Infection Control in Nursing

You are the patient's biologic barrier. Microorganisms live everywhere: water, soil, skin, GI tract, mouth, upper respiratory tract, vagina, lower urinary tract. Some are harmless flora, some are lethal, and the nurse at the bedside is the one who keeps the environment safe.

What is Infection?

Infection is the growth of microorganisms in body tissue where they are not usually found.

• Infectious agent. The microorganism itself, the source: a germ, a virus, or another microbe.
• Asymptomatic. Infection that produces no clinical evidence of disease (also called subclinical).
• Disease. A detectable alteration in normal tissue function.
• Virulence. A microorganism's ability to produce disease, the severity it causes, and its communicability.
• Pathogenicity. The ability to produce disease. A pathogen is a microorganism that causes disease.
• Asepsis. Freedom from disease-causing microorganisms. Aseptic technique decreases the chance of transferring microorganisms from one place to another.
• Medical asepsis. Practices that confine a microorganism to a specific area, limiting its number, growth, and transmission.
• Surgical asepsis. Sterile technique. Practices that keep an area or object free of all microorganisms, including spores.
• Sepsis. Acute organ dysfunction occurring secondary to infection.

Types of Microorganisms

Four major categories cause infection in humans: bacteria, viruses, fungi, and parasites.

• Bacteria. The most common infection-causing microorganisms. Several hundred species cause disease in humans and travel through air, water, food, soil, body tissues and fluids, and inanimate objects.
• Viruses. Made primarily of nucleic acid, so they must enter living cells to reproduce. Common families include rhinoviruses (the common cold), hepatitis, herpes, and human immunodeficiency virus.
• Fungi. Yeasts and molds. Candida albicans is a yeast considered normal flora in the human vagina.
• Parasites. Live on other organisms. They include protozoa (such as the one that causes malaria), helminths (worms), and arthropods (mites, fleas, ticks).

Types of Infection

Infection occurs when microorganisms invade a part of the body where host defenses are ineffective and the pathogen causes tissue damage.

• Local infection. Limited to a specific part of the body.
• Systemic infection. Microorganisms spread and damage different parts of the body.
• Bacteremia. A culture of the blood reveals microorganisms.
• Septicemia. Bacteremia that results in systemic infection.
• Acute infection. Appears suddenly or lasts a short time.
• Chronic infection. Develops slowly over a long period and may last months or years.

Nosocomial and Health-related Infections

Nosocomial infections originate in the hospital and are a subgroup of healthcare-associated infections (HAIs). Most trace back to a break in technique, so know the usual culprits and the lapse that lets them in.

• Urinary tract. Escherichia coli (improper catheterization technique), Enterococcus species (contamination of a closed drainage system), and Pseudomonas aeruginosa (inadequate hand hygiene).
• Surgical sites. Staphylococcus aureus including MRSA (inadequate hand hygiene), Enterococcus species including vancomycin-resistant strains (improper dressing change technique), and Pseudomonas aeruginosa.
• Bloodstream. Coagulase-negative staphylococci (inadequate hand hygiene), Staphylococcus aureus, and Enterococcus species (improper IV fluid, tubing, and site care technique).
• Pneumonia. Staphylococcus aureus (inadequate hand hygiene), Pseudomonas aeruginosa, and Enterobacter species (improper suctioning technique).

Chain of Infection

The chain of infection has six links. Break any one and you stop transmission.

• Etiologic agent. Whether a microorganism produces infection depends on the number present, its virulence and potency, its ability to enter the body, host susceptibility, and its ability to live in the host.
• Reservoir. The source of microorganisms: other humans, the client's own flora, plants, animals, or the general environment. A carrier is a person or animal reservoir of an infectious agent that usually shows no clinical signs of disease.
• Portal of exit from reservoir. The microorganism must leave the reservoir. Common human exits are the respiratory tract, GI tract, urinary tract, reproductive tract, blood, and tissues.
• Method of transmission. The route to a new host. Direct transmission is immediate person-to-person transfer through touching, biting, kissing, or sexual intercourse. Indirect transmission is either vehicle-borne (a substance that carries the agent into a susceptible host) or vector-borne (an animal or insect that carries the agent). Airborne transmission involves droplets or droplet nuclei (the residue of evaporated droplets from an infectious host, such as someone with tuberculosis) that can remain in the air for long periods.
• Portal of entry to susceptible host. Microorganisms must enter the body, often by the same route they used to leave the source.
• Susceptible host. Anyone at risk for infection. A compromised host is at increased risk for one or more reasons.

Defenses Against Infection

The body has nonspecific and specific defenses against infection.

Nonspecific Defenses

Nonspecific defenses protect against all microorganisms regardless of prior exposure. They include anatomic and physiologic barriers and the inflammatory response.

