Secondgeneration Cephalosporins

Second-generation cephalosporins have a broader spectrum than first-generation agents and are active against Enterobacter spp., indole-positive Proteus spp., and Klebsiella spp. Their serum half-lives are generally ~1—2 hours.

Cefoxitin is resistant to some ¡5-lactamases produced by gram-negative rods. This antibiotic is less active than the first-generation cephalosporins against gram-positive bacteria, but is more active against anaerobes, especially B. fragilis. Cefoxitin's special role is for treatment of certain anaerobic and mixed aerobic-anaerobic infections, such as pelvic inflammatory disease and lung abscess.

Cefaclor's concentration in plasma after oral administration is ~50% of that achieved after an equivalent oral dose of cephalexin. However, cefaclor is more active against H. influenzae and Moraxella catarrhalis, although some ¡ -lactamase-producing strains may be resistant. Loracarbef is similar in activity to cefaclor, which is more stable against some ¡ -lactamases.

Cefuroxime is similar to loracarbef with broader gram-negative activity against some Cit-robacter and Enterobacter spp. Unlike cefoxitin, cefmetazole, and cefotetan, cefuroxime lacks activity against B. fragilis. The drug can be given every 8 hours. Concentrations in CSF are ~10% of those in plasma; the drug is effective (but inferior to ceftriaxone) for treatment of meningitis owing to H. influenzae (including strains resistant to ampicillin), N. meningitidis, and S. pneumoniae.

Cefuroxime axetil is the 1-acetyloxyethyl ester of cefuroxime. Between 30% and 50% of an oral dose is absorbed and then hydrolyzed to cefuroxime; resulting concentrations in plasma are variable.

Cefotetan, like cefoxitin, has good activity against B. fragilis and several other species of Bacteroides and is slightly more active than cefoxitin against gram-negative aerobes. Hypopro-thrombinemia and inhibition of vitamin K activation with bleeding have occurred in malnourished patients receiving cefotetan; this is preventable if vitamin K is also administered.

Cefprozil is an orally administered agent that is more active than first-generation cephalosporins against penicillin-sensitive streptococci, E. coli, P. mirabilis, Klebsiella spp., and Citrobacter spp.

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment