Antibiotics, AMR Flashcards
Empiric treatment for bacteremia with S.aureus
- Vanco
- Dapto
- De-escalate to anti-staph B-lactams, e.g.:
- Cefazolin
- Oxacillin
- Nafcillin
Empiric treatment for bacteremia with coagulase-negative staphylococci?
If hospitalized: (?MSSE)
- Vanco
- Dapto
If B-lactamase:
- Oxacillin
- Nafcillin
If non-B-lactamase:
- Penicillin
Empiric treatment for bacteremia with Enterococcus spp.
- Vanco
- Ampicillin (usually ok but not always, but greater killing activity than Vanco)
Intrinsic resistance of Enterococcus spp.
- Cephalosporins
- Macrolides
- Clindamycin
Which GPC are intrinsically resistant to Vancomycin?
- E. casseliflavus
- E. gallinarum
- Leuconostoc
- Lactobacillus (80%)
- Pediococcus
- Erysipelothrix
- Weissella confusa
(And the GPB Clostridium innocuum)
Which bacteria contain AmpC resistance?
- Serratia
- Providencia + Pseudomonas
- Indole+ Proteus (=vulgaris; but this is debatable since it’s a different class, = Class A ceph’ase)
- Citrobacter freundii complex
- Enterobacter (esp. E.cloacae)
- K. aerogenes
- Hafnia alvei
- Acinetobacter baumannii
- Morganella morgannii
Can also have in plasmid (uncommon), seen with E.coli + Klebsiella
For which organisms are cephalosporins ineffective?
“LAME”
- Listeria
- Atypicals (e.g.Mycoplasma, Chlamydia)
- MRSA
- Enterococci
Which antibiotic classes are enterococci intrinsically resistant to?
- Cephalosporins
- Aminoglycosides (low-level)
Unlike AmpC’s, ESBL’s are characteristically susceptible to…
Cefoxitin (and other cephamycins)
What is the empiric abx treatment for MRSA?
Which abx are NOT acceptable?
Empiric:
- Vanco
Avoid:
- Beta lactams (acquired R)
- Cipro (poor GP coverage)
What is the empiric abx treatment for MSSA?
Which abx are NOT acceptable?
Empiric:
- Cefazolin
- Anti-staphylococcal BLms
Avoid:
- Cipro (poor GP coverage)
What is the empiric abx treatment for E.faecalis?
Which abx are NOT acceptable?
Empiric:
- Penicillin
- Vanco
Avoid:
- Cipro (poor GP coverage)
What is the empiric abx treatment for streptococci?
Which abx are NOT acceptable?
Empiric:
- Non-VGS = Penicillin
- VGS = CRO
Avoid:
- SXT ({})
- Cipro (poor GP coverage)
Beta-lactam antibiotics: Overall traits + MOA Classes
Cidal vs. CW synthesis 1. Penicillins 2. Cephalosporins 3. Carbapenems 4. Monobactams
Good abx for Pseudomonas
PIP/TAZO CFTAZ CFEP MERO CIP TOB
Good abx for S.aureus (+ MRSA)
S. aureus: CLOX CPLXN (gen. 1) MRSA: CLIN VANC
Good abx for Enterococcus
AMP AMOX VANCO (except VRE)
Good abx for ANO2
CFOX PIP/TAZO AMOX/CLAV
SPICE organisms
Encode a chromosomal, inducible BL’ase enzyme called AmpC: Serratia Providencia Indole+ Proteus spp. Citrobacter Enterobacter (K. aerogenes)
What is the drug of choice for treating S.maltophilia
SXT
Can you use tigecyline for an MDRP.aeruginosa?
No, P.aeruginosa is intrinsically resistant.
Can you use micafungin on a Candidaspp. in the CSF?
No, doesn’t penetrate CSF.
Can you use daptomycin for an MRSA PNA?
No, DAPTO is inactivated by lung surfactants (both MRSA and MSSA).
How can you test for the presence/absence of penicillinases in a bacterium?
Zone edge test (a.k.a. beach vs. cliff test) & blaZ PCR
