Host Microbe Interactions Flashcards
Define symbiosis
interaction between two different organisms living in close physical association. It is a mutually beneficial relationship between two dissimilar organisms
Define mutualism
An association between two organisms where both parties involved are benefiting
Define parasitism
Unilateral benefit for one party involved.
Usually the host is suffering and the other organism is benefiting
Define pathogen
A microbe capable of causing the host damage and/or disease
Define opportunistic pathogens
An organism that is a member of the resident microbiota (or normally inhabiting the external environment) that causes infection under certain circumstances
Define symbiont
Member of the resident microbiota that confers benefit to the host
Define pathobiont
Member of the resident microbiota that causes disease when loss of the normal balance between the host and resident microbiota occurs
Define dysbiosis
Imbalnces in the resident human microbiota or our responses to them
Name the two beneficial relationships
Mutualism
Commensalism
Name the three types of detrimental relationships
Predation/parasitism (where the host is infected)
Amensalism (Microbe or host is injured
Competition (Struggle for resources)
What is opportunistic infection?
It is caused by an organism that is a member of the normal microbiota or normally exhibits the external environment
What are some examples of situations opportunistic microbes can take advantage of to spread infection?
Can enter through damaged epithelium
Presence of a foreign body
Transfer or bacteria from one sit to another
Suppression of the immune system
Distruption of the normal microbiota
Unknown precipitating factor
Impairment of host defences by exogenous pathogen
Which microorganisms can cause caries?
Streptococcus mutans Lactobacillus spp. Actinomyces spp.
Which microorganism can cause periodontal disease?
Porphyromonas gingivalis Tannerella forsythia Aggregatibacterium Actinomycetemcomitans Spirochaetes
Which microorganisms can cause aspiration pneumonia?
Staphylococcus spp. Anaerobes
Which microorganisms can cause abscesses?
Streptococci,
actinomyces
Gram-negative anaerobes
What can lead to the selection of pathogens?
Ecological pressures
Give examples of some ecological stresses
Host defences
Diet
Hormones
Exogenous species
How can organisms seek nutrients?
Chemotaxis
Biofims
How can organisms uptake and transport nutrients?
By diffusion
Active transport
Group translocation
Name some endogenous nutrients in saliva
Amino acids Peptides Proteins Vitamines Glycoproteins Gases
Name some endogenous nutrients in the gingival crevicular fluid
Albumin
Proteins
Glycoproteins
Haem
Name some exogenous nutrients
Fermentable carbohydrates
Dairy prodcyts like milk (casein)
Alternative sweeteners like sorbitol, xylitol and saccharin
What are exogenous nutrients?
The process whereby substances entering the body from the environment are assimilated
What are endogenous nutrients?
The assimilation by the body of substances that are found in the organism itself
Sucrose can be converted into 2 EPS
What does EPS stand for and what are the 2 EPS
EPS= Extracellular polymers
The 2 EPS that sucrose can be converted into are:
Glycan and fructan labile in plaque
Which enzyme converts sucrose to glycan?
Glucosyltransferases
Which enzyme converts sucrose to fructan labile in plaque?
Fructosyltransferase
Sucrose can be converted an IPS
What does IPS stand for and what is the IPS
IPS= Intracellular polymers
The IPS that sucrose is converted to is a glycogen like compounded for storage
What is catabolism?
The breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy
What is anabolism?
The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy
What are Saccharolytic bacterium?
They are capable of hydrolyzing or otherwise metabolizing a sugar molecule resulting in the production of energy
What are Asaccharolytic bacterium?
Incapable of breaking down carbohydrates for energy.
What is glucose converted to in the process of glycolysis?
Pyruvate
How does respiration produce ATP?
By electron transport phosphorylation using proton motive force
What is the electron acceptor in aerobic respiration?
Oxygen
What is a byproduct of aerobic respiration?
Water
What is the electron acceptor in denitrification?
