Antimicrobials And Resistance Flashcards
Antimicrobials:
Antibacterial (antibiotic), antivirals, antifungal, antiprotozoal
Antibacterial classes
Bacetericidal / Bacteriostatic (stops growth)
Broad vs Narrow treatment spectrum
Target site
Chemical structure
Choosing antibiotic:
Active? Can it reach site (blood brain barrier)? IV vs oral? Dosing frequency? Interaction with other drugs? Toxicity? (Renal failure) Monitoring?
How can we measure antibiotic activity?
Disc sensitivity
Minimum inhibitory concentration (MIC)
Two ways of measuring MIC?
Broth microdilution (broths with doubling antibiotic conc)
E test (strip with antibiotics increasing strength up strip)
Classes of antibacterials
Cell wall syntheis
Cell membrane
Protein synthesis
Nucleic acid synthesis
Cell wall synthesis interferers (antibacterials)
Beta-lactams (penicillin, cephalosporins)
Glycopeptides
Cell membrane function intereferes (antibacterial)
Polymixins (colistin) but veru toxic to kidneys
Protein synthesis interefers (antibacterial)
Tetracyclines
Aminoglycosides
Macrolides
Nucleic acid synthesis intereferes (antibacterial)
Quinolones
Trimethoprim
Rifampicin
How do vancomycin and penicillin work?
Weaken cell wall linkage
Cell lyses
Types of resistance
Intrinsic
Aquired
Adaptive
Intrinsic reisistance
No target or access for the drug
Permanent
Aquired resistance
Aquires new genetic material/mutates to become resistant
Usually permanant
Adaptive resistance
Organism responds to stress (of antibiotic) and switches on resistance gene
Antibiotic is only given at sub-theraputic level
