Bacteria and human disease Flashcards
What are Kochs Postulates
They were a set of conditions set out by the bacteriologist Koch that would help link the bacteria to the disease
List Kochs Postulates
- Microbe must be found in abundance in organism suffering the disease, but not found in healthy organisms
- The microbe must be isolated from the disease organism and grown in culture
- The cultured microbe should cause disease when introduced into healthy organism
- The microbe must be reisolated from inoculate, diseased experimental host and identified as being identical to original specific causative agent
How might microbiota cause disease
Dysregulation in the microbiota population may cause an increase in the clinically relevant microbe population due to environmental triggers.
At first, the population of these is too low to be clinically relevant.
Why was there a need to develop new Kochs postulates?
Some of the conditions didn’t match the diseases.
For example, some bacteria in microbiota could cause illness. Seen as these bacteria could be found in both healthy and diseased patients, it did not filt Koch’s postulates.
What are new Koch’s postulates
- Present in sufficient number to cause disease
- Generate high levels of specific antibodies
- Produce relevant virulence factors
- Cause disease in appropriate animal model
- ON elimination must result in clinical improvement
What is dental plaque?
Found on surface of teeth. Brushed away on mornings and evenings.
Commonly contains two bacterial strains:
Streptococcus mutans
Streptococcus mitis
Why is S. mutans ‘bad’?
In normal conditons feeds on carbohydrates to form acid in small concentrations.
After a large sugar meal however, these bacteria strip away the nutrients from S. mitis and form more acid.
The high concentration of acid together with nutrient depletion reduces the concentration of healthy S. mitis.
Why does prolonged high sugar diet lead to caries?
The high acid concentration produced by S. mutans selects bacteria that can survive high pH environments.
This leads to caries.
What is Acne Vulgaris?
A chronic inflammatory condition affecting sebaceous glands.
Sometimes results in cutaneous scars and mental health issues.
What is the aetiology of acne?
Complex.
Caused by
Hormonal changes
Immune hypersensitivity
Abnormal keratinisation
Bacterial growth
What is the pathophysiology of acne?
- Abnormal desquamation of the neck of follicle causes accumulation of sebum
- P. acnes aggrevates by inducing over-expression of IL-1a by macrophages and keratinocytes
- P. acnes causes complement activation and release of pro-inflammatory cytokines like IL-1, IL-8 and TNF-a from macrophages
- This leads to inflammation
- Results in the formation of pustule
What proof links microbiota and obesity?
Stool sample injected into germ-free mice
One sample taken from normal-sized female twin
One sample taken from obese counterpart
The mice were given the same diet
The mice with obese stool became obese.