Anatomic and Physiologic Barriers

• Intact skin and mucous membranes are the first line of defense.
• The nasal passages trap microorganisms, dust, and foreign material with moist mucous membranes and cilia.
• The lungs have alveolar macrophages (large phagocytes) that ingest microorganisms, dead cells, and foreign particles.
• The oral cavity sheds mucosal epithelium to clear colonizers.
• Saliva flow and partial buffering help prevent infection. Saliva contains microbial inhibitors: lactoferrin, lysozyme, and secretory IgA.
• Tears wash microorganisms from the eye and contain inhibiting lysozyme.
• The high acidity of the stomach prevents microbial growth.
• Resident flora of the large intestine block disease-producing microorganisms, and peristalsis moves microbes out.
• After puberty, lactobacilli ferment sugars in vaginal secretions, creating a vaginal pH of 3.5 to 4.5 that inhibits many disease-producing microorganisms.
• Urine flow has a flushing, bacteriostatic action that keeps bacteria from ascending the urethra, and an intact mucosal surface adds a barrier.

Inflammatory Response

Inflammation is a local, nonspecific response that destroys or dilutes the injurious agent, limits its spread, and promotes tissue repair. It runs in three stages.

• First stage, vascular and cellular responses. Constriction then dilatation of small vessels, increased permeability, increased leukocytes, swelling, and pain. Leukocytes begin to engulf the infection.
• Second stage, exudate production. Exudation of fluid and dead cells: serous (clear), purulent (thick pus with leukocytes), and sanguineous (bloody).
• Third stage, reparative phase. Tissue repair through regeneration (same tissue), stroma (connective tissue), parenchyma (functional part), and fibrous tissue (scar).

Specific Defenses

Specific defenses involve the immune system and have two components: antibody-mediated and cell-mediated.

Antibody-Mediated Defenses

Also called humoral (circulating) immunity. These defenses reside in the B lymphocytes and are carried out by antibodies produced by B cells.

• Active immunity. The host produces antibodies in response to natural antigens (infectious agents) or artificial antigens (vaccines). Activated B cells differentiate into plasma cells and may produce antibodies of five immunoglobulin classes: IgM, IgG, IgA, IgD, and IgE.
• Passive immunity. The host receives antibodies from another source, natural (from a nursing mother) or artificial (from an injection of immune serum).

Cell-Mediated Defenses

Cellular immunity works through the T-cell system. On exposure to an antigen, lymphoid tissues release large numbers of activated T-cells into the lymph system and general circulation. There are three main groups:

• Helper T cells support the function of the immune system.
• Cytotoxic T cells attack and kill microorganisms and sometimes the body's own cells.
• Suppressor T cells suppress the helper and cytotoxic T cells.

Nursing Management

Nursing Assessment

Obtain the history, perform the physical assessment, and gather laboratory data.

• History. Assess how much the client is at risk for infection and any complaints suggesting an infection is present.
• Physical exam. Signs and symptoms vary by site. Sneezing, watery or mucoid nasal discharge, and nasal stuffiness point to the nose and sinuses. Urinary frequency and cloudy or discolored urine point to a urinary infection.
• Laboratory data. Findings that indicate infection: elevated leukocyte count, increases in specific leukocytes on the differential WBC count, elevated erythrocyte sedimentation rate, and urine, blood, sputum, or other drainage cultures positive for pathogens.

Nursing Diagnosis

• Potential complication of infection: fever.
• Imbalanced nutrition: less than body requirements.
• Acute pain.
• Impaired social interaction or social isolation.
• Anxiety.

Nursing Care Planning and Goals

• Maintain or restore defenses.
• Avoid the spread of infectious organisms.
• Reduce or alleviate problems associated with the infection.

Implementation

• Preventing nosocomial infections. Meticulous medical and surgical asepsis prevents the transport of infectious microorganisms.
• Hand hygiene. Clean both the nurse's and the client's hands before eating, after using the bedpan or toilet, and after contact with any body substance. For routine care, wash vigorously under a stream of water for 15 to 20 seconds with granular soap, soap-filled sheets, or liquid soap, at the start of the shift, when hands are visibly soiled, and after using the toilet.
• Nutrition. A balanced diet keeps skin intact, helps it repel microorganisms, and keeps the immune system working.
• Fluid. Fluid intake supports output that flushes the bladder and urethra, removing microorganisms.
• Sleep. Adequate sleep renews energy and supports health.
• Stress. Excessive stress predisposes people to infection. Teach stress-reducing techniques.
• Immunizations. Immunizations have dramatically lowered the incidence of infectious diseases. They should begin shortly after birth and finish in early childhood, with boosters as scheduled.
• Disinfecting. Interrupt the first links (agent and reservoir) with antiseptics (inhibit growth of some microorganisms) and disinfectants (destroy pathogens other than spores), and by sterilization. Both have bactericidal or bacteriostatic properties: bactericidal destroys bacteria, bacteriostatic prevents their growth and reproduction.
• Sterilization. Destroys all microorganisms, including spores and viruses. Four common methods: moist heat (steam under pressure, which reaches temperatures higher than the boiling point), gas (ethylene oxide, which disrupts microbial metabolism), boiling water (the most practical, inexpensive home method), and radiation (ionizing and non-ionizing, used for disinfection and sterilization).

