Infection Flashcards
Name 7 clinical markers of infection
- Low BP
- raised blood glucose
- high ESR (erythrocye sedimentation rate)
- high CRP
- high temp
- high RR
- high pulse
what abx are contraindicated/should be avoided in children?
tetracyclines contraindicated in <12yrs
quinolones cause arthopathy
what abx should be avoided in elderly and why?
clindamycin due to high C. diff risk
what abx are nephrotoxic?
what drugs should you avoid in renal impairment (what are the exceptions)?
aminoglycoside, glycopeptide
avoid tetracyclines except minocycline/doxycycline
avoid nitrofurantoin in eGFR <45ml/min
what abx can be hepatotoxic?
what abx needs to be reduced in hepatic impairment?
rifampicin, tetracyclines
reduce metronidazole if severely impaired
what abx can increase risk of cholestatic jaundice?
co-amoxiclav, flucloxacillin
what abx should be avoided in pregnancy ? MCAT QS
metronidazole
chloramphenicol
aminoglycosides
tetracyclines
quinolones
sulphonamides
what abx are most likely to cause antibiotic-resistant colitis and thrush?
clindamycin and broad spectrum abx
what abx to treat staphlococci?
flucloxacillin
what abx to treat MRSA?
vancomycin
what abx to treat streptococci?
benzylpenicllin or phenoxymethypenicillin
what abx to treat anaerobic bacteria?
metronidazole
what abx to treat pseudomonas aeruginosa?
gentamicin
Describe clindamycin (MoA? wide/narrow spec?, bacterostatic or bacteriosidal)
- inhibits protein synthesis
- narrow spectrum
- bacteriostatic
whats the difference between bacteriostatic and bacteriosidal?
bacteriosidal kills bacteria whereas bacteriostatic inhibts growth
what should patients on clindamycin do if they have diarrhoea and why?
stop immediately and see GP - antibiotic associated colitis, c. diff
Describe Linezolid (MoA? wide/narrow spec?, bacterostatic or bacteriosidal)
- inhibits protein synthesis
- narrow spec (only active against gram-positive)
- bacteriostatic
give 2 examples of gram-positive bacteria linezolid is active against?
what’s it an alternative to?
MRSA (alternative to vancomycin), anaerobes
what are the 2 safety warnings you should counsel patients on linezolid on?
- optic neuropathy if used longer than 28 days, counsel pt on signs of visual impairment and new visual symptoms
- blood disorders (thrombocytopenia, anaemia, leucopenia) in those receiving more than 10- 14 days, pre-exisitng myelosuppression, recieivng drugs that may have adverse effects on Hb, blood count, plt function, severe renal impairment - must monitor FBC weekly
what should you do if significant myelosupression occurs whilst on linezolid?
stoptreatment unless considered essential
if a pt has recently been on SSRI, TCA, MAOI and needs linezolid what interval must you leave and why?
leave 2 weeks due to interactions and risk of hypertensive crisis
what class of drug is linezolid?
therefore what must you counsel the pt to avoid?
reversible MAOI
avoid consuming large amount of tyramine
whats the MoA of trimethorprim?
narrow or broad? Bacertiostatic or bactericidal?
inhibits DNA synthesis
narrow spectrum
bactericidal
what the most common indication and dose for trimethoprim?
UTIs
200mg BD
T/F trimethorpim is safe in pregnancy
false - is teratogenic (folate antagonist) in first trimester
in what pt group is trimethoprim contraindiacted (this is also a long term use risk of trimethoprim, pt should be counselled)
blood dyscracsias
counsel on fever, sore throat, rash, mouth ulcers
what does trimethoprim do to potassium
raises it - causes hyperkalaemia
Chloramphenicol MoA? Broad or narrow spec? bacteriostatic or bactericidal?
inhibitis protein synthesis, broad spec, bacteriostatic
is chloramphenicol routinely used?
what are the bad side effects?
