These are broad-spectrum antibiotics. Most are semi-synthetic derivatives of cephalosporin C, an antibiotic originally derived from a sewage outfall in Sardinia.

First-generation examples still in use include cephalexin and cefadroxil. They are orally active and, along with second-generation cefaclor, have a similar antimicrobial spectrum. They are used for ‘resistant’ urinary infections and urinary infections in pregnancy. Cephalosporins have a similar pharmacology to that of penicillin, and about 10 per cent of patients allergic to penicillin will also be hypersensitive to cephalosporins. They are effective in treating SEPTICAEMIA, PNEUMONIA, MENINGITIS, biliary-tract infections and PERITONITIS.

Second-generation cefuroxime and cefamandole are less vulnerable to penicillinases and are useful for treating ‘resistant’ bacteria and Haemophilus influenzae and Neisseria gonorrhoea. Third-generation cephalosporins include cefotaxime, ceftazidime and others; these are more effective than the second-generation in treating some gram-negative infections, especially those causing SEPTICAEMIA.