The widespread use of antibiotics in hospitals provides strong selection pressure for the emergence and persistence of bacterial antibiotic resistance. Examples of resistance traits that have recently emerged include beta-lactam and aminoglycoside resistance in enterococci, resistance to third-generation cephalosporins and aminoglycosides in Enterobacteriaceae, and glycopeptide resistance in enterococci and coagulase-negative staphylococci. In many instances, the organisms exhibiting these novel resistances have been responsible for outbreaks of nosocomial infections. The continuing tendency of nosocomial pathogens to develop or acquire new antibiotic-resistance traits poses significant problems regarding the treatment and control of hospital infections.