no - reserved for life threatening infections
blood dyscrasias and grey baby syndrome so avoid in pregnancy
Metronidazole MoA, broad or narrow? Bacteriostatic or bactericidal?
inhibits DNA synthesis
narrow spec (higher activity againsr anaerobic and protozoa)
bactericidal
why must patients avoid alcohol with metronidazole?
casuses dislfiram-like reaction, will make pt sick
name 4 common SE of metronidazole
GI distrubances, taste disturbance, oral mucositis, furred tounge
Nitrofurantoin MoA? Broad or narrow? Bacteriostatic or bactericidal?
damages bacterial DNA
narrow spec (only urinary pathogens)
bactericidal
can nitrofurantoin be used in pregnancy?
no - neonatal haemolysis
what can nitrufuranotin do to urine?
turn it yellow/brown
whats the MoA of aminoglycosides? Broad or narrow? Bacteriostatic or bactericidal?
bind irrversibly to bacterial ribosomes
broad spec
bactericidal
what organism are aminoglycosides particualy active against?
pseudomonas aeruginosa (gram-negative aerobe)
name 5 aminoglycosides (ANTS G)
Amikacin - gent resistance
Neomycin - bowel sterilsation
Tobramycin - CF
Streptomycin - reserved for TB
Gentamicin
why are aminoglycosides given IV?
not absorbed by gut
what 5 pt types must you determine serum concentration of gentamicin in?
- elderly
- obestity
- cystic fibrosis
- when using high doses
- renal impairment
what should you do with gentamicin if post-dose ‘peak’ level after 1 hour is to high?
what range of levels are you looking for usually and in endocarditis?
reduce the dose
5 - 10mg/ml
3 - 5 mg/ml in endocarditis
what should you do with gentamicin if the pre-dose ‘trough’ level before the next dose is to high?
what pre-dose levels do we look for normally and in endocarditis?
increase the dosing interval, keep dose the same
<2mg/ml
<1mg/ml for endocarditis
how should you dose gentamicin in renal impairment?
what if the renal impairment is severe (<30ml/min)
increase the dosing interval in renal impairment, in severe impairment reduce the dose
what are the main SE of gentamicin?
nephrotoxicity
irreversible ototoxicity
most common in elderly pt and in renal failure as renally cleared.
what are the sign of nephrotoxicity in gentamicin?
low urine output/creatine clearance, high serum creatinine, urea
what drugs interact with gentamicin increases the risk of ototoxicity?
loop diuretics, cisplatin
what’s the MHRA advice related to gentamicin?
potenial for histamine related adverse drug reactions with some batches
- some batches may contain histamine residual from manufacturing process
- monitor for signs of histamide related reactions
what does gentamicin do to electrolytes?
hypO K, Ca, Mg
name 3 glycopeptides
vancomycin
teicoplanin
televancin
glycopeptide MoA? broad or narrow? Bactericidal or bacterostatic?
inhibit cell wall synthesis
narrow spec (gram +ve inc MRSA)
bactericidal
what pre-dose (trough) levels do you look for when monitoring vancomycin normally and in endocarditis or complicated S. aureus?
10 - 15mg/ml
15 - 20mg/l for endocarditis
name 6 SE of vancomycin when given parenterally
- nephrotoxicity
- ototoxicity
- red-man syndrome
- blood dyscrasias
- skin disorders
- thrombophlebitis
Tetracylinces MoA? Broad or narrow? bacteriostatic or bactericidal?
inhibits bacterial protein synthesis (binds 30s subunit)
broad spec
bacteriostatic
what tetracylcine is used in malaria and chlamydia OD?
doxyxycline
what SE should you consel patients about?
benign intracrainal hypertension - tell pts to stop in headache and visual disturbances
what are the contraindications related to tetracyclines?
children under 12
pregnancy & breastfeeding - depost in growing bone and teeth cause teeth discolouration and dental hypoplasia
Tetracyclines should be avoided in renal impairment except which 2?
doxycycline and minocycline (rarely used)
are tetracyclines advised in hepatic impairment?
no as hepatotoxic
what are the 4 counselling points with doxycycline?
