Multiresistant bacteria as a hospital epidemic problem.

Since the introduction of antibiotics into clinical use, bacteria have protected themselves by developing antibiotic resistance mechanisms. Currently, there are increasing problems worldwide with multiresistant bacteria. These problems are especially evident within hospitals, where they frequently present as nosocomial epidemics. Currently, the most important nosocomial resistance problems on a global scale are caused by methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and Enterobacteriaceae with plasmid-encoded extended-spectrum beta-lactamases. In this review we describe the characteristics of nosocomial epidemics of these three groups of multiresistant nosocomial pathogens. Despite the differences in bacterial species, the differences in mechanisms of resistance, the different ecological niches and the different infections caused by these pathogens, there are striking similarities in the variables determining nosocomial spread. The existence of each of these multiresistant micro-organisms and their concurrent spread seem to result from extensive antibiotic use and lapses in compliance with infection control measures. Problems with these bacteria became evident as monoclonal outbreaks, soon followed by establishment of endemicity especially in intensive care units. Finally, endemicity seems to be established on general hospital wards and in chronic care facilities and nursing homes, creating a continuous influx of colonized patients into special care wards. High compliance with infection control measures and a prudent and more restrictive use of antibiotics are the key measures to prevent these epidemics.