Transcript How Does Infection Occur?/The Chain of Infection

How Does Infection Occur?/The
Chain of Infection
Rationale/Objectives
Infection control is an increasingly important
aspect of health care for both the client and the health
care professional.
Upon completion of this lesson, the student will be able to:
• identify the cycle of the infectious process;
• investigate ways to protect themselves and patients from
infection; and
• research common human pathogens.
How Does Infection Occur?
1. Microorganisms = small, living organisms not
visible to the naked eye
2. Pathogens = microorganism that cause
disease
3. Susceptible Host = an organism capable of
contracting a specific disease
4. Disease results if the invading pathogen
causes impairment in the host
Types of Pathogens
There are different types of pathogens,
including:
• i. Fungi
• ii. Bacteria
• iii. Viruses
• iv. Protozoans
• v. Prions
Bacteria
i. Single-celled organisms
ii. Live in a variety of environments
iii. Only 1% cause disease
iv. Usually killed by antibiotics
v. Examples of diseases caused by bacteria:
1. Pneumonias
2. Strep throat
3. Tuberculosis
Viruses
i. Smallest of pathogens
ii. Viruses can reproduce only by invading a host cell
iii. NOT cured by antibiotics
iv. Examples of diseases caused by viruses:
1. Chicken pox
2. Colds
3. Flu (influenza)
4. Small pox
5. HIV
Types of Diseases: How they’re
classified
a. Endogenous = infection or disease originates within the body
Examples:
i. Metabolic disorders
ii. Birth defects
iii. Tumors
b. Exogenous = infection or disease originates outside the body
Examples:
i. Pathogenic organisms
ii. Radiation
iii. Chemicals
iv. Trauma
v. Electric shock
vi. Temperature extremes
Types of Infection: How they’re
classified
c. Nosocomial = infections acquired by an individual in a
healthcare facility
• Usually present in the facility and transmitted by
healthcare workers to the patient
• These infections can be particularly dangerous. They are
sometimes resistant to treatment because they have
already survived exposure to treatment materials.
d. Opportunistic = infections that occur when the body’s
defenses are weak
Types of Infection: How they’re
classified
A. Aerobic- means the organism requires oxygen
to live
B. Anaerobic- means it lives and reproduces in
the absences of oxygen.
Common Body Defenses
a. Mucous membrane: lines the respiratory, digestive,
and reproductive tracts
b. Cilia: tiny hair-like structures that line the respiratory
tract to propel pathogens out of the body
c. Coughing and sneezing
d. Hydrochloric acid: destroys pathogens in the
stomach
e. Tears in the eye: contain chemicals that kill bacteria
f. Fever: kills pathogens via heat
g. Immune response: body produces white blood cells
and antibodies to fight pathogens
Chain of Infection
• Chain of infection = conditions that must exist
for disease to occur and spread
Causative Agent =
A pathogen such as a bacterium or virus that can cause
disease
•In order for an infection to occur there must be an infectious agent.
•Therefore no bugs = no disease.
•Example #1, consider walking near someone who sneezes as you pass by. Are you
exposed to a communicable disease? If the person who sneezes did so because of
some external irritant such as pepper entering the nose, there is no infectious agent.
Without an infectious agent, you cannot become ill.
• Example #2, consider you encounter a patient who has partied a bit too hearty.
While assessing his condition, the patient proceeds to vomit on your shirt and the
stench of an alcoholic beverage now permeates your clothing. Have you been exposed
to a communicable disease? Not unless there is an infectious viral or bacterial agent
present in the patient’s stomach or the patient has gastric bleeding.
As the situation progresses, your partner begins to vomit. Was your partner exposed
to an infectious disease from the patient? Most likely, your partner is having a
sympathy reaction to the patient’s vomiting.
Solution :
• Identify individuals who are infected or colonized & treat appropriately
• Disinfecting surfaces such as counters or equipment with a specific cleanser can also
destroy infectious agents. Without a causative agent, there is no Chain of Infection.
•Wash hands!
Reservoir =
The place where a causative agent can live
Common reservoirs:
a. Human body
b. Animals
c. Environment
d. Fomites = nonliving objects such as doorknobs, cups, utensils, needles
To be considered infectious, there must be a sufficient quantity of bugs to cause an infection.
