Lecture 10 Microorganism And Disease Flashcards
What is mutualism
Beneficial associations
Example - bacteria providing vitamin precursors in gut
What is Commensalism
Passive associations
Example– non pathogenic Staphylococci
What is Parasitism
Microorganism causes harm
Example – pathogenic bacteria
What is Microbiology
The study of micro organisms
Example of good bacteria (Probiotics)
•Clostridium Butyricum
Produces important fatty acids
•Bifidobacteria
Modulates immune response and produces vitamins
•Lactobacilli
Produces vitamins and minerals , boost immunity and protects against carcinogens
Example of Bad bacteria
•Clostridium Difficile
Causes diarrhoea and abdominal pain
•Campylobacter
Also known as “food poisoning” it is found in uncooked chicken
•Enterococcus Faecalis
A common source of post surgical infection
How do we prove a pathogen
Koch’s Postulate
Explain Koch’s Postulate
1.The m/o must be present in the diseased and not in a healthy animal
2.M/O must be cultivated in pure culture
3.Pure culture inoculated into 2nd animal disease
4.Pure culture from 2nd animal should be same as 1st.
Exceptions to Koch’s Postulate
•Some pathogens difficult to culture.
•Some diseases are caused by combinations of
-Pathogens
-Physical, environmental
-Genetic factors
•Animal models and ethics: inoculation of healthy susceptible host not always possible (the postulate could never be fully applied to HIV)
Name the group of factors that can define host specificity
Virulence factors
What do Adhesions recognise
Specific receptors
Secretion of enzymes allows microorganisms to alter what
Their environment
What is Leukocidins used for
To destroy White blood cells (WBC)
What is Catalase used for
to protect from reactive oxygen species in the Macrophage
Some blood borne pathogens have the ability to secrete coagulase which leads to coagulation allowing microorganisms to
form clots which in turn can provide a physical hiding place from the immune system.
What do Cytotoxins do
kills or affects the functions of host cells
What do Neurotoxins do
Interferes with nerve cells
What do Enterotoxins do
affects cells lining gut tract
Example of Neurotoxins
•Clostridum botulinum
•Clostridium tetanii
secrete extremely potent neurotoxins which lead to two very different forms of fatal paralysis
Example of Enterotoxins
•Clostridium perfringens
secretes an enterotoxin which can induce gastroentertis on its own
Is a virulence or colonization factor directly involved in causing a disease
Virulence factor
What is a colonization factor necessary for
A disease to progress but is not directly involved
Where are Endotoxins primarily found
In Gram negative organism
Example of Colonization factors
•Adhesins
•Flagella
Both for motility
Example of an Endotoxin
Lipopolysaccharide (LPS)
When are Endotoxins released
•On cell death
•Through membrane blebbing
Example of Anti-phagocytic factors
•Capsules
•Anti-phagocytic compounds
What is Phagocytosis blocked by
The capsule
Example of Opportunist Pathogens
•S. aureus commonly found on skin but pathogenic in blood infections
•C. difficile takes advantage of antibiotic treatments changing microbiome
Name the 3 modes of disease transmission
•Contact transmission
•Vehicle transmission
•Vector transmission
Explain Contact transmission in Disease transmission
•Direct contact-person to person
•Indirect contact-needles, toothbrushes
•Droplet transmission- spread via droplet nuclei
Explain Vehicle transmission in Disease transmission
•Air
•Drinking water
•Food
Explain Vector transmission in Disease transmission
•Biological
•Mechanical
Name the 2 basic protections from infection
•Skin
•Mucous membrane
How does Skin protect from infection
•Acts as barrier tight layer of packed cells
•Entrance through cuts
How does Mucous membrane protect from infection
•line the body cavities that are open to the outside world (nose)
What is the adaptive immunity system also known as
Acquired immunity
Explain Acquired immunity
•Develops from birth, as we encounter various pathogens
•Antigens trigger specific response
Name the components of Bacterial cells
•Cell walls, capsules
•Flagella
•Proteins (internal + external)
•Toxins
•Food may have antigens that provoke allergic reactions
What are Antigens recognised by
Antigenic determinants (epitopes)
Name the types of Antigens
•Exogenous
•Endogenous
•Auto
Examples of Exogenous antigens
•Toxins
•Components of microorganism cell wall
Explain Endogenous Antigens
•M/O that reproduce within the body
•Immune system can’t see the microorganism so must look for antigen
•Require in-corporation into host cell’s cytoplasmic membrane.
Explain Auto antigens
Antigens on normal uninfected cells which are inappropriately targeted
Name the types of Antibodies
•IgM
•IgA
•IgD
•IgG
•IgE
(MADGE)
How many polypeptide chains in Antibodies
4 polypeptide chains
How many identical long chains and how many short chains in an Antibody
•2 long
•2 short
What type of bond links chains
Disulphide bond
What shape are Antibodies
Y shaped
