Antimicrobial Compounds Flashcards
Another type of Cell Wall Antibiotics
- GLYCOPEPTIDES
Beta-Lactam Antibiotics
- Narrowest to wides
NARROW
- Penicillins
- Cephalosporins
- Gen 1
- Gen 2
- Gen 3
- Carbapenems
BROADEST
Beta-Lactams
- Gram type
- Narrowest
- Broadest
- Used against Gram positive AND Gram negative
- Penicillin and ampicillin are narrow
- 1st generation cephalosporins are narrow
- 3rd and 4th generation cephalosporins have broader coverage, usually used for more resistant organisms
- Carbapenems are VERY broad and typically used as an antibiotic of last resort
Definintion
Resistance
Sensitive
Resistance
- When an organism no longer responds to therapy OR is associated with failure in vitro (eg antibiotic no longer has a clinical effect in vitro)
Sensitive
- When an organism responds to an antimicrobial and has activity (clinical) in vivo
Definition
Narrow Spectrum Antibiotics
Broad Spectrum Antibiotics
NARROW
- Active against a small group of bacteria
BROAD
- Active against a wide variety of bacteria
Definitions:
Bactericidal
Bacteriostatic
Bactericidal
- Kills susceptible bacteria, host responses not needed
Bacteriostatic
- Inhibits local bacterial growth and relies on host defences to clear the bacteria
Fluoroquinolones
- Example
- Spectrum
- Used for
CIPROFLAXIN
- Excellent drugs with a broad spectrum of activity
- Good tissue penetration
- in GRAM POSITIVES
Used for
- CAP
- UTI
Four Main Antimicrobial Targets + Examples
- Cell Wall Synthesis
- Directly interferes with membrane formation and stabilization etc
- Penicillins, cephalosporins, carbapenems, monobactams - Nucleic acid synthesis
- Typically when going from DNA to RNA to Protein
- Interferes with some aspect of transcription
- Sulfonamides, quinolones, rifampin - Protein Synthesis
- Going from RNA to protein
- Some aspect of translation
- Macrolides, tetracycline - Key Metabolic Agents
- Things the bacteria need for growth
- Folate inhibtors etc
Glycopeptides
- Function
- Non Beta-lactam cell wall active agents
- Act only on the cell wall of GRAM POSITIVES
- Stops the extension of the peptidoglycan unit of the bacterial cell wall
- Interferes with the D-ala D-ala (repeated alanine all across the cell wall keeps it patent) binding and causes the bacteria to die
Stops the extension of the bacterial cell wall
Glycopeptides
- Two examples
- Vancomycin
- Teicoplanin
Target - Cell Wall Synthesis
- Beta-lactam ring is the central component of all beta lactam antibiotics
- Bind to the TRANSPEPTIDASE enzyme complex that facilitates the reaction that crosslinks NAG and NAM, therefore blocking cell wall development
Target - Metabolic Requirements
- Broad function
- Two examples + what they target
METABOLIC INHIBITORS
- Prevent an organism from using something it needs in order to survive
- Inhibit the active form of folic acid
Two examples
- Trimethoprim
- Structural analog of DHF (dihydrofolic acid), competitive inhibitor of dihydrofolate reductase
- Prevents the formation of tetrahydrofolic acid - Sulfamethoxazole
- Structural analog of PABA
- Competitively inhibits synthesis of DHF
Target - Nucleic Acid Synthesis
- Broad definition
- What they act on/function
- Example
NUCLEIC ACID INHIBITORS
- Interfere with
- DNA GYRASE
- TOPOISOMERASE
Example
- Fluoroquinolones
Target - Protein Synthesis
- Broad definintion
- Function
- Two categories + example from each
PROTEIN SYNTHESIS INHIBITORS
- Binds to parts of the ribosome (either the 50S subunit or the 30S subunit) and prevents protein synthesis in bacteria
50S
- Macrolides
30S
- Tetracycline
Three Examples of Protein Synthesis Inhibitors
- What they act on
- What they do
- Tetracyclines
Act on: 30S
- Block the attachment of tRNA to the ribosome - Macrolides
Act on: 50S
- Prevent continuation of protein synthesis - Chloramphenicol
Acts on: 50S
- Prevents peptide bonds from being formed
