Lecture 12 3/7/24 Flashcards
How do cephalosporins differ from penicillins?
the beta-lactam ring is attached to a 6-membered ring in the cephalosporin, making it more resistant to beta-lactamases
What are the characteristics of cephalosporin pharmacokinetics?
-poor oral absorption
-short half-lives
-renal elimination
-considerable renal accumulation
-time-dependent activity
What are the cephalosporin classifications and admin. routes?
-1st gen: parental, oral
-2nd gen: parenteral
-3rd gen: parenteral, oral
-3rd gen, anti-pseudomonal: parenteral
-4th gen: parenteral
What is the spectrum of first gen. cephalosporins?
-high susceptibility of gram pos. aerobes and FAs
-decent susceptibility of gram pos. anaerobes and gram neg. aerobes
-some susceptibility of gram neg. anaerobes and FAs
Which bacteria exhibit resistance against first gen. cephalosporins?
-MRSA
-MRSP
-Enterococcus spp.
-Pseudomonas spp.
-Enterobacter spp.
-Bacteroides fragilis
What is the parenteral first gen. cephalosporin?
cefazolin
What are the oral first gen. cephalosporins?
-cefadroxil
-cephalexin
What is the intramammary first gen. cephalosporin?
cephapirin
What is the spectrum of second gen. cephalosporins?
-decent susceptibility of gram pos. bacteria
-high susceptibility of gram neg. bacteria
Which second gen. cephalosporin is able to treat Bacteroides fragilis and other anaerobes?
cefoxitin
Which bacteria exhibit resistance to second gen. cephalosporins?
-Pseudomonas
-Enterococcus spp.
-MRSA
What are the general characteristics of second gen. cephalosporins?
-limited applications in animals
-more expensive than first gens.
-used based on susceptibility test results
What is the spectrum of third gen. cephalosporins?
-high susceptibility of gram pos. and neg. aerobes, gram neg. FAs
-decent susceptibility of gram pos. anaerobes
-decent susceptibility of gram pos. FAs and gram neg. anaerobes EXCEPT Bacteroides
Which bacteria exhibit resistance to third gen. cephalosporins?
-some Serratia spp.
-some Enterobacter spp.
-Pseudomonas aeruginosa
-Enterococci
-MRSA
-MRSP
What are the main uses of third gen. Ceftiofur?
-resp. infections in food animals
-UTIs in small animals
What are the characteristics of third gen. Cefovecin?
-broader activity against Staph.
-single-dose SQ injectable
What are the characteristics of third gen. Cefpodoxime?
-prodrug
-broader activity against Staph.
-given once daily as an oral tablet
-extra-label use may require higher dose frequency for higher MICs
What is the spectrum of third gen. antipseudomonal cephalosporins?
-high susceptibility of gram pos. and neg. aerobes; especially gram neg. FAs
-decent susceptibility of gram pos. anaerobes
-some susceptibility of gram pos. FAs and gram neg. anaerobes EXCEPT Bacteroides
What are the general characteristics of third gen. antipseudomonal cephalosporins?
-higher activity against difficult to treat gram neg. organisms
-ceftazidime is most active against Pseudomonas
-not used without susceptibility test
What are the characteristics of cephalosporin use in food species?
-banned for use in cattle, swine, poultry if not approved specifically for that species
-banned for use at unapproved levels/frequencies/durations/routes
-banned for disease prevention
What are the exceptions to bans on cephalosporins in food animals?
-use of approved cephapirin products
-extralabel condition at a label dose in approved species
-use in minor species
What are the clinical uses of ceftiofur?
-colibacillosis in poultry
-resp. tract infections in horses/food animals
-metritis in cattle
-UTIs in small animals
What is the clinical use for cephapirin?
mastitis prophylaxis/treatment
What are the clinical uses for cefadroxil/cephalexin/cefpodoxime/cefovecin?
-skin and soft tissue infections in small animals
-UTIs in dogs
What is the clinical use for cefazolin?
surgical prophylaxis
What are the clinical uses for cefoxitin?
-septic peritonitis
-mixed infections
What is the clinical use for ceftazidime?
serious infections involving Pseudomonas or resistant gram. neg. bacteria
What are the adverse effects associated with cephalosporins?
-diarrhea
-thrombocytopenia
-neutropenia
What is the spectrum of carbapenems?
high susceptibility of all gram neg. and gram pos. categories
Which bacteria exhibit resistance to carbapenems?
-MRSA
-some Enterobacter spp.
-Pseudomonas aeruginosa
-Enterococcus faecium
What are the general characteristics of carbapenems?
-all are human products
-typically IV admin.
-more bactericidal
-reserved for severe infections that would otherwise require multiple antibiotics
What are the characteristics of Meropenem?
-broad spectrum
-beta-lactamase stable
-IV or SQ admin.
-used mostly in small animals for resistant infections
What are the characteristics of Imipenem-cilastatin?
-broad spectrum
-beta-lactamase stable
-potent and expensive
-IV, IM, or SQ admin.
-used for resistant infections
-culture and susceptibility testing done first
What are the characteristics of Ertapenem?
-more human applications
-Pseudomonas is usually intrinsically resistant
What are the limitations of carbapenem use in vet med?
-no CLSI breakpoints
-culture and susceptibility results for one carbapenem do not transfer to another
What are the adverse effects associated with carbapenems in people?
-nephrotoxicity
-injection site reactions
-seizures
