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87 Cards in this Set
- Front
- Back
What are 5 things to do before the lab results come back?
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1. establish evidence of infection and the probable site = allows to narrow down pathogens
2. obtain culture and susceptibility specimens 3. propose microbiological diagnosis 4. Determine the need for empiric therapy 5. initiate chemotherapy |
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What is Empiric Therapy?
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initiating treatment prior to determination of
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What type of antiobiotic is recommended before the lab results come back?
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Broad coverage, but narrower drug selectivity should be made when lab results come in
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What are the 4 things to ask youself when selecting drugs in Chemotherapy?
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1. Can the drug affect the pathogen?
2. Are the pharmacokinetics of the drug appropriate? 3. Is the drug appropriate for the patient? 4. Is this the ideal drug? |
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When selecting drugs for chemotherapy, what questions do you ask yourself about if the pharmacokinetics of the drug are appropriate?
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1. Will it reach the site needed
2. is it appropriate for hepatic and/or renal status of patient? 3. can you avoid undesirable drug-drug interaction? |
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When selecting drugs for chemotherapy, what are some things that you ask yourself when you are considering if the drug is appropriate for the patient?
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1. age, reproductive status, disease states
2. Allergies (penicillin) 3. Genetic factors affecting kinetics and dynamics |
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What are some things to ask yourself when considering if this is the ideal drug during your selection in chemotherapy?
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1. Oral vs. parenteral
2. cidal vs. static 3. Cost 4. Stage in the effective lifetime of the drug |
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ICWS = ?
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Inhibitors of Cell Wall Synthesis
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Where do Beta-lactam antibiotics block enzymatic steps?
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Outside of the cell or in the Periplasmic space
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T or F: Penicillins have a very low Chemotherapeutic Index
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False: they have an extremely high Chemotherapeutic Index = very selective toxicity
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Are Penicillin bacteriostatic or bacteriocidal?
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BacteriCIDAL in growing, proliferating cells
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What microbes are Penicillins primarily used against and why?
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Gram + b/c they don't have that outer lipid to get thru
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What are the 2 mechanisms of action of Penicillins?
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1. Covalent binding to transpeptidases = inhibit transpeptidation rxn = inhibit cross-linking of cell wall
2. Activate Murein Hydrolases (Autolysins) = make breaks in the cell wall as start point for synthesis |
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What is the importance of Penicillins activating Murein Hydrolases?
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If you block transpeptidation but the murein hydrolases are not activated then you get a static situation where there is no cell growth but also no holes in the cell wall
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While many Penicillin are acid-sensitive, why are they still given orally?
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b/c high doses allow for 30-50% to make it thru
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What are 4 acid-stable Penicillins
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1. Phenoxy- (Penicillin V = oral = probably should be acid stable)
2. Oxa- 3. Cloxa- 4. Carbenicillin indanyl |
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What is the name of the penicillin that can be given as a "depot" preparation = penicillin salt that has low water solubility, is injected IM as a 2-wk supply
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Benzathine Penicillin G
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Penicillin distributes good to most tissues, including these 3
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1. Pleural
2. Pericardial 3. Synovial **encompassing compartments |
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What 3 places does Penicillin have POOR penetration into?
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1. Eye
2. Prostate 3. CNS (except in meningitis) |
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What are Penicillins excreted by?
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Tubular secretion = Organic Acid secretory system
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What blocks the secretion of Penicillin thereby increasing its half-life?
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Probenecid
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What Penicillin is excreted in the bile?
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Nafcillin = could use in renal failure
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What 2 penicillins are excreted in both Urine and Bile
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Oxa-
Cloxa- |
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Half-life of Penicillin = ?
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1/2 - 1 hour
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Which Penicillins are PRIMARILY used against Gram +
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Pen G and Pen V
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Name the 3 Anti-staphylococcal penicillins
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1. Naf-
2. Methi- 3. Isoxazoyl penicillins (Ox-, clox-, diclox-) |
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List the 6 Extended Spectrum penicillins
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1. Ampi-
2. Amoxa- 3. Carbeni- indanyl 4. Pipera- 5. Ticar- 6. Mezlo- |
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What do the Extended spectrum penicillins have activity against?
