Abstract
During the last several decades we have experienced the emerging and reemerging of infectious pathogens and diseases. The outbreaks of infection due to these pathogens sometimes occur via the sources and/or routes which have not been recognized during previous studies on epidemiology and pathogenesis of the diseases. There are many factors contributing to the increase in infectious diseases. Namely, medical progress often results in an increasing number of immunocompromised patients. Common, usually avirulent, commensal and environmental organisms become pathogens to these patients. The evolution of organisms acquiring resistance to antimicrobial agents, disinfectants, and environmental stimuli also relates to the high incidence of nosocominal (hospital-acquired) infections as well as to the clinical situation of the patients. Because of these tendencies, as risks of nosocominal infections, are characteristic especially in major health care centers such as large teaching hospitals, most health care workers are obliged to participate actively in control and preventive efforts in addition to their traditional roles. In this review I discuss the recent characteristics of nosocominal pathogens and the environments surrounding the hospitalized patients to design effective strategies for and to facilitate the infection control activities.
