Exam 2 Study Guide
Chapter 28: Infection Prevention and Control
The incidence of infectious diseases such as AIDS, influenza, pneumonia, COVID-19, measles,
and sexually transmitted infections is a significant public health problem in the United States and
around the world. Multiple factors affect the spread of infectious diseases, such as humans’
susceptibility, drug resistance, human tendency to avoid vaccination, and drug
immunosuppression. The incidence of patients who develop infections as the direct result of
contact with health care personnel is an increasing health problem.
NATURE OF INFECTION
● It is important to know the difference between an infection and a colonization.
○ An infection results when a pathogen invades tissues and begins growing within a
hose
○ Colonization is the presence and growth of microorganisms within a host but
without tissue invasion or damage
○ Disease or infection results only if the pathogens multiply and alter normal tissue
function. Some infectious diseases such as viral meningitis and pneumonia have a
low risk of no risk for transmission.
○ If an infectious disease can be transmitted directly from one person to another, it
is termed a communicable disease. If the pathogens multiply and cause clinical
signs and symptoms, the infection is symptomatic. If clinical signs and symptoms
are not present, the illness is termed asymptomatic.
CHAIN OF INFECTION
● The presence of a pathogen does not mean that an infection will occur. INfection occurs
in a cycle that depends on the presence of all of the following elements :
○ An infectious agent or pathogen
■ Microorganisms include bacteria, viruses, fungi, and protozoa.
Microorganisms on the skin are either resident or transient flora. Resident
organisms (normal flora) are permanent residents of the skin and within
the body, where they survive and multiply without causing illness.
■ The potential for microorganisms or parasites to cause disease depends on
the number of microorganisms present; their virulence, or ability to
produce disease; their ability to enter and survive in a host; and the
susceptibility of the host. Resident microorganisms are not virulent.
■ Resident microorganisms can cause serious infection when surgery or
other invasive procedures allow them to enter deep tissues or when a
patient is severely immunocompromised (has an impaired immune
system)
■ Transient microorganisms attach to the skin when a person has contact
with another person or object during normal activities
, ● Party crashers: like random people that show up to your party, eat
your snacks, and leave
○ They don't live there, get picked up from contact, leave
easily with handwashing, cause trouble (most likely to
cause infection)
○ Transient = Temporary troublemakers
○ A reservoir or source for pathogen growth
■ A reservoir is a place where microorganisms survive, multiply, and await
transfer to a susceptible host.
■ Common reservoirs are humans and animals (hosts), insects, food, water,
and organic matter on inanimate surfaces (fomites, like a door handle)
■ To thrive, organisms require a proper environment, including appropriate
food, oxygen, water, temperature, pH, and light.
■ Food
● Microorganisms require nourishment
■ Oxygen
● Aerobic bacteria require oxygen for survival and for
multiplication sufficient to cause disease. Aerobic organisms cause
more infections in humans than anaerobic organisms
● Anaerobic bacteria thrive where little or no free oxygen is
available
■ Water
● Most organisms require water or moisture for survival
■ Temperature
● Microorganisms can live only in certain temperature ranges. Each
species of bacteria has a specific temperature at which it grows
best
● Cold temperatures tend to prevent growth and reproduction of
bacteria (bacteriostasis)
● A temperature or chemical that destroys bacteria is bactericidal
■ pH
● The acidity of an environment determines the viability of
microorganisms. Most microorganisms prefer an environment
within a pH range of 5.0-7.0
■ Light
● Microorganisms thrive in dark environments such as those under
dressings and within body cavities
○ A portal of exit from the reservoir
■ After microorganisms find a site to grow and multiply, they need to find a
portal of exit if they are to enter another host and cause disease.
, ■ Portals of exit include sites such as blood, skin and mucous membranes,
respiratory tract, genitourinary tract, gastrointestinal tract, and
transplacental (mother to fetus)
○ A mode of transmission
■ Each disease has a specific mode of transmission. Often you are able to do
little about the infectious agent or the susceptible host, but by practicing
infection prevention and control techniques such as hand hygiene, you can
interrupt the mode of transmission
■ One microorganism is sometimes transmitted by more than one route
■ Contact
● Direct
○ Person-to-person (fecal, oral) physical contact between
source and susceptible host.
○ A health care provider’s hands become contaminated by
touching germs present on a patient, medical equipment, or
high-touch surfaces, and the health care worker then carries
the germs on the hands and spreads to a susceptible person.
● Indirect
○ Personal contact of susceptible host with contaminated
inanimate object (e.g., needles or sharp objects, soiled
linen, dressings, environment)
■ Droplet
● An infected person coughs or sneezes, creating droplets that carry
germs short distances (within approximately 6 feet). These germs
can land on a susceptible person’s eyes, nose, or mouth and can
cause infection (e.g., pertussis or meningitis).