One bacterium or virus will generally not cause an infection. Further, these bugs need to be
concentrated in a specific location such as the airways, lungs, blood, or other body area. But, the
body is not the only reservoir that can harbor these bugs. Consider the sharps container or any
piece of soiled equipment. Once a needle has been used, it is placed into a sealed sharps
container. This container is a reservoir for infectious diseases and, if opened, could pose a
serious threat to the employees.
Solution :
• Employee health exams and screening
• Environmental sanitization including floors, walls, exam tables, and beds
•Cleaning contaminated equipment does two things – it destroys the infectious agent and
eliminates the reservoir.
• Standard precautions
• Medical asepsis
• Proper hygiene
Portal of Exit =
The way for a causative agent to escape from the reservoir
Pathogens can leave the body through …
• Urine, feces, saliva, blood, tears, mucous discharge, sexual secretions, and
wounds
From the reservoir, the bugs need a way out of the body. The passage out of the body can
include the nose, mouth, open injury, or any other way to leave the reservoir. If an infectious
agent is trapped inside the reservoir and cannot leave, there is no risk of infection. For example,
think about that sharps container mentioned earlier. There is an infectious agent and reservoir,
but because the container is sealed, there is no way for the agent to get out.
In another example, consider drawing a vial of blood from a patient with Hepatitis B for testing
at the hospital. You have drawn the blood that is in a sealed container. Is there an infectious
agent? Yes. Is there a reservoir? Yes. Is there a portal of exit? No, the vial is sealed. Because the
vial is sealed, the Chain of Infection is broken.
Solution:
• Appropriate hand hygiene
• Use of personal protective equipment
• Clean dressings over wounds
• Medical asepsis
• Control of excretions/secretions
• Covering the mouth and nose when coughing/sneezing
• Proper trash and waste disposal
• Standard precautions
Mode of Transmission =
The way that causative agent can be transmitted to a host
a. Direct contact = person-to-person
• Examples include: sex, saliva/kissing, handshake/touching
b. Indirect contact = contaminated substances
• Examples include: food, air, soil, insects, animals, feces, equipment
The infectious agent must have a way from its reservoir to the new host. In thinking about the vial of blood
above, if the cap to the vial was removed, there would be a portal of exit, but the blood must still get from
the vial onto you. If the blood spills onto your clothing or hands, there is a mode of transmission. In another
example, consider a person with the flu and chest congestion. The infectious agent is the flu virus, the
reservoir is the patient’s lungs and airways, and the portal of exit is the mouth and nose. When coughing,
the patient expels infectious fluids from the airways into the air. This creates a droplet mode of transmission
that transports the agent to the new host. Can this mode of transmitting the flu virus be blocked? Covering
the mouth when coughing is a courtesy to those nearby and reduces, but does not eliminate the risk of
transmitting the illness.
Solution: • Appropriate hand hygiene
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Standard precautions
Rooms with air flow control
Safe food handling
Transmission-based precautions
Sterilization of equipment and supplies
Medical and surgical asepsis
Use of personal protective equipment
Proper disposal of contaminated objects
Portal of Entry =
A way for the causative agent to enter a new host
Different portals of entry include:
a. Breaks in the skin
b. Respiratory tract
c. Digestive tract
d. Genitourinary tract
e. Circulatory system
Each of these areas of the body can permit the entry of invading bacteria or viruses. Yet, each of these areas
has natural barriers against invasion.
• The nose and airways
mucus and hair-like fibers called cilia also, sneezing and coughing remove
bacteria
• Eyes
tears
• Mouth
contains enzymes in the saliva that begin to destroy the bacteria or viruses as they enter the
body
• Stomach
stomach acid may destroy the bugs that survive the mouth before entering the intestines,
also diarrhea and vomiting remove bacteria
• The skin
has natural barriers including oils containing fatty acids that tend to destroy infectious
agents or make the skin a less hospitable environment. Additionally, the outermost layer of the skin,
epidermis consists of dead cells that slough away with washing. Washing away these dead cells also
washes away the infectious agent.
Solution:
• Aseptic technique
• Sterile technique or surgical asepsis
• Medical sepsis
• Wound care
• Proper disposal of needles/sharps
• Maintaining skin integrity
Susceptible Host =
An individual who can contract the disease
Humans become susceptible if …
a. Large numbers of pathogens invade the body
b. Body defenses are weak-immune system down
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First, when an infectious agent enters the body it is not recognized by the body,
which does not know how to fight the invasion. The body’s immune system does,
however, act to produce antibodies that will respond to the agent and destroy it in
the future. For example, as a child you may have had the chickenpox. When you
first contracted the illness, the body did not recognize the virus and did not know
how to fight it. Your body did develop antibodies to the virus and, when the virus
tries to invade your body in subsequent years, your immune system recognizes and
destroys it quickly.
