Antimicrobials Flashcards
Which is dose-related, having a hypersensitive reaction or having issues with toxicity?
Toxicity has to do with dose (too much)
Hypersensitive (allergic) reaction does not depend on dose
When are surgical prophylactic antibiotics given?
Less than one hour before surgery
Is ampicillin or amoxicillin more likely to be given by mouth? Which of these drugs has a higher incidence of skin rash?
Amoxicillin is given by mouth more because it is more efficiently absorbed from the GI tract
Ampicillin has a highest incidence of skin rash among penicillins, used for H flu and E coli
**Note: these are both broad-spectrum, second generation penicillins
Are penicillins bactericidal or bacteriostatic? What organisms do they work against? How is it excreted?
Bactericidal
Penicillin against pneumococcal, meningococcal, streptococcal (gram pos), second generation against gram neg
Renal excretion
Adverse reactions to penicillins?
Hypersensitivity (more than the other antimicrobials)
Cross sensitivity between penicillin and cephalosporins (this is due to the beta-lactam ring in both)
Cephalosporin: broad or narrow spectrum? bacteriostatic or bactericidal? How is it excreted?
Broad spectrum
Bactericidal
Renal excretion
3 generations: 1-cefazolin (ancef), 2-cefoxitin, 3-cefotaxime
Adverse reactions of cephalosporins?
Allergic reactions (rash) Cross sensitivity between cephalosporins and penicillin
Why are cephalosporins used in orthopedic surgery?
They penetrate into the joints
Are aminoglycosides bactericidal/ bacteriostatic? Which organisms are they effective against? How is it excreted?
Bacteriocidal
Gram neg bacteria.. Narrow!
Renal excretion
What are side effects of aminoglycosides?
Ototoxicity: irreversible vestibular/cochlear destruction over time
Nephrotoxicity: reversible, accumulation in renal cortex can cause tubular necrosis (neomycin #1 nephrotoxic, monitor BUN/creatinine)
Skeletal muscle weakness: inhibit ACh release (myasthenia gravis are sensitive), also issue with reversing muscle relaxant, calcium can help
Prolongs neuromuscular blockade: potentiated, reappears in PACU
Why should use of Streptomycin and Kanamycin (aminoglycosides) be limited?
Why should plasma concentrations of Gentamycin by monitored?
Increased occurrence of vestibular damage with Streptomycin and Kanamycin
Gentamycin becomes toxic over 9 mcg/mL
Which aminoglycoside is used for hepatic comas? Hint: this is also the aminoglycoside that is most nephrotoxic.
Neomycin
Tetracyclines: Bactericidal or bacteriostatic? Uses? Where excreted?
Bacteriostatic
Used for acne treatment (decreases fatty acid content of sebum)
Excreted in urine and bile
Side effects of tetracyclines?
Permanent discoloration of teeth
Phototoxicity
Macrolides (Erythromycin/Zithromax): bacteriostatic or bactericidal? Broad or narrow spectrum? How is it metabolized/excreted?
Can be bacteriostatic or bacteriocidal (by inhibiting protein synthesis)
Narrow spectrum against gram +
Metabolized by cytochrome P-450 (smooth ER of liver), excreted by bile (so no need to alter dose for renal disease patients)
Macrolides (Erythromycin) adverse effects?
GI intolerance: N/V
increased gastric emptying
QT effects: prolongs cardiac repolarization, increased incidence of torsades de pointes
Thrombophlebitis
Lindomycins (Clindamycin): bacteriostatic/ bactericidal? Uses? Should dose be decreased for renal or liver disease?
Bacteriostatic
Used for serious infections in GI tract or female genital tract
Decrease dose with severe liver disease (metabolized in liver), elimination is only slightly prolonged with renal disease so this doesn’t require dose adjustment
Clindamycin side effects?
Pseudomembranous colitis (severe diarrhea), when patient gets diarrhea, this med should be discontinued Pre and post junctional effects at neuromuscular junction, not antagonized with anticholinesterases or calcium (not effective when reversing neuromuscular blocker), extended time of neuromuscular blockade