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29 Cards in this Set
- Front
- Back
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MIC
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concentration that inhibits visible growth
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MBC
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concentration that kills (>99.9% reduction)
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Therapeutic index
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toxic dose/effective dose
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Bactericidal
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serum concentration > MBC, kills bacteria
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Bacteriostatic
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reversibly inhibits growth, serum concentration > MIC but < MBC
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Postantibiotic effect
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lack of growth even after removing antibiotic (allows longer dosing interval)
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Synergism
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effect of two antibodies markedly increased (2+2=6)
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Antagonism
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effect of two antibodies decreased (2+2=1)
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Indifference
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no change in effect (2+2=4)
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Reasons for antibiotic failure
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• Undrained pus (#1 reason)
• Inadequate spectrum, dose, penetration • Unidentified pathogens • Drug interactions • Resistance • Inadequate host defenses • Superinfection |
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Cell wall synthesis antibiotics
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o Bacitracin
o Beta lactams |
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Folic acid metabolism antibiotics
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o Trimethoprim
o Sulfonamides/sulfones |
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DNA replication antibiotics
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o Quinolones
o Nitroimidazoles |
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Protein synthesis
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o Aminoglycosides
o Macrolides o Lincosamides o Streptogramins o Amphenicols o Tetracyclines |
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Beta lactam antibiotics features
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-bacterialcidal
-Inhibit cell wall synthesis by inhibiting cross-linkage of peptide side chains -High therapeutic index and safe in pregnancy -Eliminated through kidney -Look at creatinine clearance before prescribing! -Side effects = rash, anaphylaxis, hematologic toxicity |
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Beta lactam antibiotic resistance mechanisms
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o Hydrolysis by beta lactamases
o Alteration of penicillin binding sites |
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Penicillins features
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-Do not get into the prostate or eye
-Need dose adjustment in renal failure |
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Penicillin is the drug of choice for
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• Strep (except strep pneumo)
• Meningococci • Syphilis • Dental infection • Actinomycosis |
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antistaphylococcal penicillin features
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-Drugs like Oxacillin that cover gram positive
-NOT effective against MRSA - |
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Aminopenicillin features
how do bugs fight back |
-drugs like ampicillin and amoxicillin
-cover a lot of gram negatives -better for E coli, hemophilus(sinusitis, otitis, bronchitis) Destroyed by bera lactamases |
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antipseudomonal features
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-Piperacillin
-active against B. fragilis -given IV for serious gram negative infection |
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Beta lactamase inhibitor features
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-Limited antibacterial activity by themselves
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Specific Beta lactamase inhibitors
Augmentin? Timentin? Unasyn? Zosyn? |
-Augmentin: For haemophilus and moraxella
-Timentin: For serious gram negative infection -Unasyn: Adds anaerobic coverage -Zosyn: Potent broad spectrum agent (covers pseudomonas, positives and negatives, beta lactamase resistant) |
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Aminoglycosides are synergistic with
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vancomycin, penicillin
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Aminoglycosides are effective for
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gram negative bacilli, staph, mycobacteria
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Aminoglycosides toxicity
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-Narrow therapeutic index
-can accumulate in kidney -High peak levels cause ototoxicity |
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What makes Aminoglycosides unique among protein synthesis inhibitors
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they are bactericidal
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Gentamicin are most active against
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gram positive cocci
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Tobramicin are more active against
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Pseudomonas
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