• Vaccinations work the same way. By getting a vaccination against a particular
illness, you stimulate the immune system to fight the invading bug. Because the
body can successfully defend against the organism, you are not susceptible to the
illness.
Solution :
• Treatment of disease
• Recognition of patients at risk
• Immunization
• Exercise
• Proper nutrition
As with other links in the chain, if you are not susceptible to the infectious agent, the
Chain of Infection is broken and you will not become ill.
How the chain can be continued or
broken
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Video – Mythbusters
Part 2
How many “test subjects” were involved in each experiment?
How many were considered “control subjects” in the experiments?
How was “contamination” demonstrated?
In the first experiment, how many subjects were contaminated?
For those that were not contaminated, what steps were taken to
prevent contamination?
• In the second experiment, how many were contaminated?
• What steps were taken to prevent contamination in the second
scenario?
• What have you learned from these experiments about protecting
yourself if others are ill and protecting others if you are ill?
Video-BODY SNATCHERS
BODY SNATCHERS
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Video Clip Body Story Episode 1 part 3 of 4 –body snatchers
Part 3 of 4
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http://www.youtube.com/watch?v=D2Uuc76DvlI
Part 4 of 4
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http://www.youtube.com/watch?v=soIDiqxtTjM
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IN YOUR JOURNAL COPY/ ANSWER THE FOLLOWING QUESTIONS
identify the causative agent, reservoir, portal of exit, mode of transmission , portal of entry , susceptible host
List all of Holly’s defenses that the bacteria came across :
How do Holly cells communicate with each other ?
How does the virus fool the cell allowing it to enter?
Once the virus is in Hollys throat cell what does it begin to do ?
How many viruses are born from that single throat cell
In 2 hours how many throat cells has the virus infected ?
How does Hollys immune system fight back?
How do microphages get rid of cell debris?
Explain why does Holly feel cold?
Explain why it is a good thing that Holly can't find any pain medication to take for her fever?
What job do Dendritic cells do?
What are the function of T-cells and B-cells?
Why is Holly coughing ?
What are the purpose of memory cells ?
What is the “last trick “ the virus plays?
The cycle of infection can be broken at
any link of the chain
A. The infectious agent can be neutralized or destroyed by treatment
B. The reservoir host must maintain personal hygiene
C. The portal of exit is closed by the use of proper attire (gowns, gloves,
other clothing), control of body secretions, and proper hand washing
D. The route of transmission is minimized through proper hand washing,
disinfection and sterilization and proper disposal of contaminated
materials.
E. The portal of entry is blocked by asepsis, disinfection, and sterilization
procedures.
F. Host susceptibility is broken when the health and wellness of an
individual is maintained.
VIDEOS
Top 5 Deadliest Diseases
http://www.youtube.com/watch?v=gf2bObJGFkg
Published on Aug 26, 2012
Hank scares our pants off with a tale of the five deadliest infectious diseases in the world.
The Age of Viruses - The world's most dangerous Virus (full documentary)
http://www.youtube.com/watch?v=w-bC6pfzxxo
Published on May 30, 2013
Viruses are supposed to be the biological weapons of the future.They are everywhere. Millions of viruses around us, interact, invade. Virus able to evolve,
change your environment, jump from one species to another. Scientists continue its track. Looking hiding in nature, in animals that viruses use to travel
from one place to another planet ... but not always find them.
In recent decades there have been many diseases that so far only affected animals. These diseases, caused by very aggressive virus, appear with high
frequency in Africa, and requires a high financial contribution in order to eradicate them. Marburg virus, influenza, dengue, yellow fever, Ebola virus, human
immunodeficiency virus, Epstein-Barr...
To find answers we enter for the first time in the High Security Center Biological where the most dangerous viruses in history and the emerging service. And
the World Health Organization explains how he manages to monitor the emergence of new viruses and diseases in any country.
Modern Black Death - The Next Pandemic - BBC Horizon
https://www.youtube.com/watch?v=nT9ctpQNXRE
Published on Jul 6, 2013
This is an amazing documentary put together by BBC Horizon. It's a fascinating look at what could happen if the the virus mutates. The likelihood of that
happening is not as remote as you might think. Watch the video and then decide. Time: 1 hour 28 minutes. (www.CoughyCup.com)
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https://www.youtube.com/watch?v=GQFUziWNj2c
Asepsis is the absence of infection.
