Chain of Infection

What is the chain of infection?

A sequence of circumstances where all events must occur to develop an infection

What are the chain of infection links in order?

Infectious Agent (pathogen)

Reservoir

Portal of Exit

Mode of Transmission

Portal of Entry

Susceptible Host

What are the common types of infectious agents?

Bacteria

Viruses

Protozoa

Rickettsiae

Fungi

Helminthes

What is bacteria?

Single celled prokaryotic microorganisms (without a nuclear membrane) that multiply rapidly

What are viruses?

DNA or RNA is encased in a protein coating

Viruses cannot reproduce where?

Outside of a living host cell

What is protozoa?

Unicellular eukaryotic microorganisms (with a nuclear membrane) that can infect the blood, brain, intestines and other body areas

What is rickettsiae?

Are transmitted to humans by the bites of lice, ticks and fleas that act as vectors

What is fungi?

Tiny primitive organisms, that contain no chlorophyll

What is helminthes?

Parasitic worms or flukes

What is reservoir?

A place where the pathogen grows and may or may not multiply

Give some examples of reservoirs

Patient, staff member, animal, food

What is portal of exit?

An exit route for pathogens to leave its host

Give some examples of portal of exit

Blood, skin, mucous membranes, respiratory tract, genitourinary tract, and gastrointestinal tract

What is mode of transmission?

The manner in which an infectious agent moves from one source to another

Give some examples of mode of transmission

Touch, airborne droplets, medical instruments, mosquitoes, vermin

What are two types of contact for HAIs?

Direct Contact

Indirect Contact

What is direct contact?

Person to person or physical contact between source and susceptible host

Give some examples of direct contact

Fecal, oral

What is indirect contact?

Contact with contaminated inanimate objects

Give some examples of indirect contact

needles, utensils, hospital equipment

How does vector transmission occur?

Through a bite

Give some examples of vector transmission

fleas, ticks, mosquitoes

How does a droplet infection occur?

When the droplets from an infected hosted person are projected a short distance to the host's nasal mucosa, mouth or conjunctiva

How does airborne transmission occur?

When infectious particles dispersed in the air enter the host by inhalation

Give some examples of airborne transmission

coughing, sneezing

What is portal of entry?

Place where a pathogen enters the body

Give some examples of portal of entry

break in skin, mucous membrane, mouth, nose, genitourinary tract

What is susceptible host?

A personal who becomes ill after pathogens enter the body because they cannot fight off the pathogen

What is the most effective barrier to infection?

Intact skin

Any portal of _____ can also because a portal of _____.

exit; entry

What makes a human a susceptible host?

Virtue of age, weak state of health, or broken skin

Are people that require invasive procedures at risk for infection?

Yes