Host Microbe Interractions (LEC 2) Flashcards
(34 cards)
What is the HOST and associated MICROBIOTA relationship under normal HEALTHY conditions
SYMBIOTIC
Definition of SYMBIOSIS
Close MUTUALLY BENEFICIAL relationship between 2 DISSIMILAR organisms
Mutualism (host relationship)
Association between 2 organisms = BOTH partners benefit from association
(Reciprocal benefit)
COMMENSALISM
host relationship
1 member BENEFITS,
other UNAFFECTED (no harm)
(Shelter and food)
PARASITISM (host relationship)
1 member BENEFITS,
other HARMED
(Unilateral benefit)
PATHOGEN
Microbe / microorganism
capable of causing host damage / disease
(E.g. Streptococcus mutants -caries)
OPPORTUNISTIC PATHOGEN
Organism member of resident microbiota / normally inhabits external environment
CAUSES INFECTION UNDER CERTAIN CIRCUMSTANCES
(E.g Immunodeficient individuals)
SYMBIONT
Member of resident biota
BENEFITS HOST
DYSBIOSIS
IMBALANCE in resident microbiota / our response to imbalance
(Opposite to SYMBIOSIS)
PATHOBIONT
Member of Resident microbiota
Causes disease when normal balance between HOST & RESIDENT MICROBIOTA lost (DYSBIOSIS)
When does DYSBIOSIS occur?
When there is a breakdown in homeostasis
OPPORTUNISTIC INFECTION
Caused by a member of NORMAL MICROBIOTA / normally inhabits external environment
- Damage to epithelium (bacteria invade)
- Foreign body presence
(catheter- contamination ) - Transfer to other site (of body)
- Suppression of immune system
(I.S. Regulates microbe colonisation) - Disruption of normal microbiota
(change in normal environmental conditions) - Unknown precipitating factor
(change in host microbial dynamics) - Impairment of host defences by exogenous pathogens (come from environment we live in)
Which normal oral microbiota cause CARIES ?
Streptococcus mutans
Lactobacillus spp.
Actinomyces spp.
Which normal oral microbiota cause PERIODONTAL DISEASE ?
Porphy-romonas gingivalis
Tann-erella (not Cinderella) forsythia
Spirochaetes
Aggregati -bacterium actinomycete -comitans
Which normal oral microbiota cause ASPIRATION PNEUMONIA
Staphylococcus spp.
Anaerobes
Which normal oral microbiota cause INFECTIVE ENDOCARDITIS?
a-haemolytic streptococci
Staphylococcus spp.
Which normal oral microbiota cause ABSCESSES?
Streptococci
Actinomyces
Gram-negative anaerobes
Which normal oral microbiota cause CANDIDIASIS ?
Candida spp.
What complex interactions occur between the HOST and microbiota ?
(Homeostasis)
-Antagonistic and synergistic (synchronised) interactions to help with homeostasis
(E.g production of anti microbial compounds /agents produced by our human cells OR certain microbes that are competing for resources in microbial habitat )
-negative feedback
What can breakdown microbial homeostasis ?
SELECTION OF PATHOGENS
Due to ecological pressure
Can predispose a microbial site to disease
What are the ecological stress factors on microbial homeostasis?
Host defenses (competing for resources )
Diet
Hormones
Exogenous species
Bacteria require nutrients to live & some acquire this through what?
- CHEMOTAXIS = Movement of an organism towards a substance / chemical
- BIOFILM= source of nutrients through metabolism of other micro organisms present (we don’t produce what they require)
- CONTROL = induction / repression
Depending on nutrient availability, certain microbial processes, genes of protein expression may be induced or repressed
MECHANISMS that transport NUTRIENTS into bacterial cells ?
- DIFFUSION (passive / facilitated)
- ACTIVE TRANSPORT
- GROUP TRANSLOCATION
What 2 types of NUTRIENTS do ORAL MICROORGANISMS rely on for growth?
-ENDOGENOUS nutrients (substances originating within us) saliva glycoprotein crevicular fluid blood
-EXOGENOUS nutrients (External)
Food from our diet
