7.4 HOST-MICROORGANISM INTERACTIONS - TRANSMISSION Flashcards
✓Most pathogen are acquired from
external sources
Pathogens usually exit the infected patient most frequently from the
respiratory tract and gastrointestinal
tract
transmission to the new host usually occurs via
airborne respiratory droplets or fecal contamination of food and water
Four (4) important portals of entry for pathogenic organisms
GIT, GUT, respiratory tract, integumentary system
Mucous membranes of the GIT, GUT, repiratory tract and conjunctiva
DISEASES
conjunctivitis, trachoma, ophthalmia
neonatorum
punctures, injections, bites, cuts, wounds, surgery, and splitting of the skin or mucus membrane due to swelling or drying
✓Parenteral route
some organisms have many portals of entry
(Yersinia and B. anthracis)
ROUTES OF TRANSMISSION
- Airborne Transmission
- Transmission by Food and Water
- Close Contact
- Cuts and Bites
- Arthropods
- Zoonoses
Respiratory Spread
→ common
→aerosolized by coughing, sneezing, and talking
Airborne Transmission
—inhalation of infectious particles in liquid droplet dxs
TB,
Brucellosis,
Tularemia,
Legionellosis and
Plague
→residue from the evaporation of fluid from larger droplets and are light enough to remain airborne for long periods
Droplet Nuclei
→infection occurs via the fecal-oral route
Transmission by Food and Water
Transmission by Food and Water spp
Enterotoxigenic E. coli (ETEC)
Vibrio cholera
Enterotoxigenic E. coli is the common cause of
TRAVELER’S DIARRHEA
→enterotoxin that causes the outpouring of fluid from the cells into the lumen of the intestine
Vibrio cholera
Preformed toxins [spp] [fecal oral route]
Clostridium botulinum,
Bacillus cereus, and
S. aureus
→passage of organisms by salivary, skin, and genital contact
Close Contact
→infection by the mouth flora
Cuts and Bites
→dog-bite and cat-bite infections
Pasteurella multocida
→tick, flea, or mite bite
Arthropods
Arthropods dxs
→relapsing fever,
plague,
Rocky Mountain spotted fever,
Lyme disease,
typhus
→depends on contact with animals or animal products
→arthropod vectors (plague), contact with secretions (brucellosis), and contact with animal carcasses and products (tularemia, listeriosis)
Zoonoses