cephalosporins

introduction

similar to penicillins, cephalosporins are beta lactam ring antibiotics which kill bacteria by compromising their cell wall
generally NOT active against LAME : Listeria, Atypicals (including Mycoplasma and Chlamydia), MRSA, enterococci
Poorly cross BBB and not used in Rx of meningitis except 3rd gens.
see also penicillins and hypersensitivity reactions

less Gram +ve cover, more Gram -ve cover
some active against B. fragilis & thus used in mixed anaerobe infections such as peritonitis, diverticulitis:
- eg. cefotetan, cefoxitin
others active against H. influenzae:
- eg. cefaclor, cefamandole, cefuroxime, cefotetan, cefoxitin

some cross BBB and can be used in meningitis
similar activity against Gram-positive organisms as first-generation cephalosporins
are zwitterions that can penetrate the outer membrane of Gram-negative bacteria
greater resistance to beta-lactamases than the third-generation cephalosporins
can be used against Pseudomonas aeruginosa
examples:
- cefclidine, cefepime, cefpirome
- oxacephems: flomoxef

ceftobiprole:
- powerful antipseudomonal characteristics and appears to be less susceptible to development of resistance
ceftaroline:
- introduced in Australia in 2013
- does not have the anti-pseudomonal or VRE coverage of ceftobiprole
- less effective against some Gram negatives
- binds to the altered penicillin binding proteins produced by certain penicillin resistant bacteria
- broad spectrum coverage includes E. coli, H. influenzae, Klebsiella pneumoniae, MRSA, penicillin non-susceptible Str. pneumoniae
- used to Rx skin, soft tissue infections and community acquired pneumonia (with an adjunctive antibiotic such as clarithromycin, and clinical cure rates were a touch better than for ceftriaxone with clarithromycin)
- 90% renal excreted, half life 2.5hrs
- 10% develop a positive Coombs test
- usual adult dose: 600mg iv infusion over 1hr bd