I: Antimicrobials Flashcards
Name 4 classifications of antimicrobials.
- Antibacterial
- Antifungal
- Antiviral
- Antiprotozoal
Name 4 ways in which antibacterial agents can be classified.
- Bactericidal or bacteriostatic
- Spectrum (i.e.high or low)
- Target site (mechanism of action)
- Chemical structure (antibacterial class)
Name some idea features of antimicrobial agents.
- Selectively toxic
- Few adverse effects
- Reach site of infection
- Oral/IV formation
- Long half-life
- No interference with other drugs
Name 4 different mechanisms of action that the classes of antibacterials may have.
- Affecting cell wall synthesis
- Affecting membrane function (least common)
- Affecting protein synthesis
- Affecting nucleic acid synthesis
Name 2 classes of antibacterials which affect cell wall synthesis.
- B-lactams
- Glycopeptides
Name 3 classes of antibacterials which affect protein synthesis.
- Tetracyclines
- Aminoglycosides
- Macrolides
Name 1 class of antibacterials which affect cell membrane function.
- Polymixins
Name 1 class of antibacterials which affect nuclei acid synthesis.
Quinolones
Name 3 types of resistance.
- Intrinsic
- Acquired
- Adaptive
What is intrinsic resistance?
When there is no target for the drug, this is usually permanent.
What is acquired resistance?
When new genetic material is either acquired or formed from mutated material. This is usually permeant.
What is adaptive resistance?
When the organism responds to stress. This is usually reversible.
By which mechanisms might organisms use to resist antimicrobials?
- Drug inactivating enzymes (e.g. B-lactamases)
- Altered target (e.g. Target enzyme has lowered affinity for the antibacterial)
- Altered uptake (e.g. A decrease in permeability or and increase in efflux)
Name 2 ways in which organisms can undergo genetic antibiotic resistance.
- Chromosomal gene mutation
- Horizonal gene transfer
What is chromosomal gene mutation?
When all susceptible organisms are killed, so only thoughts who have mutated survive to become the dominant strain.
Name 3 ways in which horizontal gene transfer may occur.
- Conjugation (weird bacteria sex)
- Transduction (injected by bacteriophage)
- Transformation (free chunks of DNA can get through cell wall via porins)
What is the minimum inhibitory concentration? (MIC)
A measure of the activity of an antibiotic.
What is Penicillin mainly active against?
Steptococci
What combination antibiotic is a effective B-lactamase inhibitor?
Co-amoxiclav
What are the antibacterial class of cephalosporins effective against?
Relatively broad spectrum but no anaerobes activity
What antibiotic would be used to treat meningitis?
Cetriaxone
What are the antibacterial class of carbapenems effective against?
- Very broad spectrum
- Active against most gram negs
- Generally safe in penicillin allergy
Name a carbapemem antibiotic.
Meropenem
Give an example of antibiotic which would be classified as a glycopeptide.
Vancomycin
What are the antibacterial class of glycopeptides effective against?
- Active against most gram positive
- Narrow therapeutic window
What are the antibacterial class of tetracyclines effective against?
- Broad spectrum
- Usually gram positive
- Used in penicillin allergy
- Active in chlamydia and some Protozoa
- Shouldn’t be given to <12
Give an example of antibiotic which would be classified as a tetracycline.
Doxycycline
Give an example of antibiotic which would be classified as a aminoglycoside.
Gentamicin
What are the antibacterial class of aminoglycosides effective against?
- Profound activity against gram neg
- Good activity on blood and urine
- Small therapeutic window
- Generally reserved for severe gram neg sepsis
Give an example of antibiotic which would be classified as a macrolide.
Erythromycin
What are the antibacterial class of macrolides effective against?
- Mild gram positive infections
What are the antibacterial class of quinolones effective against?
- Inhibit DNA gyrase
- Very active against gram negative
Give an example of antibiotic which would be classified as a macrolide.
Ciprofloxacin
What are trimethoprim and sulphonamides used for clinically, and by which mechanism do they achieve this?
- Inhibitors of folic acid synthesis
- UTI
What is co-trimoxazole used for?
- Treat PCP
- Has active against MRSA
By what mechanism do anti-fungals work? Give one example of an antifungal.
- Inhibit cell-membrane synthesis
- Fluconazole
Name an antiviral which is active against herpes simplex.
Aciclovir
What is metronidazole?
An antibactrial and antiprotozoal agent used clinically for things such as dysentery, diarrhoea and vaginitis.
TRUE OR FALSE: all exposure to antimicrobials results in antimicrobial resistance.
TRUE: the resistance is effectively irreversible.
Define MDR (multi-drug resistant).
When a microbe is non-susceptible to at least one agent in three or more classes.
Define XDR (Extensively drug resistant).
When a microbe is non-susceptible to at leas one agent in all but two or fewer classes.
Define PDR (pan-drug resistance).
When a microbe is non-susceptible to all agents in all categories.
What is antimicrobial stewardship?
The appropriate use of antimicrobials which optimise clinical outcomes. In doing so toxicity and other adverse effects are minimised with reduced costs. This ultimately limits the selection for antimicrobial resistant strains.
Name 3 stewardship intervention types and describe how they work.
- Persuasive (The team is educated into making the appropriate choice)
- Restrictive (The team has to either request prior authorisation or undergo automatic stop orders when prescribing)
- Structural (The team undergoes quality monitoring and rapid lab tests to ensure the stewardship is relevant)