■ Airborne
● Organisms are carried in droplet nuclei or residue or evaporated
droplets suspended in air during coughing or sneezing. Germs are
aerosolized by medical equipment or by dust from a construction
zone (e.g., nontuberculous mycobacteria or Aspergillus).
■ Vehicles
● Contaminated items. For example, sharps (e.g., needles, IV
insertion devices) injuries can lead to infections (e.g., HIV, HBV,
HCV) when bloodborne pathogens enter a person through a skin
puncture by a used needle or sharp instrument.
● Water
● Drugs, solutions
● Blood
, ● Food (improperly handled, stored, or cooked; fresh or thawed
meats)
■ Vector
● External mechanical transfer (flies)
● Internal transmission such as parasitic conditions between vector
and host such as:
● Mosquito
● Louse
● Flea
● Tick
○ A port of entry to a host
■ Organisms enter the body through the same routes they use for exiting.
Factors such as a depressed immune system that reduce body defenses
enhance the chances of pathogens entering the body
○ A susceptible host
■ Susceptibility to an infectious agent depends on an individual’s degree of
resistance to pathogens
■ Although everyone is constantly in contact with large numbers of
microorganisms, and infection does not develop until an individual
becomes susceptible to the strength and numbers of the microorganisms
○ BREAK THE CHAIN! Preventing infections involves breaking the chain of
infection!
THE INFECTIOUS PROCESS
● By understanding the chain of infection, you have knowledge that is vital in preventing
infections. When a patient is at risk for an infection, take precautions to break the
infection chain.
● If an infection is localized, a patient usually experiences localized symptoms such as
pain, tenderness, warmth, and redness at the wound site
● An infection that affects the entire body instead of just a single organ or part is systemic
and can become fatal if undetected and untreated
● The nurse is responsible for implementing infection control practices, properly
administering antibiotics, monitoring the response to drug therapy, using proper hand
hygiene, following Standard Precautions, and using Isolation precautions when necessary
● Defenses against infection
○ Normal floras
■ The body normally contains microorganisms that reside on the surface and
deep layers of skin, in the saliva and oral mucosa, and in the GI and GU
tracts.
■ Normal flora do not usually cause disease when residing in their usual area
of the body, but instead participate in maintaining health
Chapter 28: Infection Prevention and Control
The incidence of infectious diseases such as AIDS, influenza, pneumonia, COVID-19, measles,
and sexually transmitted infections is a significant public health problem in the United States and
around the world. Multiple factors affect the spread of infectious diseases, such as humans’
susceptibility, drug resistance, human tendency to avoid vaccination, and drug
immunosuppression. The incidence of patients who develop infections as the direct result of
contact with health care personnel is an increasing health problem.
NATURE OF INFECTION
● It is important to know the difference between an infection and a colonization.
○ An infection results when a pathogen invades tissues and begins growing within a
hose
○ Colonization is the presence and growth of microorganisms within a host but
without tissue invasion or damage
○ Disease or infection results only if the pathogens multiply and alter normal tissue
function. Some infectious diseases such as viral meningitis and pneumonia have a
low risk of no risk for transmission.
○ If an infectious disease can be transmitted directly from one person to another, it
is termed a communicable disease. If the pathogens multiply and cause clinical
signs and symptoms, the infection is symptomatic. If clinical signs and symptoms
are not present, the illness is termed asymptomatic.
CHAIN OF INFECTION
● The presence of a pathogen does not mean that an infection will occur. INfection occurs
in a cycle that depends on the presence of all of the following elements :
○ An infectious agent or pathogen
■ Microorganisms include bacteria, viruses, fungi, and protozoa.
Microorganisms on the skin are either resident or transient flora. Resident
organisms (normal flora) are permanent residents of the skin and within
the body, where they survive and multiply without causing illness.
■ The potential for microorganisms or parasites to cause disease depends on
the number of microorganisms present; their virulence, or ability to
produce disease; their ability to enter and survive in a host; and the
susceptibility of the host. Resident microorganisms are not virulent.
■ Resident microorganisms can cause serious infection when surgery or
other invasive procedures allow them to enter deep tissues or when a
patient is severely immunocompromised (has an impaired immune
system)
■ Transient microorganisms attach to the skin when a person has contact
with another person or object during normal activities
, ● Party crashers: like random people that show up to your party, eat
your snacks, and leave
○ They don't live there, get picked up from contact, leave
easily with handwashing, cause trouble (most likely to
cause infection)
○ Transient = Temporary troublemakers
○ A reservoir or source for pathogen growth
■ A reservoir is a place where microorganisms survive, multiply, and await
transfer to a susceptible host.
