Basic Nursing:Foundations of
Skills & Concepts
Chapter 21
INFECTION
CONTROL ASEPSIS
Flora
Microorganisms that occur or have
adapted to live in a specific environment.
 Two types:
 Resident (always present).
 Transient (episodic).

Pathogens
Microorganisms that cause disease.
 These include:
 Bacteria.
 Fungi.
 Viruses.
 Protozoa.
 Rickettsia.

Virulence

The frequency with which a pathogen
causes disease.
Factors Affecting Virulence
Strength of pathogen to adhere to healthy
cells.
 Ability of pathogen to damage cells or
interfere with the body’s normal regulating
systems.
 Ability of pathogen to evade attack of
white blood cells.

Bacteria
Small, one-celled microorganisms that
lack a true nucleus or mechanism to
provide metabolism.
 Only small percent of bacteria are
pathogenic.
 Common bacterial infections include
diarrhea, pneumonia, gonorrhea,
meningitis, impetigo, and urinary tract
infections.

Viruses
Organisms that live only inside cells.
 They cannot get nourishment or
reproduce outside cells.
 Common viral infections include influenza,
measles, common cold, chickenpox,
hepatitis B, genital herpes, and HIV.

Fungi
Grow in single cells, as in yeast, or in
colonies, as in molds.
 Most are not pathogenic and make up
many of the body’s normal flora.
 Fungi can cause infections of the hair,
skin, nails, and mucous membranes.

Protozoa
Single-celled parasitic organisms with the
ability to move.
 Common protozoan infections include
malaria, gastroenteritis, and vaginal
infections.

Rickettsia
Intracellular parasites that need to be in
living cells to reproduce.
 Spread through fleas, ticks, mites, and
lice.
 Common rickettsia infections include
typhus, Rocky Mountain spotted fever,
and Lyme disease.

Infection

An invasion and multiplication of
pathogenic microorganisms that occurs in
body tissue and results in cellular injury.
Chain of Infection
Infectious agent
Susceptible Host
Reservoir
Or Source
Portal of Entry to Host
Mode of Transmission
Portal of Exit
from Reservoir or
Source
Agent
An entity capable of causing disease.
These may be:
Biological (bacteria, viruses, fungi,
protozoa, Rickettsia).
 Chemical (pesticides, food additives,
medications, industrial chemicals).
 Physical (environmental factors, like
heat, light, noise, radiation, and
machinery).

Reservoir
A place where the agent can survive.
The most common reservoirs are:
Humans.
 Animals.
 Environment.
 Fomites (objects contaminated with an
infectious agent, e.g. bed pans, urinals,
linens, instruments, dressings, etc.).

Portal of Exit
The route by which an infectious agent
leaves the reservoir to be transferred to a
susceptible host. Includes:

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Sputum from respiratory tract.
Semen, vaginal secretions, or urine, from the genitourinary tract.
Saliva and feces, from the gastrointestinal tract.
Blood.
Draining wounds.
Tears.
Modes of Transmission
The process that bridges the gap between
the portal of exit of the infectious agent from
the reservoir or source and the portal of
entry of the susceptible “new” host.Includes:

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Contact transmission (direct contact with infected
person, indirect contact through fomite, or close
contact with contaminated secretions).
Airborne transmission.
Vehicle transmission (through contaminated
substances such as water, milk, drugs, or blood).
Vectorborne transmission (through fleas, ticks, lice,
and other animals).
Host
A simple or complex organism that can
be affected by an agent.
 A susceptible host lacks resistance to
an agent and is vulnerable to disease.
 A compromised host has impaired
defense mechanisms and is susceptible
to infection.
Factors Affecting Susceptibility
to Infection
Age.
 Concurrent
diseases.
 Stress.
 Immunization and
vaccination status.

Occupation.
 Nutritional Status.
 Heredity.
 Lifestyle.

Breaking the Chain of Infection
Between Agent and Resevoir
 Cleansing.
 Disinfection.
 Sterilizing.
Cleansing
The removal of soil or organic material
from instruments and equipment. Four
steps:

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Rinsing the object under cold water.
Applying detergent and scrubbing object.
Rinsing the object under warm water.
Drying the object prior to sterilization or
disinfection.
Disinfection
The elimination of pathogens, except
spores, from inanimate objects.

Disinfectants are chemical solutions used to clean
inanimate objects.

Germicides are chemicals that can be applied to
both animate (living) and inanimate objects for the
purpose of eliminating pathogens.
Sterilization
The total elimination of all
microorganisms including spores.

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Instruments used for invasive procedures must be
sterilized.
Moist heat or steam, radiation, chemicals, and
ethylene oxide gas used for sterilization.
Autoclaving sterilization, using moist heat, is used
in most hospital settings.
Breaking the Chain of Infection
Between Reservoir and Portal

Proper Hygiene.

Clean Dressings.

Clean Linen.

Clean Equipment.
Breaking the Chain of Infection
Between Portal of Exit and Mode of
Transmission

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Clean dressings on all injuries.
Clients should be encouraged to cover the mouth
and nose when sneezing or coughing, as should the
nurse.
Gloves must be worn whenever necessary.
Proper disposal of contaminated items.
Breaking the Chain of Infection
Between Mode of Transmission and Portal
of Entry

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Nurses wearing barrier protection (gloves, masks,
gowns, goggles).
Proper handwashing.
Proper disposal of contaminated equipment and
linens.
Breaking the Chain of Infection
Between Portal of Entry and Host

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Maintaining skin integrity.
Using sterile technique for client contacts.
Avoiding needle sticks.
Proper disposal of sharps.
Breaking the Chain of Infection
Between Host and Agent
 Proper nutrition.
 Exercise.
 Immunization.

Normal Defense Mechanisms

A host’s immune system serves as a
normal defense mechanism against the
transmission of infectious agents.

Immune system recognizes presence of
antigens, foreign proteins that cause the
formation of an antibody.
Nonspecific Immune Defense
Skin and normal flora.
 Mucous membranes.
 Sneezing, coughing, and tearing reflexes.
 Elimination and acidic environment.
 Inflammation.

Inflammation
A nonspecific cellular response to tissue
injury.
 Characteristics include:
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Redness (erythema).
Heat.
Pain.
Swelling (edema).
Loss of function.
Pus (purulent exudate).
Specific Immune Defense

This is an immune defense mounted
specifically against an invading antigen.

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Skin and normal flora.
Mucous membranes.
Sneezing, coughing, and tearing reflexes.
Elimination and acidic environment.
Inflammation.
Stages of Infection

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Incubation (the time interval between entry of an
infectious agent into host and onset of symptoms).
Prodromal (from onset of nonspecific symptoms to
specific symptoms of illness).
Illness (period of specific signs and symptoms of
infection).
Convalescence (from disappearance of acute
symptoms until client returns to previous state of
health).
Nosocomial Infections
An infection acquired in a hospital or other
health care facility that was not present or
incubating at the time of the client’s
admission.
 Also referred to as hospital-acquired
infections.

Asepsis
The absence of microorganisms.
 Two types of asepsis:


Medical (those practices used to reduce the number,
growth, and spread of microorganisms).

Surgical (practices that eliminate all microorganisms
and spores from an object or area).
Medical Asepsis

Handwashing is the first line of defense
against infection and is the single most
important practice in preventing the
spread of disease.
Surgical Asepsis Techniques
Surgical handwashing.
 Sterile field and equipment.
 Donning surgical attire.
 Donning sterile gloves.
 Gowning and closed gloving.
 Disposal of infectious materials.
