Chapter 6: Antibiotics Flashcards
Iodophors (Betadine)
Antiseptic: good for GPCs and GNRs; poor for fungi
Chlorhexidine gluconate (Hibiclens)
Antiseptic: good for GPCs, GNRs, and fungi
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
Resistance caused by a mutation of cell wall-binding protein
Methicillin-resistant S. aureus (MRSA)
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 if the trough is too high?
Decrease frequency of doses (increase time interval between doses)
Penicillin
GPCs: streptococci, syphilis, Neisseria meningitides (GPR), Clostridium perfringens (GPR), beta-hemolytic Streptococcus, anthrax
- Not effective against Staphylococcus or Enterococcus
Antibiotics: anti-staph penicillins (staph only)
Oxacillin and nafcillin
Antibiotics: same as penicillin but also picks up enterococci
Ampicillin and amoxicillin
Unasyn (ampicillin/sulbactam)
Augmentin (amoxicillin/clavulanic acid): bugs
- Broad spectrum: pick up GPCs (staph/strep), GNRs +/- anaerobic coverage.
- Effective for enterococci; not effective for Pseudomonas, Acinetobacter, or Serratia
Timentin (ticarcillin/clavulanic acid)
Zosyn (piperacillin/sulbactam): bugs, side effects
(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
1st - generation cephalosporins (cefazolin, cephalexin): bugs
- GPCs: staph and strep
- Not effective for Enterococcus; does not penetrate CNS
Why is ancef (cefazolin) good for prophylaxis?
It has a long half life.
2nd - generation cephalosporin (cefoxitin, cefotetan, cefuroxime): bugs
- GPCs, GNRs, +/- anaerobic coverage; lose some staph activity.
- Not effective for enterococcus, pseudomonas, acinetobacter, serratia
- Effective only for community-acquired GNRs
Why is cefotetan good for prophylaxis?
It has a long half life.
3rd - generation cephalosporin (ceftriaxone, ceftazidime, cefepime, cefotaxime): bugs, side effects
- GNRs mostly, +/- anaerobic coverage.
- Not effective for enterococcus; effective for pseudomonas, acinetobacter, and serratia
- Side effects: cholestatic jaundice, sludging in gallbladder (ceftriaxone)
Monobactam (aztreonam): bugs
GNRs, picks up pseudomonas, acinetobacter, serratia
Carbapenems (meropenem): bugs, side effects
- Given with cilastin
- Broad spectrum: GPCs, GNRs, and anaerobes
- Not effective for MEP: MRSA, Enterococcus, Proteus
- Side effects: seizures.
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
Bactrim (TMP/SMX): bugs, side effects
GNRs, +/-GPCs
- Not effective for enterococcus, pseudomonas, acinetobacter, serratia
- Side effects: teratogenic, allergic reactions, renal damage, SJS, hemolyis in G6PD
Quinolones (Ciprofloxacin, levofloxacin, norfloxacin): bugs
- Some GPCs, mostly GNRs
- Not effective for enterococcus, picks up Pseudomonas, acinetobacter, serratia
- 40% of MRSA sensitive; some efficacy PO and IV.
Aminoglycosides (gentamicin, tobramycin): bugs, side effects
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
What is aminoglycoside resistance secondary to?
Resistance due to modifying enzymes leading to decreased active transport
Erythromycin (macrolides): bugs, side effects
- 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
Vancomycin (glycopeptides): bugs, side effects
- GPCs, Enterococcus, Clostridium difficile (with PO intake), MRSA)
- Binds cell wall proteins
- Side effects: HTN, Redman syndrome (histamine release), nephrotoxicity, ototoxicity
What is resistance to vancomycin (glycopeptides) due to?
Resistance develops from a change in cell wall-binding protein
Synercid (streptogramin - quinupristin-dalfopristin)
Linezolid (oxazolidinones): bugs
GPCs, includes MRSA, VRE
Tetracycline: bugs, side effects
- GPCs, GNRs, syphilis
- Side effects: tooth discoloration in children
Clindamycin: bugs, side effects
- Anaerobes, some GPCs
- Good for aspiration pneumonia
- Can be used to treat C. perfringens
- Side effects: pseudomembraneous colitis
Metronidazole (Flagyl): bugs, side effects
- Anaerobes
- Side effects: disulfiram-like reaction, peripheral neuropathy (long-term use)
Amphotericin
Antifungal: binds sterols in wall and alters membrane permeability
- Side effects: nephrotoxic, fever, hypokalemia, hypotension, anemia
- Liposomal type has fewer side effects
Voriconazole
Itraconazole
Antifungal: inhibit ergosterol synthesis (needed for cell membrane)
Anidulafungin (Eraxis)
Antifungal: inhibits synthesis of cell wall glucan
Prolonged broad-spectrum antibiotics +/- fever
Itraconazole
Tx: invasive aspergillosis
Voriconazole
Tx: candidemia
Anidulafungin
Tx: fungal sepsis other than cadida and aspergillus
Liposomal amphotericin
Tuberculosis drugs
RIPE: rifampin, isoniazid, pyrazinamide, ethambutol
Isoniazid
TB: inhibits mycolic acids (give with pyridoxine
-Side effects: hepatotoxicity, B6 deficiency
Rifampin
TB: inhibits RNA polymerase
-Side effects: hepatotoxicity, GI symptoms, high rate of resistance
Pyrazinamide
TB:
-Side effect: hepatotoxcity
Ethambutol
TB:
- Side effect: retrobulbar neuritis
Acyclovir
Inhibits viral DNA polymerase
Used for HSV infections, EBV
Ganciclovir
Inhibits viral DNA polymerase
Used for CMV infections
- Side effects: decreased bone marrow, CNS toxicity
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