A. Medical asepsis: practices and techniques that are designed to
protect individuals from the spread of disease
1. Antiseptic: substances that inhibit the growth of bacteria.
Some of these substances can be used on the skin.
2. Disinfectant: substances or practices that cannot be used on
the skin. This includes chemicals and boiling.
3. Sterile: absence of all microorganisms
B. Surgical asepsis: the use of sterile technique to handle
equipment, maintain sterile fields, change dressings and
dispose of contaminated materials without introducing harmful
microorganisms
Epidemiology: tracing the occurrence of health related
events in society.
A. Epidemiologist is a person who specializes in the study
of outbreaks of diseases within a population group
1. Endemic: refers to the ongoing presence of a disease
within a population, group, or area. For example, the
common cold is always present within a population.
2. Epidemic: is a sudden and widespread outbreak of a
disease within a population, group or area. For
example a sudden wide spread outbreak of measles is
an epidemic.
3. Pandemic: refers to an outbreak of a disease occurring
over a large geographic area, possibly worldwide. For
example, AIDS is pandemic.
Activity: Exploring the chain of infection
Open hyperlink and explore how the chain of
infection occurs for each virus below .
• http://ricn.on.ca/chainoftransmission/
• Droplet Transmission: Direct
 Bacterial Meningitis
 Group A Strep
 Common Cold
 Influenza
• Airborne Transmission: Indirect
 Chickenpox
 Measles
 Tuberculosis(TB )
INFECTION CONTROL
DISEASE TRANSMISSION PRECAUTIONS
AND PERSONAL PROTECTIVE EQUIPMENT (PPE)
• Rationale
Knowledge of standard precautions is important
in preventing nosocomial infections. The
transmission of microorganisms is different for
each infectious process.
Objectives
• Upon completion of this lesson, the student will be
able to
• differentiate between the modes of transmission;
• determine methods for breaking the chain of infection;
• select and use PPE in healthcare settings;
• assess the appropriate circumstances for when each
type of PPE
should be used; and
• correctly demonstrate how to don and remove PPE.
Standard Precautions
A. Equipment and methods that prevent the transmission of microorganisms from one person to
another.
1. Established early in the AIDS epidemic
2. Prior to the diagnosis of AIDS, personal protective equipment was used only in identified infectious
processes. Once AIDS was better understood, personal protective equipment was universally
applied to all patients.
B. These are applied to all patients/residents at all times because not all diseases are readily
observable.
1. Gloves should be worn at all times; hands should be washed for a minimum of 10 seconds and
gloves changed when moving from one patient to another.
2. Depending on the activity performed on the patient, the nature of the patient’s illness, and the
amount of exposure to blood and body fluids, other protective equipment should be worn. E.g.
gown and goggles if patient is coughing, bleeding, or has drainage from wounds or body orifices.
3. Needles should never be capped.
4. All sharps (needles, razors, etc.) should be disposed of immediately in biohazard puncture proof
sharps containers located in each room.
5. Never carry uncapped needles or sharps from one location to another. If necessary to do so, never
point toward another person or yourself. KEEP POINT TOWARD THE FLOOR OR CEILING.
6. All unknown spills or waste should be treated as potentially hazardous
Types of PPE used in healthcare
settings
1. gloves – protect hands
2. mask – protect mouth/nose
3. respirator -protect respiratory tract from airborne
infectious agents
4. goggles – protect eyes
5. face shields – protect face, mouth, nose, and eyes
6. gowns – protect skin/clothing
7. cap – protects head
Uses for PPE
1. gloves – Use when touching blood, body fluids, secretions,
excretions, contaminated items; for touching mucus
membranes and non-intact skin.
2. gowns – Use during procedures and patient care activities
when contact of clothing/ exposed skin with blood/body
fluids, secretions, or excretions is anticipated
3. mask and goggles or a face shield – Use during patient care
activities likely to generate splashes or sprays of blood, body
fluids, secretions, or excretions
Transmission-based precautions
1. Airborne
a. diseases that are spread through the air
b. examples include chickenpox, measles, TB
2. Droplet
a. diseases spread by droplets, as in a sneeze or cough
b. examples include certain types of meningitis and pneumonia, pertussis, influenza, mumps,
German Measles.
