[Fifty years of cephalosporins: rationale for success]

The cephalosporins constitute the antibiotic class possibly showing the widest flexibility of usage, due to their very great versatility in terms of molecular features, antibacterial spectrum, and administration schedules. In this half-century, cephalosporins have undoubtedly figured as one of the most commonly used and most successful classes of antibiotics against a vast range of bacterial infections. Cephalosporin activity against Gram-positive bacteria is generally good and, above all, largely predictable on the basis of the epidemiological data. Methicillin-resistant staphylococci and enterococci, of course, are excluded from their spectrum of action. Despite the diffusion of resistance mechanisms among Gram-negative organisms, mostly broad- and extended-spectrum beta-lactamases, cephalosporins are still highly effective against the vast majority of H. influenzae, Enterobacteriaceae and, albeit to a lesser extent, Pseudomonas spp. The growing diffusion of resistance, however, makes thorough assessment of antibiotic assay data mandatory, especially for Gram-negative strains isolated from departments at particularly high risk. Observance of these basic precautions may contribute towards the improved use of cephalosporins and towards maintaining their substantial efficacy in the face of the disturbing worldwide increase in resistance to all known antibiotics.