Antibiotics Midterm Flashcards
-illins
Related to PCN
-cyclins
Related to tetracyclins
-mycins
Related to macrolide antibiotics
What does Vancomycin target?
Peptidoglycan in cell walls, gram positive bacteria
What does Chloramphenicol target?
Ribosomal subunits
Bacteriostatic vs. Bactericidal
Bacterial growth vs. Bacterial death
MIC vs. MLD
Minimal inhibitory concentration vs minimal lethal dose. MIC is the lowest concentration needed to inhibit growth in 99% and MLD is minimal amount needed to kill 99.9%
Drugs that target essential metabolic pathways?
Sulfa/Trimethoprim
P-Aminosalicylic acid
Drugs that target nucleic acid synthesis
Rifampin and Rifabutin
Quinolones
Metronidazole (flagyl)
Drugs that disrupt bacterial membranes
Polymyxins/Colistin (Polymixin E)
Specific effect of sulfa drugs
These are broad spectrum antibiotics that inhibit folic acid biosynthesis from the start. Often used with trimethoprim which inhibits another step in the pathway by stopping the cell from using pools of materials it has already made. Both of these guys act as competitive inhibitors.
S + T = Bactrim
What other drug is Sulfa related to?
P-aminosalicylic acid - Effective against TB
Drugs that are bactericidal
Rifampin and Rifabutin
Quinolones
Metronizadole (Flagyl)
Polymixins
How do rifampin and rifabutin work?
narrow spectrum, gram + bacteria. Binds to beta subunit of RNA polymerase, inhibits transcriptional initiation
How do quinolones work?
inhibit DNA replication by inhibiting bacterial DNA gyrases and/or topoisomerase IV
How does flagyl work?
narrow spectrum, administered as a prodrug, disrupts DNA structure, inhibits DNA replication, causes breaks and mutations (enzymes to convert prodrug only in bacterial cells)
How do Polymixins work?
narrow spectrum, inserts hydrophobic tail into membrane, hydrophilic head group disrupts PE and LPS on membrane (host dos not have PE or LPS)
What drugs target the bacterial cell wall?
Vancomycin
PCN
How does Vanco work?
Prevents transglycosylation in the cell wall
How does PCN work?
Inhibits transpeptidation by mimicking the beta-lactam molecule to bind transpeptidases and carboxypeptidases.
All -cillins work in this way
What do we give -cillins to help the mfight bacteria resistances?
Clavulanic acid, which when given with the -cillin, fights the Beta-lactamase that inhibits the antibiotic.
Ex. Augmentin = Amoxicillin + clavulanic acid
What drugs target the cell membrane
Polymixins
Daptomycin
How do polymixins work?
Integrates a lipophilic tail in the outher membrane and destroys it. Effects Gram negative bacteria.
How does Daptomycin work?
Affects gram negative bacteria making it a good alternative to Vancomycin. Integrates lipophilic tail in membrane and destroys it. Calcium dependent though