Pathophys Exam 2 Flashcards
What determines the degree of Pathogenicity of a organism?
1) Virulence
2) The host’s defense
Virulence Definition
The ability of a microorganism to produce disease.
Virulence depends on?
1) Ability of organism to attach and enter host.
2) Ability of organism to produce endotoxins and exotoxins.
3) Ability of organism to induce host cell responses that cause injury.
What are the Types of Host Defense?
1) Inflammatory response
2) Innate response
3) Acquired response
Inflammatory Response
- Active process involving leukocytes and chemical mediators.
- The function is to kill the organism, to minimize damage, and to prevent further injury.
Innate Response
- Non-specific immunity
- No memory
- Includes physical barriers like mucous membranes, epithelium (first line of defense), keratinized stratified squamous; environmental factors like pH and temperature; and also phagocytosis by netrophyls and macrophages.
Acquired Response
- Highly specific
- Has memory
- Response to foreign substance improves with each exposure
- Includes Humeral (antibody and immunoglobulin mediated immunity) and cell mediated immunity.
Sources of Infectious Diseases
1) Endogenous Organisms
2) Exogenous Organisms
3) Nosocomial Infections
4) Community Infections
Endogenous Organisms
- Involves one own microflora, generally due to opportunistic organism.
- Generally due to impaired or supressed host’s defense system.
Exogenous Organisms
- Derived from the external environment, humans, or animals.
- Can be from body fluids, blood, feces, urine, respiratory secretions, semen, saliva, tears, and any mucous associated with mucous membranes.
Fomite
- It is a physical object that serves to transmit an infectious agent from person to person.
- Can be door knobs, combs, needles
Nosocomial Infections
- Infection contracted at the hospital due to hospital stay.
- It’s secondary to patient’s original condition.
- Contracted within 48 hrs of hospitalization or up to 30 days after discharge.
Community Infections
-Infections contracted outside of a health care facility.
How organisms enter the body? (12)
1) Direct contact
2) Penetration wounds
3) Incision wounds
4) Abrasion, lacerations and avulsions
5) Deep puncture wounds
6) Inanimate objects
7) Insect bites and burrowing insects
8) Burrowing helminth larvae
9) Burns
10) Ingestion
11) Contaminated water
12) Inhalation
Direct contact
- Exposure of intact mucous membrane or skin to contaminated tissue, fluids or fomites.
- Includes parasitic diseases like mites (scabies), lice, and dermatomycosis like ringworms and candida albican.
- Also STDs, HPV, strap and staph causing impetigo and folliculiti, transmission from mother to baby.
Penetration wounds
-Causes breaching of epithelial barrier of body
Acanthoamoeba
-Protozoan disease of cornea
Incision wounds
- Cuts thru epithelium with sharp object
- Contamination may occur from the object or opportunistic organism.
- Staph and Strep are the most common for incision infections.
Abrasion, lacerations and avulsions
- May involve opportunistic or environmental pathogens.
- Associated with more tissue trauma and therefore more necrosis.
- Most often bacterial infections but fungi may occur.
Deep puncture wounds
- Penetration of deeper tissue with closure of tissue surface with a clot.
- Causes damage and inoculation of tissues with microorganisms.
- Ex: animal bites, gram negative and anaerobic bacteria with endo and exo toxin release as when stepping on nails
Inanimate objects
- May involve same organisms from abrasions, lacerations and avulsions.
- Most concerning are the anerobic organisms such as clostridium tetani that can cause devastating systemic effects.
Some Organisms involved in Abrasion, Lacerations and Avulsions
- staph aureus
- strep epidermis
- psedomonas aeroginosa
- hemophilus influenza
- clostridium species
Insect bites and burrowing insects
- Fleas- give staph, strep, and yersinia pestis (plague)
- Lice- Richettsia peovwazekii - thyphus
- Assassin bug- chagas disease
- Ticks- Rocky Mt Spotted Fever (rickttsia rickttii), Lyme’s disease (borrelia burgdorferi)
- Mosquitoes- yellow fever, Viral encephalitis, West Nile fever, malaria (plasmadium), heart worm disease (helminth)
Burrowing helminth Larvae
-Can penetrate skin soon after hatchin
Cutaneous larval migrans
-Body migration of hookworms and round worms larvae
