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87 Cards in this Set

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What are 5 things to do before the lab results come back?
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
What is Empiric Therapy?
initiating treatment prior to determination of
What type of antiobiotic is recommended before the lab results come back?
Broad coverage, but narrower drug selectivity should be made when lab results come in
What are the 4 things to ask youself when selecting drugs in Chemotherapy?
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?
When selecting drugs for chemotherapy, what questions do you ask yourself about if the pharmacokinetics of the drug are appropriate?
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?
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?
1. age, reproductive status, disease states

2. Allergies (penicillin)

3. Genetic factors affecting kinetics and dynamics
What are some things to ask yourself when considering if this is the ideal drug during your selection in chemotherapy?
1. Oral vs. parenteral
2. cidal vs. static
3. Cost
4. Stage in the effective lifetime of the drug
ICWS = ?
Inhibitors of Cell Wall Synthesis
Where do Beta-lactam antibiotics block enzymatic steps?
Outside of the cell or in the Periplasmic space
T or F: Penicillins have a very low Chemotherapeutic Index
False: they have an extremely high Chemotherapeutic Index = very selective toxicity
Are Penicillin bacteriostatic or bacteriocidal?
BacteriCIDAL in growing, proliferating cells
What microbes are Penicillins primarily used against and why?
Gram + b/c they don't have that outer lipid to get thru
What are the 2 mechanisms of action of Penicillins?
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
What is the importance of Penicillins activating Murein Hydrolases?
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
While many Penicillin are acid-sensitive, why are they still given orally?
b/c high doses allow for 30-50% to make it thru
What are 4 acid-stable Penicillins
1. Phenoxy- (Penicillin V = oral = probably should be acid stable)
2. Oxa-
3. Cloxa-
4. Carbenicillin indanyl
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
Benzathine Penicillin G
Penicillin distributes good to most tissues, including these 3
1. Pleural

2. Pericardial

3. Synovial

**encompassing compartments
What 3 places does Penicillin have POOR penetration into?
1. Eye

2. Prostate

3. CNS (except in meningitis)
What are Penicillins excreted by?
Tubular secretion = Organic Acid secretory system
What blocks the secretion of Penicillin thereby increasing its half-life?
Probenecid
What Penicillin is excreted in the bile?
Nafcillin = could use in renal failure
What 2 penicillins are excreted in both Urine and Bile
Oxa-

Cloxa-
Half-life of Penicillin = ?
1/2 - 1 hour
Which Penicillins are PRIMARILY used against Gram +
Pen G and Pen V
Name the 3 Anti-staphylococcal penicillins
1. Naf-
2. Methi-
3. Isoxazoyl penicillins (Ox-, clox-, diclox-)
List the 6 Extended Spectrum penicillins
1. Ampi-
2. Amoxa-
3. Carbeni- indanyl
4. Pipera-
5. Ticar-
6. Mezlo-
What do the Extended spectrum penicillins have activity against?
Gram + and Gram -

HELPS kill Enterococci
1. H. influenza
2. E. coli
3. Listeria monocytogenes
4. Proteus mirabilis
5. Salmonella
6. Enterococci
List the 4 Anti-Pseudomonal Penicillins
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
Since Pseudomonas can rapidly become resistant, what should you use in combo with Anti-Pseudomonal Penicillins?
Aminoglycoside or Fluoroquinolone
What pathogen are Anti-pseudomonal penicillins also active against?
Proteus
Which penicillin has a RASH incidence rate of 10%?
Ampicillin
What illness has a 90% incidence rate for Ampicillin rash?
Mononucleosis
What is the major penicillin adverse effect?
Hypersensitivity reaction
What % of people claim to be allergic to penicillin?
5-8%
Describe "Complete cross-reactivity" of penicillin
if you're allergic to one, you're allergic to all
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
What can be induced by high doses of Penicillin and in what particular condition is it more likely?
Seizures