■ Common reservoirs are humans and animals (hosts), insects, food, water,
and organic matter on inanimate surfaces (fomites, like a door handle)
■ To thrive, organisms require a proper environment, including appropriate
food, oxygen, water, temperature, pH, and light.
■ Food
● Microorganisms require nourishment
■ Oxygen
● Aerobic bacteria require oxygen for survival and for
multiplication sufficient to cause disease. Aerobic organisms cause
more infections in humans than anaerobic organisms
● Anaerobic bacteria thrive where little or no free oxygen is
available
■ Water
● Most organisms require water or moisture for survival
■ Temperature
● Microorganisms can live only in certain temperature ranges. Each
species of bacteria has a specific temperature at which it grows
best
● Cold temperatures tend to prevent growth and reproduction of
bacteria (bacteriostasis)
● A temperature or chemical that destroys bacteria is bactericidal
■ pH
● The acidity of an environment determines the viability of
microorganisms. Most microorganisms prefer an environment
within a pH range of 5.0-7.0
■ Light
● Microorganisms thrive in dark environments such as those under
dressings and within body cavities
○ A portal of exit from the reservoir
■ After microorganisms find a site to grow and multiply, they need to find a
portal of exit if they are to enter another host and cause disease.
, ■ Portals of exit include sites such as blood, skin and mucous membranes,
respiratory tract, genitourinary tract, gastrointestinal tract, and
transplacental (mother to fetus)
○ A mode of transmission
■ Each disease has a specific mode of transmission. Often you are able to do
little about the infectious agent or the susceptible host, but by practicing
infection prevention and control techniques such as hand hygiene, you can
interrupt the mode of transmission
■ One microorganism is sometimes transmitted by more than one route
■ Contact
● Direct
○ Person-to-person (fecal, oral) physical contact between
source and susceptible host.
○ A health care provider’s hands become contaminated by
touching germs present on a patient, medical equipment, or
high-touch surfaces, and the health care worker then carries
the germs on the hands and spreads to a susceptible person.
● Indirect
○ Personal contact of susceptible host with contaminated
inanimate object (e.g., needles or sharp objects, soiled
linen, dressings, environment)
■ Droplet
● An infected person coughs or sneezes, creating droplets that carry
germs short distances (within approximately 6 feet). These germs
can land on a susceptible person’s eyes, nose, or mouth and can
cause infection (e.g., pertussis or meningitis).
■ Airborne
● Organisms are carried in droplet nuclei or residue or evaporated
droplets suspended in air during coughing or sneezing. Germs are
aerosolized by medical equipment or by dust from a construction
zone (e.g., nontuberculous mycobacteria or Aspergillus).
■ Vehicles
● Contaminated items. For example, sharps (e.g., needles, IV
insertion devices) injuries can lead to infections (e.g., HIV, HBV,
HCV) when bloodborne pathogens enter a person through a skin
puncture by a used needle or sharp instrument.
● Water
● Drugs, solutions
● Blood
, ● Food (improperly handled, stored, or cooked; fresh or thawed
meats)
■ Vector
● External mechanical transfer (flies)
● Internal transmission such as parasitic conditions between vector
and host such as:
● Mosquito
● Louse
● Flea
● Tick
○ A port of entry to a host
■ Organisms enter the body through the same routes they use for exiting.
Factors such as a depressed immune system that reduce body defenses
enhance the chances of pathogens entering the body
○ A susceptible host
■ Susceptibility to an infectious agent depends on an individual’s degree of
resistance to pathogens
■ Although everyone is constantly in contact with large numbers of
microorganisms, and infection does not develop until an individual
becomes susceptible to the strength and numbers of the microorganisms
○ BREAK THE CHAIN! Preventing infections involves breaking the chain of
infection!
THE INFECTIOUS PROCESS
● By understanding the chain of infection, you have knowledge that is vital in preventing
infections. When a patient is at risk for an infection, take precautions to break the
infection chain.
● If an infection is localized, a patient usually experiences localized symptoms such as
pain, tenderness, warmth, and redness at the wound site
● An infection that affects the entire body instead of just a single organ or part is systemic
and can become fatal if undetected and untreated
● The nurse is responsible for implementing infection control practices, properly
administering antibiotics, monitoring the response to drug therapy, using proper hand
hygiene, following Standard Precautions, and using Isolation precautions when necessary
● Defenses against infection
○ Normal floras
■ The body normally contains microorganisms that reside on the surface and
deep layers of skin, in the saliva and oral mucosa, and in the GI and GU
tracts.
■ Normal flora do not usually cause disease when residing in their usual area
of the body, but instead participate in maintaining health
