Factors Influencing Development of Nosocomial Infection

According to the Centers for Disease Control and Prevention, a nosocomial infection is one that develops 48 to 72 hours after admission to a health care facility 1. Multiple factors contribute to the transmission of infectious organisms in hospitals, long-term care facilities and rehabilitation centers; they include the type of infectious organism, the patient’s proximity to the source of infection, the means by which the organism could potentially be transmitted, and the status of the patient’s immune system. Ultimately, it is the responsibility of the facility to develop policies and procedures designed to interrupt the transmission of infectious organisms from the source to patients.

Is This an Emergency?

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Type of Organism

There are many infectious organisms that need to be monitored in health care facilities. One method used to monitor the predominant microorganisms found in a facility is to track the culture and sensitivity reports generated from laboratory study results. Some of the more highly infectious organisms found in health care facilities are multi-drug resistant organisms such as MRSA, the seasonal influenza viruses and noroviruses, which cause gastroenteritis. These bacterial and viral organisms put patients at risk due to the ease with which they are transmitted from person to person.

Proximity to the Source

Patients come in very close proximity to their roommates, health care workers, family members and visitors, all of whom may be potential sources of infection. Some illnesses, such as the H1N1 influenza viruses, are infectious before the affected person has developed any signs and symptoms of the disease, during which time the patient is transmitting the organism to others. There is very little opportunity to interrupt the cycle of transmission at this stage, other than to practice standard precautions with all patients. Standard precautions distance possible sources of infection by supporting the theory that all patients are potential sources of infectious organisms. Hand washing between contact with each patient and basic barrier protection in the form of gloves, masks and protective equipment is implemented when indicated.

Transmission of the Organism

Influenza viruses travel through the air in the form of droplet’s that may be inhaled when an infected person coughs, sneezes, or exhales forcefully. The organisms may also be picked up when a person touches contaminated surfaces and then touches his or her own eyes, nose or mouth. Noroviruses are transmitted from one person to the other by hand contact with surfaces touched by infected persons or by infected dietary personnel during meal preparation. Multi-drug resistant organisms such as MRSA may be transferred from one patient to another on the hands of health care workers if they do not follow basic standard precautions, including hand washing between contact with patients.

Status of the Immune System

The status of a patient’s immune system plays a major role in fighting infections. Acute and chronic illnesses, advancing age and some classes of medication tax a patient’s immune system, placing patients at highest risk for infection. Those with compromised immunity are much more likely to develop a nosocomial infection in a health care facility where so many patients congregate in one setting; with this in mind, health care facilities implement infection control and prevention programs, including mandatory staff education. Interrupting the cycle of infection by adhering to basic standard precautions not only supports patient safety by preventing the development of nosocomial infections, but it is also the standard for all credentialed health care facilities.