Antimicrobials Flashcards
If a patient is severely immunocompromised, what type of antibiotic should you give them?
Bactericidal
Without our normal flora, we can be exposed to
Superinfections. Our normal flora competes with pathogens for nutrients and secrete substances that can kill opportunistic bacteria
When might you not want to give antibx?
If the person is allergic and the surgery has low risk for infection
The prophylactic antibiotic should be given no earlier than _____
1 hour before surgery
Does a brief course of antibiotics result in resistant organisms?
There is no evidence of this. Peri-operatively we usually only give 1 dose, but may be continued up to 48 hours post-op
Do we usually give broad or narrow antibx?
Anesthesia usually gives broad. The antibx will depend on pt tolerances and location of the surgery
Do antibiotics cross the BBB?
Highly variable
When might the surgeon want you to hold off on the antibiotics?
If pt is in OR for a wound cleaning (remember that antibiotics are more effective if infected material is removed!)
Are hypersensitivity reactions from antibiotics dependent or independent of dose?
Independent
Things to keep in mind with parturients
Most antimicrobials cross the placenta and enter breast milk. Also concern for teratogenecity.
Considerations for the elderly
Renal and liver impairment
Decreased plasma protein (higher free fraction)
Reduced gastric motility and acidity
Increased body fat
Which is better absorbed from the GI tract, ampicillin or amoxicillin?
Amoxicillin! (think of Moxi)
Renal excretion of Penecillin
90%
MOA for penicillin?
Interferes with cell wall synthesis and stability
These antimicrobials belong to the beta-lactam family
Penicillins, cephalosporins,
Only these antimicrobials are bacteriostatic
Tetracyclines, macrolides (can be either), lincomycins, and sulfonamides
How are viruses classified?
By if they contain DNA or RNA. They never contain both!!
This HIV protease inhibitor is the most potent inhibitor of the cytochrome P-450 system
Ritonavir
Acyclovir and Valacyclovir
Antivirals for herpes. Excreted by the kidneys.
Vidarabine
Antiviral for cytomegalic inclusion disease and HSV encephalitis. This antiviral is mutagenic and carcinogenic.
Famciclovir
Antiviral for acute herpes zoster (shingles)
Ganciclovir
Antiviral for CMV. Risk of hematologic toxicity
Amantadine
Antiviral for Influenza A. Renally excreted.
Antibiotic that inhibits the P-450 system
Cipro (fluoroquinolone)
Antibiotic that induces the P-450 system
Rifampin
Antibiotic whose MOA is bactericidal by acting on DNA and RNA polymerase
Rifampin
This antibiotic has the most potent effect at the NMJ
Polymyxin B and Colistimethate. These are mostly prejunctional, and potentiate with NDNMBs. Not reliable reversed with neostigmine or calcium.
This antibiotic can cause pseudomembranous colitis
Clindamycin
This antibiotic can treat pseudomembranous colitis
Flagyl (even when caused by clinda)
Example of an antifungal
Amphotericin B.
Biggest risk of amphotericin B
Renal impairment. 80% of people will experience renal impairment. Most recover, but some have permanent reduction in GFR. Follow plasma creatinine.
Amphotericin B is a terrible bitch to your kidneys
Method of action for antivirals (interferons)
1) Binds to receptors on host cell membranes, causing production of enzymes that inhibit viral replication and degrade viral RNA
2) Enhances tumoricidal activity of macrophages
Biggest symptom of interferons
Flu-like symptoms
Three different mechanisms of antivirals for AIDS
1) Nucleoside reverse transcriptase inhibitors (impostor host cells)
2) Non-nucleoside reverse transcriptase inhibitors (inhibits the function of enzymes used by the virus)
3) Protease inhibitors (binds to HIV protease)
Effect of protease inhibitors on the P-450 system
Inhibits the P-450 system.
Which protease inhibitor is the most potent inhibitor of the P-450 system?
Ritonavir
MOA of penicillins
Interferes with enzymes responsible for cell wall construction and stability
Main method of excretion of macrolides
Bile
How to remember macrolides.
Remember the erythromycin is a macrolide. We used this to increase gastric emptying. Therefore, the main SE of this is GI intolerance (Cramping, N/V/D, especially with IV infusion). Also with GI stuff, it is excreted through bile and is metabolized by the P-450 system.
SE of erythromycin
GI intolerance (cramping, N/V/D) especially with IV infusion, QT prolongation, and thrombophlebitis with prolonged IV use.
Ciprofloxacin has a ________ effect on the P-450 system and has an elimination half time of _____
Inhibitory
3-8 hours
SE of Cipro
Minimal SE. Mild GI disturbance
All GPCRs will undergo _____
Desensitization
MOA of ciprofloxacin
Interfering with the enzyme responsible for maintaining the helical structure of DNA
Adverse effects of sulfonamides
Increases the effects of PO anticoagulants, skin rash to anaphylaxis, drug fever, hepatotoxicity, and rare incidence of hemolytic anemia
Polymyxin B and Colistimethate have mostly (pre/post) junctional effects on the NMJ
Mostly prejunctional (“B”efore the synapse!)
With what antibiotic class do you want to measure coags?
Sulfonamides
Is rifampin able to cross the BBB?
Hellz to the yea
