Antibiotics Flashcards
Bacitracin
Gram +
Bactericidal
Cell wall - peptidoglycan polymerization
Fosfomycin
Gram + & -
Bactericidal
Cell wall - NAG formation
Cycloserine
Cell wall - prevents D-Ala-D-Ala bond
Beta lactams
Broad spectrum
Bactericidal
Cell wall - inhibit penicillin bind proteins/crosslinking
R membered ring - similar to D-Ala
Penicllins
Beta-lactam
Bactericidal
Cell wall
Cephalosporins
Beta-lactam
Bactericidal
Cell wall
Carbapenems
Beta-lactam
Bactericidal
Cell wall
Monobactams
Beta-lactam
Bactericidal
Cell wall
Glycopeptides
Gram +
Bactericidal
Cell wall - prevents crosslinking, acts on PBP
Ex. vancomycin
Lipoglycopeptides
Gram +
Bactericidal
Cell wall & membrane - prevents crosslinking, acts
Acid-fast bacilli
Ethambutol - arabinogalactan
Isoniazid and ethionamide - mycolic acid synthesis
Cell wall targeting
Affect bacteria when they are growing dividing
Cell membrane targeting
Intercalation into lipid membrane by forming pores or carpets
Sulfonamides
Gram + & -
Bacteriostatic
Folate metabolism - inhibit PABA (earlier)
Trimethoprim
Gram + & -
Bacteriostatic
Folate metabolism - inhibit dihydrofolate reductase
Bactrim
Comines sulfonamide and trimethoprim
Bactericidal
Quinolones
Gram + & -
DNA replication - inhibit topoisomerase
2 six member rings
Nitroimidazoles
Bactericidal
DNA replication - cytotoxic product, promote strand breakage
Nitrofurans
Same as nitroimidazoles (Bactericidal
DNA replication - cytotoxic product, promote strand breakage) but only aerobic bacteria
Rifamycin
Gram + & -
Bactericidal
RNA replication - inhibit RNA polymerase
Macrocyclics
Only C. difficile
RNA replication - blocks RNA poly binding
Aminoglycosides
Bactericidal
Protein synthesis - incorrect insertion of amino acids
Tetracyclines
Bacteriostatic
Protein synthesis - amino acids can’t be inserted
Glyclyclines
Bacteriostatic
Protein synthesis - amino acids can’t be inserted
Macrolides
Bind reversibly
Protein synthesis - prevent amino acid chain from existing
Ketolides
Bind reversibly
Protein synthesis - prevent amino acid chain from existing
Like macrolide but 2 bindings sites instead of one
Lincosamides
Bind reversibly
Protein synthesis - prevent amino acid elongation
Chloramphenicol
Bind reversibly
Protein synthesis - prevent amino acid elongation
Slightly different binding site to lincosamide
Streptogramins
Protein synthesis - prevent peptide bond formation and elongation
Macrolides, Lincosamides, Streptogramins
All bind to same area but slightly different actions
Oxazolidinones
Gram +
Protein synthesis - inhibit initiation
Pleuromutilins
Gram +
Bacteriostatic
Protein synthesis - prevent initiation and elongation
Fusidic acid
Gram + & -
Bacteriostatic
Protein synthesis - prevent energy for motion of ribosome
Breakpoint
MIC when bacteria is deemed susceptible or non-susceptible to antibiotic
MIC testing
Borth dilution
E-test (ruler in plate)
Kirby-Bauer (patches of antibiotic)
Post-antibiotic effect
How long is antibiotic effective when concentration is less than MIC
AUC/MIC dosing
Time and concentration dependent
Interval and dose
Antibiotic is reversibly inhibiting so have to keep up activity
Glycopeptides
Consider toxicity
T dosing
Time dependent
More frequent interval, irreversible but over time, new formed so have to keep up with killing
Penicillin
Cmax/MIC dosing
Depends on PAE
Large dosing, one large dose is enough because it is irreversible - causes PAE because effects last even after
Aminoglycoside
General resistance
Outer membrane proteins - block entry of antibiotic
Efflux pump - low level resistance, can be unregulated
Beta-lactam resistance
PBP don’t bind well (MRSA)
Decreased permeability
Modifying enzymes
Beta-lactamases on the rise (esp group 2)
Beta-lactamases
Produced by bacteria to break down beta-lactam antibiotics
ESBL
MBL
KPC
CRE
KPC & CRE
On the rise, source of concern
Esp CRE because it is to common bacteria
NDM-1
Easily transferred amongst people, many resistance genes
Quinolone resistance
Mutations in DNA gyrase/topoismerase
Decreased permeability
Active efflux pumps
Protection of DNA gyrase/topoisomerase
Aminoglycoside resistance
Methylation of rRNA
Decreased permeability
Active efflux pumps
Direct inactivation
MLSB
Reisstance to one - resistance to all
Methylation of rRNA
Active efflux pumps
Linezolid resistance
Methylation of rRNA