Infection Prevention and Control

Because you cannot always know which clients carry infectious organisms, the CDC and other bodies set guidelines that all healthcare workers follow to keep organisms in blood and other body tissues from moving from client to others.

Standard Precautions

Use standard precautions for every hospitalized client, regardless of diagnosis or infection status.

• Designed for all clients in the hospital.
• They apply to blood; all body fluids, excretions, and secretions except sweat; nonintact (broken) skin; and mucous membranes.
• They reduce transmission from recognized and unrecognized sources.
• Perform hand hygiene after contact with blood, body fluids, excretions, secretions, and contaminated objects, whether or not gloves were worn.
• Wear clean gloves when touching blood, body fluids, secretions, excretions, and contaminated items.
• Wear a mask, eye protection, or face shield when splashes or sprays are expected.
• Wear a clean, nonsterile, water-resistant gown when care is likely to produce splashes or sprays, to protect clothing.
• Handle soiled client care equipment carefully to prevent transfer of microorganisms.
• Handle all soiled linen as little as possible.
• Place used needles and other sharps directly into puncture-resistant containers as soon as you are done.

Transmission-based Precautions

Add these to standard precautions for clients with known or suspected infections spread by airborne, droplet, or contact transmission.

Airborne Precautions

Standard precautions plus:

• Place the client in an airborne infection isolation room with negative air pressure, 6 to 12 air changes per hour, and either discharge of air to the outside or a filtration system for the room air.
• If a private room is not available, cohort the client with another infected with the same microorganism.
• Wear an N95 respirator mask when entering the room of a client known or suspected to have primary tuberculosis.
• Susceptible people should not enter the room of a client with rubeola (measles) or varicella (chicken pox).
• Limit the client's movement outside the room to essential purposes, and place a surgical mask on the client during transport.

Droplet Precautions

Standard precautions plus:

• Place the client in a private room.
• If a private room is not available, cohort with another infected with the same microorganism.
• Wear a mask when working within 1 meter (3 ft) of the client.
• Limit the client's movement outside the room to essential purposes, and place a surgical mask on the client during transport.

Contact Precautions

Standard precautions plus:

• Place the client in a private room.
• If a private room is not available, cohort with another infected with the same microorganism.
• Wear gloves as in standard precautions.
• Wear a gown on entry if you may contact infected surfaces or items, or if the client is incontinent or has diarrhea, a colostomy, or wound drainage not contained by a dressing.
• Limit the client's movement outside the room.
• Dedicate noncritical care equipment to a single client or to clients with the same infecting microorganism.

Personal Protective Equipment

Apply PPE according to the risk of exposure to potentially infective materials.

Gloves

• Gloves serve three purposes: they protect the hands when handling body substances, they reduce the chance the nurse transmits endogenous microorganisms to the client, and they reduce the chance the nurse's hands carry microorganisms from one client or object to another.
• Change gloves between client contacts.
• Clean the hands each time gloves are removed, for two reasons: the gloves may have imperfections or be damaged during wear, allowing microorganism entry, and the hands may become contaminated during glove removal.

Gowns

• Wear clean or disposable water-resistant gowns or plastic aprons during procedures when the uniform is likely to be soiled.
• Wear sterile gowns when changing the dressings of a client with extensive wounds.
• Single-use gown technique (one wear before discard or laundering) is standard practice.

Face Masks

• Masks reduce transmission of microorganisms by droplet, airborne routes, and splatter of body substances.
• The CDC recommends masks be worn by those close to the client when the infection is transmitted by large-particle aerosols (droplet); these travel short distances by close contact (about 1 m or 3 ft).
• All individuals entering the room wear a mask when the infection is transmitted by small-particle aerosols (droplet nuclei), which stay suspended and travel great distances.

Eye Wear

• Protective eye wear (goggles, glasses, face shields) and masks are indicated when body substances may splatter the face.
• If the nurse wears prescription eyeglasses, wear goggles over them, since protection must extend around the sides.

Sterile Technique

An object is sterile only when it is free of all microorganisms. Sterile technique is used in operating rooms and special diagnostic areas, and also for many general-care procedures: injections, wound dressing changes, urinary catheterization, and IV therapy. In general care, all principles of surgical asepsis apply, though not every step below is always required.

Principles of Surgical Asepsis

• All objects used in a sterile field must be sterile.
• Sterile objects become unsterile when touched by unsterile objects.
• Sterile objects out of sight, below the waist, or below table level are considered unsterile.
• Sterile objects may become unsterile from prolonged exposure to airborne microorganisms.
• Fluids flow in the direction of gravity.
• Moisture passing through a sterile object draws microorganisms from unsterile surfaces by capillary action.
• The edges of a sterile field are considered unsterile.
• The skin cannot be sterilized and is unsterile.
• Conscientiousness, alertness, and honesty are essential to maintaining surgical asepsis.