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INTRODUCTION TO
INFECTION
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INFECTION
1. DEFINITION
2. CAUSES – MODES OF DISEASETRANSMISSION
3. CHAIN OF INFECTION
4. PROCESS BREAKAGE
5. PREVENTION
6. UNIVERSAL PRECAUTIONS
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Infection is the
lodgement andmultiplication of
organism in the
tissue of host
Biofilms of the different
types of bacteria
Microcolonies
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INFECTIOUS DISEASE
Any microorganism that can cause a disease suchas a bacterium, virus, parasite, or fungus. Reasons
that the organism will cause an infection are
virulence (ability to multiply and grow),
invasiveness (ability to enter tissue), andpathogenicity (ability to cause disease).
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TYPES OF INFECTIOUS AGENTS
BACTERIA
FUNGI
PROTOZOA
RICKETTSIA VIRUSES
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NATURE OF MICROORGANISMS
Microorganisms (microbes) are
small, living organisms that are
not visible to the naked eye.Pathogens (germs) are
microorganisms that cause
disease.
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NATURE OF MICROORGANISMS
At times, a microorganism that is beneficial in
one body system can become pathogenic when
it is present in another body system.Escherichia coli (E. coli) bacteria:
Large intestine: beneficial, part of the
natural flora.
Urinary system: causes an infection.
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TYPES OF MICROORGANISMS
BacteriaSimple, one-celled
microorganisms that areclassified according totheir shape andarrangement.
Cause diseases such asstrep throat, pneumonia,meningitis andtuberculosis.
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TYPES OF MICROORGANISMSFungi A plantlike organism thatlives on dead organic matter.
Yeasts and molds can bepathogenic.
Cause conditions such asringworm, athlete’s foot,yeast infections, and thrush.
Antifungal medications Usedto treat patient.
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TYPES OF MICROORGANISMS
ProtozoaOne-celled animal like organisms
often found in decayed materialsand contaminated water.Many contain flagella which allow
them to move freely.Cause diseases such as malaria,
trichomonas, and amebic dysentery.
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TYPES OF MICROORGANISMS
Rickettsiae
Parasites that live inside the cells of
other living organisms.
Commonly found in fleas, lice, ticks, and
mites and are transmitted to humans by
the bites of these insects.
Cause diseases such as Rocky Mountainspotted fever and typhus fever.
Antibiotics are effective against many
diseases.
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TYPES OF MICROORGANISMS
Viruses
Smallest of all microorganisms – visible onlyusing an electron microscope.
Cannot reproduce unless they are insideanother living cell.Spread by contact with blood and otherbody fluids.
Difficult to destroy. Not affected byantibiotics.
Associated with diseases such as thecommon cold, chicken pox, herpes, hepatitisB, measles, warts, polio, influenza, and
AIDS.
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VIRUSES
Three viruses are of major concern to the
health care worker:Hepatitis B – leads to destruction and scarring of
liver cells. Vaccine is available.
Hepatitis C – also causes serious liver damage. No
vaccine. Often misdiagnosed as the flu.
AIDS/HIV – suppresses the immune system. No
cure and no vaccine.
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FACTORS THAT
INFLUENCE MICROBIALGROWTHFollowing factors influence microbial growth:
TemperaturepH, or the values used in chemistry to express thedegrees of acidity or alkalinity of a substance
DarknessFoodMoistureOxygen
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FACTORS THAT
INFLUENCE MICROBIALGROWTH Aerobic microbes – live only
in the presence of oxygen.
Anaerobic microbes – grow
best in the absence of oxygen.
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CAUSING AN INFECTION
Pathogenic microorganisms cause infection
and disease in different ways.Produce poisons (toxins) which harm the body. Ex:
Tetanus.
Allergic reaction in the body causing runny nose,
watery eyes, sneezing.
Attack and destroy the living cells they invade. Ex:
Malaria (rbc’s).
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CLASSIFICATION OF INFECTION
Endogenous – disease originates within thebody. Ex: metabolic disorders, congenitalabnormalities, tumors.
Exogenous – disease originates outside thebody. Ex: chemical agents, electricalshock, trauma.
Nosocomial – acquired by an individual in
a health care facility (workers to patient).Many are antibiotic resistant, life-threatening.
Opportunistic – occur when the body’sdefenses are weak. Ex: pneumonia w/AIDs.
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Focal infection: It is a condition where due to
infection at localized sites like appendix and
tonsil, general effects are produced.
Cross infection: When a patient suffering from a
disease and new infection it set up from
another host or external source
CLASSIFICATION OF INFECTION
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STAGES OF INFECTIOUS DISEASE
Incubation period – no symptoms. Prodromal period – mild and
generalized symptoms (fever,
weakness, headache). Invasive stage – symptoms specific to
the disease.
Decline stage – symptoms subside.Convalescence – no symptoms,
health returns to normal.
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CHAIN OF INFECTION
For an infection to develop,
each link of the chainmust be connected.
Breaking any link of the chain
can stop the transmissionof infection!
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CHAIN OF INFECTION
Chain of
infection
contains six
elements. If
broken,
infection will
not occur.
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CHAIN OF INFECTION
Infectious Agent – pathogen such as
a bacteria or virus.
Reservoir – a place the pathogen
can live.Examples: human body, animals, the
environment, fomites.
Fomites are objects contaminated with
infectious material that contains
pathogens.Ex: doorknobs, bedpans, linens, instruments.
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CHAIN OF INFECTION
Portal of Entry – way to enter the new
reservoir or host.Respiratory tract, mucous membranes, and
gastrointestinal tract are common.Damaged skin.
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CHAIN OF INFECTION
Susceptible Host – one that is capable of being
infected.Microorganisms must be present in large enough
quantity to be virulent.The host must be susceptible.Individuals with an immunity to certain pathogens
will not be susceptible.
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CHAIN OF INFECTION
Mode of Transmission – way inwhich it can be transmitted toanother reservoir or host where it
can live.Can be through direct contact or airborne droplet.Contaminated hands are one of the most commonsources of direct transmissions.
Hand washing is one of the mosteffective means of preventing the spreadof pathogens.
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CHAIN OF INFECTION
Portal of Exit – way to escape from thereservoir in which it has beengrowing.UrineFecesSalivaRespiratory tract
SkinBloodGastrointestinal tractMucous dischargeTears
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BODY DEFENSESIf defense mechanisms are intact and theimmune system is functioning, a humancan frequently fight off the causative agentand not contract the disease.Mucous membranes (traps pathogens)Cilia (propel pathogens out of respiratory tract)Coughing and sneezingHydrochloric acid (stomach)Tears in the eyes(contain bacteriocidal chemicals)FeverInflammation (wbc’s destroy pathogens)Immune response (produce antibodies)
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SIGNS & SYMPTOMS OF
INFECTION Redness Swelling Tenderness Warmth
Drainage Red streaks leading awayfrom wound
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BREAKAGE OF CHAIN OF
INFECTION
There are various methods of breaking the chain
of infection to reduce harm to patient and
prevent disease
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THANK YOU
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