DR. HANA OMER. Symbiotic Relationships Symbiosis means “to live together” Describes the...
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Transcript of DR. HANA OMER. Symbiotic Relationships Symbiosis means “to live together” Describes the...
INFECTION DR. HANA OMER
Symbiotic RelationshipsSymbiosis means “to live together”
Describes the relationship between microorganisms and their host
Three types MutualismCommenalismParasitism
The Three Types of Symbiotic Relationships
Normal MicrobiotaAlso termed normal flora .
Refers to the organisms that colonize the body’s surfaces without normally causing disease .
Two typesResident microbiotaTransient microbiota
Resident MicrobiotaAre a part of the normal microbiota
throughout life .Most are commensal .Like : streptococcus bacterium can live for
months in the throat without causing harm and then suddenly cause an acute attack of tonsillitis .
Resident Microbiota
Resident Microbiota
Transient MicrobiotaRemain in the body for only hours to months
before disappearing .Cannot persist in the body…because…
Competition from other microorganismsElimination by the body’s defenses cellsChemical or physical changes in the body
Example Clostridium difficile in The intestine .
Contamination vs. InfectionContamination – it is the presence of
microbes in or on the body .
Infection – results when the organism has invaded the body’s external defenses, multiplied, and become established in the body .
Portals of EntrySites through which pathogens enter the
body
Four major types :-SkinMucous membranesPlacentaParenteral route
Infection vs. DiseaseInfection is the invasion of the host by a
pathogen .
Disease results only if the invading pathogen alters the normal functions of the body .
The most common cause of infection 1. Bacteria .2. Fungi (yeasts and molds) .3. Viruses .4. Protozoa .5. Helminths ( worms ) .