Week 1- Intro to Infection Flashcards
(36 cards)
What is infection?
Colonization of a host by a MICROBIAL species
What types of infection can there be?
1) Localized = specific place
2) Systemic = spread to several regions/ areas of the body
What can cause an infection? - Common (2)
Virus- only DNA or RNA surrounded by a protein shell (have to have a host cell). Useless w/o host cell. COVID
Bacteria- much larger than a virus, usually singled celled-organism. Can reproduce in or outside cells. Strep, TB, UTI
What can cause an infection? - Rare (4)
1) Fungal- spore forming organism
2) Protozoa- typically live in water/environments
3) Helminths- parasitic worms
4) Prions- proteinaceous infectious particles, only composed on protein (mad cow disease)
Modes of transmission
- Microorganism must have RESORVIOR (humans, animals, insects, enviornments)
Modes of transmission (2)
1) Direct- droplet, short range aerosols. Sneezing or coughing
2) Indirect- airborne when the particles stay in the air
*Vehicle and vector born
Difference between vehicle v. vector born
Both INDIRECT
vehicle- indirect transmit through food, water, or blood.
vector- when something carries the disease. Fleas, misquotes and ticks.
How does the organism get into the body?
Portal of entry
1) Oropharynx & Nasopharynx (bronchial airways, lungs, stomach and GI tract)
2) Genitourinary tract (urinary tract)
What is the bodies biggest barrier of infection?
Skin
Types of portal of entry- movement of bacteria across intestinal lining
- Translocation- movement of bacteria across the intestinal lining. Occurs frequently in peritoneal cavity, bloodstream
Types of portal of entry- directly into blood
Blood transfusion contamination/ needle stick
Types of portal of entry- placental barrier crossing
Maternal- fetal transmission- cross the placental barrier and directly into fetus. Can occur during childbirth
Stages of infection: 1
Incubation period- microorganism in the body. NO symptoms, it is growing and multiplying
Stages of infection: 2
Prodromal stage: symptoms but non-specific, may feel tired or have a little fever
Stages of infection: 3
Acute stage: full blown, can’t get out of bed
Stages of infection: 4
Illness is getting better, still there some
Stages of infection: 5
Resolution phase, infection is out of the body and feel back to normal
Stages of infectious (inflammatory process)
1) Injury
2) Increased permeability
3) Immigration of leukocytes
4) Phagocytosis
5) Exudate
6) Systemic symptoms
Stages of infectious: injury
- Initial insult to area occurs
- Very brief period of vasoconstriction (to stop bleeding and prevent movement of invading organisms)
-THEN, VASODILATION… allows blood to flow freely into the area, brings immune cells to the area, warmth/redness/swelling
Stages of infectious: Increased permeability
At site of injury
- Fluid pulled out of vascular space (because injury rarely occurs directly in vascular space (blood vessel)
-Fluid moves out of the vessel to the place of injury
Stages of infectious: immigration of leukocytes
From the fluid out of the vascular space –> neutrophils attracted to area of injury
- these neutrophils attach to the endothelium of injured cells and move through into surrounding injured tissues
- other cells involved: eosinophils, NK cells, monocytes
Stages of infectious: Phagocytosis
Once leukocytes (white blood cells) make it to area of injury, phagocytosis can occur
- neutrophils and monocytes are the specific WBCs involved
-they recognize, engulf and destroy invading organisms
Stages of infectious: exudate
Transport leukocytes to injured area, dilute toxins that must be present, and transport nutrients for healing process.
- Exudate is the ‘stuff’ that comes from fluid leaking from blood vessels, along with cells and debris
Stages of infectious: systemic symptoms
Can occur if infectious process doesn’t remain localized
- total body response –> stimulate the hypothalamic fever set point
