Week 1- Intro to Infection

Question 1

What is infection?

Answer 1

Colonization of a host by a MICROBIAL species

Question 2

What types of infection can there be?

Answer 2

1) Localized = specific place
2) Systemic = spread to several regions/ areas of the body

Question 3

What can cause an infection? - Common (2)

Answer 3

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

Question 4

What can cause an infection? - Rare (4)

Answer 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)

Question 5

Modes of transmission

Answer 5

• Microorganism must have RESORVIOR (humans, animals, insects, enviornments)

Question 6

Modes of transmission (2)

Answer 6

1) Direct- droplet, short range aerosols. Sneezing or coughing
2) Indirect- airborne when the particles stay in the air
*Vehicle and vector born

Question 7

Difference between vehicle v. vector born

Answer 7

Both INDIRECT
vehicle- indirect transmit through food, water, or blood.

vector- when something carries the disease. Fleas, misquotes and ticks.

Question 8

How does the organism get into the body?

Answer 8

Portal of entry

1) Oropharynx & Nasopharynx (bronchial airways, lungs, stomach and GI tract)

2) Genitourinary tract (urinary tract)

Question 9

What is the bodies biggest barrier of infection?

Answer 9

Skin

Question 10

Types of portal of entry- movement of bacteria across intestinal lining

Answer 10

• Translocation- movement of bacteria across the intestinal lining. Occurs frequently in peritoneal cavity, bloodstream

Question 11

Types of portal of entry- directly into blood

Answer 11

Blood transfusion contamination/ needle stick

Question 12

Types of portal of entry- placental barrier crossing

Answer 12

Maternal- fetal transmission- cross the placental barrier and directly into fetus. Can occur during childbirth

Question 13

Stages of infection: 1

Answer 13

Incubation period- microorganism in the body. NO symptoms, it is growing and multiplying

Question 14

Stages of infection: 2

Answer 14

Prodromal stage: symptoms but non-specific, may feel tired or have a little fever

Question 15

Stages of infection: 3

Answer 15

Acute stage: full blown, can’t get out of bed

Question 16

Stages of infection: 4

Answer 16

Illness is getting better, still there some

Question 17

Stages of infection: 5

Answer 17

Resolution phase, infection is out of the body and feel back to normal

Question 18

Stages of infectious (inflammatory process)

Answer 18

1) Injury
2) Increased permeability
3) Immigration of leukocytes
4) Phagocytosis
5) Exudate
6) Systemic symptoms

Question 19

Stages of infectious: injury

Answer 19

• 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

Question 20

Stages of infectious: Increased permeability

Answer 20

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

Question 21

Stages of infectious: immigration of leukocytes

Answer 21

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

Question 22

Stages of infectious: Phagocytosis

Answer 22

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

Question 23

Stages of infectious: exudate

Answer 23

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

Question 24

Stages of infectious: systemic symptoms

Answer 24

Can occur if infectious process doesn’t remain localized
- total body response –> stimulate the hypothalamic fever set point

Question 25

Hypothalamic fever set point

Answer 25

Fever set point increases –> helps body conserve heat
-stimulates defense mechanism to help rid body of organisms
-In heat, some bacteria less virulent and divide slower
-improves OWN immune system
- better neutrophil and macrophage function
-improves antibody release and T cell activation

Question 26

Colonization

Answer 26

When bacteria inhibit a specific body site and do not cause signs and symptoms of infection.

-non-symptomatic staph infection on skin

Question 27

Infection

Answer 27

Clinical signs and symptoms of illness of inflammation/illness.

Caused by tissue damage r/t invasion of micro-organism

Question 28

How to know if someone has an infection?

Answer 28

-Vital signs
-Labs

Question 29

Cultures

Answer 29

Gram stain
- returned within hours
- takes a strain of bacteria and shows whether gram (+) or gram (-).
- Also show shape and arrangement

*gram (-) more dangerous. Capsule hidden by slime later

Question 30

Gram stain: culture and sensitivity

Answer 30

-takes at least 24 hr for a basic result
-may take up to 72 hr for full identification

Question 31

Blood cultures

Answer 31

• Aerobic and anaerobic bottles
  -ideally 2 sets obtained
  -at least one peripheral stick
  -high likelihood of contaiminatinon

Question 32

Urine culture: normal values

Answer 32

1) dipstick –> pH (5.0-9.0)
2) nitrites –> negative
3) leukocyte esterase –> negative
4) blood –> RBC <5

Question 33

Infection in healthcare setting

Answer 33

• Nosocomial –> infections that occur while in a healthcare facility. Drug resistance is a huge problem

Question 34

Drug resistance

Answer 34

MRSA (methicillin resistant Staph aureus) - resistant to specific drug

CRE- Carbapenem resistant - resistant to entire class of drugs

MDRO-multi drug resistant organism

Question 35

Superinfection

Answer 35

New infection that occurs during treatment for a DIFFERENT infection.

Antimicrobials we use to treat initial/primary infection, inhibit or kill NORMAL helpful flora

Typically occurs within the GI tract. Skin/mucosal surfaces

Question 36

Examples of super infection

Answer 36

C.Diff
Candidiasis (yeast)- Thrush in the mouth. Or in mucous membranes. Goal is prevention (Mycostatin/ Nystatin)