aminoglycosides are minimally metabolized, while Moxifloxacin is highly metabolized.
4) Excretion= renal vs. nonrenal.
ex) don't give penicillin in renal failure |
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Term
| What are the 3 characteristics of Pharmacodynamics? |
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Definition
1) Mechanism of action
2) Concentration (large dose less often)- Aminoglycoside (poor metabolism)
3) Time-dependent (low dose more regularly)- Beta-lactam (penicillin)
4) Exposure dependent- combination of the 2- Vancomycin and all others |
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Term
| What is the difference in action between Tetracyclines, Macrolides (azythromycin, erythromycin), Penicillins, Cephalosporins and Aminoglycosides? |
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Definition
1) Tetracyclines and Macrolides are BACTERISTATIC
2) Penicillin, Cephalosporin and Aminoglycoside (as well as vancomycin, flouroquinolone and monobactam) are BACTERICIDAL. |
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Term
How do Beta-lactam antibiotics such as Penicillin, Cephalosporin, Carbapenems and Monobactams act to inhibit bacteria?
What are some mechanisms of resistance? |
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Definition
1) Beta-lactams Inhibit cell wall synthesis by inhibiting cross-linking of peptidoglycans by PBPs.
- They DO NOT work against Enterococcus UNLESS you add aminoglycoside.
2) Mechanisms of resistance include:
Altered PBPs in gram (+)
Overexpression of efflux pumps, loss of porins and beta-lactamases in gram (-) |
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Term
How do the actions of Vancomycin/Televancin differ from Beta-lactams?
How does resistance occur to these drugs? |
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Definition
1)
-Vancomycin binds D-Ala and inhibits peptidoglycan chain synthesis before cross-linking would occur
-Televancin does the same but also disrupts bacterial cell membranes, alterning membrane potential and permeability.
2) Resistance to Vancomycin and Televancin occurs via
-Altered D-Ala:D-Ala binding to D-Ala:D-lactate/serine -Cell wall thickening. |
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Term
Which groups of antibiotics are "protein synthesis inhibitors"?
Which are 50S inhibitors vs. 30S inhibitors? |
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Definition
These drugs cause ribosomes to "read" the wrong signal
1) Aminoglycoside, Macrolide, Tetracycline, Linezolid, Clindamycin, Tigecycline
2) 50S- initiation (Linezolid) or translocation of tRNA to ribosome preventing elongation (macrolides, clindamycin)
3) 30S- tRNA access (tetracycline, tigecycline) or bind 16S rRNA component of ribosome (aminoglycoside) |
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Term
| How do Trimethoprim/Sulfamethoxazole work to fight bacterial infections? |
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Definition
Inhibitors of DNA/RNA synthesis.
1) TMP (Dihydrofolate reductase inhibitor) and SM (Dihydropteroate synthase inhibitor) act synergistically to inhibit purine synthesis |
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Term
| How do Rifamycins (rifampin), Fidaxomicin and Fluoroquinolones (FQ's) work to fight bacterial infections? |
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Definition
Both are DNA/RNA synthesis inhibitors
Short- Rifampin (DNA-dependent RNA Poli), Fidaxomicin (bacterial RNA poli), FQ (topoisomerase)
1) Rifampin inhibits DNA-depdnet RNA Polimerases (resistance can occur through target site mutation)
2) Fidaxomicin inhibits transcription of bacterial RNA Poli
3) FQ's inhibit topoisomerases (resistance through target mutations) |
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Term
| Which DNA damaging agents are used to fight bacterial infections? |
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Definition
1) Nitrofurantoin is reduced to form oxygen radicals (resistance follows mutations that inhibit reductase activity)
2) Metronidazole undergoes Anaerobic "nitro-reduction" from its pro-drug form into radical metabolites that bind DNA (resistance is rare unless intrinsically resistant) |
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Term
| Which Cell Membrane damaging agents are used to fight bacterial infections? |
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Definition
1) "Daptomycin" depolarizes cell membrane through K+ efflux leading to cell death (resistance through thickened cell membrane or binding site)
2) "Polymyxins" insert into membranes, interact with phospholipids and act as cationic detergents (resistance through binding site) |
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Term
| Which drugs DO NOT require adjustments for renal insufficiency? |
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Definition
1) Beta-lactams (ceftriaxone, naf/ox)
2) Moxifloxacin |
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Term
| The elimination of which drugs depends on Hepatic function? |
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Definition
1) Tigecycline (staph and adenobacter)
2) Rifampin (DNA-dependent RNA Poli) |
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Term
| Which drugs exhibit very good oral absorption |
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Definition
1) Flouroquinolones (broad spectrum to treat hospital-acquired)
2) Tetracyclines (30S inhibitor that blocks tRNA:ribosome interaction)
** Both can be given with di and tri-valent cations to decrease absorption via chelation** |
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Term
| Tobramycin has poor CNS distribution. How could you maximize efficacy? |
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Definition
| Give it in large doses, infrequently, since it is concentration-dependent |
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Term
| How can Natural Penicillins be used to treat Enterococcus? |
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Definition
| Must give with Aminoglycosides |
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Term
| Tobramycin has poor CNS distribution. How could you maximize efficacy? |
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Definition
| Give it in large doses, infrequently, since it is concentration-dependent |
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Term
| How can Natural Penicillins be used to treat Enterococcus? |
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Definition
| Must give with Aminoglycosides |
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Term
| Which Penicillins are useful broad-spectrum antibiotics against anaerobic organisms? |
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Definition
Extended Spectrum Penicillin PLUS B-lactamase such as Ticarcillin/Clavalanate (IV) and Piperacillin/Tazobactam (IV)
These drugs treat Bacteroides fragilis, which is a broad indicator for gram anaerobes and
These drugs treat Bacteroides fragilis, which is a broad indicator for gram anaerobes and |
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Term
| Which Penicillin would you use to treat a case of Bacteroides fragilis? |
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Definition
Aminopenicillin Plus B-lactamase inhibitor such as Ampicillin/Sulbactam (IV) and Amoxicillin/Clavulanate or "Augmentin" (PO).
