Microbiome Flashcards
(19 cards)
What is the microbiome?
The microbiome refers to the collection of microorganisms (bacteria, fungi, viruses, parasites) living in and on the human body in a normal, often beneficial, manner.
What are key benefits of the human microbiome?
It helps prevent colonization by pathogens, produces vitamins (e.g., B and K), supports digestion, and contributes to immune system development and homeostasis.
Where is the highest abundance and diversity of microbes found in the human body?
In the colon (large intestine), which hosts a dense and diverse microbial community.
What is meant by the microbiome being stable?
An individual’s microbiome remains relatively constant over time, even after disturbances like antibiotics, but is highly variable between individuals.
How is the microbiome acquired?
It begins at birth, influenced by delivery mode (vaginal vs C-section), and develops with diet and environmental exposure. Some evidence suggests possible prenatal colonization.
What is the role of diet in shaping the microbiome?
Diet influences microbiome composition—e.g., breastfed infants have more Bifidobacteria; vegetarians have more lactic acid bacteria, while meat-eaters have more Bacteroides.
What are opportunistic pathogens?
Members of the normal microbiota that can cause disease if they translocate to sterile sites or if host immunity is compromised. Example: E. coli causing UTIs.
What is dysbiosis?
An imbalance in the microbiome, often associated with disease states such as Crohn’s disease, obesity, allergies, or metabolic dysfunction.
What microbial groups dominate the colon microbiome?
Firmicutes (e.g., Clostridium, Lactobacillus) and Bacteroidetes (e.g., Bacteroides).
What are biofilms and where are they found in the body?
Biofilms are communities of microorganisms attached to surfaces. Dental plaque is a well-known example of a multi-species biofilm in the mouth.
How does the skin microbiome differ from the gut?
The skin is a harsh, dry, acidic environment colonized mainly by gram-positive bacteria (e.g., Staphylococcus), fungi (e.g., Candida), and is less diverse than the gut.
What are probiotics?
Viable, non-pathogenic organisms that, when ingested, confer health benefits to the host, often by improving gut health or supporting immune function.
What properties must a good probiotic have?
Human origin, resistance to gastric acid and bile, ability to colonize the gut, safety, and demonstrated health benefits.
What is a well-known strain of probiotic E. coli?
E. coli Nissle 1917, isolated during WWI from a soldier who resisted enterocolitis, is used pharmaceutically for its probiotic effects.
How can probiotics be administered?
Through fermented foods like yoghurt and cheese, or as pharmaceutical products containing specific strains with proven benefits.
Why can’t all microbial DNA detected in stool be attributed to living organisms?
Some detected DNA (e.g., from mushrooms or Saccharomyces) may originate from recently consumed food, not resident gut flora.
How do different regions of the gut vary in microbial density?
Microbial density and diversity increase from the stomach (acidic, low microbes) to the colon (anaerobic, highly populated).
How do antibiotics affect the microbiome?
They can disrupt microbial balance, reduce diversity, and allow opportunistic pathogens like Candida to overgrow.
How can the microbiome affect diseases not obviously related to infection?
Changes in microbiome composition have been linked to autism, diabetes, obesity, allergies, and other non-infectious diseases, though causality is unclear.
