what give if patient had pseudomonal or pyelonephritis if allergic to penicillin?
quinolone - ciprofloxacin
for bone and joint infections what is first line? (remember combo)
if pen allergic what give for pseudomonas?
what is eg of quinolone?
what is spectrum of quinolone?
staph but NOT STREP
all G-ve including pseudomonas
not anti-anaerobic so if treating gut infection add metronidazole
what is the only non-beta lactam anti-pseudomonal?
what is the penetration of cipro?
v gd penetration intracell
adequate brain penetration
what are 2 main problems with cipro?
is cipro liscenced for everyone?
not liscenced in pregnancy and not yet in children
which group of children get lots of pseudomonal lung infections?
so use cipro off licence - document risk v benefit
what is drug of choice for food poisoning?
ciprofloxacin - salmonella
what is ciprofloxacin very good for and why?
concentrates very well into that tissue
when should you NOT give cipro?
skin, soft tissue
what is special about cipro and its anti-pseudomonal activity?
its the only oral anti-pseudomonal
only one for pen allergic
what are the newer quinolones called? and advantage?
have activity against PNEUMOCOCCAL
what is site of action of quinolones?
DNA gyrase- not cell wall acting
so single agent to treat pneumonia
what is disadv of newer quinolones?
what is spectrum of aminoglycosides?
G+ve: staph NOT strep
G-ve: potent, including pseudomonas
route of gentamicin?
SE of gentamicin?
where in body will gent act best?
100% water soluble - so not lipid soluble so wont cross BBB, no penetration into cells or tissue
if remove O2 it will not work
so only a bacteraemia agent - blood
not lung consolidation as no oxygen
not for cellulitis!
but can be used as an adjunct
when would you add gentamicin?
if suspect septicaemia - rigors
what is gent an adjunct for?
IE: anti-microbial synergy against strep and staph
beta lactam creates leaky cell wall and gentamicin enters and acts on ribosome
what are the 2 types of resistance?
what are the 3 steps required for resistance?
1. genetic modification: mutation/acquire DNA or plasmid/loss of DNA
2. selection pressure
3. add antibiotic - selective advantage
name 4 methods of resistance?
1. B lactamase production
2. efflux pumps
3. target site alteration eg PBP or ribosomal binding site
4. impermeability: porins loss in G-ve
5. bypass ie even though the antibiotic blocks one enzyme, the organism will make another enzyme
why are porins only related to G-ve organisms?
G-ve have thick outer membrane: LPS which is hydrophilic so they evolved to get porins for things to get through and also antibiotics could get through! but when loss them the antibiotics cant get through
what mechanism of resistance does MRSA use?
PBP2a: unable to bind B-lactam abx
name 5 ways to reduce resistance?
1. narrow spectrum antibiotic to reduce the potential selection pressure on other organisms
2. culture before use broad spectrum antibiotics then target the antibiotic to the organism once know the organism = DE-ESCALATION
3. multiple drugs of different MOA = COMBINATION THERAPY
4. reserve new abx
5. prescribe when necessary
6. stop antibiotic early when you know its not the right organism as the longer the bacteria is exposed to a selection pressure, more resistance!
7. dose: short sharp dose. cipro acquires resistance in stepwise mutations
how do you stop infection spreading?
name 4 iv Rx for MRSA
name 4 oral Rx for MRSA
tetracycline eg doxycycline
what are the 3 last ditch Rx for MRSA? and routes
1. linezolid: iv and oral
2. daptomycin: iv only
which type of MRSA infection can you not use daptomycin and why?
MRSA pneumonia as it is inactivated by surfactant
what are the SE of linezolid?
irreversible: neuropathy, inc optic neuropathy
reversible: BM suppression
what is MOA of glycopeptides?
inhibit cell wall synthesis by steric hindrance ie as they are bulky they can physically stop the molecules coming together to make the cell wall.
what is the disadvantage of glycopeptides?
they are big molecules
so don't penetrate tissue well
stay in blood (so good to Rx MRSA bacteraemia)
what is the disadvantage of vancomycin?
need to measure levels - which is useful for MRSA bacteraemia as want to know how much is getting to the organism
what is the major SE of fusidic acid?
if there is a deep seated pneumonia or osteomyelitis MRSA, what is Rx?
vanco/teic + oral drug eg rifampicin (as oral has better absorption)
when is the most likely scenario to use doxycycline in MRSA infection?
mild MRSA infection eg cellulitis
which agent is used for prosthesis infected by MRSA?
rifampicin as penetrates biofilms well
when is the only use vancomycin orally?
c diff diarrhoea (2nd line after metronidazole) as it stays in gut where we want it to act
what is Rx for a man due for operation but has MRSA in nose?
need to decolonize. treat at home
5 days MUPIROCIN up nose
adjust surgical prophylaxis to cover MRSA
what does ESBL stand for?
extended spectrum beta lactamases
what makes an organism ESBL?
if it is able to hydrolyse 3rd generation cephalosporins and penicillins
which organisms commonly have ESBL?
enterobacteriacaea eg E Coli, Klebsiella
what is Rx for systemic ESBL infection?
2. amikacin (aminoglycoside) - sometimes
4. tigecycline (tetracycline)
what are SE of colistin?
which carbapenem would you use for ESBL, why?
ertapenem as it does not have pseudomonal activity
don't want to use meropenem as you increase the selection pressure and get resistance of mero to pseudomonas as it is everywhere in environment
how Rx local ESBL infection? eg UTI
which abx use for ESBL UTI in pregnancy?
if a pregnancy patient is pen allergic and has a simple UTI, what is Rx?
1st gen ceph
if a pregnant woman is pen allergic and has a complex UTI, what is Rx?