Session 4 Flashcards
(26 cards)
What are the ideal features of antimicrobials agents?
Selectively toxic Few adverse effects Reach site of infection Oral/IV formulation Long half life = infrequent dosing No interference with other drugs
What antibacterial interferes with cell membrane function?
Polymixins
What antibacterial interferes with nucleic acid synthesis?
Quinolones
What antibacterials effect cell wall synthesis?
Beta lactams
Glycopeptides
E.g penicillin and vancomycin
What antibacterials effect protein synthesis?
- tetracyclines
- aminoglycosides
- macrolides
What are the 3 types of resistance?
Intrinsic
- no target or access for the drug
Acquired
- acquire new genetic material or mutates
Adaptive
- organisms responds to stress, usually reversible
Mechanisms of resistance?
- drug inactivating enzymes
- altered target
- altered uptake
What is the genetic basis for antibiotic resistance?
Chromosome gene mutation = in the presence of antibiotic only mutated bacteria survive
Horizontal gene transfer = one bacteria fuses with another and transfers its antibiotic resistant genes to it = resistance spreads.
What is the minimum inhibitory concentration?
The minimum concentration of antibiotic that inhibits bacterial growth
What are the subgroups of beta lactams?
Penicillins
Cephalosporins
Carbapenems
Monobactams
What are the classes of penicillins?
1) penicillin - Active mainly against streptococcus
2) amoxicillin - also some activity against gram negatives
3) flucloxacillin - active against staph and strep
4) b lactamase inhibitor combinations e.g. co amoxiclav and piperacillin/tazobactam
What are cephalosporins activity?
Generations increase gram negative and decrease with gram positive
Cetriaxone has good activity in cerebral spinal fluid
What are carbapenems?
Example e.g meropenem
Very broad spectrum and active against most gram negs
Generally safe in penicillin allergy
Give a type of glycopeptides and describe its activity.
Vancomycin
- active against most gram pos
- some enterococcus resistant
- resistance in staph rare
What do tetracyclines do?
Tetracyclines and doxycycline
- similar spectrum, both oral only
- broad spectrum but specific use in penicillin allergy
- active in atypical pathogens in pneumonia
- active against chlamydia and some Protozoa
Give an example of an aminoglycoside and state what it does.
Gentamicin
- profound activity against gram negs
- good activity in blood. Urine
- potentially nephrotoxic/ototoxic
- therapeutic drug monitoring required
- generally reserved for severe gram neg sepsis
What are macrolides? give an example.
E.g erythromycin
- well distributed including intracellular penetration
- alternative to penicillin for mild gram pos infections
- also active against atypical respiratory pathogens
What are quinolones? Give an example.
E.g. ciprofloxacin
- inhibit DNA gyrase
- very active against gram negs
- also active against atypical pathogens
- increasing resistance and risk of C. difficile
What do trimethoprim and sulphonamides do?
- inhibitors of folic acid synthesis
- trimethoprim used for UTI
- when combined with sulphamethoxazole = co- trimoxazole, used to treat PCP and has activity against MRSA.
What do the anti-fungals Azoles and polyenes do?
Azoles
- active against yeast and molds
- inhibit cell membrane synthesis
- fluconazole used to treat candida
Polyenes
- inhibit cell membrane function
- nystatin for tropical treatment of candida
- amphotericin for IV treatment of systemic fungal infections
What do the antiviral aciclovir and oseltamivir (tamiflu) do?
Aciclovir
- when phosphorylated inhibits viral DNA polymerase
- herpes simplex
- varicella zoster (chicken pox and shingles)
Oseltamivir (tamiflu)
- inhibits viral neuroamindase
- influenza A and B
What is metronidazole?
An antibacterial and antiprotozoal agent
- active against anaerobic bacteria
- also active against Protozoa
What is prophylaxis?
Treatment given or actions taken to combat disease
What is multi drug resistance?
Non susceptibility to at least one agent in three or more antimicrobials categories
