Host Microbe Relationship Patricia Sidelsky 2007.
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Transcript of Host Microbe Relationship Patricia Sidelsky 2007.
Host Microbe Host Microbe RelationshipRelationshipPatricia SidelskyPatricia Sidelsky
20072007
Microbe host Microbe host relationshipsrelationships
Symbiosis – Coexistence of two or Symbiosis – Coexistence of two or more organisms to the success of more organisms to the success of the other in the environment. Can the other in the environment. Can evolve specific mechanisms to evolve specific mechanisms to maintain this relationshipmaintain this relationship
1. Mutualism1. Mutualism 2. Commensalism2. Commensalism 3. Parasitism3. Parasitism
MutualismMutualism
Both partners in a relationship are Both partners in a relationship are dependent upon each otherdependent upon each other
Each contributes to the success of Each contributes to the success of the other organism in a particular the other organism in a particular environmemtenvironmemt
RhizobiumRhizobium and legumes and legumes
Coral and ZooxanthellaeCoral and Zooxanthellae
Coral Bleaching can lead Coral Bleaching can lead to death of the reefto death of the reef
Leaf cutter antsLeaf cutter ants
Ruminants - Gut Ruminants - Gut reactions: Sequencing reactions: Sequencing ruminal bacteriaruminal bacteria
CommensalismCommensalism
Microbes that share space on the Microbes that share space on the skin as well as the metabolic skin as well as the metabolic productsproducts
Coexist – the partners in the Coexist – the partners in the relationship do not contribute to the relationship do not contribute to the success of their fellow microbes, but success of their fellow microbes, but neither are they harmedneither are they harmed
E. ColiE. Coli in the gut in the gut
E. coliE. coli lives in an enriched lives in an enriched environment high in nutrientsenvironment high in nutrients
In return E. coli produces Vitamin K In return E. coli produces Vitamin K for blood clottingfor blood clotting
Parasitism and Parasitism and PathogensPathogens
Pathogens are disease producing Pathogens are disease producing organismsorganisms
The parasite benefits from the The parasite benefits from the relationshiprelationship
The host is harmedThe host is harmed +/- relationship+/- relationship
Flat worms - Flat worms - PlatyhelminthesPlatyhelminthes
CestodesCestodes TrematodesTrematodes
SchistosomiasisSchistosomiasis
SchistosomesSchistosomes
Clinorchis senensis - Clinorchis senensis - LiverLiver
TapewormTapeworm
TapewormTapeworm
Protozoan parasites – Protozoan parasites – Plasmodium vivax and Plasmodium vivax and Plasmodium falciparumPlasmodium falciparum
Giardia lambliaGiardia lamblia
Entamoeba histolyticaEntamoeba histolytica
Key termsKey terms
Infection refers to the presence or a Infection refers to the presence or a parasitic organism or pathogen( implies parasitic organism or pathogen( implies that they are established and that they are established and reproducing)reproducing)
Infestation – A word usually limited to Infestation – A word usually limited to larger parasites like helminths or wormslarger parasites like helminths or worms
Contamination – refers to the presence of Contamination – refers to the presence of microbes( can be on the surface of an microbes( can be on the surface of an inanimate object )inanimate object )
DiseaseDisease
Disturbance in the state of health Disturbance in the state of health that may result in the infection of that may result in the infection of human tissue by microbeshuman tissue by microbes
Changes in the host that interfere Changes in the host that interfere with normal functionwith normal function
Fever, diarrhea, inflammation, Fever, diarrhea, inflammation, irreparable damageirreparable damage
PathogenicityPathogenicity
Ability to produce diseaseAbility to produce disease Invasion of pathogenInvasion of pathogen Release of molecules by pathogenRelease of molecules by pathogen Host response to invaderHost response to invader
RelationshipsRelationships
Normal flora – normal microbiota – Normal flora – normal microbiota – Many organisms have well Many organisms have well established associations with established associations with humanshumans
Resident microbiota – microbes that Resident microbiota – microbes that are always present – skin, orifices, are always present – skin, orifices, interior of nose and throat – Tend to interior of nose and throat – Tend to colonize mucous membranescolonize mucous membranes
