Chapter 6: Antibiotics Flashcards
Kills and inhibits organisms on body
Antiseptic
Kills and inhibits organisms on inanimate objects
Disinfectant
All organisms killed
Sterilization
Antiseptic: good for GPCs and GNRs; poor for fungi
Iodophors (Betadine)
Antiseptic: good for GPCs, GNRs, and fungi
Chlorhexidine gluconate (Hibiclens)
Inhibitors of cell wall synthesis
Penicillins, cephalosporins, carbapenems, monobactams, vancomycin
Inhibitors of the 30S ribosome and protein synthesis
Tetracycline, aminoglycosides (tobramycin, gentamicin), linezolid
Inhibitors of the 50s ribosome and protein synthesis
Erythromycin, clindamycin, Synercid
Inhibitor of DNA helicase (DNA gyros)
Quinolones
Inhibitor of RNA polymerase
Rifampin
Produces oxygen radicals that breakup DNA
Metronidazole (Flagyl)
- PABA analogue
- Inhibits purine synthesis
Sulfonamides
- Inhibits dihydrofolate reductase which inhibits purine synthesis
Trimethoprim
Bacteriostatic antibiotics
Tetracycline, clindamycin, erythromycin (all have reversible ribosomal binding), Bactrim
Have irreversible binding to ribosome and are considered bactericidal
Aminoglycosides
Mechanism: penicillin resistance
Due to plasmids for beta-lactamase
MC method of antibiotic resistance
Transfer of plasmids
Resistance caused by a mutation of cell wall-binding protein
Methicillin-resistant S. aureus (MRSA)
Resistance caused by a mutation in cell wall-binding protein
Vancomycin-resistant enterococcus (VRE)
Resistance due to modifying enzymes leading to a decrease in active transport of this antibiotic into the bacteria
Gentamicin resistance
Vancomycin
- Peak
- Trough
Vancomycin
- Peak: 20-40 ug/mL
- Trough: 5-10 ug/mL
Gentamicin
- Peak
- Trough
Gentamicin
- Peak: 6-10 ug/mL
- Trough:
What if the peak is too high?
Decrease amount of each dose
What is the trough is too high?
Decrease frequency of doses (increase time interval between doses)
Antibiotics for:
- GPCs: streptococci, syphilis, Neisseria meningitides (GPR), Clostridium perfringens (GPR), beta-hemolytic Streptococcus, anthrax
- Not effective against Staphylococcus or Enterococcus
Penicillin
Antibiotics: anti-staph penicillins (staph only)
Oxacillin and nafcillin
Antibiotics: same as penicillin but also picks up enterococci
Ampicillin and amoxicillin
Antibiotics:
- Broad spectrum: pick up GPCs (staph/strep), GNRs +/- anaerobic coverage.
- Effective for enterococci; not effective for Pseudomonas, Acinetobacter, or Serratia
Unasyn (ampicillin/sulbactam)
Augmentin (amoxicillin/clavulanic acid)
Ampicillin / sulbactam
Unasyn
Amoxicillin / clavulanic acid
Augmentin
Beta-lactamase inhibitors
Sulbactam and clavulanic acid
- Antipseudomonal penicillins
- GNRs: enterics, pseudomonas, acinteobacter, serratia
- Side effects: inhibits platelets; high salt load
Ticarcillin and piperacillin (antipseudomonal penicillins)
- Broad spectrum: pick up GPCs (staph/strep), GNRs, anaerobes
- Effective for enterococci; effective for pseudomonas, acinetobacter, serratia
- SE: inhibits platelets, high salt load
Timentin (ticarcillin/clavulanic acid)
Zosyn (piperacillin/sulbactam)
Ticarcillin / clavulanic acid
Timentin
Piperacillin / sulbactam
Zosyn
- GPCs: staph and strep
- Not effective for Enterococcus; does not penetrate CNS
First generation cephalosporins (cefazolin, cephalexin)
Why is ancef (cefazolin) good for prophylaxis?
It has a long half life.
- GPCs, GNRs, +/- anaerobic coverage; lose some staph activity.
- Not effective for enterococcus, pseudomonas, acinetobacter, serratia
- Effective only for community-acquired GNRs
Second-generation cephalosporin (cefoxitin, cefotetan, cefuroxime)
Why is cefotetan good for prophylaxis?
It has a long half life.
- GNRs mostly, +/- anaerobic coverage.