These drugs are also good against MSSA (aerobic gram +), and B-lactamase producing H. inluenzae (aerobic gram -) |
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Term
| Which Penicillin would you use to treat a case of Lyme disease? |
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Definition
Aminopenicillin such as Ampicillin/Amoxicillin (IV/PO)
These drugs will also work against Aerobic Gram (-) organisms such as E. coli and Proteus mirabilis |
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Term
| Which Penicillins are excellent treatments for Methicillin-sensitive Staphyloccus? |
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Definition
Penicillinase Resistant Penicillins such as Oxacillin/Nafcillin (IV) and Dicloxacillin (PO)
These drugs have hepatic elimination, so NO RENAL DOSING |
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Term
| What type of Penicillin would be most effective at treating a B-lactamase producing strain of H. influenzae? |
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Definition
An Aminopenicillin PLUS b-lactamase inhibitor such as Ampicillin/Sulbactam (IV) or Amoxicillin/Clavulanate (PO)
This would also be a good choice for Bacteroides fragilis, because it has potent anaerobic coverage |
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Term
Aminopenicillins PLUS Beta-Lactamase inhibitor such as "Ampicillin/Sulbactam" (IV) and "Amoxicillin/Clavulanate" (PO)
1) Aerobic Gram (+)
2) Aerobic Gram (-)
3) Other organisms
4) Adverse Effects
5) Comments |
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Definition
1) Same as Aminopenicillins but also handles MSSA staph
2) Same as Aminopenicillins but also handles B-lactamase producing H. influenzae and some strains of Klebsiella sp and E. coli.
3) Same as Aminopenicillins PLUS anaerobic activity including Bacteroides fragilis)
4) Same as pencillin but with Diarrhea.
5) IV-PO equivalents |
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Term
Aminopenicillins such as "Ampicillin/Amoxicillin"
1) Aerobic Gram (+)
2) Aerobic Gram (-)
3) Other organisms
4) Adverse Effects
5) Comments |
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Definition
1) Streptococcus, Enterococcus PLUS Listeria monocytogenes
2) E.coli Proteus mirabilis, Haemophilus influenzae (resistance from beta-lactamase)
3) Treponema pallidum (Syphilis) PLUS Lyme
4) Hypersensitivity (rash) and seizure (high dose) |
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Term
Natural Penicillins such V (PO), G-benzathine (IM), G-procaine (IM) and G-Na/K (IV).
1) Aerobic Gram (+)
2) Aerobic Gram (-)
3) Other organisms
4) Adverse Effects
5) Comments |
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Definition
1) MOST streptococcus spp. (except pneumoniae) and Enterococcus (if given with aminoglycoside)
2) Minimal
3) Treponema pallidum (Gram - spirochete in Syphilis)
4) Hypersensitivity (rash) and maybe seizures (high dose)
5) Can't treat Staph b/c beta-lactamase |
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Term
| Why would you choose to treat with Extended Spectrum Penicillin PLUS B-lactamase inhibitor? |
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Definition
Broad spectrum from gram (-) (Pseudomonas)
Broad spectrum for Anaerobic (including Bacteroides fragilis) |
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Term
| How do Gram (-) bacteria defend themselves against Beta-Lactam Antibiotics? |
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Definition
1) Alter Porins
2) Beta-lactamase enzymes bound to cytoplasmic membrane acting locally in the periplasmic space.