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Gram + and Gram -
HELPS kill Enterococci 1. H. influenza 2. E. coli 3. Listeria monocytogenes 4. Proteus mirabilis 5. Salmonella 6. Enterococci |
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List the 4 Anti-Pseudomonal Penicillins
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1. Carbeni- indanyl
2. Pipera- 3. Ticar- 4. Mezlo- = Extended Spectrum minus Amoxicillin, Ampicillin **powerful drugs so only use when indicated to protect Therapeutic Value **TCPM = Takes Care of Pseudomonas Mortality |
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Since Pseudomonas can rapidly become resistant, what should you use in combo with Anti-Pseudomonal Penicillins?
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Aminoglycoside or Fluoroquinolone
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What pathogen are Anti-pseudomonal penicillins also active against?
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Proteus
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Which penicillin has a RASH incidence rate of 10%?
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Ampicillin
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What illness has a 90% incidence rate for Ampicillin rash?
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Mononucleosis
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What is the major penicillin adverse effect?
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Hypersensitivity reaction
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What % of people claim to be allergic to penicillin?
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5-8%
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Describe "Complete cross-reactivity" of penicillin
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if you're allergic to one, you're allergic to all
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Hypersensitivity of Penicillins T or F:
1. Is dependent on therapeutic dose 2. Rapid onset (20-30 min) 3. Can occur without prior known exposure 4. There is no success with skin test screening |
1. False = HS is not dependent on dosage
2. True 3. True 4. False = there is some success |
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What can be induced by high doses of Penicillin and in what particular condition is it more likely?
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Seizures
Renal Failure |
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What is transient resistance to Penicillin?
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when the cell is not dividing
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How is MRSA resistant to penicillins? (2)
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-has changes in its cell wall that blocks penicillins access to PBP's in the Periplasmic space
-structural changes in PBP's |
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How do microbes acquire B-lactamase production?
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Plasmid-mediated
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What are the B-lactamase-resistant penicillins?
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Naf-
Oxa's- (Oxa, Cloxa, Dicloxa) Methi- |
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List 3 Beta-lactamase inhibitors
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1. Clavulanic acid
2. Sulbactam 3. Tazobactam |
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What is the mechanism of action of B-lactamase
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break open B-lactam ring between the C=0 and N
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What are the 3 problems associated with Penicillin use/overuse?
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1. Sensitization = HS rxn
2. Selection for resistant strains (90% Staph are resistant) 3. Superinfection by resistant organisms = decrease sensitive microbes, allows for overgrowth of resistant microbes |
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What are the most common microbes that cause Superinfection when overusing penicillin
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Proteus
Pseudomonas Serratia Fungi |
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T or F: Structure and function of Cephalosporins is similar to Penicillins
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True
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True or False: Cephalosporins are more sensitive to Beta-lactamases than penicillins
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False = Cephalosporins are less sensitive to B-lactamases
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T or F: Cephalosporins have a broader spectrum of activity than Penicillins
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True
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T or F: Cephalosporins are more toxic than Penicillins, particularly renal
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True
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T or F: Penicillins are more expensive than Cephalosporins
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False = cephalosporins are more expensive
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What is the general rule regarding administering Penicillins or Cephalosporins
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If penicillin will work then use it
- only use Cephalosporin if penicillin doesnt work |
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T or F: Many Cephalosporins have poor oral absorption
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True
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List the general properties as you increase in generations of Cephalosporins
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1. Greater gram - activity
2. some with less gram + activity (except Generation 4) 3. Less B-lactamase sensitivity 4. Cephalosporinase-resistant 5. less toxic to patient 6. better distribution = especially to CNS |
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What adverse effect are you more likely to see with Oral Cephs than Pens?
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GI distress --> Nausea, vomiting
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Why do Cephs have local irritation as one of their adverse effects?
