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Antiseptic:
kills and inhibits organisms on body
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Disinfectant
kills an inhibits organisms on inanimate objects
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Sterilization:
all organisms killed
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Common antiseptics in surgery:
1) Iodophors (betadine) - good for GPCs, GNRs, and poor fungi
2) Chlorhexidine gluconate (hibiclens)- good for GPCs, GNRs, and fungi
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Inhibit cell wall synthesis:
- 1) penicillins
- 2) cephalosporins
- 3) carbapenems
- 4) monobactams
- 5) vancomycin
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Inhibitors of 30S ribosome and protein synthesis:
- 1) tetracycline
- 2) aminoglycosides (tobramycin, gentamycin)
- 3) linezolid
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Inhibitors of the 50S ribosome and protein synthesis:
- 1) erythromycin
- 2) clidamycin
- 3) chloramphenicol
- 4) synercid
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Inhibitors of DNA helicase (DNA gyrase):
quinolones (bid dosing)
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Inhibitors of RNA polymerase:
rifampin
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Produces oxygen radicals that breakup DNA-
metronidazole (flagyl)
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Sulfonamides
- 1) PABA analogue
- 2) inhibit purine synthesis
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Trimethoprim
- 1) inhibits dihydrofolate reductase
- 2) inhibits purine synthesis
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Bacteriostatic agents:
- 1) clindamycin
- 2) erythromycin
- 3) tetracycline
- 4) chloramphenicol
- (all have reversible ribosomal binding)
- 5) bactrim
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Bactericidal
Aminoglycosides have irreversible binding to ribosome and are considered bactericidal
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PCN resistance:
plasmids for beta-lactamase
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Whats the most common method for antibiotic resistance?
Transfer of plasmids
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Methicillin-resistant S. aureus (MRSA)
resistance to methicillin caused by mutation of cell wall-binding protein
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Vancomycin resistant enterococcus
resistance develops from mutation in cell wall-binding protein
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Gentamycin resistance:
resistance due to modifying enzymes leading to decrease in active transport
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Vancomycin drug levels
- peak 20-40 ug/mL
- trough 5-10ug/mL
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Gentamicin
- peak 6-10ug/mL
- trough <1ug/mL
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What do you do if the peak is too high?
decrease amount of each dose
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What do you do if trough is too high
decrease frequency of doses (increase time interval between doses)
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Penicillin
- 1) GPC
- 1- streptococci
- 2- beta-hemolytic streptococcus
- 3- neisseria meningitides (GPR)
- 4- Clostridium perfringes (GPR)
- 5- syphillis
- 6- anthrax
- 2) Not effective against staphylococcus or enterococcus
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Oxacillin/nafcillin:
anti-staph penicillins (staph only)
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ampicillin/amoxicillin
same as penicillin but also picks up enterococci
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Unasyn (ampicillin/sulbactam) and augmentin (amoxicillin/clavulanic acid)
- 1) broad spectrum- pick up GPCs (staph and strep), GNRs, +/- anaerobic coverage
- 2) Effective for enterococci
- 3) not effective for :
- 1- pseudomonas
- 2- acinetobacter
- 3- serratia
- 4) sulbactam and clavulanic acid are beta-lactamase inhibitors
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Ticarcillin/piperacillin
- 1) antipseudomonal penicillins
- 2) GNRs-
- 1- enterics
- 2- psedomonas
- 3- acinetobacter
- 4- serratia
- 3) Side effects:
- 1- inhibits platelets
- 2- high salt load
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Timentin (ticarcillin/clavulanic acid) and Zosyn (piperacillin/sulbactam)
- 1) Broad spectrum- pick up GPCs (staph and strep), GNRs, anaerobes
