Principles of Principles of InfectionInfection

What is an infection?What is an infection? an infection results if pathogens

increase in number and alter the functioning of normal tissues

Some infections can spread to other people -- contagious

Principles of InfectionPrinciples of Infection understanding the basic principles

of infection is essential for any health care worker in any field of health care.

1.1. Chain of InfectionChain of Infection

2.2. Signs and Symptoms of InfectionSigns and Symptoms of Infection

3.3. AsepsisAsepsis

Chain of InfectionChain of Infection in order for an infection to result, six in order for an infection to result, six

factors must be presentfactors must be present these factors occur in a cyclical patternthese factors occur in a cyclical pattern if the chain is broken, infection will not if the chain is broken, infection will not

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Infectious Agent – pathogen such as a Infectious Agent – pathogen such as a bacteria or virus.bacteria or virus.

Reservoir – a place in which the Reservoir – a place in which the pathogen can grow and multiply eg. pathogen can grow and multiply eg. humans, insects, food, waterhumans, insects, food, water– Fomites are inanimate objects Fomites are inanimate objects

contaminated with infectious material that contaminated with infectious material that contains pathogenscontains pathogens» Ex: doorknobs, bedpans, linensEx: doorknobs, bedpans, linens

Chain of InfectionChain of Infection

Portal of Exit – way for the pathogen to Portal of Exit – way for the pathogen to escape from the reservoir in which it has escape from the reservoir in which it has been growing.been growing.– Respiratory tractRespiratory tract– SkinSkin– BloodBlood– Gastrointestinal tractGastrointestinal tract– Mucous membranesMucous membranes

Chain of InfectionChain of Infection

Chain of InfectionChain of Infection Mode of Transmission – way in which a Mode of Transmission – way in which a

pathogen can be transmitted to another pathogen can be transmitted to another reservoir.reservoir.– eg. the virus that causes chickenpox can eg. the virus that causes chickenpox can

be transmitted by direct contact or be transmitted by direct contact or airborne droplet.airborne droplet.

– Contaminated hands are one of the most Contaminated hands are one of the most common modes of transmission.common modes of transmission.»Hand washing is one of the most effective Hand washing is one of the most effective

means of preventing the spread of means of preventing the spread of pathogens.pathogens.

Portal of Entry – way for the pathogen Portal of Entry – way for the pathogen to enter the new reservoir or host.to enter the new reservoir or host.

same as the portal of exitssame as the portal of exits– Respiratory tract, mucous membranes, Respiratory tract, mucous membranes,

and gastrointestinal tract are common.and gastrointestinal tract are common.– injured skininjured skin

Chain of InfectionChain of Infection

Chain of InfectionChain of Infection Susceptible Host – someone that is Susceptible Host – someone that is

capable of becoming infected.capable of becoming infected.– Microorganisms must be present in large Microorganisms must be present in large

enough quantity to be virulent (and enough quantity to be virulent (and cause disease).cause disease).

– individuals with an immunity to certain individuals with an immunity to certain pathogens will not be susceptiblepathogens will not be susceptible» Individuals can develop immunity from Individuals can develop immunity from either natural events, such as prioreither natural events, such as prior exposure, or artificial events, such asexposure, or artificial events, such as immunization immunization

can occur when enough can occur when enough pathogens invade a susceptible pathogens invade a susceptible hosthost

Two types of infection:Two types of infection:– at a local site of injuryat a local site of injury– generalized throughout the bodygeneralized throughout the body

Signs & Symptoms of InfectionSigns & Symptoms of Infection

Local infections usually result from Local infections usually result from injury to the skininjury to the skin– RednessRedness– SwellingSwelling– TendernessTenderness– WarmthWarmth– drainagedrainage

Generalized infections are Generalized infections are accompanied by fever, malaise, loss of accompanied by fever, malaise, loss of appetite, swollen lymph nodesappetite, swollen lymph nodes

Signs & Symptoms of InfectionSigns & Symptoms of Infection

aseptic techniques are used to keep aseptic techniques are used to keep an area free of pathogensan area free of pathogens

Two types:Two types:– Medical asepsis or “clean technique”Medical asepsis or “clean technique”– Surgical asepsis or “sterile technique”Surgical asepsis or “sterile technique”

AsepsisAsepsis

used to maintain a clean environment used to maintain a clean environment in order to reduce the number of in order to reduce the number of microorganismsmicroorganisms

Common medical asepsis practices:Common medical asepsis practices:– hand washinghand washing– using personal protective equipment using personal protective equipment

(PPE) like gloves(PPE) like gloves– routine cleaning of the environmentroutine cleaning of the environment

Medical AsepsisMedical Asepsis

used to maintain a sterile environmentused to maintain a sterile environment– no microorganisms or spores (cells no microorganisms or spores (cells

produced by bacteria)produced by bacteria) areas in the operating room are sterileareas in the operating room are sterile to remain sterile, only sterile items can to remain sterile, only sterile items can

come in contact with other sterile come in contact with other sterile itemsitems

Surgical AsepsisSurgical Asepsis