MRSA Flashcards
What are the medically important resistant organisms?
MRSA
VRE
ESBL
CPO
clostridium difficile
MRSA aka
Methicillin Resistant Staphylococcus aureus
What is methicillin?
a penicillinase resistant penicillin i.e. similar to flucloxacillin.
if an organism is resistant to methicillin, it will be resistant to all of the b-lactam antimicrobials
what is methicillin used for?
Used in lab to determine whether organisms are sensitive to flucloxacillin
What makes a microbe methicillin resistant?
MRSA has an altered penicillin binding protein compared to MSSA
Now flucloxacillin is essentially ineffective. It cant bind to the different penicillin binding protein, substrate altered
Tx options for MRSA?
ORAL doxycycline, trimethoprim, clindamycin , or co-trimoxazole
where is staph. aureus widely carried?
nose, throat, groin
what severe invasive infection scan MRSA cause?
bloodstream infections,
osteomyelitis, endocarditis, cellulitis, abscesses etc
MRSA colonise with or without infection?
Most often colonisation without infection.
VRE aka?
Vancomycin Resistant Enterococci
tx for normal s. aureus vs MRSA infection?
more limited in abx for MRSA compares t normal s. aureus
most common eterococci?
Enterococcus faecium
Enterococcus faecium colonise what?
gut
when does VRE occur?
exposed to many antibiotics
e.g. after MRSA infection using vancomycin for prolonged period of time. wipe out gut organisms. allow low numbers of VRE to proliferate
- VRE colonise GI tract in patients exposed to multiple antibiotics.
- Can cause invasive disease e.g. endocarditis.
tx for VRE?
Enterococci are intrinsically only sensitive to a limited number of antitbiotics. (1 OR 2 abx)
ESBL aka?
ESBL – extended spectrum beta-lactamase
Resistant to beta-lactam antibiotics, often cephalosporins too
What do b-lactamases do?
degrade the beta-lactam antimicrobials
major cause of AMR
how to ESBL cause resistance?
Confer a range of resistance mechanisms, enzymatic degradation of
antibiotic, reduced porins, increased efflux.
May be associated with further resistance mechanisms such as resistance
to aminoglycosides and carbapenems (CPE).
CPO aka?
Carbapenem producing organisms
how are CPO causing AMR?
Multiply resistant bacteria.
* Typically only sensitive to a few antibiotics of last resort.
* Can colonise gut of healthy individuals.
* When associated with infection few treatment options.
* Associated with high mortality.
* Can colonise healthcare environment.
* Now a notifiable organism.
* Most feared – risk of serious outbreaks.
REISTSANT TO LAST LINE F ANTIBIOTICS
- even developed resistance to carbapenems. tx options are severely reduced
what bacteria are CPO?
USUALL GUT ORGANISMS
E.coli, pseudomonas for example
management for CPO pt?
isolation for pt and infection control
c. difficile?
- Inherently resistant organism.
- Selected out by broad-spectrum antibiotic use.
- Can dominate, produce toxins and cause infection in the large intestine.
- Range of disease from mild diarrhoea to life-threatening toxic megacolon.
- Can occur in severe hospital outbreaks
what type f bacteria is c. difficile?
Gram-positive, spore-forming obligate anaerobe
