The nurse plays a critical role in preventing and controlling infectious disease. The beginning nursing student participates significantly in the prevention process from the initial introduction to nursing care. An important component in preparing for clinical nursing practice is an understanding of the infection process and prevention techniques. Microbiology and other science courses provide background information about pathogenic organisms. The transfer of these scientific principles to the applied art and science of nursing involves an awareness of the dynamics of the infectious process.

Contributing Factors to the Process of Infection
The presence of infectious microorganisms and an individual's weakened health condition are two contributing factors to the infection process. Illness and injury influence the body's ability to resist pathogenic microorganisms. Lowered resistance to microorganisms occurs under conditions of poor nutritional status, open wounds, invasive therapies, or a suppressed immune system. These conditions, associated with illness and injury, become more dangerous when the patient is very old or very young. Within the health care setting the number of infected or colonized individuals is quite high. As a result, the health care setting is an environment rich in pathogenic microorganisms.

Antibiotic therapy, the primary medical treatment for infection, also promotes a great danger: the development of drug-resistant strains of microorganisms, such as MRSA or VRE. Many of these organisms colonize in a host without causing an acute infection. Colonization is the presence and multiplication of a microorganism without tissue invasion or damage. A patient with microorganism colonization does not show signs of infection and is not immediately recognized as a reservoir of an infectious agent.

Prevention and Control
Currently health care workers have an abundance of scientific knowledge about pathogenic organisms and their transmission from one person to another. Methods to control the spread of the microorganisms are standardized in recommendations from the Centers for Disease Control and Prevention (CDC), and the Occupational Safety and Health Administration (OSHA).

In nursing, measures to prevent the transmission of infectious microorganisms from patient to patient become a significant component of care. This prevention is achieved through the practice of medical asepsis and standard precautions. Standard precautions include universal precautions and nosocomial infection.

CHAIN OF INFECTION
A model used to understand the infection process is the chain of infection.