NO3-
What is a byproduct of denitrification
NO2-
What is the electron acceptor in Sulphate reduction
SO4-
What is a byproduct of Sulphate reduction
H2S
What is the electron acceptor in Methanogenesis
CO2
What is a byproduct of Methanogenesis
CH4
Go through the steps in fermentation
- Glucose is converted into fructose biphosphate (2 ATP->2ADP)
- Fructose biphosphate converted into 2 triose-phosphate
- 2 triose-phosphate
converted into 2 phosphoglyceric acid
(2 NADH->2NAD+) - 2 phosphoglyceric acid converted into 2 pyruvic acid (2 ADP->2ATP)
- 2 pyruvic acid converted into 2 LACTIC ACIDS
What are the end products for the Homolactic acid
fermentation pathway?
Lactic acid
What are the end products for the Heterolactic acid fermentation pathway?
Lactic acid
ethanol
CO2
What are the end products for the ethanolic fermentation pathway?
Ethanol
CO2
What are the end products for the propionic acid fermentation pathway?
Propanoic acid
CO2
What are the end products for the mixed acid fermentation pathway?
Ethanol Acetic acid Lactic acid Succinic acid Formic acid CO2 H2
What are the end products for the butanediol fermentation pathway?
Butanediol
CO2
What are the end products for the butyric acid fermentation pathway?
Butyric acid
butanol
acetone
CO2
What are the end products for the amino acid fermentation pathway?
Acetic acid
NH4+
CO2
What are the end products for the fermentation methanogenesis pathway?
CH4
CO2
What does the enzyme urease break down?
Urea into NH3 and CO2
Name 3 host structural
proteins/glycoproteins
Hyaluronidase
Chondroitin sulphatase
Collagenase
What is the breakdown of L-arginine into NH4+ called?
Arginine metabolism
Go through the 2 ways L-arginine is broken down?
- L-arginine is converted into L-citrulline
L-citrulline is then converted into carbamoylphosphate by the addition of a inorganic phosphate and L-ornithine
Carbamoylphosphate is then converted into NH3 in a process of decarboxylation using ATP
Then NH3 is protonated into NH4+ - L-arginine is converted into NH3
NH3 is then protonated into NH4+
What is L-arginine hydrolysed into in arginine metabolism?
Ammonia
What is the nefeit of the lactate production lactate utilisation relationship?
Less caries as the glucose that was converted into lactate gets utilised by veillonella into acetate and propionate which are weaker acids
talk through the steps of how a climax community is reached
Transmission acquisition Pioneer species Succession Increasing species diversity Climax community
What are The 2 sources of nutrients for the resident microbiota
Endogenous (saliva, GFC)
exogenous (diet)
Streptococcus mutans can cause what?
Dental caries
Gram-negative anaerobes can cause what?
Abscesses
NO3- is what in denitrification?
Electron acceptor
Actinomycetemcomitans can caise what?
Periodontal disease
What word describes bacterium that are capable of hydrolyzing or otherwise metabolizing a sugar molecule resulting in the production of energy
Saccharolytic
Staphylococcus spp. Can cause what?
Aspiration pneumonia
Streptococci can cause what?
Abscesses
What is SO4- in sulphate reduction?
Electron reduction
Aggregatibacterium can cause what?
Periodontal disease
Lactobacillus spp. Can cause what?
Dental caries
What is glucosyltransferases and what does it do?
It is an enzyme that converts sucrose to glycan
Tannerella forsythia can cause what?
Periodontal disease
CO2 is what in Methanogenesis
The electron acceptor
Actinomyces spp. Can cause what?
Dental caries
What is fructosyltransferase and what does it do?
It’s an enzyme that converts sucrose to glycan
Anaerobes can cause what?
Aspiration pneumonia
Porphyromonas gingivalis can cause what?
Periodontal disease
Spirochaetes can cause what?
Periodontal disease
What are the two types of cellular metabolisms?
Catabolism
Anabolism
What word describes bacteria that is Incapable of breaking down carbohydrates for energy.
Asaccharolytic
The conversion of glucose to pyruvate is called what?
Glycolysis
Oxygen is what in aerobic respiration?
The electron acceptor
Define commensalism
When one party in an association is benefiting and the other is not affected
What are organisms that are not pathogens called?
Commensos
When does synergism occur?
Synergismoccurs when two or more hormones produce the same effects in a target cell and their results are amplified.
What are the sources of nutrients for the resident microbiota are called?
- Exogenous sources
2. endogenous sources
