Antibacterial Agents 2 Flashcards
To learn this unit's antimicrobials and their functions
Bacteria have a _S ribosome made up of a _S large subunit and _S small subunit
70; 50; 30
Humans have a _S ribosome made up of a _S large subunit and _S small subunit
80; 60; 40
These classes affect the 30S subunit of bacterial ribosomes
Aminoglycosides and tetracyclines
These classes affect the 50S subunit of bacterial ribosomes
Cloramphenicol, Macrolides, Lincosamides, Streptogramins, and Oxazolidinones
Streptomycin is an example of what class?
Aminoglycosides
Gentamicin is an example of what class?
Aminoglycosides
Are aminoglycosides static or cidal?
Bactericidal, used mainly against Gram(-) rods
Streptomycin is unique because it can also be used against what bacterial agents?
Mycobacteria
What type of bacteria are intrinsically resistant to aminoglycosides?
anaerobes
How do bacteria build resistance to aminoglycosides?
- Enzymatic inactivation through phosphylation, adenylation, or acetylation (similar to B-lactamase)
- Alter the target through methylation of rRNA or mutation of the ribosomal proteins
- Alter exposure through decreased uptake and increased efflux
Aminoglycosides are synergistic with what other class?
B-lactams
B-lactams are synergistic with what other class?
aminoglycosides
Are tetracyclines static or cidal?
Bacteriostatic for intracellular bacteria, G(+), and G(-)
Doxycyline is an example of what class?
tetracyclines
Mixing a bacteriostatic drug and a bactericidal drug will have what kind of effect?
Antagonistic (i.e. B-lactams only work on actively dividing cells and bacteriostatic agents prevent active division)
How do bacteria form resistance to tetracyclines?
- Alter drug exposure through >28 classes of efflux pumps
2. Alter drug target through ribosome protection proteins
Is chloramphenicol static or cidal?
Bacteriostatic (but can be ‘cidal against important encapsulated organisms)
How do bacteria form resistance to chloramphenicol?
They enzymatically inactivate the drug through acetyl transferases
Are macrolides static or cidal?
Bacteriostatic mainly against Gram(+) with some Gram(-) exceptions
Erythromycin is an example of what class?
macrolides
Azithromycin is an example of what class?
macrolides
Are lincosamides static or cidal?
Bacteriostatic for Gram(+) and (-)
Lincosamides are important because they work against what kind of bacteria?
anaerobic
Clindamycin is an example of what class?
Lincosamides
Are streptogramins A & B static or cidal?
Individually they are bacteriostatic but together they are bacteriocidal
How do bacteria show resistance to macrolides, lincosamides, and streptogramin B? (MLSB)
- Cross-resistance due to similar mechanisms of action
2. Alter the drug target through methylation by erm genes
Are oxazolidinones static or cidal?
Bacteriostatic against many G(+) that have expresses resistance to other antibiotics
Linezolid is an example of what class?
Oxazolidinones
How do bacteria form a resistance to oxazolidinones?
Alter drug target through mutations in 23S rRNA gene
Which agents act on mycobacterial cell wall?
isoniazid and ethambutol
Which class disrupts the cell membrane of Gram(+) bacteria?
lipopeptides
What are the antibiotics that inhibit peptidoglycan synthesis?
phosphomycin, cycloserine, bacitracin, glycopeptides, and B-lactams
What is the best class to use against anaerobic organisms?
lincosamides
