Lecture 1/2: Normal Flora Flashcards
What organism plays a role in the development of an alternate microbiome during puberty in the female lower urinary tract?
Lactobacillus acidophilus.
What does commensal mean in microbiology?
What would the opposite of commensal be?
Commensal refers to organisms that are normally present on skin and mucous membranes of healthy hosts.
The opposite of commensal is pathogenic.
What surfaces would constitute external commensal habitats?
The skin.
What surfaces would constitute the internal commensal habitats?
Mucous membranes:
- Lower urinary tract
- Lower female genital tract.
- Digestive tract
- Upper respiratory tract
Does the lower respiratory tract have normal flora?
The lower respiratory tract does have sparse traces of Pseudomonas, Streptococcus, Prevotella, and Veillonella. But not clear if this is normal microbiota or just transient organisms. So in short, no.
Why do bacteria colonise humans?
Why might there be quite a large variety of commensal organisms?
There are many large areas on the human body for these organisms to inhabit, all providing fluid/nutrients/heat/osmotic stability.
The large variety of organisms results from a variety in microenvironments that the human body has. For example obligate anaerobes can inhabit the colon, facultative anaerobes can inhabit the skin, and some microorganisms such as L.acidophilus can inhabit acidic conditions (e.g. lower female reproductive tract).
What are some examples of unique environmental conditions that can be seen in the human habitat?
The large bowel is a largely anaerobic environment.
The female lower reprod. tract is acidic (around 4.5 pH) (After puberty).
The stomach is extremely acidic (pH 1.5 to 3.5)
The skin is relatively dry.
Upper respiratory system is highly aerobic.
Some parts of the mouth, such as under the tongue.
What is the parasite - host relationship?
The classification of organisms that groups them into commensal or parasitic depending on the amount of damage done to the host.
Lots of damage = pathogen.
“Insignificant” damage = commensal.
“Insignificant” damage + benefits = commensal.