3) Altering transpeptidase structures
4) Efflux pumping |
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Term
| How do Gram (+) bacteria defend themselves against Beta-Lactam Antibiotics? |
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Definition
1) Secreted beta-lactamase act outside of peptidoglycan wall (penicillinase)
2) Alter transpeptidase structures (e.g. MRSA resistant to ALL penicillins)
3) Efflux pumping |
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Term
| Why would you prescribe an Aminopenicillin such as Ampicillin or Amoxicillin instead of a natural G or V form of Penicillin? |
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Definition
- Better gram-negative coverage (E. coli and other enterics such as Haemophilus influenzae (70%) and Proteus mirabili) because of better penetration through the outer membranes and better PBP-binding.
- They also can treat Lyme and Gram (+), Aerobic Listeria
- still inhibited by Penicillinase. |
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Term
| Why would you prescribe a Penicillinase-resistant drug and what are there names? |
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Definition
1) Nafcillin/Oxacillin (IV), Dicloxacillin (PO)
2) MSSA that are penicillinase-producing, Hepatic elimination
** Typical treatment for an infected wound. Send them home on Dicloxacillin!** |
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Term
| Why would you prescribe an Anti-Aseudomonal Penicillin (i.e. Extended Spectrum + B-lactamase inhibitor) drug and what are there names? |
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Definition
1) Carboxypenicillins (Ticarcillin/Clavulanate) (IV)
Ureidopenicillins (Piperacillin/Tazobactam) (IV)- most effective
2) Broad-spectrum gram (-) coverage (Pseudomonas)
Broad Anaerobic coverage (Bacteroides fragilis) |
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Term
| Why would you use Cephalosporins over Penicillins? |
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Definition
1) Resistant to beta-lactamases
2) New R-group allows for more drug manipulations in lab |
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Term
| What is the relationship between Cephalosporin and gram (+) vs. gram (-) effectiveness? |
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Definition
1) Higher generations have MORE gram (-) coverage
2) High generations have LESS gram (+) coverage (1st generation is best for staph and strep)
EXCEPTION- IV generation is better at both
**MRSA and Enterococci is resistant to all because it changed its transpeptidase |
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Term
| Why would you prescribe a 1st generation Cephalosporin and what are there names? |
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Definition
1) Beta-lactam resistant and Good MSSA and Streptococcus coverage (NO enterococcus and poor gram - coverage).
- Limited E. coli and Klebsiella coverage
2) Cefazolin (IV)
Cephalexin and Cefadroxil (longer half-life) (PO) |
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Term
| Why would you prescribe a 2nd generation Cephalosporin and what are there names? |
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Definition
1) 2A supplements 1st generation with H. influenzae coverage
2B loses MSSA coverage but can cover most B. fragilis (anaerobe coverage) making more useful for intra-abdominal and pelvic infections.
2A= Cefuroxime (IV/PO)
Cefaclor and Cefprozil (PO)
2B= Cefoxitin (IV) |
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Term
| Why would you prescribe a 3rd generation Cephalosporin and what are there names? |
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Definition
1) -Excellent streptococcus coverage
- Broad gram - coverage (not Pseudomonas EXCEPT for Ceftrazidime (IV))
- Ceftriaxone has biliary elimination with increased half life (gold standard for community-acquired meningitis, N. gonorrhea and Neuro Lyme)
- Ceftaroline gets MRSA (like Ceftriaxone + MRSA)
2) Ceftibuten (PO)
Cefdinir (PO)
Cefpodoxime (PO)
Ceftriaxone (IV)
Cefataxime (IV)
Cefixime (PO)
Ceftrazidime (Broad gram - coverage with Pseudomonas)
Ceftaroline (IV) ONLY B-lactam against MRSA |
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Term
| What is the only beta-lactam to effectively treat MRSA? |
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Definition
Ceftaroline (IV)- essentially Ceftriaxone + MRSA
- 3rd generation Cephalosporin. |
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Term
| Which 2 Cephalosporins cover Pseudomonas (broad gram -)? |
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Definition
1) Ceftrazadine (IV)- 3rd generation
2) Cefepime (IV)- 4th generation and better MSSA than Ceftrazadine |
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Term
| What aerobic organisms do the Cephalosporins treat? |
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Definition
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Term
| Why would you prescribe a Monobactam and what is it called? |
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Definition
1) Aztreonam (IV)
2) Safe to use in patients who have allergies to other beta-lactams, ONLY GRAM NEGATIVE for Pseudomonas and others
- often give it with gram-positives such as Vancomycin and Clindamycin. |
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Term
| When would you prescribe Vancomycin (PO/IV) or Televancin (IV)? |
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Definition
- Glycopeptide with good Gram + coverage (MRSA, strep and Enterococcus but NOT VRE)
- C. dif from hospital
- poor gram- and anaerobic coverage.
- look for "Red Man's Syndrome" with rash and hypertension as well as Nephrotoxicity |
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Term
| What is unique about Cefoxitin (IV)? |
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Definition
| It is a 2nd Generation Cephalosporin (2B) with coverage against anaerobes (B. fragilis), but with poor coverage against MSSA |
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