Antimicrobials Flashcards
How can we control microbes?
- Sterilisation
- Disinfection
- Antimicrobial
What is chemotherapy?
- Treatment of a disease with a chemical substance
What is a antimicrobial?
- Chemical substance that kills or inhibits microorganisms
What is a antibacterial?
- A chemical substance that inhibits bacteria
What is an antibiotic?
- A chemical substance produced by a microorganism that inhibits bacteria
What are the 4 principles when developing antibacterial agents?
- Safety
- Spectrum
- Absorption/distribution
- Resistance
What pharmacological properties need to be considered when developing a drug?
- Active ingredients
- Formulation
- Lipophilicity
- Mode of action
What is minimum inhibitory concentration (MIC)?
- Lowest concentration of a drug that prevents visible growth of bacteria
- The lower the concentration of drug, the more effective the antimicrobial
What is a bacteriocidal?
- Kills bacteria
What is a bacteriostatic?
- Prevents replication
What are the 5 different modes of actions?
- Cell wall inhibitors
- Folate inhibitors
- DNA inhibitors
- Cell membrane disruptors
- Protein synthesis inhibitors
What is the mode of action of cell wall inhibitors?
- Inhibits transpeptidase enzymes, which prevents cross bonds
Name two examples of cell wall inhibitors
- Penicillins
- Cephalosporins
What are penicillins?
- Divided into 6 groups
- Renal excretion
- Risk of hypersensitivity but generally safe
- Example: Synulox and Depocillin
What are cephalosporins?
- Divided into four generations
- Better safety than penicillins
- Example: Convenia
What is the mode of action of DNA inhibitors?
- Affects DNA/RNA
Give 3 examples of DNA inhibitors
- Fluoroquinolones
- Nitroimidazoles
- Rifampin
What are fluoroquinolones?
- Act on DNA gyrase to inhibit transcription
- Relatively safe but contraindicated in growing animals
- Example: Baytril
What are nitroimidazoles?
- Damages DNA strands and prevents repair
- Relatively safe but neuro signs seen
- Example: Metrobactin
What is rifampin?
- Inhibits RNA polymerase, which inhibits transcription
- Resistance can develop quickly
- No veterinary license, used on the cascade
What is the mode of action of protein synthesis inhibitors?
- Targets prokaryotic ribosomes
Give 6 examples of protein synthesis inhibitors
- Tetracyclines
- Chloramphenicols
- Aminoglycosides
- Macrolides
- Lincosamides
- Fusidic acid
What are tetracyclines?
- Disrupt amino acid attachment at ribosomes
- Resistance seen
- Relatively safe
- Example: Ronaxan and Engemycin
What are chloramphenicols?
- Prevents peptide bond formation
- Example: Nuflor
What are aminoglycosides
- Distorts mRNA codes
- Ototoxic and nephrotoxic
Give two examples of folate inhibitors
- Sulponamides
- Trimethoprim
Give an example of a cell membrane inhibitor
- Polymixins
What are good properties of an ideal antimicrobial?
- Good activity
- Readily absorbed
- Distributed to target site
- Resilient to resistance mechanisms
- Limited side effects and hypersensitivity
