CHAIN OF INFECTION

INFECTIOUS AGENT A microbial organism with the ability to cause disease. The greater the organism's virulence (ability to grow and multiply), invasiveness (ability to enter tissue) and pathogenicity (ability to cause disease), the greater the possibility that the organism will cause an infection. Infectious agents are bacteria, viruses, fungi, and parasites.

RESERVOIRA place within which microorganisms can thrive and reproduce. For example, microorganisms thrive in human beings, animals, and inanimate objects such as water, table tops, and doorknobs.

PORTAL OF EXITA place of exit providing a way for a microorganism to leave the reservoir. For example, the microorganism may leave the reservoir through the nose or mouth when someone sneezes or coughs. Microorganisms, carried away from the body by feces, may also leave the reservoir of an infected bowel.

MODE OF TRANSMISSIONMethod of transfer by which the organism moves or is carried from one place to another. The hands of the health care worker may carry bacteria from one person to another.

PORTAL OF ENTRYAn opening allowing the microorganism to enter the host. Portals include body orifices, mucus membranes, or breaks in the skin. Portals also result from tubes placed in body cavities, such as urinary catheters, or from punctures produced by invasive procedures such as intravenous fluid replacement.

SUSCEPTIBLE HOSTA person who cannot resist a microorganism invading the body, multiplying, and resulting in infection. The host is susceptible to the disease, lacking immunity or physical resistance to overcome the invasion by the pathogenic microorganism.

PREVENTION AND CONTROL OF INFECTION:

Breaking the Chain

Medical AsepsisThe practice of medical asepsis helps to contain infectious organisms and to maintain an environment free from contamination. The techniques used to maintain medical asepsis include hand washing, gowning and wearing facial masks when appropriate, as well as separating clean from contaminated or potentially contaminated materials and providing information to patients about basic hygienic practices. Appropriate hand washing by the nurse and the patient remains the most important factor in preventing the spread of microorganisms.

Standard PrecautionsStandard precautions combine the major features of universal precautions and body substance isolation. These standard precautions alert the health care worker to patient situations that require special barrier techniques. These barrier techniques are used when working with any patient where potential or actualized contact with blood or body fluid exists.

Universal PrecautionsUniversal precautions help control contamination from bloodborne viruses such as human immunodeficiency virus (HIV) and hepatitis viruses. When in contact with a patient's blood or any body secretion that may be contaminated with blood, protective measures such as wearing gloves, gown, facial mask, and/or goggles must be followed.

Body Substance IsolationBody substance isolation protects against bacterial organisms that may exist in body substances. Body substance isolation applies in all patient encounters regardless of the diagnosis. The application of gloves for contact with moist body surfaces and areas of nonintact skin, gowns when in contact with body secretions, and facial mask when in danger of contact with respiratory droplet secretions, prevents the contamination of both health care worker and patient.

Patient Situation: 1The Spread of InfectionAn elderly patient, hospitalized with a

gastrointestinal disorder, was on bed rest and required assistance for activities of daily living. The patient had frequent uncontrolled diarrhea stools and the nurse provided excellent care to maintain cleanliness and comfort. Following one episode of cleaning the patient and changing the bed linen, the nurse immediately went to a second patient to provide care. The nurse's hands were not washed before assisting the second patient.

CHAIN OF INFECTIONEscherichia coli

Large intestine E. coli, bacteria in the large intestine of humans forms the greater part of the normal intestinal flora.

E. coli exited the body in feces.

The nurse removed the contaminated linen from the bed. The E. coli organism contaminated the hands of the nurse who then provided morning care to another patient.

The second patient receiving care had a Foley catheter. The nurse manipulated the tubing attached to the catheter. The E. coli organism on the nurse's hands contaminated the catheter tubing and ascended to the patient's meatus and then into the urinary bladder.

The second patient with a Foley catheter. This patient was elderly and had a chronic illness necessitating complete bed rest. The Foley catheter contaminated by the E. coli organism provided a direct route into the urinary bladder.

Patient Situation: 2The Nurse Breaks the Chain A patient assigned for morning care has an open wound on her left lower leg.

The wound is draining and when last cultured, the microorganism MRSA was identified.

In preparation for bedmaking, hands of the nurse were washed. Clean linen and a bag for soiled linen were gathered from the linen room and placed on the patient's clean bedside stand.

To remove the soiled linen from the bed, the following procedure was followed: Hands washed Gloves worn Each side of the soiled linen ends folded towards the middle of the bed Soiled linen held away from the nurse's clean uniform Soiled linen placed in the linen bag for later discard Protective gloves removed Hands washed

The nurse applied principles of medical asepsis and standard precautions with the use of body substance isolation to contain the infectious organism at many points in the chain of infection.

MRSA

Patient's infected wound

Draining from the open wound BREAK IN THE CHAIN

Nurse used proper hand washing techniques, wore protective gloves and properly handled the linen.  

MRSA commonly transferred on hands of the nurse by indirect contactBREAK IN THE CHAIN

Proper hand washing, gloving and handling of linen

BREAK IN THE CHAINOrganisms isolated with use of medical asepsis and body substance isolation

You just PROTECTEDYour susceptible host

THANK YOU!!