Transcript Transmission and Growth of Microorganisms

Transmission and
Growth of
Microorganisms
Illinois CTE
Curriculum Revitalization Initiative
Health Science and Technology
Aerobic Microorganisms
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require oxygen to live
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Anaerobic
Microorganisms
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live and reproduce in
the absence of
oxygen
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What do microorganisms
require to live and grow?
All require a reservoir (host).
 All require water and nourishment from the
reservoir.
 Most require a warm and dark
environment.
 Most grow best at body temperature.
 Most are destroyed by heat and light.
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Asepsis and Maintaining
Medical Asepsis
Asepsis is the absence of diseaseproducing microorganisms.
 Contamination is the process of
becoming unclean.
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Aseptic Techniques
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are directed toward maintaining
cleanliness and eliminating or preventing
contamination.
 Antiseptic
is a substance that destroys or
inhibits the growth of bacteria and other
microorganisms on living tissue.
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Common Aseptic
Techniques
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Hand washing
Good personal hygiene
Use of disposable gloves when
contacting body secretions or
contaminated objects
Proper cleaning of instruments and
equipment
Thorough cleaning of the environment
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Maintaining Medical
Asepsis
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Avoid touching your clothing with soiled linen, table paper, supplies,
or instruments. Roll used table paper or linens inward with the clean
surface outward.
Always consider the floor to be contaminated. Any item dropped
onto the floor must be considered dirty and discarded or cleaned to
its former level of asepsis before being used.
Clean tables, counters, and other surfaces frequently and
immediately after contamination. Clean areas are less likely than
dirty ones to harbor microorganisms or encourage their growth.
Always presume that blood and body fluids from any source are
contaminated. Follow OSHA and CDC guidelines to protect yourself
and to prevent the transmission of disease.
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Four Main Classes of
Infection and Disease
Endogenous
 Exogenous
 Nosocomial
 Opportunistic
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Endogenous
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Endogenous infections or
disease originate within the
body.
Examples of endogenous
infections or disease include
metabolic disorders, congenital
abnormalities, tumors, and
microorganisms within the body.
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Exogenous
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Exogenous infections or
disease originate outside
the body.
Examples of exogenous
infections or disease
include pathogenic
organisms that invade the
body, radiation, chemical
agents, trauma, electric
shock, and temperature
extremes.
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Nosocomial
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Nosocomial infections are acquired during a stay in a health agency
such as a hospital or long-term care facility.
Nosocomial infections are usually present in the facility and
transmitted by health care workers to the patient.
Nosocomial infections are caused by normal flora or by microbes
transmitted to the person from another source.
Many of the pathogens transmitted in this manner are antibioticresistant and can cause serious and even life-threatening infections
in patients.
Some examples of nosocomial infections include staphylococcus,
pseudomonas, and enterococci.
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Opportunistic
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Opportunistic infections are those
that occur when the body’s defenses
are weak.
Opportunistic infections normally do
not occur in individuals with intact
immune systems.
Examples of opportunistic infections
include Pneumocystis carinii
pneumonia or Kaposi’s sarcoma in
individuals with AIDS.
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Requirements for Transmission
of Microorganisms
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A causative agent or pathogen is needed.
A reservoir (host) is required, which includes
human body, animals, the environment and
fomites.
Fomites are objects contaminated with
infectious material that contains the pathogen.
Examples of fomites include doorknobs,
bedpans, urinals, linens, instruments, and
specimen containers.
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Modes of Transmission
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Blood, body fluids, secretions, excretions
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Animals
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Bites
Wound dressings
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Bites
Contact
Insects
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Direct contact
Non-frequent dressing changes
Non-sterile practices during dressing changes
Direct contact
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Shaking hands
Kissing
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Modes of Transmission,
cont.
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Personal items
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Toothbrush
 Comb
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Eating and drinking utensils
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Silverware
 Drinking glassware
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Water
Food
Air
Coughing, sneezing, talking,
laughing, singing
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Body Defenses in Fighting
Infection/Disease
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Mucous membrane
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Cilia
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Mucous membranes line the respiratory,
digestive, and reproductive tracts and trap
pathogens.
Cilia are tiny hair-like structures that line the
respiratory tract and propel pathogens out of
the body.
Coughing and sneezing
Hydrochloric acid
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It destroys pathogens in the stomach
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Body Defenses in Fighting
Infection/Disease, cont.
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Tears in the eye
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Fever
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Many organisms cannot survive at
body temperatures above normal.
Inflammation
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Tears contain bacteriocidal
chemicals.
Leukocytes, or white blood cells,
destroy pathogens.
Immune response
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The body produces antibodies,
which are protective proteins that
combat pathogens.
 Interferon and complement are
protective chemicals secreted by
cells.
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How are the three
levels of aseptic control
similar and different?
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Antisepsis
Antiseptics prevent or inhibit growth of
pathogenic organisms but are noteffective
against spores and viruses.
 Antiseptics can usually be used on the
skin.
 Examples of antiseptics include alcohol
and betadine.
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Disinfection
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Disinfectants destroy or kill pathogenic
organisms but are not always effective against
spores and viruses.
Chemical disinfectants are used in disinfection.
Disinfectants can damage or irritate the skin and
are mainly used on objects, not people.
Examples of disinfectants include bleach
solutions and zephirin.
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Sterilization
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Sterilization is a process that destroys all
microorganisms, both pathogenic and nonpathogenic, including spores and viruses.
Examples of sterilization procedures include
steam under pressure, gas, radiation, and
chemicals.
These procedures are used on equipment or
objects, not on people.
The autoclave is the most common piece of
equipment used for sterilization.
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