M15 - antibiotics Flashcards
define antibiotics
a drug used to treat or prevent infection caused by micro-organisms
define bacteriostatic
inhibit the growth of bacteria
define bacteriocidal
kills bacteria
are antibiotics considered a subsititute for a functional immune system?
no
list some features of an ideal antibiotic
Selective toxicity/minimal toxicity to host
long half life
no adverse drug interactions/side effects
list some antibiotic targets
- cell wall
- ribosomes
- dna replication
cell wall protects cell from internal osmotic pressure, what is it targeted by?
B-lactam (penicillins) and glycopeptide antibiotics
what is the bacteria cell wall made up of?
repeated sugar units cross linked by peptide side chains
which antibiotic causes suicide of the cell?
penicillin
amoxycillin has a wide spectrum and a wide tissue distribution, what % binds to plasma proteins?
20
what is special about co-amoxiclav?
inhibits beta-lactamases and provides better pain relief 2-3 days after
what is co-amoxiclav not suitable for
empiric prescribing
for empiric prescribing, is penicillin better than amoxycillin
penicillin
list three advantages of penicillin (beta-lactam antibiotcics)
safe
narrow to wide spectrum
variety
list three disadvantages of penecillin
resistance
rapidly excreted
hypersensitivity
how do glycopeptides inhibit peptidoglycan synthesis?
binds to end of peptide side chains and prevents its incorporation into the cell wall
what does protein synthesiis involve?
ribosomes moving along mRNA molecules that have been transcribed from DNA
what is side effect of glycopeptides?
can cause renal toxicity
list a couple of antibiotics targeting protein synthesis
tetracyclines –> deoxycyline
macrolides –> erythromycin
lincosamides –> clindamycin
what is toxic regarding aminoglycosides? (gentamicin)
causes damage to kidneys and VIII cranial nerve (deafness and dizziness), so need to monitor blood levels of aminoglycosides
what is the mode of action of tetracyclines?
actively transported into cell
what is the adverse effect of tetracycline?
destruction of normal intestinal flora resulting in increased secondary infections;staining and impairment of the structure of bone and teeth
what is the mode of action of lincosamides?
prevents peptide bond synthesis
where is lincosamides (clindamycin) found and used?
high concentration in bones, used for abscesses of bone or soft tissue or joint replacement
which antibiotics are associated with the macrolides?
erythromycin
clarythromycin
azithromycin
which antibiotics inhibit nucleic synthesis?
metronidazol; anaerobes and protozoa
metronidazole
28% of all primary care dental prescriptions
activity against anaerobes and some parasites
ciprofloxacin (IV & oral) and levofloxacin (IV) (bacteriocidal)
they are a part of fluoroquinolones and the use of these broad spectrum antibiotics is now severely restricted in tayside in an attempt to reduce the risk of clostrum difficile gut infection, especially in elderly patients
side effect of antibiotics
metronidazole - interacts with alcohol
gentamicin - renal and VIII damage
nausea, vomiting, diarrhoea
what are the antibodies we try to avoid using?
the 4 Cs antibiotics - cephalosporins - co-ampxiclav * -ciprofloxacin - clindamycin -
