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86 Cards in this Set

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define infection
pathogenic microorganisms penetrate the host defenses, enter the tissues, and multiply
define pathologic
state that results when the infection damages or disrupts tissues and organs- disease
define infectious disease
the disruption of a tissue or organ caused by microbes or their products
define metagenomics
Metagenomics being used to identify the microbial profile inside and on humans
name some sites that harbor a knwn normal biota
skin and mucous membranes
upper respiratory tract
g.i. tract, vagina
outer urethra, external genitalia
external ear canal
external eye
what are some microbe free/sterile anatomical sites
kidneys and bladder
lungs, brain, spinal cord
muscles, bones, ovaries, testes, internal eye
Blood, urine, cs fluid, semen, amniotic fluid
describe microbial antagonism
bacterial biota benefit the human host by preventing the overgrowth of harmful microorganisms
define endogenous infections
caused by biota that are already present in the body
define pathogen
a microbe whose relationship with its host is parasitic and results in infection and disease
define pathogenicity
how nasty is this critter?
what is an opportunistic pathogens
usually is already present in the body but arises because the immune system is comprimised
what are some factors that weaken host defenses and increase susceptibility to infection?
old age and extreme youth
genetic defects and acquire defects in immunity
surgery, chemotherapy, immunosuppressive drugs, stress, other infections
define virulence
the degree of pathogenicity
what is virulence determined by?
Determined by its ability to
Establish itself in the host
Cause damage
define virulence factor
any characteristic or structure of the microbe that contributes to its virulence
What are the steps to a microbe becoming established in our bodies?
1. Microbe enters the tissues of the body by a portal of entry
2. Adhesion - attaching to the host
3. Surviving host defenses
infectious agents are either sourced _____ or ______
exogenously or
name 4 portals of entry
GI tract
respiratory tract
urogenital tracts
which portal of entry allows the greatest number of pathogens
respiratory tract
why can some std's penetrate unbroken surfaces
more permeable tissues in the urogenital tract
For most agents, infection only proceeds if the _____ _____ is present
Microorganisms with smaller IDs have ______ ______
infectious dose (ID)

greater virulence
what are the 3 ways that adhesion occurs
whar are some ways that a micro-org can survive host defenses?
antiphagocytic factors:
leukocidins - toxic to wbc's
extracellular surface layer making diff for phago to engult
some can survive inside phago's.
how could you survive a phagocytic attack if you were a pathogen?
have a durable capsule
have longer polysaccharides that string out, making it difficult for the phagocyte to engulf
produce leukocidins to kill wbc's
how do virulence factors contribute to tissue damage?
1. exoenzymes secreted by bacteria degrade bonds between host cells
2. exo toxins break down host cells themselves
3. stimulate too much inflammatory response
the power to produce toxins
a variety of diseases caused by toxigenicity
toxinoses in which the toxin is spread by the blood from the site of infection (tetanus and diphtheria)
toxinoses caused by ingestion of toxins (botulism)
toxin causes the reaction, not the organism
toxins pushed/secreted out of active cells
present in the cell, released from micro-org when cell is lysed.
accumulated damage leads to cell and tissue death
infection stays in one place - called ______
localized infection
i.e. boil
infection spreads everywhere in the body - called _______
systemic infection
infection develops in one area and then another infection caused by the same organism develops in a different area
Focal infections
infection caused by various microbes
mixed infection
infections caused in two separate areas by two separate organisms
primary and secondary infection
define "sign"
Sign: any objective evidence of disease as noted by an observer
define "symptom"
Symptom: the subjective evidence of disease as sensed by the patient
define syndrome
Syndrome: when a disease can be identified or defined by a certain complex of signs and symptoms
signs and symptoms of inflammation
Fever, pain, soreness, swelling
Granulomas and abscesses
Lesion: the site of infection or disease
fluid build up
lymph fluid build up
name some sign of infection in the blood
Changes in the number of circulating white blood cells
bacteremia or viremia
define leukocytosis
increased wbc count
define leukopenia
decreased wbc count
define septicemia
Septicemia: general state in which microorganisms are multiplying in the blood and are present in large numbers
define bacteremia or viremia
Bacteremia or viremia: microbes are present in the blood but are not necessarily multiplying
asymptomatic, inapparent infections
portals of exit for micro orgs to vacate the host
skin cells
insect bites
blood, urine, feces
a dormant state
The microbe can periodically become active and produce a recurrent disease
Long-term or permanent damage to tissues or organs is called:
define reservoir
Reservoir: the primary habitat in the natural world from which a pathogen originates
define source
Source: the individual or object from which an infection is actually acquired
define carrier
an individual who inconspicuously shelters a pathogen and spreads ith to others without any notice
what are the different types of carriers?
Asymptomatic carriers
Incubation carriers
Convalescent carriers
Chronic carrier
Passive carrier
define vector
a live animal that transmits an infectious agent from one host to another
Majority are arthropods
Larger animals can also be vectors
what actively participates in a pathogen's life cycle
biological vector
what transports the infectious agent without being infected
mechanical vectors
define zoonosis
Zoonosis: an infection indigenous to animals but naturally transmissible to humans
Human does not contribute to the persistence of the microbe
Can have multihost inovvlement
At least 150 worldwide
what is a passive carrier?
not infected, just unknowingly picks up a pathogen and passes it to someone else.
what is the best nonliving reservoir?
what are some other nonliving reservoirs?
define communicable disease
Communicable disease: when an infected host can transmit the infectious agent to another host and establish infection in that host
Transmission can be direct or indirect
Contagious agent: highly communicable
describe noncommunicable diesase
does not arise through transmission of the infectious agent from host to host
Acquired through some other, special circumstance
Compromised person invaded by his or her own microbiota
Individual has accidental contact with a microbe in a nonliving reservoir
define fomite
inanimate object / vehicle
what are the two types of transmission
contact transmission
indirect transmission
what are some examples of indirect transmission
food, water, biological products, fomites
contaminated objects - food poisoning, oral-fecal
air - droplet nuclei, aerosols
define nosocomial infection
Nosocomial infections: infectious diseases that are acquired or develop during a hospital stay
what are the most common nosocomial infections?
urinary tract infections

then, surgical sites

then respiratory
describe universal precautions
guidelines from the Centers for Disease Control and Prevention
Assume that all patient specimens could harbor infectious agents
Include body substance isolation (BSI)techniques to be used in known cases of infection
what is the causative agent called?
etiologic agent
what is the first step of Koch's postulates?
Find evidence of a particular microbe in every case of a disease
what is the second step of Koch's postulates?
Isolate that microbe from an infected subject and cultivate it in pure culture in the laboratory
what is the third step of Koch's postulates?
Inoculate a susceptible healthy subject with the laboratory isolate and observe the same resultant disease
what is the fourth step of Koch's postulates?
Reisolate the agent from this subject
define epidemiology
Epidemiology: the study of the frequency and distribution of disease and other health-related factors in defined human populations
define prevalence
Prevalence: the total number of existing cases with respect to the entire population
Prevalence = (total number of cases in population / total number of persons in population) x 100 = %
define incidence
Incidence: the number of new cases over a certain time period
Incidence = number of new cases / total number of susceptible persons
define mortality rate
Mortality rate: the total number of deaths in a population due to a certain disease
define morbibity rate
Morbidity rate: the number of persons afflicted with infectious diseases
endemic occurrence
focused in a specific region (of a country) i.e. hanta virus
epidemic occurrence
widespread occurrence spread between communities
sporadic occurrence
pops up out of nowhere
pandemic occurrence
widespread occurance between continents