37 Questions
What term is used for ALL organisms present on and in human bodies, often causing no harm?
Indigenous microbiota
Which of the following body sites is considered a strictly sterile site, according to the text?
Blood
What is disrupted in dysbiosis, leading to harm to the host?
Indigenous microbiota
Which project focused on the role of the gut microbiome in training the immune system and modulating it to decrease autoimmune disease risk?
Human Microbiome Project
What is a common example of an opportunistic pathogen mentioned in the text?
E. coli causing UTI
Where are Indigenous microbiota NOT found?
Blood
What is the term used to describe temporary residents on and inside our bodies?
Transient microbiota
Which term describes a symbiotic relationship where two dissimilar organisms live together and both benefit?
Mutualistic
What does microbial ecology study the interactions of microbes with, apart from other microbes?
Nonliving world
Which of the following is an example of a mutualistic symbiotic relationship?
E. coli in our gut
In commensalistic symbiosis, the relationship is beneficial to which of the organisms?
Only one organism
What term describes a symbiotic relationship where one organism benefits at the cost of another?
Parasitic
What is the role of lichens in a symbiotic relationship?
Mutualistic
What do we call a symbiotic relationship that benefits neither of the organisms involved?
Neutral
Which of the following is NOT a characteristic of the indigenous microbiota of the mouth?
Dry and lacking in moisture
Which of the following bacteria is most often implicated in the formation of dental plaque?
Streptococcus mutans
Which of the following is NOT a characteristic of the indigenous microbiota of the lower respiratory tract?
Harbors a diverse array of microbes
Which of the following is NOT a common organism found in the indigenous microbiota of the mouth?
Archaea
Which of the following is a characteristic of the indigenous microbiota of the gastrointestinal (GI) tract?
It is a long tube lined with mucous membranes
Which of the following is NOT a common organism found in the indigenous microbiota of the upper respiratory tract?
Anaerobic bacteria
Which of the following is a key function of the indigenous microbiota in the mouth?
Preventing tooth decay and gum disease
Which of the following is a characteristic of the indigenous microbiota of the skin?
Low pH and lack of nutrients
Which of the following anatomical locations on the skin is likely to have a higher concentration of bacteria?
Skin around mucosal openings
Which of the following factors does NOT influence the composition of the indigenous microbiota on the skin?
Exposure to ultraviolet radiation
Which of the following is a common bacterial genus found on the skin?
Propionibacterium
What is the significance of proper hand hygiene for healthcare workers?
To remove transient microbes and dead epithelial cells they may feed on
Which of the following statements about the indigenous microbiota of the eyes is correct?
Few microbes are present due to the presence of antimicrobial substances
Which of the following statements about the indigenous microbiota of the ears is correct?
The outer ear and canal contain the same microbes as the skin
Which of the following is NOT a characteristic of the indigenous microbiota in the colon?
Mostly aerobic organisms
What is the approximate number of different microbial species found in the colon?
500 to 600 species
Which of the following organisms is NOT an example of the indigenous microbiota found in the colon?
Helicobacter
What is the exception to the statement that inhibitory components inhibit the growth of most organisms in the gastrointestinal tract?
Helicobacter pylori
Where in the gastrointestinal tract are the majority of the indigenous microbiota found?
Colon
What is the primary function of bile in the duodenum?
To facilitate the digestion and absorption of lipids
What is the relationship between E. coli and the indigenous microbiota of the colon?
E. coli is a member of the indigenous microbiota, but can cause urinary tract infections.
What is the primary function of the acidic pH in the stomach?
To inhibit the growth of most microorganisms
Which of the following is a characteristic of the members of the indigenous microbiota found in the colon?
They are mostly anaerobic, aerotolerant, and facultative anaerobes.
Study Notes
Indigenous Microbiota
- Indigenous microbiota includes all organisms present on and in human bodies, causing no harm, and comprises viruses, fungi, bacteria.
- Specific regions have specific microbiomes, except for strictly sterile sites like blood, lymph, spinal fluid, and internal tissues.
Human Microbiome Project
- The Human Microbiome Project (2008) focuses on the role of the gut microbiome in training the immune system and modulating the immune system to decrease the risk of autoimmune diseases.
