Anti-infective Drugs Flashcards
(48 cards)
what are some examples of penicillin beta lactams?
Flucloxacillin
Amoxicillin
Benzylpenicillin
Penicillin V
what is the mechanism of action of penicillins?
Attaches to penicillin-binding-proteins on forming bacterial cell walls.
This inhibits the transpeptidase enzyme which cross-links the bacterial cell wall.
Failure to cross-link induces bacterial cell autolysis.
Amoxicillin provides some amount of gram-negative cover in addition to gram-positive drugs
what are the indications for penicillins? - specifically flucloxacillin and amoxicillin?
Different penicillins have different indications as different spectrum of cover.
Flucloxacillin provides Staphylococcus aureus cover whereas Amoxicillin does not.
Flucloxacillin: Soft tissue infection; Staphylococcal endocarditis; Otitis externa
Amoxicillin: Non-severe community acquired pneumonia
list some side effects of penicillins?
diarrhoea
vomiting
liver function impairment
hypersensitivity reactions
what is important clinically regarding Pharmacokinetics/dynamics for penicillin?
good oral absorption
Flucloxacillin: Beta-lactamase stable/insensitive. (Beta-lactamase producing bacteria are vulnerable to it)
Amoxicillin: Beta-lactamase susceptible. (Beta-lactamase producing bacteria are resistant to it).
what info should be given to a patient before commencing on a penicillin?
Return if symptoms persists after the course of antibiotics, may be infected with resistant organism.
Diarrhoea is a common side effect.
Report any incidence of a rash after use – risk of hypersensitivity reactions.
how is resistance in bacteria that secrete beta lactamase overcome?
by a beta lactamase inhibitor given with the penicillin e.g. clavulanic acid along with amoxicillin - co-amoxiclav
what are some examples of cephalosporin beta lactams?
ceftriaxone
cephalexin
what is the MoA of cephalosporins?
Attaches to penicillin-binding-proteins on forming bacterial cell walls.
Inhibiting transpeptidase enzyme which cross-links the bacterial cell wall.
Failure to cross-link induces bacterial cell autolysis.
Less susceptible to beta-lactamases than penicillins.
Provides both gram-positive and gram-negative cover.
What are the indications for cephalosporins?
Serious infection: septicaemia / pneumonia / meningitis
list some side effects of cephalosporins
Hypersensitivity reactions
Antibiotic-associated C.Difficile diarrhoea
Liver function impairment
what is important clinically regarding Pharmacokinetics/dynamics for cephalosporins?
renal excretion
longer half life - needs to be given once daily
what info should be given to a patient before commencing on a cephalosporin?
diarrhoea is a common side effect
report incidence of a rash after use
what is an example of a glycopeptide?
vancomycin
what is the MoA of vancomycin?
bactericidal - inhibiting cell wall synthesis in gram positive bacteria
what are the indications for vancomycin?
severe gram positive infections
MRSA
severe C. diff infection
list some side effects of vancomycin:
- Fever
- Rash
- Local phlebitis at site of injection
- Nephrotoxicity
- Ototoxicity (Rare)
- Blood disorders, including neutropenia
- Anaphylactoid reaction “red-man syndrome” if infusion rate too fast
what is important clinically regarding Pharmacokinetics/dynamics for glycopeptides?
can be given as continuous IV or pulsed infusion
long duration of action - can be given every 12 hours
therapeutic monitoring as narrow therapeutic window
what info should be given to a patient before commencing on vancomycin?
Risk of kidney damage.
Patients should report any changes in hearing.
Regular blood tests required for monitoring.
what is an example of an aminoglycoside?
gentamicin
what is the MoA of gentamicin?
binds to 30s ribosomal subunit, inhibiting protein synthesis, inducing a prolonged post-antibiotic bacteriostatic effect
bactericidal on cell wall causes rapid killing early on
synergistic when used with other antibiotics
what are the indications for gentamicin?
Severe gram-ve infections (e.g. biliary tract infection, pyelonephritis, hospital-acquired pneumonia).
Some severe gram+ve infections (e.g. soft tissue infection and endocarditis).
list the side effects of aminoglycosides?
nephrotoxicity
ototoxicity
^related to prolonged exposure to high conc.
what is important clinically regarding Pharmacokinetics/dynamics for aminoglycosides?
Give high initial dose to take advantage of rapid killing
Leave long dosing interval to minimise toxicity
Measure trough level to ensure gentamicin is not accumulating before giving more doses.
Try to limit use to approximately 3 days to minimise risk of side-effects.