Lecture 8: Microbes and Disease Flashcards
Tuesday 22nd October 2024
What did Fracastoro say in 1546?
that invisible organisms cause disease
What did Leeuwenhoek discover in 1676?
‘animalcules’
What did Jenner discover in 1798?
The smallpox vaccination
What did Snow discover in 1849?
Epidemiology of cholera
When did Koch come up with his postulates? (linking pathogens to disease)
in 1884
Who discovered the chemotherapeutic agent for syphilis?
Ehrlich in 1910
When was Penicillin discovered and who by?
In 1929 by Fleming
Are the lungs normally sterile?
Yes
Is the urinary tract usually sterile?
Yes, except for the distal region of the uretha
what protects our gastrointestinal system from bacteria?
Normal flora
Is it true that all parts of our body have microbes?
Yes
Was it a surprise when researchers found that the respiratory tract was populated with bacteria deep into our lungs (and not just towards the top)?
Yes
Where are most microbes in the human body found?
In the gut
What does the lower respiratory tract include?
Trachea, Bronchi, Lungs (usually aren’t that highly populated with bacteria)
What happens if you have poor oral health?
Your teeth will be covered by film
Why do the levels of bacteria increase as you go down the body?
- community becomes more dynamic
- pH changes
Who first suggested the idea of the ‘human microbiome’?
Joshua Lederberg
What is the microbiome?
“the ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share our body space”
What was the human microbiome project?
A US-funded project to assess the microbiome in 250 volunteers
What are the health benefits of the human microbiome?
- Preventing the attachment of bacteria to our epithelial cells
- Production of vitamins by bacteria (e.g. vitamin K in gut)
What problems are the microbiome associated with?
Obesity
Type 1 Diabetes
Crohn’s disease
Irritable bowel syndrome
Colon cancer
What do probiotics do?
They can help replenish benficial bacteria
What do prebiotics do?
They serve as a food source for beneficial bacteria in the gut
What allows for a bacteria to have virulence?
Adhesion to and entry into cells
Ability to turn off elements of the immune system
Production of toxins
What are conventional virulence factors?
- bacterial toxins
- adhesins
- cell surface carbohydrates and capsules
- secreted hydrolytic enzymes
- LPS
What are virulence factors usually encoded on ?
plasmids or through horizontal gene transfer, meaning pathogens can acquire these factors from other organisms, making non-pathogenic bacteria potentially dangerous under the right conditions.
What are some less common factors that can contribute to bacterial virulence?
- secretion machineries
- Siderophores
- catalases
- Genetic regulators
Is it true that virulence may be plasmid or phage encoded?
Yes
What are the major Staphylococcus aureus virulence factors?
Adherence
Iron uptake
Antiphagocytosis
Secretion system
Exoenzyme
Toxins
What does MRSA stand for?
Methicillin Resistant Staphylococcus aureus
What bacteria is a key example of antibiotic resistance?
MRSA
Are many MRSA strains now resistant to vancomycin?
Yes
is it true that VRSA is untreatable by any known antibiotic?
Yes
What is ‘new’ pathogen Burkholderia cepacia?
B. cepacia and related species are highly versatile bacteria, mainly associated with plants and soil
WHen was Burkholderia cepacia recognised as a potential human pathogen?
in the mid 1980s in cystic fibrosis (CF) patients
( spreads easily between CF patients, leading to changes in how CF patients are treated.)
What ‘antibiotics’ were used in the egyptian era?
Mouldy bread used to treat wounds in Egypt
What ‘antibiotics’ were used in the medieval era?
Plants used to make anti-infection treatments in medieval England
What was the first modern antibiotic and when was it discovered?
The first modern antibiotic, penicillin, was discovered in 1928.
What was the 1909 arsenic based treatment for syphilis?
Salvarasan in 1909
What are the 5 major types of antibiotic?
Beta-lactams
Macrolides
Fluoroquinolones
Tetracyclines
Aminoglycosides
What are some examples of Beta-lactams
Penicillins and cephalosporins
What do Macrolides do?
Inhibit protein synthesis
What is an example of a Macrolide?
erythromycin
What do Fluoroquinolones do?
Inhibit DNA gyrase
What is an example of a Fluoroquinolone?
ciprofloxacin
What do Tetracyclines do?
Inhibit protein synthesis
What do Aminoglycosides do?
Inhibit protein synthesis
What is an example of an Aminoglycoside?
kanamycin
Through which mechanisms do bacteria carry out antibiotic resistance?
Reduced permeability (Penicillins). This is where cell walls are altered to prevent drug entry.
Inactivation (Penicillins, Aminoglycosides
). Enzymes are produced that break down antibiotics.
Target alteration (Macrolides). Modifying drug targets
New resistance pathway (Sulfonamides)
Efflux (Tetracylines, erythromycin
). Actively pumping drugs out of bacteria.
When did Edward Jenner invent the smallpox vaccination?
in 1796
When did Louis Pasteur test a weakened anthrax vaccine on sheep?
1881
When did Louis Pasteur find asteurella multocida (chicken cholera) became much less virulent after exposure to air for a long period?
In 1879
What is tetanus caused by?
The toxins produced by bacteria Clostridium tetani- not the bacteria itself.
What does tetanus’ neurotoxin cause?
over-activity of motor neurons causing muscle spasms … hence ‘lockjaw’
What does tetanus’ vaccine target?
the toxin rather than the bacterium
What does the tetanus neurotoxin target?
The CNS, by binding to peripheral nerve terminals and travelling along axons
What is the name of the tetanus neurotoxin?
Tetanospasmin
What type of toxin is Tetanospasmin?
An AB toxin
is Tetanospasmin released by cell lysis and spread through the blood and lymph?
Yes
What impact does the fact that Tetanospasmin halts the release of of glycine & GABA neurotrasmitters have?
Glycine and GABA neurotransmitters would normally check for nervous impulses. In the presence of tetanospasmin, muscular spasms occur
Does recovery from tetanus confer immunnity?
No
Why doesn’t the recovery from tetanus confer immunity?
because even lethal doses are really small
What is the tetanus toxoid?
an inactivated form of the Clostridium tetani toxin (tetanospasmin) that has been chemically altered so that it can no longer cause disease, but still stimulates the immune system to produce a protective immune response. It is used as the primary component in tetanus vaccines.
What is meningitis?
The inflammation of the ‘meninges’, which are the protective membranes that cover the brain and spinal cord
How high is the meningitis fatality rate?
Very high
What is the major cause of bacterial meningitis?
Haemophilus influenzae
