Routes of infection Flashcards
Ways in which pathogens can transmit
From the environment
Person to person contact
Contaminated inanimate objects
Hospitals
What is transmission
Ability for a pathogen to spread from one host to another
Examples of environmental spread
Malaria and mosquitoes
Salmonella and contaminated food
Examples of direct contact for transmission
Sexual contact in HIV
Many pathogens use this mechanism, but less common as a primary transmission mechanism
Contaminated inanimate objects
Fomites settle on the object.
Many viruses cannot survive long outside the body, especially if lipid membranes
Some pathogens like fungi have more robust capsules
Common infections in hospitals
Lots of contaminated objects and sick people in one building.
MRSA and bladder cystitis caused by infected urinary catheters.
What are aerosols
Liquid droplets from infected host that evaporate due to dryness of air.
Transmits infectious agents.
Inhaled nucleus causes disease.
Common portals with pathogens
Respiratory tract Skin GI tract Genital tract Placenta or breast milk
What is a tropism?
Tropisms are conditions needed for the pathogen to survive
Types of tropisms
Cell, tissue and species
Cell tropism
Cell must display the correct receptors and co-receptors for attachment.
Intracellular pathogens need correct cellular biochemistry for pathogen replication.
Tissue tropism
Conditions of the tissue must be favourable for the pathogen
Temperature and moisture
Overcome innate defenses
Example of tissue encouraging pathogen growth
Diabetes encourages by high blood sugar content
Species tropism
Invasion of pathogen is sometimes tissue-dependent
Determined by cell and tissue tropism
