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65 terms

micro #13 infection & disease

micro #13 infection & disease
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infection
is a disturbance in the equilibrium resulting in pathogenic microbes multiplying in the tissues.
disease
is the pathologic state that results when the infection damages or disrupts tissues and organs
infectious disease
the disruption of a tissue or organ caused by microbes or their products
transient
are microbes that are present on the body for a period of and rapidly lost (not infection)
metagenomics
being used to identify the microbial profile inside and on humans
Human Microbiome Project
microbial antagonism
human host benefits from bacterial biota. Biota can produce vitamins, help digest lactose or prevent the overgrowth of harmful microorganisms by releasing bacteriocins
bacteriocins
chemicals released by one microbe that inhibit other microbes
endogenous infections
caused by biota that are already present in the body
Bifidobacteria
probiotic
Natural part of the bacterial flora in the human body and have a symbiotic bacteria-host relationship with humans.
pathogen
a microbe whose relationship with its host is parasitic and results in infection and disease
pathogenicity
Type and severity of infection depend on pathogenicity of the organism and the condition of its host. how virulant is it, does it reproduce quickly?
True pathogens
capable of causing disease in healthy persons with normal immune system
opportunistic pathogens
cause disease when defenses are compromised (host said to be immunocompromised)
virulence
1. The degree of pathogenicity
2. Determined by its ability to
A. establish itself in the host
B. cause damage
virulence factor
any characteristic or structure of the microbe that contributes to its virulence (contributes to establishment or ability to cause disease)
Exogenous
coming from the outside.
ex. another person, desk, animal
Endogenous
already existing on or in the body (normal biota or latent infection)
infectious agent comes from the body
Infections by birth canal (TORCH)
1. toxoplasmosis
2. other diseases (hepatitis, HIV, clamidia)
3. Rubella
4. Cytomeglovirus (mumps)
5. Herpes complex
Becoming established: 3 steps
1. portals of entry (skin, gastrointestinal, respiratory, urogenital) - outside environment
2. Attaching to the host (adhesion) - fimbrae, surface proteins, adhesive slimes or capsules.
3. Surviving host defenses (phagocytes, some use anti-phagocytic factors
antiphagocytic factors
used by some pathogens to avoid phagocytes
antiphagocytic factors: Leukocidins
toxic to white blood cells, produced by Streptococcus and Staphylococcus
antiphagocytic factors: Extracellular Enzymes
Break down and inflict damage on tissues or dissolve the host's defense barriers
ex. mucinase, keratinase, collagenase. some react with components of blood
Bacterial Toxins
Specific chemical product that is poisonous to other organisms
Toxigenicity
the power to produce toxins
Toxinoses
a variety of diseases caused by toxigenicity
Toxemias
toxinoses in which the toxin is spread by the blood from the site of infection (tetanus and diphtheria)
Intoxications
toxinoses caused by ingestion of toxins (botulism)
endotoxin
gram negative only, lipopolysaccharides
necrosis
accumulated damage leads to cell and tissue death
Sign
any objective evidence of disease as noted by an observer
Symptom
the subjective evidence of disease as sensed by the patient
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
Edema
accumulation of fluids in afflicted tissue
Granulomas and abscesses
walled off collections of inflammatory cells and microbes in the tissues
Lymphadenitis
swollen lymph nodes
lesion
the site of infection or disease
Leukocytosis
increase in WBC
leukpenia
a decrease in the number of WBCs
septicema
general state in which microorganisms are multiplying in the blood and are present in large numbers
Bacteremia or viremia
microbes are present in the blood but are not necessarily multiplying
Reservoir
primary habitat in the natural world from which a pathogen originates (can be inanimate)
Source
the individual or object from which an infection is actually acquired
Carrier
an individual who inconspicuously shelters a pathogen and spreads it to others without any notice
Vector
a live animal that transmits an infectious agent from one host to another
Majority are arthropods
Larger animals can also be vectors
Biological vector
actively participates in a pathogen's life cycle. (ex. mosquito, bites, feces, regurgitate blood)
some of part of life cycle of MO takes place
Mechanical vectors
transport the infectious agent without being infected (ex. flies)
Zoonosis
an infection indigenous to animals but naturally transmissible to humans
ex. rabies, yellow fever
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
Noncommunicable disease
1. does not arise through transmission of the infectious agent from host to host
2. Acquired through some other, special circumstance (ex. cut)
3. Compromised person invaded by his or her own microbiota
4. Individual has accidental contact with a microbe in a nonliving reservoir
AB toxins
target organs
indirect transmission
1. Vehicle: any inanimate material commonly used by humans that can transmit infectious agents (food, water, biological products, fomites)
- Contaminated objects (doorknobs, telephones, etc.)
- Food poisoning
- Oral-fecal route
2. Air as a vehicle
- Indoor air
- Droplet nuclei
- Aerosols
Nosocomial infections
infectious diseases acquired or developed during a hospital stay
Etiologic agent
the causative agent
Robert Koch
developed a standard for determining causation that would stand the test of scientific scrutiny
Koch's Postulates
1. Find evidence of a particular microbe in every case of a disease
2. Isolate that microbe from an infected subject and cultivate it in pure culture in the laboratory
3. Inoculate a susceptible healthy subject with the laboratory isolate and observe the same resultant disease
4. Reisolate the agent from this subject
Epidemiology
study the outbreak of the disease
Prevalence
total number of existing cases w/ respect to the population
= (total number of cases in population / total number of persons in population) x 100 = %
incidence
the number of new cases over a period of time
= number of new cases / total number of susceptible persons
mortality rate
the total number of deaths in a population due to a certain disease
morbidity rate
the number of persons afflicted with infectious diseases
endemic
disease that exhibitsa a relatively steady frequency over a long time period in a particular geographic locale (ex. lyme disease = found where ticks are located)
sporadic
occasional cases are reported at irregular intervals in random locales
epidemic
revalence of an endemic or sporadic disease is increasing beyond expectations. clusters of breakouts
pandemic
spreada of an epidemic across continents