What is the microbiome?
Microbes including bacteria and fungi are everywhere: on the surfaces we touch and in the air we breathe. Some are on our bodies, and some within. Some are transient, or temporary, members of our bodies while others stay much longer. The microbes frequently associated with our bodies make up what we call our microbiota, which has also been called our normal microflora. You may have also heard it called the microbiome, which includes culturable microbes that can be grown outside of the body, in addition to non-culturable microbes known to be associated with our bodies. According to a preprint article by Sender, Fuchs, and Milo, the number of microbes in our microbiome has been suggested to match the number of our cells. That’s a lot of microbes!
Because they are our normal microflora, do they ever make us sick?
Yes! Our normal flora can cause disease if they end up in a different location within the body. For example, a skin microbe can enter the bloodstream through an open wound and travel to other parts of the body where it may exhibit harmful effects. Another instance in which they cause disease is if a change in your body helps only certain members of your microflora grow better, thereby changing the balance of microbes present. Because these changes disrupt the balance of these populations, they may also alter your health. In fact, many diseases are linked to disruptions in our microbiome, including inflammatory bowel disease, diabetes, ulcers, and more!
Here are some other microbial diseases you might not have known are caused by otherwise normal microflora:
- Strep Throat (a.k.a. acute pharyngitis)
Figure 1. Colonies of Streptococcus pyogenes on a blood agar plate. The presence of clear zones around the colonies indicates these bacteria are capable of lysing (killing) blood cells. (Source: Richard R. Facklam, Ph.D., CDC)
Causative Agent: Streptococcus pyogenes (S. pyogenes) (Group A Streptococcus)
Location: Streptococci are normal inhabitants of our bodies, in which the Group A Streptococcus (GAS) organism S. pyogenes is commonly found in areas such as our nasal passages, throat, and skin.
How it causes disease: Typically, the development of strep throat results from inhalation of airborne droplets containing S. pyogenes from another individual. This new strain (or type) of S. pyogenes was able to establish an infection in your oropharynx (throat) and grow so well that it outgrew some of your resident microflora. S. pyogenes produces toxins, so more S. pyogenes means more damage.
- Toxic Shock Syndrome (TSS)
Figure 2. Light microscopy image of methylene blue stained **Staphlyococcus aureus. (Source: CDC)
Causative Agent: Staphylococcus aureus (S. aureus)
Location: S. aureus is found on the surface of 30% of healthy individuals, and at least once in the lifetime on 90% of people. The most prominent sites of encounter with S. aureus are the skin and soft tissue (the layers under the skin and lining the muscles). However, S. aureus can grow on almost any organ or tissue.
How it causes disease: Some strains of S. aureus produce toxins called toxic shock syndrome toxin 1 (TSST-1). These strains are not found in every individual, but if present, are low in number. In the case of menstruating women, use of a high absorbency tampon introduces oxygen into an otherwise anaerobic (no oxygen) environment, triggering TSST-1 production by these organisms. Your immune cells normally respond to S. aureus infection through temporary interactions with each other that induce the release of pro-inflammatory cytokines (chemical messengers that call more immune cells to the site of infection). The TSST-1 toxin is a superantigen that locks these immune cells in a permanent interaction, resulting in the massive release of cytokines and extensive damage to the tissues. In non-menstrual cases of TSS, rashes and peeling of the skin also occur.
- Yeast Infections
Figure 3. Microscopy image of **Candida albicans, the fungus that causes yeast infections.
(Source: Dr. Lucille K. Georg, CDC)
Causative Agent: Candida albicans (C. albicans)
Location: C. albicans can be found on the skin. It commonly manifests as a vaginal yeast infection in women but can also affect men.
How it causes disease: Changes in pH can alter the way organisms grow: some do better, others do worse. Bacteria called Lactobacilli produce a lot of lactic acid and keep C. albicans growth in check. Often, antibiotic use or hormonal changes disrupt this balance by killing these Lactobacilli, which enables C. albicans to outgrow your other microflora. That’s why probiotics (live bacteria) made with Lactobacilli and prebiotics (substances that enhance the growth of Lactobacilli) are increasingly used to maintain a healthy balance in our bodies.
As you can see, your microbiome is important for your health. Proper maintenance of our bodies such as a healthy diet and good hygiene can greatly affect our normal microflora, and thus, our overall health.
 Engleberg, N. C., T. Dermody, and V. DiRita. 2013. Mechanisms of microbial disease. Schaechter’s mechanisms of microbial disease. 5th ed. Baltimore, MD: LIppincott Williams & Wilkins.
More From Thats Life [Science]
- Dying Tomatoes, Healthy Kittens, and the EMP500: Why you should care about the International Society for Microbial Ecology
- The Purebred Poodle Problem
- Let It Glow
- I’m Likin’ That Lichen
- Celebrate the Holidays with a Decorative Parasite
- Sleeping One Hemisphere at a Time
- Through the Mycologist's Hand Lens: Deceptive Decomposers
- Life Science in Outer Space!
