Microbiology Lecture 3: Normal Flora and Microbiota

Which bacterium is associated with vaginal health by keeping the pH low?

Which of the following bacteria is a main cause of dental plaque?

What is the name of the procedure that transplants fecal matter from a healthy donor into a recipient to restore the gut microbiome?

What is the name of the phenomenon where the presence of one microorganism prevents the colonisation of another microorganism?

Which bacterium is able to metabolize 164 drugs, including levodopa?

Which of the following factors can affect the diversity of the microbiome?

What is the ratio of human cells to bacterial cells in the human body?

What is the term used to describe the microorganisms that are permanent residents of certain body sites?

Which of the following body sites are usually sterile?

How does the microbiome contribute to human health?

Which of the following is a benefit of the microbiome in the gut?

What is the name of the compound produced by the microbiome that has neuroprotective properties?

Which of the following is a type of microbiota that is associated with infections of prosthetic heart valves and prosthetic joints?

What is the name of the research initiative that was funded by the National Institutes of Health Common Fund from 2007-2016?

Normal Flora and Microbiota

Normal flora refers to the permanent microorganisms that inhabit certain body sites, such as the skin, oropharynx, colon, and vagina.
Human cells to bacterial cell ratio is approximately 1:1.

Microbiome

The human microbiome consists of microorganisms that live in and on the human body.
The microbiome is composed of diverse microorganisms, including bacteria, archaea, viruses, fungi, and protists.
The microbiome plays a crucial role in human health and disease.

Gut Microbiome

The gut microbiome is composed of two largest phyla: Firmicutes (64%) and Bacteroidetes (23%).
Firmicutes include gram-positive rods, such as Clostridium and Faecalibacterium.
Bacteroidetes include gram-negative rods, such as Bacteroides and Prevotella.

Role of Microbiome in Human Health

The microbiome contributes to human health by:
- Occupying attachment sites, preventing colonization by pathogens
- Producing chemical compounds, such as bacteriocins and vitamins B and K
- Serving a nutritional function, such as producing short-chain fatty acids (SCFAs)
- Producing metabolites and bioactive compounds

Microbiome in Different Body Sites

Skin: Staphylococcus epidermidis, Candida albicans, and Staphylococcus aureus are common microorganisms found on the skin.
Oropharynx: Viridans streptococci, such as Streptococcus sanguinis and Streptococcus mutans, are found in the oropharynx.
Vagina: Lactobacillus species dominate the vaginal microbiome, maintaining a low pH and preventing the growth of pathogens.
Urethra: Staphylococcus epidermidis and fecal flora, such as Escherichia coli, are found in the urethra.

Factors Affecting Microbiome

Diet: Food and drinks can alter the microbiome diversity, such as phosphoric acids in fizzy drinks, coffee, and tea.
Drugs: Antimicrobials, proton pump inhibitors, and chlorhexidine can disrupt the microbiome.
Environment: Chlorinated water, processed foods, and fast foods can affect the microbiome.

Microbiome and Disease

Dysbiosis, or an imbalance of the microbiome, can contribute to various diseases, including enteric infections and oral cavity infections.
The microbiome can influence the metabolism of drugs, and certain strains, such as Bacteroides dorei, can metabolize multiple drugs.
The microbiome can also influence the bioavailability of certain nutrients, such as dopamine.

This quiz covers the normal flora and microbiota, including the colon microbiome, its composition, and the characteristics of different phyla. It is based on a lecture by Dr. Hadi Hussein Shwani, PhD, and is part of the National Institutes of Health Common Fund.