Antibiotics Flashcards
Name the components of the CURB65 score
Confusion - new onset Urea > 7mmol/L RR >/= 30 BP - SBP =90 or DBP = 60 65 - age >65
score 0-1 = low risk, consider home treatment
score of 2 - 9.2% 30 day mortality. Admit or monitor as outpatient closerly
score of 3-5 - admit and manage as severe (30-day mortality of 22%)
If a patient is able to take penicillin what would be the antibiotic of choice for someone with pnemonia with a CURB65 score or 1?
oral amocicillin 500mg 8-hrly
if IV needed you can give the same IV
what antibiotics could you use for a CURB65 score of 2?
oral doxycycline 100mg 12hrly or oral amoxicillin + clarithromycin or IV benzylpenicillin 1.2g 6hrly + IV clarithromycin 500mg 12 hrly
what antibiotics would you use in a patient with a CURB65 score of 3+?
IV co-amoxiclav 1.2g 8hrly + IV clarithromycin 500mg 12 hrly
what is the difference between a bacteriocidal and a bacteriostatic antibiotic?
bacteriocidal kills bacteria
bacteriostatic prevents growth of bacteria allowing natural immune mechanisms to eliminate the bacteria
what bacteria is the commonest cause of CAP?
Streptococcus pneumoniae
what group of patients would you not use doxycycline to treat pneumonia?
children - tetracyclines affect bone development
what drug should a patient stop taking if they are on clarithromycin?
statins, warfarin etc.
they inhibit CYP enzymes meaning the level of statins and warfarin in the system will increase and patient is at more risk of side effects
If a patient is allergic to penicillin, what would be first line in someone with a CURB65 score of 1?
oral doxycycline 100mg 12hrly
or
IV clarithromycin 500mg 12hrly
if a patient is allergic to penicillin, what would you use in a patient with a CURB65 score of 2?
oral doxycycline 100mg 12 hrly or oral clarithromycin 500mg 8-hrly or IV clarithromycin 500mg 12hrly
If a patient is allergic to penicillin what would be the treatment for a patient with a CURB65 score of >/= 3?
IV cefotaxime 1g 8hrly + IV clarithromycin 500mg 12hrly
what is meant by antimicrobial stewardship?
an organisational or healthcare-system-wide approach to promoting and monitoring judicious use of antimicrobials to preserve their future effectiveness
what local or national guidelines should prescribers follow for principles of good prescribing (3 things)
- prescribing the shortest effective course
- the most appropriate dose
- route of administration
why are broad spectrum antibiotics avoided where possible in CAP?
to reduce likelihood of C.diff colonisation.
what antibiotics are most frequently implicated in predisposition to C.diff acquired diarrhoea?
fluoroquinolones, clindamycin, broad-spec penicillins and cephalosporins
what is involved the sepsis 6 pathway?
- administer O2 (aim to keep sats at >94% or 88-92% for T2RF)
- take blood cultures
- IV antibiotics
- IV fluids
5 check serial lactates - measure urine output
Name the red flag symptoms for sepsis (10)
- Responds only to voice or pain or is unresponsive
- Acute confusional state
- Systolic BP = 90 or a drop of >40 from normal
- HR >130
- RR >/= 25
- Needs O2 to keep SpO2 >92%
- non-blanching rash, mottled/ashen/cyanotic
- Not passed urine in last 18hr/UO <0.5ml/kg/hr
- Lactate >/= 2mmol/l
- Recent chemotherapy
name 3 common causes of atypical bacteria causes of pneumonia
- Legionella pneumophilia
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
what antibiotics could you use to treat pneumonia caused by Legionella spp?
fluoroquinolone or clarithromycin
what is the MOA of penicillins
cell wall damage whcih causes cell swelling, lysis and then cell death
what types of bacteria does benzylpenicillin have activity agains?
relatively narrow specturm. some activity against some Gr+ organisms (e.g. streptococci, bacillus) and Gr- cocci (e.g. Neisseria spp.) Not active against Gr- bacilli
name two broad spectrum penicillins
amoxicillin
co-amoxiclav
what can be given alongside co-amoxiclav to make it more effective against resistant strains?
clavulanic acid (a beta-lactamase inhibitor)
what do penicillinase-resistant penicillins have activity against?
narrow spectrum of activity against Gr+ staphylococci
name a penicillinase-resistant penicillin
flucloxacillin
what is the spectrum of activity like for cephalosporins and carbapenems?
broad
what is the MOA of cephalosporins and carbapenems?
prevent new bacteria from forming by disrupting cell wall growth due to presence of a beta-lactam ring
when might you prescribe cephalosporins or carbapenems?
2nd and 3rd-line option for UTI and RTIs.
for very
What antibiotics are used to treat TB and how long do you use each of them?
for 2 months: rifampicin, isoniazid, ethambutol, pyrazinamide
for a further 4 months continue on: rifampicin and isoniazid
what is multi-drug resistant TB classified as?
TB caused by M.tuberculosis that is resistant to at least rifampicin and isoniazid
what is extensively drug resistant TB defined as in terms of resistnace?
resistance to rifampicin, isoniazid, plus any agent of the fluoroquinolone family, plus at least one of the aminoglycosides or polypeptides.
rifamycins such as rifampicin induce cytochrome P450 isoenzymes and in doing so can reduce blood plasma concentrations of some drugs - name two important ones?
oestrogen - so may reduce effectiveness of the oral contraceptive pill, warfarin, sulphonylureas, phenytoin
what is the MoA of tetracyclines?
inhibit bacterial protein synthesis - 30S inhibitor
what TB drug can cause red-green colourblindness followed by reduced visual acuity? are these effects permanent?
ethambutol.
effects are dose-related and usually reversible
what are the two main bacterial causes of infective endocarditis?
Staphylococcus aureus (31%) Viridians group Streptococcus (17%)
what antibiotic would you use for initial blind therapy of infective endocarditis in someone with a native valve
amoxicillin and consider adding low-dose gentamicin
what antibiotic would you use for initial blind therapy of infective endocarditis in someone with a native valve who is allergic to penicillins?
vancomycin + gentamicin
what antibiotic would you use for initial blind therapy of infective endocarditis in someone with a prosthetic valve
vancomycin + rifampicin + low dose gentamicin
what antibiotic would you use for Native valve endocarditis caused by staphylococci
flucloxacillin
if penicillin allergic - vancomycin + rifampicin
what antibiotic would you use for sensitive streptococci?
benzylepenicillin
if allergic - vancomycin + gentamicin
what gram stain of bacteria is vancomycin active against?
Gr+
what is the MoA of vancomycin
inhibits synthesis of cell walls of Gr+ bacteria
name some examples of macrolides and their MOA
e.g. clarithromycin, erythromicin, azithromycin,
Inhibit bacterial protein synthesis
how do aminoglycosides work? give some examples of drugs
they inhibit protein synthesis (30S inhibitors)
e.g. gentamicin, amikacin, neomycin