- 5 Things You Didn’t Know About Rats
- Watermelon Snow
- Critter Candid Cam
- Three Cool Plants in Hot Places
- A parasite only a moth could love
- Telling tales of plants and their names
- The Colorful World of Primate Hair
- Where do fish go in winter?
- You Scratch My Back and I’ll Scratch Yours
- Alien Microbes: How studying hyperthermophiles can help us discover life on other planets
- Life, the universe, and everything: Dreams of being a biophysicist
- Bug Sleuth – One Entomologist’s Mission to ID a Mysterious Swarm of Wasps
- Horny and Hungry: The Dilemma of Sexual Cannibalism
- Who’s who? The elusive difference between butterflies and moths
- Tuberculosis - A Romantic Disease?
- Ode to a Few Arachnids
- Monotropa uniflora - This wildflower is pretty wild
- Eavesdropping in the Animal Kingdom: Sneaky Creatures Just Trying to Get Ahead
- Trypanosomes - A Weird Pathogen You Haven't Heard Of
- A Beautiful 9/11 Tribute, but a Fiasco for Migratory Birds
- Cats can have AIDS, too.
- Part 2: Does catching Pidgeys help you notice Pigeons? Interviews with Pokémon Go Researchers
- Biodiversity in my Backyard: Encounters with Pidgeys and Dratinis, Part 1
- Fins, Limbs, Rays, and Digits – A Beginner’s Guide to Terrestrial Living
- Fins, Limbs, Rays, and Digits – A Beginner's Guide to Terrestrial Living
- Five things that really stink about the Brown Marmorated Stink Bug
- Tricks but no Treats - An Orchid’s Guide to Making a Fool of Your Pollinator
- Tracking the lost years - where do baby sea turtles grow?
- Posing as a Bird Mama: the adventures of a researcher-turned-bird-parent
- Hot moves and sexy sons · When Boys Become Men By Dancing
- The hungry caterpillar in real life
- Mantis Shrimp Vision - Seeing in Secret Code
- When It Comes to Bird Beaks - Size Matters
- Is your gut trying to kill your resolve? · Mind over microbe
- Recent talk of walls in the media has brought up a lot of emotions, but what do walls do in nature? · When a Wall is just a Wall
- Bees are more than buzzing insects around you · May the Bees Be With You: Maintaining the Sweet Balance in Life
- Neither a toad nor a worm · Nematodes: The super microscopic animal!
- Snap! Flash! Bang! Find out how ocean-dwelling pistol shrimp fire bubble ‘bullets’ to stun their unsuspecting prey. · How Pistol Shrimp Kill with Bubbles
- Who needs males after all?
- Ecology and Behavior of Woodchucks · Opposition Research on My Garden’s Greatest Nemesis
- Vision in Jumping Spiders · Watching Your Every Move
- Slimed and Consumed - The Blob is Real!
- The Evolution and Ecological Impacts of Cats · Lion in Sheep's Clothing
- What happens when frogs have to compete for acoustic space and a chance to be heard? · Struggling to be Heard - Competition in a Complex Soundscape
- Think Genghis Khan and Napoleon were the most successful invaders? Think again. · Invasive Species and Invasion: Part 1
- When, and how, terror birds invade
- 8 Reasons Plants Are Amazing
- Too Clean for Comfort · How our obsession with cleanliness might be hurting our health
- Stop, evaluate, and listen - serotonin surges when a female is present
- No Teeth, Long Tongue, No Problem - Adaptations for Ant-eating
- The Good, the Bad, and the Ugly - Predators, Parasitoids, and Parasites
- How our microbiome affects our health and vice versa · If you don't care for your microbiome, you might want to start
- Finding new ways to grow bacteria to progress science · Culturing the Least Cultured Members of Society
- Hit the Road Jack
- What Happened to Your Nose?
- Building better plants - Norman Borlaug and the Green Revolution
- Love Songs for Nobody - Birdsong in Winter
- We know we get infections from time to time. Why does this happen? · The Evolution of Virulence
- How cheese rinds may be a valuable tool for microbial discovery · The Unseen World – On Cheese?
- Find Me Where the Wild Things Are
- A commentary on how to make science more ‘clickable’ · You won’t believe this simple trick to tell if your coral is healthy or not
- Some species hide in plain sight, but scientists have ways to suss them out · Cryptic Species Hide in Plain Sight
- Minuscule Hitchhikers Pinch a Ride · Creature Feature - Pseudoscorpions
- World Fish Migration Day 2016!
- Walking With Giant Anteaters
- Why we should care about sea turtles · When A Sea Turtle Balanced Earth
- More ›