cephalosporins

see also;

• antibiotics
• wikipedia

• 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

• mainly for Gram +ves & some Gram -ves
• eg. cephalexin, cephazolin/cefazolin

• 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

• expanded Gram -ve cover, even less Gram +ve cover
• cross BBB adequately for Rx of meningitis
• used in H.influenzae septicaemia
• eg. cefotaxime, ceftriaxone, ceftazidime

• 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