- Not effective for enterococcus; effective for pseudomonas, acinetobacter, and serratia
- Side effects: cholestatic jaundice, sludging in gallbladder (ceftriaxone)
Third-Generation cephalosporin (ceftriaxone, ceftazidime, cefepime, cefotaxime)
Antibiotics: GNRs, picks up pseudomonas, acinetobacter, serratia
Monobactam (aztreonam)
Antibiotics:
- Given with cilastin
- Broad spectrum: GPCs, GNRs, and anaerobes
- Not effective for MEP: MRSA, Enterococcus, Proteus
- Side effects: seizures.
Carbapenems (meropenem, imipenem)
Why are carbapenems given with cilastin?
Prevents renal hydrolysis of the drug and increase half-life
What are carbapenems not effective for?
MEP
- MRSA, Enterococcus, and Proteus
- GNRs, +/-GPCs
- Not effective for enterococcus, pseudomonas, acinetobacter, serratia
- Side effects: teratogenic, allergic reactions, renal damage, SJS, hemolyis in G6PD
Bactrim (TMP/SMX)
Trimethoprim / sulfamethoxazole
Bactrim
- Some GPCs, mostly GNRs
- Not effective for enterococcus, picks up Pseudomonas, acinetobacter, serratia
- 40% of MRSA sensitive; some efficacy PO and IV.
Quinolones (Ciprofloxacin, levofloxacin, norfloxacin)
- GNRs
- Good for pseudomonas, acinetobacter, and serratia; not effective for anaerobes (need O2)
- Synergistic with ampicillin for Enterococcus
- Beta-lactams (ampicilin, amoxicililn) facilitate penetration
- Side effects: reversible nephrotoxicity, irreversible ototoxicity
Aminoglycosides (gentamicin, tobramycin)
What is amino glycoside resistance secondary to?
Resistance due to modifying enzymes leading to decreased active transport
- GPCs, best for community-acquired pneumonia and atypical pneumonias
- Side effects: nausea (PO), cholestasis (IV)
- Also binds motilin receptor and is pro kinetic for bowel
Erythromycin (macrolides)
- GPCs, Enterococcus, Clostridium difficile (with PO intake), MRSA)
- Binds cell wall proteins
- Side effects: HTN, Redman syndrome (histamine release), nephrotoxicity, ototoxicity
Vancomycin (glycopeptides)
What is resistance to vancomycin (glycopeptides) due to?
Resistance develops from a change in cell wall-binding protein
- GPCs, includes MRSA, VRE
Synercid (streptogramin - quinupristin-dalfopristin)
Linezolid (oxazolidinones)
- GPCs, GNRs, syphilis
- Side effects: tooth discoloration in children
Tetracycline
- Anaerobes, some GPCs
- Good for aspiration pneumonia
- Can be used to treat C. perfringens
- Side effects: pseudomembraneous colitis
Clindamycin
- Anaerobes
- Side effects: disulfiram-like reaction, peripheral neuropathy (long-term use)
Metronidazole (Flagyl)
Antifungal: binds sterols in wall and alters membrane permeability
- Side effects: nephrotoxic, fever, hypokalemia, hypotension, anemia
- Liposomal type has fewer side effects
Amphotericin
Antifungal: inhibit ergosterol synthesis (needed for cell membrane)
Voriconazole
Itraconazole
Antifungal: inhibits synthesis of cell wall glucan
Anidulafungin (Eraxis)
Prolonged broad-spectrum antibiotics +/- fever
Itraconazole
Tx: invasive aspergillosis
Voriconazole
Tx: candidemia
Anidulafungin
Tx: fungal sepsis other than cadida and aspergillus
Liposomal amphotericine
Tuberculosis drugs
RIPE: rifampin, isoniazid, pyrazinamide, ethambutol
TB: inhibits mycolic acids (give with pyridoxine
-Side effects: hepatotoxicity, B6 deficiency
Isoniazid
TB: inhibits RNA polymerase
-Side effects: hepatotoxicity, GI symptoms, high rate of resistance
Rifampin
TB:
-Side effect: hepatotoxcity
Pyrazinamide
TB:
- Side effect: retrobulbar neuritis
Ethambutol
Inhibits viral DNA polymerase; used for HSV infections, EBV
Acyclovir
Inhibits viral DNA polymerase; used for CMV infections
- Side effects: decreased bone marrow, CNS toxicity
Ganciclovir
Broad spectrum antibiotics can lead to…
Superinfection
Antibiotics effective for enterococcus
Vancomycin
Timentin / Zosyn
Ampicillin / amoxicillin
Gentamicin w/ ampicillin
Effective for Pseudomonas, Acinetobacter, Serratia
Ticarcillin / piperacillin Timentin / Zosyn Third generation cephalosporins Aminoglycosides (gentamicin and tobramycin) Meropenem / imipenem Fluoroquinolones
Purpose of perioperative antibiotics
- Used to prevent surgical site infections
- Need to be given within 1 hour before incision