Microbiota and Normal Flora Overview

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Questions and Answers

What role does the gut microbiota play in the immune response?

It directly produces antibodies.

It induces the formation of all types of T cells uniformly.

It replaces the need for lymphoid follicles.

It influences the maturation and function of the immune response. (correct)

What happens to colonization resistance when antibiotics are used?

It has no effect on the gut microbiota.

It becomes stronger, preventing C.difficile overgrowth.

It is enhanced by the growth of beneficial bacteria.

It is lost, allowing C.difficile to overgrow. (correct)

What is a potential consequence of the normal flora being displaced?

Enhanced immune response.

Reduction in pathogenic infections.

Development of conditions like pseudomembranous colitis. (correct)

Increased production of healthy microbiota.

Which of the following statements is true regarding the effects of normal flora?

They can convert harmless substances into carcinogenic derivatives. Signup and view all the answers

In which scenario can normal flora become pathogenic?

When individuals are immunocompromised. Signup and view all the answers

Which part of the eye is protected from bacterial colonization by tears, mucus, and oil?

Conjunctiva Signup and view all the answers

What type of flora is typically found in the outer ear and auditory canal?

Normal flora Signup and view all the answers

Which microorganism can cause acute bacterial pneumonia in immunocompromised individuals?

Streptococcus pneumoniae Signup and view all the answers

What primarily causes the absence of bacteria in the stomach?

High acidity and gastric enzymes Signup and view all the answers

Which part of the gastrointestinal tract has the highest concentration of bacteria?

Large intestine Signup and view all the answers

What is the status of the urinary tract organs like kidneys, ureters, and urinary bladder?

Usually sterile Signup and view all the answers

What type of bacteria predominantly inhabits the vagina?

Lactobacillus spp. Signup and view all the answers

What happens to normal flora in the lower gastrointestinal tract if they relocate?

They become pathogenic Signup and view all the answers

What are microbiota primarily composed of?

Bacteria, fungi, protozoa, and viruses Signup and view all the answers

What is true about the composition of gut microbiota?

It includes bacteria, viruses, fungi, and parasites Signup and view all the answers

What happens when the number of resident microbiota is significantly reduced?

Opportunistic microbes can cause infections Signup and view all the answers

Which of the following best defines normal microbiota?

Microorganisms that reside in the body without causing harm Signup and view all the answers

Which of the following factors does NOT affect the composition of a person's microbiota?

Hair color Signup and view all the answers

What is the estimated weight of the gut microbiota in a healthy human?

2 kg Signup and view all the answers

At what stage in life does a human's normal microbiota begin to establish?

At birth Signup and view all the answers

What is the role of normal body flora in the host?

Contributes to the host's defense and health Signup and view all the answers

What is the main reason transient microbiota are temporary inhabitants of the human body?

They may not be able to compete with resident normal flora. Signup and view all the answers

Which of the following sites is NOT known for harboring resident microbiota?

Hair Follicles Signup and view all the answers

What type of bacteria primarily constitutes the skin microbiota?

Aerobic Bacteria Signup and view all the answers

Which factor contributes to the temporary nature of transient microbiota on the skin?

Production of sweat and oil Signup and view all the answers

What is the role of Cutibacterium acnes in the skin?

It is primarily found in sweat glands and hair follicles. Signup and view all the answers

Which of the following microorganisms is most abundant on the skin?

Staphylococcus epidermidis Signup and view all the answers

Which microbial species is primarily found in the conjunctiva of the eye?

Staphylococcus aureus Signup and view all the answers

How do resident skin microbiota contribute to preventing infections?

They occupy niches that could otherwise be taken by pathogens. Signup and view all the answers

What role do beneficial bacteria in the vagina primarily serve?

Keeping the pH acidic to prevent infections Signup and view all the answers

Which of the following substances do microbiota in the gut provide that is essential for digestion?

Vitamin K Signup and view all the answers

How do microbiota stimulate immune system development in newborns?

