6 - Antibiotics Flashcards
What are the different ways that anti-bacterial agents can be classified?
What questions should be asked when choosing an antibiotic?
- Is it active against the target organism?
- Does it reach site of infection?
- Is it available in right formulation?
- Does it interact with other drugs?
- What is the half life? (dosing)
- Is there toxicity issues?
- Does it need therapeutic drug monitoring?
- Is patient allergic?
What are the different mechanisms of actions of antibacterials and outline a few classes of each?
What are some ways of working out the right does of an antibiotic?
- Find the minimum inhibitory concentration, e.g E test, disc test, broth microdilution
What is the exact mechanism of action of penicillin and vanomycin?
Penicillin: Block penicillin binding protein binding site that normall causes cross linking in cell wall
Vanomycin: Sits on peptidoglycan residue that normally binds to the penicillin binding protein so it can no longer bind
What are the different types of bacterial resistance?
Intrinsic: Never was sensitive to antbiotic
Adaptive: antibiotic given not high enough concentration to kill bacteria but enough to switch on genes that confer resistance
What are some mechanisms of antibacterial resistance?
- Drug inactivating enzymes, e.g beta-lactamases
- Altered target for antibiotics so lower affinity, using enzymes
- Altered uptake, lower permeability, increase efflux
- Mutation of targets
What is horizontal gene transfer?
Way that bacteria can share their resistance genes
What are the different classes of beta-lactams?
What are some examples of beta-lactams and what are they effective against?
When are cephalosporins used and give an example of this type of drug?
When are carbapenems used and give a few examples of them?
What are a few examples of glycopeptide antibacterials?
- Teicoplanin: Similar to vanomycin, only needed once a day
- Vancomycin: Most G+ve, IV (apart from clos.diff where oral), Therapeutic drug monitoring, resistance rare in staphs but common in enterococci
What are some examples of tetracycline and what are they used for?
- Doxycycline and Tetracycline
- Can’t be fiven to pregnant or breastfeeding women either as stain developing teeth of babies yellow
What is an example of an aminoglycoside and what is it used for?
- Gentamycin
- Therapeutic drug monitoring needed
- Potentially nephro/ototoxic so be careful in patients with renal issues
- Reserved for gram neg sepsis
What are some examples of macrolides and what are they used for?
- Erythromycin and clarithromycin
What is an example of a quinalone and what is it’s action?
- Ciprofloxacin
- Associate with tendinitis, aortic dissection and CNS effects
Describe the use of trimethoprim.
- Inhibits folic acid synthesis
- Used for UTI’s
- Can be combined with sulphamethoxazole to help against MRSA and pneumocystis jirovecii
What are the two types of antifungals and some examples of each?
Azoles:
- Inhibit cell membrane synthesis
- Fluconazole:* treat candida
- Posaconazole:* active against apergillus
Polyenes:
- Inhibit cell membrane function
- Nystatin:* Topical candida
- Amphotericin:* IV treatment of systemic fungal infections
What are some examples of antivirals?
- Aciclovir
- Osteltamivir
- Specialist agents for HIV
How does aciclovir work?
How does oseltamivir work?
Describe the use of metronidazole.
- Antibacterial and antiprotozoal agent
What are the three different definitions of anti-microbial resistance?
