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32 Cards in this Set
- Front
- Back
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What are the 3 symbiotic relationships between microbes and their hosts? |
1. mutualism 2. commensialism 3. parasitism
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Describe mutualism? |
both members benefit from interaction |
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Describe commensalism |
one member of the relationship benefits w/out significantly affecting the other |
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Describe parasitism |
parasites benefit from the host while harming it, though some hosts sustain only slight damage |
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What is normal microbiota? |
-sometimes called normal flora -microbes that colonize the surfaces of the body w/out normally causing disease -acquired after birth
-Two types: resident microbiota and transient microbiota |
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Describe resident microbiota? |
-remain a part of the normal microbiota of a person throughout life
-found on skin and mucous membranes of parts of the GI tract |
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Describe transient microbiota? |
-remain in body for a few hours, day, or months before disappearing
-found in same places as resident but cannot persist as long |
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How do normal microbiota become opportunistic pathogens? (3) |
-introduction of a member of the normal microbiota into unusual site in the body -immune suppresions -changes in normal microbiota |
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What are some common routes of entry for invading pathogens? |
-ear -conjunctiva of eye -nose -mouth -placenta -vagina/penis -urethra -insect bite -broken skin -anus |
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What is adhesion? |
the process by which microorganisms attach themselves to cells
-required to successfully est. colonies w/in the host |
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What is necessary for adhesion to happen? |
-adhesion factors - specialized structures or attachment proteins (suckers or hooks)
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What is an infection? |
the invasion of the host by a pathogen |
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When does disease occur? |
if the invading pathogen alters normal body functions |
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What is etiology? |
-the study of the cause of a disease -diseases have various causes |
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Why is it useful to use Koch's postulates when discussing etiology? |
-a set of postulates one must satisfy to prove that a particular pathogen causes a particular disease
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What is the germ theory of disease? |
a disease is caused by infections of pathogenic microorganisms (germs) |
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What are Koch's 4 postulates? |
1. the suspected agent (virus, bacterium etc...) must be present in every case of the disease 2. that agent must be isolated and grown in pure culture 3. the cultured agent must cause the disease when it is inoculated into a healthy experimental host 4. the same agent must be reisolated from the diseased experimental host |
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What is pathogenicity? |
-the ability of an organism to cause a disease |
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What is virulence? |
the degree of pathogenicity - the relative ability of a pathogen to infect a host and cause disease |
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What are virulence factors? |
-a variety of traits that interact w/ a host and enable the pathogen to enter a host, adhere to host cells, gain access to nutrients, and escape detection or removal by the immune system
-two factors = adhesion factors and biofilm formation others include extracellular enzymes, toxins and antiphagocytic factors |
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Describe extracellular enzyme virulence factor? |
-pathogens that secrete enzymes that enable them to dissolve structural chemicals in the body thereby maintaining the infection, invading further and avoiding body defenses |
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Describe toxin virulence factors? |
-chemicals that either harm tissues or trigger host immune responses that cause damage - hard to sometimes tell between extracellular enzymes and toxins
-two types end and exotoxin |
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Describe Exotoxins? |
-toxins that are central to their pathogenicity in that they destroy host cells or interfere w/ host metabolism
3 types- cytotoxins; neurotoxins; eneterotoxins
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Describe endotoxins |
-aka Lipid A -lipid portion of the membrane's lipopolysaccharide -can be released when gram-neg bacteria divide, die naturally, or are digested by phagocytic cells such as macrophages -cause fever, inflammation, diarrhea, hemorrhaging, shock, and blood coagulation |
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Describe antiphagocytic factors |
-exist in capsule that are made of chemicals similar to those found in the body therefore the body doesn't fight it -also exists in bacteria that produces chemicals that prevent the fusion of lysosomes with phagocytic vesicles which allow the bacteria to survive inside the phagocytes |
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What are the 3 groups of disease transmission? |
-contact transmission -vehicle transmission -vector transmission |
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Describe contact transmission? |
-can occur through direct, indirect, or droplet transmission |
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Describe vehicle transmission |
-can occur via air, drinking water, and food, as well as bodily fluids being handled outside the body |
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Describe vector transmission |
-vectors are animals that transmit diseases from one host to another - vectors can either be biological or mechanical
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Describe biological vectors |
-not only transmit pathogens but serve as hosts for the multiplication of a pathogen during some stage of the pathogen's life cycle (like ticks, lice, mosquitoes, fleas etc...) |
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Describe mechanical vectors |
-are not required as hosts by the pathogens they transmit; such vectors only passively carry pathogens to new host on their feet or other body parts |
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Describe 2 things when concerning epedimiology and public health |
-prevent disease by educating public and working on limiting disease transmission (CDC) |
