Beta-lactamases, beta-lactamase inhibitors, and skin and skin-structure infections.

beta-Lactamases have been known since the early 1940s when they were recognized as a major mechanism of resistance in Staphylococcus aureus. The synthesis of semisynthetic penicillins provided agents that overcame the resistance of staphylococci, but as gram-negative bacteria became increasingly important as the cause of infections, plasmid-mediated beta-lactamases were recognized in the Enterobacteriaceae, Haemophilus, and chromosomally mediated beta-lactamases in Klebsiella, and Bacteroides were found to be the mechanism of resistance of these species to ampicillin and related penicillins. Two approaches to the problem have been developed. One is to make stable compounds. This has been possible in the cephalosporin family. The other method has been to find inhibitors of beta-lactamases. Clavulanate is a beta-lactamase inhibitor that, in combination with amoxicillin, allows the combination to inhibit many of the organisms that are resistant to amoxicillin. Similarly, clavulanate has been combined with ticarcillin to provide a parenteral agent to inhibit beta-lactamase-producing bacteria and retain activity against Pseudomonas. Sulbactam has been combined with ampicillin. The combination of suicide inhibitors with other beta-lactams has provided agents that inhibit many of the bacteria present in mixed cutaneous infections. Clinical studies have established the efficacy of the clavulanate-amoxicillin and clavulanate-ticarcillin combinations in skin and skin-structure infections. These agents offer an alternative to other drugs when treating cutaneous infections.