- avoid sun exposure (photosensitivity)
- do not take antacid 2 hours before/after taking (decreased absorption)
- avoid milk
- swallow whole with plenty of fluid Oesophageal irritation)
what are the 3 counselling points for tetracycline?
- don’t take antacid 2 hours before/after (decreased absorption)
- avoid milk
- swallow whole with glass of water
what counselling point is given for all tetracyclines?
avoid indiegestion remedies 2 hours before/after
Quinolones MoA? Broad or narrow? Bacteriostatic or cidal?
inhibit DNA synthesis
broad spec
bactericidal
what are the common uses of quinolones?
lower RTIs, UTIs
name 4 quinolones
ciprofloxacin
levofloxacin
moxifloxacin
ofloxacin
what are the 4 key SE associated with quinolones?
- seizures
- tendon damage, stop if tendonitis suspected
- QT prolongation (especially moxifloaxacin)
- arthtopathy \9joint disease) - avoid in pregnancy, children, adolescent
what are 3 key interactions associated with quinolones?
- increase QT prolongation (SSRI, amiodarone, macrolide, antipsychotics)
- increased risk of seizures with ciprofloaxacin and theophylline
- NSAIDs induce convulsions
what are 3 key counselling points with certain quinolones?
- driving - quinolones can impair performce of skilled tasks
- antacid - leave 2 hours, avoid milk with cipro and norflaxacin
- protect from sunlight - ofloxacin
Macrolides MoA? Broad or narrow? Bacteriostatic or bactericidal?
inhibits bacterial protein synthesis (inhibits 50S)
broad spec
bacteriostatic
name 3 common macrolides and how many times a day they’re given and what counselling advice you should give
- azithromycin - OD dosing - before food/ 2hour gap with indigestion remedies
- Clarithromycin - BD - taste disturbances
- Erythromycin - QDS/BD - 2 hour gap with indigestion remedies
all = take with or after food
what factors increase a pt’s risk of QT prolongation?
bradycardia, heart disease, hypO K, hypO Mg, concomitant QT prolongation drugs
what class of abx can cause ototoxcity at high doses?
macrolides
Do macrolides have a risk or nephrotoxicity or hepatotoxicity?
hepatotoxicity
Erythromycin and Clarithromycin are potent enzyme inhibitors - name 2 common interactions to look out for
- warfarin - increased risk of bleeding
- statins - increased risk of myopathy
Penicillin and cephalosporins: MoA, broad or narrow? bacteriostatic or cidal?
interfere with bacterial cell wall synthesis
broad
bactericidal
what penicillins are more narrow spec and beta-lactamse sensitive?
benzylpenicillin
phenoxymethylpenicillin
T/F penicillin can be given as intrathecal injection
false - risk of encephalopathy, cerebral irritation can be fatal
T/F you should stop penicllin if a rash occurs lasting up to 72 hrs
false - continue in non-serious penicllin allergy
what happens if you give penicillins for sore throats?
maculopapular rash in glandular fever
what penicillin has a high resistance rate?
ampicillin
name the penicllin that can only be given parenterally.
benzylpenicillin
what penicillin is used to treat strep throat?
phenyoxymethlypenicllin Pen V
what 2 penicillins are antipseudomonal?
piperacillin with tazobactam
ticaricillin with clavulanic acid
name the 1st generation cephalosporins (cefa)
cefalexin
cefadroxil
cefradine
name the 2 2nd generation cephalosporins ( 2 foxes for tea)
cefuroxime
cefaclor
name the 4 3rd generation cephalosporins (contain t except one)
- cefixime
- ceftriaxone
- cefotaxime
- ceftazidime
what route are 3rd generation cephalosporins given?
parenteral
if someone is penicllin allergic and there are no other alternatives, what generation of cephalosporin can you give?
3rd generation of cefuroxime
