Bacterial pathogens of increasing significance in hospital-acquired infections.

Despite the introduction of many effective antibiotics and an increased understanding of appropriate infection control measures, new pathogens continue to emerge as nosocomial opportunities. Some of these bacteria have developed increased antibiotic resistance; others have acquired the ability to survive in antiseptics, in intravenous infusion solutions, or on intravascular catheters; and still others are ubiquitous in the hospital and readily colonize compromised patients. Because some of these organisms are fastidious, they have not always been readily cultured and identified. Other species have not been fully appreciated as nosocomial pathogens because of taxonomic uncertainties. The changing spectrum of hospital-acquired infection continues to pose new challenges that necessitate the development of highly active agents such as imipenem for effective treatment.