By competing with pathogens for resources Signup and view all the answers

Which of the following genera of bacteria is found in greater numbers in patients with inflammatory bowel diseases?

Proteobacteria Signup and view all the answers

What effect does the transplantation of fecal bacteria from obese mice to nonobese mice have?

Nonobese mice become obese Signup and view all the answers

What is a major function of normal flora in protecting the body?

Killing harmful pathogens and competing for nutrients Signup and view all the answers

In healthy individuals, which bacteria are typically more prevalent in the stool compared to those with certain diseases?

Firmicutes and Bacteroidetes Signup and view all the answers

What is one significant role of microbiota in relation to infectious diseases?

Offering resistance to infectious diseases Signup and view all the answers

Study Notes

Microbiota

Microbiota are microorganisms, primarily bacteria, fungi, protozoa, and viruses, commonly inhabiting the human body.
They are essential for normal bodily functions.
Many are harmless and some are beneficial.
The microbiota varies depending on location, age, sex, diet, etc.

Learning Objectives

Students should define normal microbiota and its functions.
They must define permanent and temporary flora.
They should explain the role of permanent flora.
Students should study the microbiota in different body parts.
They need to understand how the normal flora protects from diseases and their development.

What are Microbiota or Normal Flora?

Microbiota weighs approximately 2.5 kg in the human colon.
The microbiota consists mainly of bacteria.
These organisms are continuously present in the human body.
Under healthy conditions, microbiota are harmless and sometimes beneficial.
The collective term for these organisms which inhabit the body is also called microbiota, commensals, or microflora.

About Gut Microbiota

The human gut contains roughly 100 trillion microbes.
Microbiota is approximately 10 times the number of microbial cells found in the entire human body.
The gut microbiota encompasses around 5000 different species.
It weighs approximately 2 kg.
The gut microbiota includes bacteria, viruses, fungi, and parasites.
Major species of bacteria include Prevotella, Ruminococcus, Bacteroidetes, and Firmicutes.

The Human Microbiome: What is Known? What is Unknown?

25 phyla, 2,000 genera, and 5,000 species are known.
80% of the metagenome is mappable.
316 million genes are known.
Undetected unknowns include hidden taxa and strain-level diversity.
~20% of the sequences do not match microbial genomes.
~40% of genes lack matches in functional databases.

Stuff about Microbiota

A fetus is sterile at birth.
Microbiota develops after birth through contact with the environment, mother, air, food.
Microbiota populations are unique to each individual and are influenced by several factors.
Reduced amounts of normal microbiota can lead to infections by opportunistic microbes, like Candida albicans.
The human body microbiota is crucial in developing natural resistance.

Why Should We Know About Microbiota?

Understanding how infections result from injuries or specific body sites is important.
Identification of microorganisms from infection sites is essential.

Transient Microbiota

Transient microbiota is present temporarily on and within the human body.
Transient microbes, residing in moist, warm body regions.

Why are these microbes temporary?

Washing from external parts through bathing
Incapable of competing with resident flora.
Killed by resident flora products.
Can't survive in acidic or alkaline sites.
Removal by bodily secretions.

Where can we find Microbiota?

Microbiota is present in body parts exposed to external environments.
This includes Skin, Eyes and Ears, Respiratory Tract, Oral Cavity (Mouth), Gastrointestinal Tract, and Urogenital Tract.

Skin

Skin acquires transient bacteria from the environment.
Skin becomes dry and produces sweat and oil, causing transient bacteria to either die or be washed away.
Resident bacteria inhabit any layer of skin.
Aerobic bacteria like Staphylococcus epidermidis and Staphylococcus aureus reside on the outer skin layers.
Anaerobic bacteria like Cutibacterium acnes are prevalent in deeper layers like hair follicles and sweat glands.

Eyes

The conjunctiva mainly has Staphylococcus epidermidis.
Staphylococcus aureus, Corynebacterium diphtheroids, and Streptococcus pneumoniae in lesser amounts.

