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-disease state from presence of pathogens
-disease- producing microorganisms
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
bacteria, virus, fungi
-most significant and comonly observe infection causing agent. can be shaped: spehirical (cocci), rod (bacilli), corkscrew (spirochetes).
bacteria that has thick wall cell, resist decolorization (loss of color) and stained violet
bacteria with more complex cell walls, decolorized by etoh, and do not stain.
antibiotics are classified specifically effective to this type of bacteria
gram-positive or broadspectrum organisms
-bacteria requiring O2 to live
-bacteria can live w/o O2
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
-mold and yeast (athletes foot ringworm) yeastpresent in air, soil and H2O.
-tx w/ antifungal infection but resistant to TX
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.
occurs with predictability in 1 specific population can appear in different location
- therefore, countries draw info from one another to learn more about tx
organism that does not produce disease, inhabit sites in the body's natural defense sys.
bacteria that normally don't cause prob but may potentially harmful
- ex: e. coli - resides in the instestinal tract, if migrates to urinary tract can lead to uti
growth and multiplication of org is the natural habitat of the org.
-can be people, food, soil animals, water, milk, inanimate obj.
- -nurses can be reservoirs, can transfer pathogenic org to pt. ex: artificial nails/ineffective handwashing
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.
- -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
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
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
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.
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
means of transmission that spread through infected host by cough, sneeze, talk or attached to dust particles
-less than 5 mcm
same as airborne but droplet particles are greater than 5 mcm
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
degree of resistance a potential host has to the pathogen.
- - hospital pt have weak state of immunity and have less resistance. more susceptible to infection.
stages of infection
- -incubation period
- -prodromal stage
- -full stage of illness
- -convalescent period
interval between pathogen'sinvasion to body and appearance of Sx.
-org are growing and multiplying
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
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
recovery period of infection
-pt may have temporary or permanent change to his previous health even after convalescent period
body's defense against infection
- -body's normal flora
- -inflammatory response
- -immune response
first line of defense
-keeps harmful bastria from invading the body
-inhabits various body sites
body's normal flora
protective mechanism that eliminates pathogens and allows tissue repair.
-neutralize, control eliminate agents
-can be acute/chronic
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
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
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
specific body responses to foreign protein (bacteria/body's own protein).
-body's attempt to protect itself
-body's responseto an antigen
-antigen-antibody rxn, overall immune response
-cell-mediated defense, involves increase lymphocytes
* 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
bacterial flora on hands:
-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
bacterial flora on hands:
-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
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
includes fever, increase pr and rr, lethargu, anorexia, tenderness and enlargement of lymph nodes.