Antibiotics: General Principles Flashcards
Gram positive bacteria (3):
- Staphylococcus
- Streptococcus
- Enterococcus
Gram negative “piddly” bacteria (7):
- Haemophilus
- Morexella
- Morganella
- Shigella
- Salmonella
- Providencia
- Neisseria
Gram negative “fence” bacteria (3):
PEK
- Proteus
- Eschericia coli
- Klebsiella
Gram negative “SPACE” bacteria (5):
- Serratia
- Pseudomonas
- Acinetobacter
- Citrobacter
- Enterobacter
Atypical bacteria (3):
CML
- Chlamydia
- Mycoplasma
- Legionella
Anaerobic bacteria (3):
- Peptostreptococcus
- Bacteroides
- Clostridium
Bactericidal:
Lethal to susceptible microorganisms.
Bacteriostatic:
Inhibitory to growth of susceptible microorganisms.
Resistant microorganism:
Concentration of drug required to inhibit or kill a microorganism cannot be achieved safely.
Postantibiotic effect:
PAE
- Persistent effect of an antimicrobial on bacterial growth following brief exposure of organisms to a drug.
- Aminoglycosides and fluoroquinolones.
Concentration dependent killing:
Killing dependent on peak concentration. Optimal kill occurs when concentration exceeds 10x MIC.
- Quinolones and aminoglycosides.
Time dependent killing:
Killing is dependent on amount of time the concentration stays above the MIC (40-50% of the time).
- Beta-lactam antibiotics.
MOA of Penicillins/cephalosporins/carbapenems/aztreonam:
Prevents cross-linking of peptidoglycan strands by inhibiting transpeptidases.
MOA of Vancomycin:
Inhibits peptidoglycan synthetase and polymerization of linear peptide.
MOA of aminoglycosides:
Inhibits 30 S ribosome; causes misreading of mRNA.
MOA of chloramphenicol:
Inhibits peptidyl transferase and peptide band formation.
MOA of erythromycin, clindamycin and lincomycin:
Inhibits 50 S ribosome.
MOA of tetracyclines:
Inhibits binding of aminoacyl tRNA to ribosome; 30 S ribosome.
Polymixin B and colistin:
Interference with cell membrane function.
- Cationic detergent.
Rifampin:
Inhibits DNA-dependent RNA polymerase.
Fluoroquinolones:
Interferes with supercoiling of DNA by action on DNA gyrase.
Isoniazid and ethambutol:
Inhibits lipid synthesis.
Sulfonomides and trimethoprim:
Prevents synthesis of folic acid.
Mechanisms of resistance to penicillins and cephalosporins (3):
- Beta-lactamases.
- PBP changes.
- Porin channel changes.
Mechanism of resistance to aminoglycosides:
Enzyme inactivating.
Mechanism of resistance to macrolides:
- Methyltransferases that alter drug binding sites on 50 S ribosomal subunit.
Mechanism of resistance to tetracyclines:
Transport systems that pump drugs out of the cell.
Mechanisms of resistance to sulfonamides (2):
- Increased PABA formation.
- Target enzyme sensitivity.
Mechanisms of resistance to fluoroquinolones (2):
- Target enzyme changes.
- Drug efflux.
SPACE bug coverage:
Box and One:
- One of:
- PNC, cephalosporin, carbapenem, (aztreonam).
- One of:
- Fluoroquinolones, aminoglycosides
- Ace In The Hole: aztreonam
SPACE bug PCN’s (2):
- Piperacillin
- Ticarcillin
SPACE bug cephalosporins (2):
- Ceftazadime
- Cefepime
SPACE bug carbapenems (2):
- Imipenem
- Meropenem
SPACE bug aminoglycosides (2):
- Gentamicin
- Tobramycin
SPACE bug fluoroquinolones (2):
- Ciprofloxacin
- Levofloxacin
