Antimicrobials Flashcards
How can antimicrobials be classified
Antibacterial
Antifungal
Antiprotozoal
Antiviral
How are antibacterial agents classified
Bactericidal or bacteriostatic
Spectrum - broad or narrow
Target site
Chemical structure
What are the idea features of antimicrobial agents
Selectively toxic
Few adverse affects
Reach site of infection
Oral/IV formulation (preferentially both)
Long half-life
No interference with other drugs
Name the mechanisms of action of antibacterials
Cell wall synthesis
Protein synthesis
Cell membrane function
Nucleic acid synthesis
Which antibacterials affect cell wall synthesis
Beta-lactams
Glycopeptides
Which antibacterials affect protein synthesis
Tetracyclines
Aminoglycosides
Macrolides
Which antibacterials affects cell membrane function
Polymixins
Which antibacterials affect nucleic acid synthesis
Quinolones
What are the types of resistance and are they permanent
Intrinsic - permanent
Aquired - permanent
Adaptive - usually reversible
What are the mechanisms of resistance
Drug inactivating enzyme
Altered target - target enzyme has lower affinity for drug
Altered uptake - decreased permeability or increased efflux
How does a bacteria develop antibiotic resistance
Chromosomal gene mutation
Horizontal gene transfer - conjunction, transduction or transformation
What is minimum inhbitory concentration (MIC)
Minimum concentration of antibiotic needed for no bacterial growth
What are the catalgories of beta-lactam antibacterials
Penicillins
Cephalosporins
Carbapenems
Monobactams
What does penicillin affect and name some penicillins
Affects cell wall synthesis
Penicillin
Amoxicillin
Flucloxacillin
Co-amoxiclav
Piperacillin
Tazobactam
What do cephalosporins affect and give examples
Affects cell wall synthesis
Affects Gram -ve but not Gram +ve
Is a good broad spectrum but no anaerobe activity
Cetriaxone
What do carbapenems affect and give an example
Affects wall synthesis
Meropenem - very broad (incl anaerobes), active against most Gram -ves
What do glycopeptides affect and give an example
Affects cell wall synthesis
Vancomycin - against most gram +ve, given as IV as not absorbed, must be monitored
What do tetracyclines affect and give examples
Affect protein synthesis
Tetracycline and doxycycline - broad spectrum, oral only
What do aminoglycosides affect and give an example
Affect protein synthesis
Gentamicin - gram -ve, good activity in blood/urine (bacteraemia), usually reserved for severe gram -ve sepsis
What do macrolides affect and give an example
Affect protein synthesis
Erythromycin
What do quinolones affect and give an example
Affect nucleic acid synthesis
Ciprofloxacin
Name some antifungals and how they function
Azoles (against yeasts +/- molds) - inhibt cell membrane synthesis. Fluconazole (Candida)
Polyenes - inhibit cell membrane function
Name some antivirals and their mechanism of action and what they can be used to treat
Aciclovir - when phosphorylated inhibits viral DNA polymerase. Used for herpes simplex and varicella zoster
Oseltamivir (tamiflu) - inhibits viral neuraminidase. Influenza A and B
What is metronidazole
Antimicrobial and antiprotozoal agent
Active against anaerobic bacteria and protozoa
What are the consequences of antibacterial resistance
Treatment failure
Prophylaxis failure
Economic costs
Define the types of antimicrobial resistance
MDR (multi-drug resistant) - non-susceptibility to at least one agent in three or more antimicrobial categories
XDR (extensively drug resistant) - non-susceptibility to at least one agent in all but two or fewer antimicrobial categories
PDR (pan-drug resistant) - non-susceptibility to all agents in all antimicrobial categories
What are the IDSA’s antimicrobial stewardship objectives
Appropriate use of antimicrobials
Optimal clinical outcomes
Minimise toxicity and other adverse events
Reduce cost of health care for infections
Limit selection for antimicrobial resistant strains