- The project also explores the imbalance of the gut microbiome and its link to obesity.
- Additionally, it examines trends in microbiome development in babies born by C-section and the relationship between intestinal microbiomes and neurodevelopment.
Characteristics of Body Sites
- Brainstorm: wet, dry, accessible to air, etc.
- Swimmer's ear: an example of indigenous microbiota in the ear.
Indigenous Microbiota - Respiratory Tract
- The respiratory tract is lined with mucous membranes and has two main areas: the upper respiratory tract (nasal passage and throat) and the lower respiratory tract (larynx, trachea, bronchi, and lungs).
- The upper respiratory tract has many microbes, mostly harmless, but can carry virulent pathogens and opportunistic pathogens.
- The lower respiratory tract is generally free of microbes due to the lungs and mucous membranes.
Indigenous Microbiota - Mouth
- Characteristics: gums, crevices between teeth, deep folds of the tonsil, moist, and lots of nutrients (e.g., food particles).
- Organisms: many species of bacteria, spirochetes, yeasts, molds, protozoa, and viruses.
- Common organisms: Gram-positive and gram-negative bacteria, spirochetes, yeasts, molds, protozoa, and viruses.
- Streptococcus mutans is the bacterium most often implicated in dental plaque formation.
- Other organisms include Actinomyces, Bacteroides, Corynebacterium, Lactobacillus, Neisseria, Staphylococcus, Streptococcus, and Veionella.
Indigenous Microbiota - GI
- Characteristics: long tube lined with mucus membranes, folds, and nutrients from food.
- Inhibitory components inhibit growth of most organisms.
- Acidic pH in the stomach, except for Helicobacter pylori.
- Bile in the duodenum.
- Organisms: mostly in the lower parts of the intestines like the jejunum and ileum.
- The colon contains the largest number and variety of microbes, with around 500-600 different species.
- Characteristics: anaerobic conditions.
- Organisms: mostly obligate, aerotolerant, and facultative anaerobes.
- Examples: Actinomyces, Bacteroides, Clostridium, Enterobacter, Enterococcus, Escherichia, Klebsiella, Lactobacillus, Parabacteroides, Proteus, Pseudomonas, Staphylococcus, Streptococcus.
- Many members of the colon microbiota are opportunists.
Indigenous Microbiota - GI (Colon)
- All humans have E. coli bacteria in their colon, which are opportunists, usually causing no problems, but can cause urinary tract infections (UTIs) when they gain access to the urinary bladder.
- There are also multiple strains of pathogenic E. coli that are not indigenous.
Microbial Ecology
- Definition: the systematic study of the interactions between organisms and the world around them.
- Relationships between organisms and their environment.
- Microbial Ecology: the interrelationship between microbes and the world around them.
- Study of their interactions with other microbes, the non-living world, and humans.
Symbiosis
- Definition: two dissimilar organisms (symbionts) living together.
- Mutualistic: both benefit (e.g., E. coli in the gut).
- Commensalistic: beneficial to only one (e.g., mites in hair follicles).
- Neutral: benefit neither.
- Parasitic: benefits one at the cost of another.
Indigenous Microbiota - Skin
- Characteristics: low pH, high levels of salt, lack of nutrients.
- Organisms: vary by site, mostly fungus and anaerobic bacteria living in deeper layers of skin.
- Composition varies by:
- Anatomic location
- pH
- Moisture
- Temperature
- Saltiness
- Toxic substances
- Think of skin on the body - a huge surface area.
- Repercussions for healthcare workers: proper hand hygiene is essential to remove most potentially harmful transient microbes and dead epithelial cells they may feed on.
Indigenous Microbiota - Eyes
- Characteristics: the eye is lubricated and protected by tears, mucus, sebum, etc. containing antimicrobials like lysozymes.
- Few microbes present.
Indigenous Microbiota - Ears
- Characteristics: outer ear and canal contain the same microbes as skin.
- Middle and inner ear are generally sterile.
- Microbes get carried into these areas when coughing or sneezing, leading to infection.
Test your knowledge on the human microbiome and indigenous microbiota, including the organisms present on and inside human bodies. Learn about the specific regions with distinct microbiomes and the role of the gut microbiome in training the immune system.
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