Renal Failure
What is transient resistance to Penicillin?
when the cell is not dividing
How is MRSA resistant to penicillins? (2)
-has changes in its cell wall that blocks penicillins access to PBP's in the Periplasmic space
-structural changes in PBP's
How do microbes acquire B-lactamase production?
Plasmid-mediated
What are the B-lactamase-resistant penicillins?
Naf-
Oxa's- (Oxa, Cloxa, Dicloxa)
Methi-
List 3 Beta-lactamase inhibitors
1. Clavulanic acid
2. Sulbactam
3. Tazobactam
What is the mechanism of action of B-lactamase
break open B-lactam ring between the C=0 and N
What are the 3 problems associated with Penicillin use/overuse?
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
What are the most common microbes that cause Superinfection when overusing penicillin
Proteus
Pseudomonas
Serratia
Fungi
T or F: Structure and function of Cephalosporins is similar to Penicillins
True
True or False: Cephalosporins are more sensitive to Beta-lactamases than penicillins
False = Cephalosporins are less sensitive to B-lactamases
T or F: Cephalosporins have a broader spectrum of activity than Penicillins
True
T or F: Cephalosporins are more toxic than Penicillins, particularly renal
True
T or F: Penicillins are more expensive than Cephalosporins
False = cephalosporins are more expensive
What is the general rule regarding administering Penicillins or Cephalosporins
If penicillin will work then use it
- only use Cephalosporin if penicillin doesnt work
T or F: Many Cephalosporins have poor oral absorption
True
List the general properties as you increase in generations of Cephalosporins
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
What adverse effect are you more likely to see with Oral Cephs than Pens?
GI distress --> Nausea, vomiting
Why do Cephs have local irritation as one of their adverse effects?
b/c they are given IM and IV = irritation from injection
What drug in combo with Cephalosporin can cause Renal toxicity
Aminoglycosides

**Cephalosporins increase the Nephrotoxicity of Aminoglycosides
What is the Disulfiram effect?
-Disulfiram is used to treat alcoholism
-inhibits Aldehyde Dehydrogenase, thereby increasing conc. of Acetaldehyde = makes alcoholic sick
Name 2 Cephs that cause the Disulfiram effect
1. Cefotetan
2. Cefoperazone

*the TETAN OPERATOR cause the Disulfarim effect
2 Cephalosporins with these adverse effects:

1. Disulfiram effect

2. Bleeding and Platelet disorders
Cefotetan

Cefoperazone
What % of people who are Hypersensitive to Cephs are also cross-reactive with Pens?
5-10%
What is the only drug in the Monobactam class?
Aztreonam
What is Aztreonam (Monobactam) active against?

Not active against?
Gram - rods (Klebsiella, Pseudomonas, Serratia)

Inactive -> Gram + or Anaerobes
What are the 2 advantages of Aztreonam?
1. B-lactamase resistant

2. no cross-reactivity in Penicillin-sensitive patients
List the 2 Carbapenems
1. Imipenem

2. Meropenem
What are the Carbapenems (Imipenem & Meropenem) active against?
BROAD spectrum
- Gram -
- Gram +
- Anaerobes

DOC for Enterobacter
T or F: Carbapenems are sensitive to B-lactamase
False
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"
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
Carbapenem that is Dipeptidase-resistant
Meropenem
What is Vancomycin's MOA?
inhibits Transglycosylation (step before Transpeptidation)
What does Vancomycin bind to?
D-ala D-ala portion of Cell Wall precursors
What is Vancomycin bacteriCIDAL to?
Gram +
Important microbe Vancomycin is used for
MRSA
How is Vancomycin administered?
IV
What does Vancomycin enhance toxicity to when administered with Aminoglycosides? (2)
Ototoxicity

Renal Toxicity
Syndrome that is associated with Vancomycin and why it happens
"Red man" or "Red neck" syndrome

Vancomycin causes Histamine release
What 2 things can be done to prevent flushing syndrome associated with Vancomycin?
1. pretreatment with Antihistamines

2. Slower infusion rate
Explain the misuse/overuse problem with Vancomycin
Its utility was being squandered on unworthy bugs
What is the group of microbes that may actually grow faster with vancomycin in the culture?
Enterococci
inhibits a CYTOPLASMIC step in cell wall precursor synthesis
Fosfomycin
What is the unique feature of Fosfomycin compared to other ICWS?
must gain access to the INSIDE of the cell
Antimicrobial that is actively taken up by Glycerophosphate or G6P transporter
Fosfomycin
What administration of Fosfomycin is only approved in the US?
Oral
What is Fosfomycin clinically used for and why?
Gram - UTI

The ACTIVE drug is excreted by the kidney
What 3 groups of drugs is Fosfomycin SYNERGISTIC with?
1. Beta-lactams
2. Aminoglycosides
3. Fluoroquinolones

Fosfomycin "Air Force Base"
What is Bacitracin used for and why?
Topical antibiotic (ICWS) only (OTC) b/c it is markedly NEPHROTOXIC