Transient microbes Transient microbes
Present under certain conditionsPresent under certain conditions May require special nutrientsMay require special nutrients Not as adaptiveNot as adaptive
OPPORTUNISTIC ORGANISMS MAY BE OPPORTUNISTIC ORGANISMS MAY BE TRANSIENTTRANSIENT
Opportunistic organismsOpportunistic organisms
Able to penetrate the immune defenses if Able to penetrate the immune defenses if there is another infectious agent presentthere is another infectious agent present
Immunocompromised due to malnutrion Immunocompromised due to malnutrion or other extenuating factoror other extenuating factor
Introduced at an inappropriate body siteIntroduced at an inappropriate body site Imbalance of the normal flora due to Imbalance of the normal flora due to
antibiotic therapyantibiotic therapy Imbalance of the normal flora due to Imbalance of the normal flora due to
chemotherapychemotherapy
CandidaCandida
C. difficileC. difficile
Burkholderia cepaciaBurkholderia cepacia
How Microbes Cause How Microbes Cause DiseaseDisease
AdherenceAdherence ColonizationColonization InvasivenessInvasiveness Virulence factors and ToxinsVirulence factors and Toxins Growth and Multiplication in the hostGrowth and Multiplication in the host Exiting the hostExiting the host Cell injury and destructionCell injury and destruction
AdherenceAdherence
Adhesins - molecules that are Adhesins - molecules that are adhesive in nature and are found on adhesive in nature and are found on the tips of the fimbriaethe tips of the fimbriae
These adhere to the host cell These adhere to the host cell membrane( specificity involved membrane( specificity involved between pathogen and host)between pathogen and host)
Receptors that are Receptors that are specific for infective specific for infective agentsagents
CCR5 receptor on macrophages that CCR5 receptor on macrophages that binds to both bacteria and virusesbinds to both bacteria and viruses
Yersinia pestis - causative agent of Yersinia pestis - causative agent of the plaguethe plague
HIV- causative viral agent of AIDSHIV- causative viral agent of AIDS
CCR5 receptorCCR5 receptor
Anthrax and receptorsAnthrax and receptors
InvasivenessInvasiveness
Ability to grow in the hostAbility to grow in the host To spread through tissuesTo spread through tissues To avoid the immune defensesTo avoid the immune defenses
Virulence factorsVirulence factors
Hyaluronidase – enzyme that breaks Hyaluronidase – enzyme that breaks down connective tissue. Break down connective tissue. Break down of connnective tissue insures down of connnective tissue insures that the streptococci can spread that the streptococci can spread through epithelial tissues lining the through epithelial tissues lining the throatthroat
Coagulase( Coagulase( staphlococcus staphlococcus aureus)aureus)
Causes blood to clot – fibrin clot Causes blood to clot – fibrin clot protects the bacteriaprotects the bacteria
Walls off microorganisms so that Walls off microorganisms so that they can avoid macrophages and they can avoid macrophages and neutrophilsneutrophils
StreptokinaseStreptokinase
Dissolves blood clotsDissolves blood clots Pathogens trapped in blood clots Pathogens trapped in blood clots
are freedare freed
Exotoxin or endotoxinExotoxin or endotoxin
Exotoxins secreted or released by Exotoxins secreted or released by bacteria into the host tissuesbacteria into the host tissues
Endotoxins – Molecules present in Endotoxins – Molecules present in the cell wall or exterior covering of the cell wall or exterior covering of a bacteriuma bacterium
Hemolysins( Exotoxins)Hemolysins( Exotoxins)
Burst red blood cells and release Burst red blood cells and release hemoglobin to be used for the cell’s hemoglobin to be used for the cell’s metabolismmetabolism
AlphaAlpha Beta ( clear area around bacteria on Beta ( clear area around bacteria on
blood agar) page 397blood agar) page 397 GammaGamma
Exotoxins against WBCExotoxins against WBC
Leukocidins – release by strep and Leukocidins – release by strep and staphylococci – destroys white blood staphylococci – destroys white blood cells that are able to phagocytosed cells that are able to phagocytosed bacteriabacteria
Neutrophil and infectionNeutrophil and infection
EndotoxinsEndotoxins
LPS ( A antigen)LPS ( A antigen) Produced by Gram negative Produced by Gram negative
organismsorganisms Endotoxins released when bacteria Endotoxins released when bacteria
are killed by antibioticare killed by antibiotic Can cause severe reactionCan cause severe reaction