ID 17 Flashcards
Cephalosporins as a class..
beta lactase that are less susceptible to penicillinases.
organisms not covered by 1st-4th generation cephalosporins? exception?
LAME Listeria Atypicals (chlamydia, mycoplasma) MRSA Enterococci Exception: ceftaroline (5th generation cephalosporin, which covers MRSA)
1st gen cephalosporins?
Cefazolin
Cephalexin
1st gen cephalosporin use?
Proteus
E coli
klebsiella
other use for cefazolin?
prior to surgery to prevent s aureus wound infections
2nd gen cephalosporins?
Cefaclor
Cefoxitin
Cefuroxime
2nd gen cephalosporin use?
H influenza Enterobacter aerogenes Neisseria Serratia Proteus E coli Klebsiella
3rd gen cephalosporins?
Ceftriaxone
Cefotaxime
Ceftazidime
ceftazidime uses..
pseudomonas
ceftriaxone uses..
meningitis
gonorrhea
disseminated lyme disease
4th generation cephalosporins…
cefepime
cefepime uses…
gram negatives with increased activity against pseudomonas
gram positives
cephalosporin AE’s
1) hypersensitivity reactions
2) AIHA
3) disulfiram-like reaction
4) vitamin K deficiency
5) cross-reactivity with penicillins
6) increase nephrotoxicity of aminoglycosides
carbapenems
imipenem
meropenem
ertapenem
doripenem
imipenem as a drug and caveat
1) broad spectrum, b-lactamase resistant.
2) always administered with cilastatin
what is cilastatin? why do you give it with imipenem?
1) inhibitor of renal dehydropeptidase I
2) decreases inactivation of drug in renal tubules.
meropenem benefits
1) Decreased seizure risk
2) stable to dehydropeptidase I
carbapenem uses
Gram positive cocci
gram negative rods
anaerobes
Carbapenem AE’s
1) CNS toxicity, seizure
2) skin rash
3) GI distress
benefits of aztreonam
1) less susceptible to beta-lactamases
2) no cross-allergenicity with penicllins
aztreonam mechanism
Prevents peptidoglycan cross-linking by binding to penicillin-binding protein 3.
aztreonam has activity against
only gram negative rods
aztreonam uses?
penicillin-allergic patients and those with renal insufficiency who can’t tolerate ahminoglycosides.
vancomycin characteristics
1) bactericidal against most bacteria, except c diff
2) not susceptible to beta-lactamses
vancomycin uses..
*only gram positives–serious multidrug-resistant organisms like enterococcus, MRSA, C diff, S epidermidis
vanco AE’s
1) nephrotoxic
2) ototoxic
3) thrombophlebitis
4) diffuse flushing/red man syndrome
how do you prevent red man syndrome?
Pretreat with antihistamines + slow infusion rate.
vanco resistance mechanism
amino acid modification of D-ala D-ala to D-ala D-lac
bactericidal protein synthesis inhibitor?
ahminoglycosides, linezolid is variable
peptidyl transferase function
Forms peptide bonds between adjacent amino acids using tRNAs during translation.
amino glycoside mechanism
1) irreversible inhibition of initiation complex through 30s binding
2) can cause misreading of mRNA
3) also block translocation
antibiotic used for bowel surgery?
neomycin
amino glycoside use?
severe gram negative rods. synergistic with beta-lactams
other aminoglycoside AE?
neuromuscular blockade
main concern for ototoxicity with ahminoglycosides?
when combined with loop diuretics
amino glycoside mechanism of resistance?
acetylation, phosphorylation, or adenylation
other things that interact with tetracyclines?
iron-containing preparations
tetracycline for use in renal failure?
doxycycline (fecally eliminated)
tetracyclines and CNS penetration?
limited
why are tetracyclines good at treating rickettsia and chlamydia?
can accumulate intracellularly
MOA of resistance to tetracyclines?
Decreased uptake or increased efflux out of bacterial cells by *plasmid encoded transport pumps.
chloramphenicol mechanism?
Blocks peptidyltransferase at 50S ribosomal subunit.
chloramphenicol uses
RMSF
Meningitis
Why are premies at increased risk of chloramphenicol induced aplastic anemia?
they lack UDP-glucoronyl transferase.
chloramphenicol MOA of resistance
Plasmid-encoded acetyltransferase inactivates the drug.
clindamycin MOA
blocks peptide transfer (*translocation) at 50S ribosomal subunit.
other clindamycin use…
invasive group A strep infection
clindamycin vs. metronidazole uses
clindamycin for anaerobes above the diaphragm, metro for below diaphragm
linezolid drug class
oxazolidinones
linezolid MOA
Inhibit protein synthesis by binding to 50s subunit and preventing formation of the initiation complex.
linezolid AE’s
1) bone marrow suppression (especially thrombocytopenia)
2) peripheral neuropathy
3) serotonin syndrome
Linezolid MOA of resistance
point mutation of ribosomal RNA
where do macrolides bind to?
23S rRNA of 50S ribosomal subunit
CYP450 inhibitor macrolides?
clarithromycin and erythromycin
macrolide MOA of resistance?
methylation of 23s rRNA binding site prevents drug binding.
macrolides AE’s
gastrointestinal motility issues arrhythmia/QT prolongation acute cholestatic hepatitis rash eosinophilia
migratory thrombophlebitis?
Vein inflammation related to recurrent thrombus formation in different locations.
How does migratory thrombophlebitis present?
Redness and tenderness on palpation of extremities.
phlebitis
vein inflammation