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b/c they are given IM and IV = irritation from injection
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What drug in combo with Cephalosporin can cause Renal toxicity
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Aminoglycosides
**Cephalosporins increase the Nephrotoxicity of Aminoglycosides |
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What is the Disulfiram effect?
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-Disulfiram is used to treat alcoholism
-inhibits Aldehyde Dehydrogenase, thereby increasing conc. of Acetaldehyde = makes alcoholic sick |
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Name 2 Cephs that cause the Disulfiram effect
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1. Cefotetan
2. Cefoperazone *the TETAN OPERATOR cause the Disulfarim effect |
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2 Cephalosporins with these adverse effects:
1. Disulfiram effect 2. Bleeding and Platelet disorders |
Cefotetan
Cefoperazone |
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What % of people who are Hypersensitive to Cephs are also cross-reactive with Pens?
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5-10%
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What is the only drug in the Monobactam class?
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Aztreonam
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What is Aztreonam (Monobactam) active against?
Not active against? |
Gram - rods (Klebsiella, Pseudomonas, Serratia)
Inactive -> Gram + or Anaerobes |
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What are the 2 advantages of Aztreonam?
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1. B-lactamase resistant
2. no cross-reactivity in Penicillin-sensitive patients |
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List the 2 Carbapenems
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1. Imipenem
2. Meropenem |
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What are the Carbapenems (Imipenem & Meropenem) active against?
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BROAD spectrum
- Gram - - Gram + - Anaerobes DOC for Enterobacter |
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T or F: Carbapenems are sensitive to B-lactamase
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False
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What is the downfall of Imipenem?
How is it dealt with? |
1. inactivated by Renal Dipeptidase
2. Coadminister with Cilastatin (inhibits Dipeptidase) **with Imipenem, "the kill is LASTIN' with CILASTATIN" |
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3 properties of this drug include:
1. IV use only 2. Pseudomonas develops resistance rapidly, so use with Aminoglycosides 3. Cross-sensitivity with Penicillins |
Carbapenem = Imipenem & Meropenem
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Carbapenem that is Dipeptidase-resistant
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Meropenem
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What is Vancomycin's MOA?
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inhibits Transglycosylation (step before Transpeptidation)
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What does Vancomycin bind to?
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D-ala D-ala portion of Cell Wall precursors
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What is Vancomycin bacteriCIDAL to?
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Gram +
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Important microbe Vancomycin is used for
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MRSA
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How is Vancomycin administered?
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IV
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What does Vancomycin enhance toxicity to when administered with Aminoglycosides? (2)
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Ototoxicity
Renal Toxicity |
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Syndrome that is associated with Vancomycin and why it happens
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"Red man" or "Red neck" syndrome
Vancomycin causes Histamine release |
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What 2 things can be done to prevent flushing syndrome associated with Vancomycin?
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1. pretreatment with Antihistamines
2. Slower infusion rate |
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Explain the misuse/overuse problem with Vancomycin
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Its utility was being squandered on unworthy bugs
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What is the group of microbes that may actually grow faster with vancomycin in the culture?
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Enterococci
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inhibits a CYTOPLASMIC step in cell wall precursor synthesis
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Fosfomycin
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What is the unique feature of Fosfomycin compared to other ICWS?
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must gain access to the INSIDE of the cell
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Antimicrobial that is actively taken up by Glycerophosphate or G6P transporter
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Fosfomycin
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What administration of Fosfomycin is only approved in the US?
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Oral
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What is Fosfomycin clinically used for and why?
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Gram - UTI
The ACTIVE drug is excreted by the kidney |
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What 3 groups of drugs is Fosfomycin SYNERGISTIC with?
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1. Beta-lactams
2. Aminoglycosides 3. Fluoroquinolones Fosfomycin "Air Force Base" |
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What is Bacitracin used for and why?
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Topical antibiotic (ICWS) only (OTC) b/c it is markedly NEPHROTOXIC
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