3. Contact
a. diseases spread by contact with infected skin or objects
b. examples include herpes, impetigo, diphtheria, scabies, AIDS, MRSA
4. Reverse or Protective Isolation
a.
this concept is the opposite of every other transmission-based precaution
b.
it involves protecting the patient/resident from any infectious
c.
process carried by the health care providers or the public
d.
necessary for patients with immune deficiency/suppressed
e.
immune systems: i.e. AIDS patients, transplant patients,
f.
cancer chemotherapy patients
How airborne precautions work
1. patient’s room must be private unless both
patients have the same disease
2. room may have special ventilation equipment
3. the door of the room must remain closed
4. staff and visitors must wear masks
5. if staff has more direct prolonged contact with the
patient, it is advisable to wear gloves, gown, hair
covering, depending on the activity
6. patients should leave the room as little as possible
and wear a mask if they do leave
How contact precautions work
1. May be private or have people with same diseases together
2. Everyone entering the room must wear gloves and change
them whenever soiled
3. Gowns, mask, goggles, hair covering, should be worn
depending on length of contact and activity
4. All must wash their hands and avoid touching objects before
leaving the room
5. Patients should leave the room as little as possible and avoid
contact with other people or objects
6. Use biohazardous waste bags to dispose of any trash or items
leaving the room
7. Equipment such as thermometer, blood pressure equipment
should remain in the room, and disinfected properly when
precautions have been discontinued
Reverse Isolation
1. The health care provider puts on any
necessary equipment to prevent exposing the
compromised patient to any microorganisms
2. The equipment is determined by the care that
is to be given
Exposure
A. Should a known exposure occur to a
microorganism, i.e. HIV, the exposure must be
reported to the supervisor of the unit.
B. An incident report must be completed.
C. Depending on the exposure, the area should be
cleaned with an antiseptic solution, and if
necessary, appropriate blood tests should be
completed.
D. Follow-up must be done as required by policy
(either facility or CDC).
Application of personal protective
equipment
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Hands must be washed
C. Order of application
1. gown
2. cap
3. mask
4. gloves – sterile gloves might be required depending on what care is to be given (e.g. assisting with some sterile procedure)
D. Order of removal
1. Gloves first by never touching the outside of the glove
a. remove the first one by grabbing a place on the glove and removing
b. remove the second by hooking the finger inside the glove and removing
2. Hook the finger inside the cap and pull cap off
3. Reach behind the gown and untie, pulling the gown off and touching only the inside of the gown; roll it inside out as removing
4. Finally pull ties of mask and remove, being careful to avoid touching the hair.
5. In airborne transmission, the mask should be removed just before leaving the room (or if there is a outside foyer for application
and removal of protective equipment it should be removed there)
6. When removing equipment, all should be placed in the proper biohazardous container(s).
7. When biohazardous containers are full, they should be removed from the patient’s room through double bagging. Two people
should be doing this – one on the inside of the room, one on the outside to receive the contaminated items and help place them
in the proper protective bags. The person inside the room only touches the inside of the receiving biohazardous bag; the
person outside the room only touches the outside of the receiving biohazardous bag.
8. Lastly, hands should be washed according to protocol.
Basic PPE Application and Removal - https://www.youtube.com/watch?v=_IYrqiQjvyQ
Advanced (Ebola) PPE Application and Removal - https://www.youtube.com/watch?v=1z9nzUIK94I
What Type of PPE Would You Wear?
For each scenario, list the PPE required and describe
the type of interaction that will occur between the
healthcare worker and patient.
1. Giving a bed bath?
2. Suctioning oral secretions?
3. Transporting a patient in a wheel chair?
4. Responding to an emergency where blood is
spurting?
5. Drawing blood from a vein?
6. Cleaning an incontinent patient with diarrhea?
7. Irrigating a wound?
8. Taking vital signs?
Key: What Type of PPE Would You
Wear?
1. Giving a bed bath? (generally none)
2. Suctioning oral secretions? (gloves and mask/goggles or a face
shield) (Respondents may correctly note that this may depend on
whether open or closed suction is being used)
3. Transporting a patient in a wheelchair? (generally none)
4. Responding to an emergency where blood is spurting? (gloves,
fluid-resistant gown, mask/goggles or a face shield)
5. Drawing blood from a vein? (gloves)
6. Cleaning an incontinent patient with diarrhea? (gloves and
generally a gown)
7. Irrigating a wound? (gloves, gown, and mask/goggles or a face
shield)
8. Taking vital signs? (generally none)