- 2) Effective for enterococci; effective for pseudomonas, acinetobacter, and serratia
- 3) Side effects:
- 1- inhibit platelets
- 2) high salt load
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First generation cephalosporins:
- 1) cefazolin, cephalexin
- 2) GPCs- staph and strep
- 3) Not effective for enterococcus
- 4) Does not penetrate CNS
- 5) Ancef (cefazolin) has the longest half-life --> best for prophylaxis
- 6) Side effects: can produce positive coombs test
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Second generation cephalosporins
- 1) cefoxitin, cefotetan, cefuroxime
- 2) GPCs, GNRs, +/- anaerobic coverage; lose some staph activity
- 3) not effective for enteroccocus, pseudomonas, acinetobacter, or serratia
- 4) effective only for community-aquired GNRs
- 5) Cefotetan has the longest half-life--> best for prophylaxis
- 6) Side effects: prolonged PT
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Third generation Cephalosporins
- 1) ceftriaxone, ceftazidime, cefepime, cefotaxime
- 2) GNRs, mostly, +/- anaerobic coverage3) Not effective for enterococcus; effective for pseudomonas, acinetobacter, and serratia4) Side effects:
- 1- cholestatic jaundice (ceftriaxone)
- 2) sludging in gallbladder (ceftriaxone)
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Monobactam
- 1) aztreonam
- 2) GNRs; picks up pseudomonas, acinetobacter, and seratia
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Carbapenems
- 1) meropenem, imipenem
- 2) Broad spectrum- GPCs, GNRs, and anaerobes
- 3) not effective for MEPP:
- MRSA
- Enterococcus
- Proteus
- Pseudomonas (which can develop resistance)
- 4) Cilastin- prevents renal hydrolysis of the drug and increases half-life
- 5) Side effects: Carbapenems can cause seizures
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Bactrim:
- 1) GNRs, +/- GPCs
- 2) not effective for enterococcus, pseudomonas, acinetobacter, and serratia
- 3) Side effects (numerous):
- 1- teratogenic
- 2- renal damage
- 3- allergic reactions
- 4) Stevens-Johnson syndrome (erythema multiforme)
- 5) hemolysis in G6PD-deficient patients
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Quinolones
- 1) ciprofloxacin, levofloxacin, trovafloxacin
- 2) GPCs, mostly GNRs
- 3) not effective for Enterococcus
- 4) picks up pseudomonas, acinetobacter, and serratia
- 6) 40% of MRSA sensitive
- 7) same efficacy PO an IV
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Aminoglycosides
- 1) gentamycin, tobramycin, amikacin
- 2) GNRs
- 3) good for pseudomonas, acinetobacter, and serratia
- 4) not effective for anaerobes (need O2)
- 5) resistance due to modifying enzymes leading to decreased active transport
- 6) synergistic with ampicillin for enterococcus- beta-lactams (ampicillin/amoxicillin)
- 7) Side effects:
- 1- reversible nephrotoxicity
- 2- irreversible ototoxicity
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Erythromycin
- 1) macrolides
- 2) GPCs
- 3) best for community-acquired pneumonia and atypical pneumonias
- 4) side effects:
- 1- nausea (PO)
- 2- cholestasis (IV)
- 5) also binds motilin receptor and is prokinetic for bowel
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Vancomycin
- 1) glycopeptides
- 2) GPCs, enterococcus, clostidium difficile (with PO intake), MRSA
- 3) binds cell wall proteins
- 4) resistance develops from change in cell wall-binding sites5) Side effects:
- 1- HTN
- 2- redman syndrome (histamine release)
- 3- nephrotoxicity
- 4- ototoxicity
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Synercid
- 1) streptogramin- quinupristin-dalfopristin
- 2) GPCs; includes MRSA, VRE
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Linezolid
- 1) oxazolidinones
- 2) GPCs, includes MRSA and VRE
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Tetracycline
- 1) GPCs, GNRs, syphillis
- 2) Side effects: tooth discoloration in children
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Clindamycin
- 1) anaerobes, some GPCs
- 2)good for aspiration pneumonia
- 3) can be used to treat C. perfringens
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Metronidazole
- 1) anaerobes
- 2) Side effects:
- 1- disulfiram-like reaction
- 2- peripheral neuropathy
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Name two antibiotic interactions:
- 1) carbenicillin and ticarcillin can interfere with aminoglycosides
- 2) tetracyclines can interfere with beta-lactams
- 3) broad-spectrum antibiotics can lead to superinfection
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