Antimicrobials: Cephalosporins Flashcards
Cephalosporins MoA
Same as PCNs, they effect the cell wall.
What organism do none of the cephalosporins cover?
Enterococcus.
MTT side chains in cephalosporins may result in what (2)
prolonged PT/INR (bleeding risk)
disulfiram reaction when combined with alcohol (makes you very sick when you drink, used to be used as a negative reinforcer for alcohol abuse).
which cephalosporin is most likely to prolong PT/INR
Cefotetan
Generations of Cephalosporins
5 generations. 1st is extremely gram positive. From 1st to 5th, you gain gram negative effects while keeping gram positive effects.
First generation Cephalosporins activity
extremely gram positive
fifth generation cephalosporins are indicated in
resistant organisms
4th and 5th generation cephalosporins
the most broad antibiotics. used a lot as empirics.
Cephalosporin cross sensitivity with PCNs
1 - 3%
If they had anaphylaxis or hives to PCNs, avoid cephalosporins.
Absorption of Cephalosporins
rapid, thorough
distribution of cephalosporin
highly distributed and penetrable
A Cephalosporin metabolized 40% by the liver
ceftriaxone
Half life of cephalosporins
is mostly short except for ceftriaxone
excretion of cephalosporins
unchanged in urine, though some undergo biliary excretion.
ceftriaxone and liver disease
not contraindicated, just need to be cautious and monitor.
first generation cephalosporins include (3)
cefazolin
cephalexin
cefadroxil
1st generation Cephs are very active against (2)
Streptococcal
MSSA
1st generation ceps: weaknesses (3)
- limited activity against gram neg rods
- no anaerobic cvg
- poor CSF penetration
1st gen cephs distribution
all tissues
1st gen cephs dose reduction
If CrCl is <50 mL/min
2nd generation cephalosporins are divided
into two groups
2nd generation cephalosporins: group 1 drugs
cefuroxime
cefaclor
2nd generation cephalosporins, group 2 AKA
the cephamycins
2nd generation cephalosporins, group 2 (cephamycin) drugs
cefoxitin
cefotetan
(These have the MTT chains)
Indication of 2nd generation cephalosporins, group 2 (cephamycins)
“dirty surgery” ie: GI/GU surgeries
2nd generation cephalosporins, group 1, indicated in
respiratory infections
head/neck infections
risk with cefoxitin or cefotetan
bleeding risk
worse in cefotetan
Activity of 2nd generation cephalosporins, group 1
4
- active against strep and MSSA
- some activity against gram neg organisms (head/neck)
- no activity against gram neg anaerobe bacterioides (b. fragilis)
- variable CSF levels
Activity of 2nd generation cephalosporins, group 2 (cephamycins)
(4)
- inferior against strep and MSSA
- very good coverage against bacteroides (B fragilis)
- enhanced activity against gram negatives compared to the 1st generation and 2nd generation group 1s.
- GI/GU surgeries
Distribution of 2nd generation cephalosporins
lung female GU kidney synovial fluid peritoneal/pericardial fluid pleural fluid
Cefuroxime, a 2nd generation cephalosporin, may be used for
meningitis as it penetrates well into the CSF.
Dose adjustment for 2nd generation cephalosporins
CrCl <50 mL/min
3rd generation cephalosporins are divided into
anti pseudomonas
and others
The only time a patient will be on BID ceftriaxone is in the setting of
meningitis
3rd generation cephalosporins- anti psuedomonal
ceftazidime
third generation cephalosporins, “others” (non anti pseudomonas)
(3 for this class)
ceftriaxone
cefpodoxime
ceftazidine
cefotaxime, a third generation cephalosporins, will be used in the setting of
hyperbilirubinemia of newborns, as it will not make the condition worse like ceftriaxone will.
cefpodoxime, a 3rd generation cephalosporin, can be thought of as
an oral substitute for ceftriaxone.
What do you need to keep in mind when prescribing cefpodoxime?
it does have an MTT chain, so monitor labs if a patient is also on warfarin
dose adjustments for 3rd generation cephs
renal: CrCl <50 mL/min
hepatic for ceftriaxone
distribution of 3rd generation cephs
extensively distributed and penetrates the CSF
4th generation cephalosporin drug
cefepime
what is the broadest of the cephalosporins?
cefepime
activity of 4th gen cephalosporin, cefepime
- superior gram neg activity, with good activity against pseudomonas
- staph and strep cvg is comparable to the earlier generations
- NO activity against MRSA.
cefepime as an empiric abc
excellent
oncologic indication for cefepime
febrile neutropenia
distribution of 4th gen ceph, cefepime
same as 3rd gen.
5th generation cephalosporin
ceftaroline
ceftaroline claim to fame
anti MRSA
spectrum of activity of 5th generation cephalosporin, ceftaroline
very wide gram neg gram pos aerobic anaerobic
what conditions may you see 5th generation cephalosporin, ceftaroline, used in and what condition will you NOT see it in?
(3, 1)
respiratory infections
MRSA
S. pneumo
NOT pseudomonas.
why would you give cefepime and Vanco and metronidazole? (empiric)
cefepime for the broad spectrum and pseudomonas coverage
Vanco for MRSA
flagyl for anaerobic cvg.
then you’ll de escalate as your cultures come back
General monitoring when on cephalosporins
c&s
CBC c diff
LFTs
RFTs
pregnancy/lactation considerations for cephalosporins (4)
category B
cross placenta
may see inc Vd / clearance
crosses breast milk in small amounts
Pediatric considerations for cephalosporins
longer half lives
*no ceftriaxone in hyper-bilirubinemia infants.
Geriatric considerations for cephalosporins
dose adjust for renal insufficiency
considerations for critically ill patients receiving cephalosporins and example
may need higher doses
ie: ceftriaxone dosing for meningitis
obesity considerations for cephalosporins
may be dose adjusted up
when is the only time you’ll see ceftriaxone dosed more than once a day?
meningitis
cefepime vs ceftaroline
cefepime coveres psuedomonas but not MRSA
ceftaroline covers MRSA but not psuedomonas
3rd generation cephalosporins: ceftazidime
5
- best for pseudomonas
- weak against strep and MSSA compared to the others
- poor activity against gram neg anaerobes (covers <50% b fragilis)
- excellent CSF levels
- may see c diff
