Download The Chain of Infection

The Chain of Infection
As healthcare professionals, it is important to
understand two facts about infection:
1.The various ways infection
can be transmitted.
2. The ways the infection
chain can be broken.
There are six links
in the chain of infection:
1. Causative agent
2. Source or reservoir
3. Portal of exit
4. Mode of transmission
5. Portal of entry
6. Susceptible host
1st - The Infectious Agent
-Any disease-causing
microorganism
(pathogen)
Microorganism
A small, living plant or animal not
visible to the naked eye
Pathogens vs. Nonpathogens
Nonpathogens are
beneficial
microorganisms that
are found on and in
the human body
Pathogens cause
disease/infection
Class I - Bacteria
• Multiply rapidly
• Classified by
shape and
arrangement
Cocci
• Round or spherical in
shape
• If Cocci occur in pairs they
are diplococci
• If Cocci occur in chains
they are streptococci
• If Cocci occur in clusters or
groups they are
staphylococci
Cocci
Cocci are the most common pusproducing microorganisms
Diplococci bacteria cause diseases such
as Gonorrhea, Meningitis, & Pneumonia.
Streptococci bacteria cause diseases
such as Strep throat and Rheumatic
fever.
Staphylococci
Can cause
infections such
as
Boils
Wound
infections
Toxic shock
Bacilli
• Rod shaped
• Occur singly, in pairs, or in chains
Bacilli
Many bacilli contain flagella,
threadlike projections that
are similar to tails and
allow organisms to move
Bacilli have the ability to
form spores, thick walled
capsules. In the spore
form, bacilli are extremely
difficult to kill.
Diseases caused by different types of bacilli
include:
•Tuberculosis
•Tetanus
•Pertussis
•Whooping cough
•Botulism
•Diphtheria
•Typhoid
Class II - Protozoa
one-celled animals often
found in decayed materials
and contaminated water.
Class III - Fungi
simple, plantlike organisms that live on
dead organic matter.
Two common fungi forms:
•Yeasts
•Molds
Fungi cause diseases such as:
•Ringworm
•Athlete’s foot
•Histoplasmosis
•Thrush
Class IV - Rickettsiae
(ri-ket-se-a) parasitic
microorganisms which means they
cannot live outside the cells of
another living organism.
Commonly found in
fleas, lice, ticks, mites
Rickettsiae
transmitted to humans by the bites of
these insects (typhus fever, rocky
mountain spotted fever).
Class V - Viruses
• Difficult to kill because they are resistant to
many disinfectants and antibiotics.
• Smallest microorganism
• Cause diseases such as
 Common cold
 Measles, Mumps
 Influenza
 Chicken pox
 Warts
2nd - The Reservoir Host
-The organism in which the
infectious microbes reside
What are “Carrier Hosts?”
Hosts that do not show any outward signs
or symptoms of a disease, but are still
capable of transmitting the disease are
known as carriers.
3rd - The Portal of Exit
-Route of escape of the pathogen
from the reservoir
Examples:
respiratory
secretions, blood
exposure, breaks in
skin
4th - The Route of
Transmission
Method by which the pathogen
gets from the reservoir to the
new host
• direct contact
• air
• insects
5th - The Portal of Entry
• Route through which the pathogen enters
its new host
 Respiratory System (inhalation)
 Gastrointestinal System (ingestion)
 Urinary & Reproductive Tracts (sexual contact)
 Breaks in Skin (Protective Barrier)
6th - The Susceptible Host
• The organism that accepts the pathogen
• The support of pathogen life and its
reproduction depend on the degree of the
host’s resistance.
• Organisms with strong immune systems
are better able to fend off pathogens.
• Organisms with weakened immune
systems are more vulnerable to the
support and reproduction of pathogens.
How to interrupt the chain of
infection:
1. Pathogen Identification: identify infectious
agent and appropriate treatment
2. Asepsis and Hygiene: potential hosts and
carriers must practice asepsis and
maintain proper personal hygiene
3. Control Portals of Exit: Healthcare
personnel must practice standard
precautions (Control body secretions and
wash hands according to protocol.)
4. Prevent a Route of
Transmission
Prevent direct or indirect contact by
1.Proper hand washing
2.Disinfection & sterilization techniques
3.Isolation of infected patients
4.Not working when contagious
5. Protect Portal of Entry
Healthcare professionals must
make sure that ports of entry are
not subjected to pathogens.
(nose, mouth, eyes, open wounds,
etc.)
6. Recognition of Susceptible
Host
Healthcare professionals must
recognize and protect high-risk
patients. Cancer Patients
•AIDS Patients
•Transplant Patients
•Infants
•Elderly Patients
“Remember--breaking the chain of
infection is the responsibility
of each healthcare professional.”