Nosocomial infections represent an important cause of morbidity and mortality in hospital settings, resulting in high health care costs. The roles of an epidemic investigation are to recognize that a problem exists, to compare characteristics of affected persons with those of similar but unaffected persons (case-control study), and to identify risk factors. Integrating typing methods as part of conventional epidemiologic surveillance is cost-effective and results in a reduction in rates of nosocomial infections. During the past 10 years, there has been unprecedented progress in molecular biology and in the application of nucleic acid technology to the study of the epidemiology of human infections.
To summarize the available molecular tests for determination of the relatedness of microorganisms causing nosocomial infections, emphasizing the most useful applications of the tests to the study of the epidemiology of hospital-acquired infection; and to discuss the appropriate use of these tests in the prevention and control of hospital-associated infection.
Published English-language literature from 1980 to the present.
Pulsed-field gel electrophoresis is the method of choice for strain delineation. The newest techniques include polymerase chain reaction and multilocus sequence typing, in which various housekeeping genes that are stable markers of strain identity are sequenced. Molecular techniques are broadly applicable to the study of diverse pathogens. Typing data obtained by DNA analysis should always be considered together with epidemiologic information, because only this combination will enable the most accurate epidemiologic evaluation.