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-disease state from presence of pathogens
-disease- producing microorganisms
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six components of infection (cyclic process)
- 1. infectious agent
- 2. reservoir
- 3. portal of exit
- 4. means of transmission
- 5. portal of entry
- 6. susceptible host
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infectious agent
bacteria, virus, fungi
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-most significant and comonly observe infection causing agent. can be shaped: spehirical (cocci), rod (bacilli), corkscrew (spirochetes).
bacteria
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bacteria that has thick wall cell, resist decolorization (loss of color) and stained violet
gram-positive bacteria
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bacteria with more complex cell walls, decolorized by etoh, and do not stain.
gram-negative bacteria
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antibiotics are classified specifically effective to this type of bacteria
gram-positive or broadspectrum organisms
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-bacteria requiring O2 to live
-bacteria can live w/o O2
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samllest of all org. vivble w/ electron microscope.
infections caused by cold, deadly disease, AIDS. antibiotics are not effective.
when given Antibiotic at prodromal stage, can shorten full stage of illness
virus
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plant-like org
-mold and yeast (athletes foot ringworm) yeastpresent in air, soil and H2O.
-tx w/ antifungal infection but resistant to TX
fungi
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organism's potential to produce disease depends on:
- 1. # of org
- 2. virulence - ability to cause disease
- 3. person's immune sys
- 4. leghth and intimacy of the contact between person and microorg.
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occurs with predictability in 1 specific population can appear in different location
- endemic
- therefore, countries draw info from one another to learn more about tx
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organism that does not produce disease, inhabit sites in the body's natural defense sys.
normal flora
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bacteria that normally don't cause prob but may potentially harmful
- opportunist
- ex: e. coli - resides in the instestinal tract, if migrates to urinary tract can lead to uti
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growth and multiplication of org is the natural habitat of the org.
-can be people, food, soil animals, water, milk, inanimate obj.
- reservoir
- -nurses can be reservoirs, can transfer pathogenic org to pt. ex: artificial nails/ineffective handwashing
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individuals who are asymptomatic but can transmit disease
-ex: HIV pt, may not exhibit Sx, can transmit virus by sexaul contact or sharing needle.
-pregnant mom can transmit virus to her child through breastfeeding. birth.
carriers
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other reservoirs
- -rabies, west nile virus,
- -soil, org that causes gangrene/tetanus
- -H2O, giardia, e.coli, shigella: drinking/swimming contaminated H2O
- -food: undercooked meat, tomatoe spinach can cause e.coli
- -milk, contain listeria unless pateurized
- -inanimate obj, may sppread if a person touches contaminated article then touches his nose/eyes
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point of escape of org from reservoir
- portal of exit
- -humans: respratory, GI, genitourinary tract and breaks on skin.
- -blood and tissue can be portals of exit for pathogens
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means of transmission that involves proximity between susceptible host and infected person/carrier by touching skin, sexual intercourse.
-health workers can transmit org to pt through touching
- direct contact
- -can be prevented through proper hygiene and use of gloves
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means of transmission that involves personal contact w/ inanimate obj by touching a contaminated instrument.
- indirect contact
- -can be blood, food, water, inanimate obj (fomites) are vehicles of transmission.
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means of transmission that involves mosqiutoes, ticks lice. nonhuman carrier that transmit org from 1 host to another by injecting salivary fluid through human bites
vectors
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means of transmission that spread through infected host by cough, sneeze, talk or attached to dust particles
-less than 5 mcm
airborne route
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same as airborne but droplet particles are greater than 5 mcm
droplet route
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when organisms enter a new host. org must find an entry or it may die. same as the exit route
- portal of entry
- -humans: resp, GI, GU and skin
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degree of resistance a potential host has to the pathogen.
- susceptibility
- - hospital pt have weak state of immunity and have less resistance. more susceptible to infection.
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stages of infection
- -incubation period
- -prodromal stage
- -full stage of illness
- -convalescent period
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interval between pathogen'sinvasion to body and appearance of Sx.
-org are growing and multiplying
incubation period
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pt is most infectious
-early s/s are present but vague and nonspecific.
-fatigue, malaise to low grade fever
-pt does not realize that he is contagious
-spread of infection
prodromal stage
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presence of s/s
-determines leght and severity
-Sx are limited,
-occur in 1 body area (localized)
-Sx manifested throughout the body (systemic)
full stage of illness
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recovery period of infection
-s/s disappear
-pt may have temporary or permanent change to his previous health even after convalescent period
convalescent period
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body's defense against infection
- -body's normal flora
- -inflammatory response
- -immune response
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first line of defense
-keeps harmful bastria from invading the body
-inhabits various body sites
body's normal flora
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protective mechanism that eliminates pathogens and allows tissue repair.
-neutralize, control eliminate agents
-can be acute/chronic
inflammatory response
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cardinal signs of acute infection
- redness, heat, swelling, pain and loss in function
- -vascular and cellular stages are responsible for the appearance of these signs
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small BV constricts followed by vasodilation of arterioles and venules - increases BF causes redness and heat
-histamine is released which allows protein fluid in the area causing swelling pain and loss of function
vascular stage
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wbc moves quickly to area
-neutrophils: primary phagocyte, engulf org and consume cell debris
-exudate: clear, w/rbc, w/ pus
-damaged cells are repaired by regeneration/scar formation
cellular stage
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specific body responses to foreign protein (bacteria/body's own protein).
-body's attempt to protect itself
immune response
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-foreign material
-body's responseto an antigen
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-antigen-antibody rxn, overall immune response
-cell-mediated defense, involves increase lymphocytes
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-humoral immunity
-cellular immunity
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* factors affecting risk of infection
- -intact skin and mucuous membrane
- -normal pH level of GI, GU and skin.
- -#wbc, provides resistance
- -age sex race and hereditary (neonates and geriatrics are vulnerable)
- -immunization (acquired-vaccine /natural-body)
- -fatigue, climate, nutrition and health stat
- -stress level when increase can be a risk
- -invasive/indwelling devices
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bacterial flora on hands:
-transient:
-can be removed by freq handwashing
-more susceptible to antiseptic
- -occur on hands
- -few # in clean and exposed areas
- -attached loosely/ grease, fats and dirt
- -greater # found under fingernails
- -pathogenic/nonpathogenic
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bacterial flora on hands:
resident:
-can be removed through friction rub w/ brush
-less susceptible to antiseptic
- -found in creases in skin
- -stable in # and type
- -clings to skin by adhesion/absorption
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lab data indicating infection
-elevated wbc count
-increase specific type of wbc
-elevated erythrocyte sedimentation rate (rbc settle rapidly @bottom when inflammation is present)
-presence of pathogen in urine, blood, sputum or culture
- -wbc- 5k-10k/mm3
- -neutrophils - N 60-70% - increase in acute infection(w/pus) and stress. if decrease will be at risk for acute bact inf
- -lymphocytes - N 20-40% - increased in chronic bacterial/viral inf
- -monocyte- N 2-8% - incr severe inf and function as scavenger/phagocyte
- -eosinophil - N 1-4% - increase due to allergic rxn, parasitic inf
- -basophil - 0.5-1% - unaffected by infection
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includes fever, increase pr and rr, lethargu, anorexia, tenderness and enlargement of lymph nodes.
systemic infection
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