Problems and mechanisms of antimicrobial resistance.

Despite mankind's continuing efforts to find better and more powerful antimicrobial agents, bacteria continue to find ways to resist these agents. Recent examples include the emergence of plasmid-mediated resistance to third generation cephalosporins in E. coli, K. pneumoniae and Salmonella; the emergence of plasmid-mediated beta-lactamase in E. faecalis; the appearance of ciprofloxacin resistance among methicillin-resistant staphylococci; and, perhaps most threatening, the appearance of vancomycin resistance in E. faecalis and E. faecium, at least some of which is plasmid mediated. These examples demonstrate the continuing need for studies of resistance and for new compounds, and the need for new stategies in managing bacterial infections.