Cephalosporins: a review.

Introduction Cephalosporins are beta-lactam antimicrobials that share mechanisms of action and a similar structure with penicillins (Figure). Penicillins and cephalosporins have the same four-member “core” beta-lactam ring, but cephalosporins have an additional atom in the side ring. Modified side chains on either ring alter antimicrobial activity, resistance to beta-lactamases, or pharmacokinetics. Penicillin-susceptible pathogens usually are cephalosporin-susceptible. Exceptions are Listeria and Pasteurella sp. Cephalosporins have activity against common gram-negative organisms such as Escherichia coli, nontypeable Haemophilus influenzae (ntHi), and methicillin-susceptible Staphylococcus aureus (MSSA), but all methicillin-resistant S aureus (MRSA) and enterococci are cephalosporin-resistant. Because of minimal use or current unavailability, we will not discuss cephalothin, moxalactam, cefamandole, cefonicid, ceforanide, ceftizoxime, cefoperazone, cefpirome, cefmetazole, or cefotetan.