Ears

The middle and inner ear are sterile.
The outer ear and auditory canal contain normal flora similar to skin.
Microbes may enter the middle ear through coughs and sneezes, leading to infections.

Respiratory Tract

Upper respiratory tracts (Nose and Throat) contain many microorganisms.
Some are normal flora, others are opportunistic, and some are carried.
Lower Respiratory tract is usually sterile.

Oral Cavity (Mouth)

Oral cavity contains both aerobic and anaerobic bacteria.
Common examples are C. diphtheroids, S. aureus, and S. epidermidis.
Yeasts, molds, protozoa, and viruses also inhabit the mouth.

Oral Cavity Teeth and Gingiva

Yeasts, molds, protozoa, and viruses are present in the mouth.
Poor dental hygiene promotes bacterial growth leading to gum diseases and tooth decay.
Risks of endocarditis after dental surgeries.

Gastrointestinal Tract

Stomach has only a few bacteria due to acidity and enzymes.
Small intestine has fewer normal flora due to bile.
Colon has more normal flora, largely anaerobic organisms.

Gastrointestinal Tract Large Intestine

Colon has more bacteria compared to other body parts.
Approximately 99% of large intestine bacteria is anaerobic.
Many fungi, protozoa, and viruses are also present.
E. coli can lead to urinary tract infections if it moves out of the GI tract.

Microbiota in the Gastrointestinal Tract (GIT)

Different bacteria genera are present.
Organisms like Bacteroides fragilis lead to abdominal abscesses.

Urogenital Tract

Kidneys, Ureters, and Urinary Bladder are sterile.
The lower urethra and external opening contain bacteria, yeast, and viruses, including those found on skin.
Vaginal Lactobacillus protects against opportunistic infections (e.g., Candida and bacterial vaginosis).

Genital Organs

Male and female genitalia are sterile except the vagina.
Lactobacillus protects the vagina from fungal and bacterial infections

Normal Flora in the Vagina

Types of microorganisms found in vagina. Examples of organisms include Lactobacillus species.
Common organism thriving in the absence of normal vaginal flora is Candida albicans (yeast).

Sterile Body Zones

Listing of body parts which are essentially free from microorganisms.
Examples include the middle ear, sinuses, paranasal sinuses, larynx, trachea, blood, bronchi and others.

Beneficial Functions of Normal Flora

Protection from invaders, like pathogenic organisms
Immune development in newborns
Digestion enhancement by vitamin K provision

Importance of Microbiome

Significance of organisms in microbiome in crucial body functions, like weight control, inflammatory bowel disease, and immune response..
Fecal transplant from obese mice to germ-free mice resulted in obesity in the recipient mice, showing microbiome's significance in controlling body weight.

Harmful Effects of Normal Flora

Infections from displaced normal flora (such as in bloodstream)
Competitive advantage of pathogens due to reduced normal flora (e.g. Clostridium difficile after antibiotics)
Harmful products formed from normal flora (e.g. carcinogenic compounds from food)
Overgrowth in immune compromised individuals

Nutritional Modulation of the Gut Microbiome

Nutritional factors influencing the composition of gut microbiota.

Western and Plant-Based Diets' Impact on Microbiome

Differences in the microbiome composition related to different types of diets.
Benefits and risks of different dietary patterns regarding nutrition-related diseases and chronic conditions.

Colonization Resistance

The microbiota of the colon prevents the overgrowth of pathogens like Clostridioides difficile.
Fecal transplant from healthy individuals can cure resistant antibiotic colitis
Importance of microbial balance for overall health

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Description

Explore the fascinating world of microbiota, the microorganisms that inhabit our bodies and play vital roles in maintaining health. This quiz will help you define normal microbiota, differentiate between permanent and temporary flora, and understand their protective functions against diseases. Dive into the intricate relationships between microbiota and various body parts.