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Bacteria on the Skin - Health Benefits and Infections

A young baby already has bacteria living on his or her skin.
A young baby already has bacteria living on his or her skin. | Source

Bacteria in and on the Body

Many people believe that bacteria living in or on our body must be bad for us. In reality, most of the trillions of bacteria that share our body with us have either a beneficial or a neutral effect on our lives. In fact, it would be difficult to survive if all of our microbes disappeared. Most of the microbes live in our digestive tract, but a large population lives on the skin.

About a trillion microscopic organisms reside on or in the skin. Most of them are bacteria. The majority of these bacteria are harmless. Some are harmless most of the time but can cause a problem under certain conditions. Some may actually be helpful and are thought to boost the activity of our immune system.

The resident bacteria on the skin are sometimes known as the skin flora and are said to form the skin microbiome. They feed on dead skin cells, chemicals released by living cells and sebum. Sebum is an oily substance made by sebaceous glands. Its chief function is to lubricate and waterproof the skin.

Structure of the skin
Structure of the skin | Source

Resident and Transient Bacteria on the Skin

Bacteria on the skin are classified as resident or transient bacteria. Resident bacteria live on the surface of the skin and in its upper layer. They are our long-term companions and aren't removed by washing with soap and water. They can be removed with certain antibacterial chemicals, though. This article focuses on some effects of resident skin bacteria on our lives.

Transient bacteria are those that we pick up when we touch contaminated surfaces. They aren't as firmly integrated with our skin as our resident bacteria and can be removed by washing with soap and water. Transient bacteria are more likely to be harmful than resident ones. When health experts tell us to wash our hands to prevent infections, they are often thinking about the potentially dangerous transient bacteria that may come into contact with our skin.

An NIAID Scientist Describes Good Skin Bacteria

The species of bacteria living on and in our skin depends on the habitat. Dry skin, oily areas and areas that tend to stay moist (such as the skin between the toes) all contain different bacterial communities. Fungi also live on our skin.

Resident Skin Bacteria May Boost Immunity

Resident skin bacteria are classified as commensals. Commensalism is a relationship in which one organism benefits from the association and the other is unaffected. Mutualism may be a better name for the relationship between skin bacteria and us, however. In mutualism, both organisms benefit from their association.

Recent evidence is showing that bacteria living on the skin may help us. The evidence suggests that some may protect us from pathogens (microbes that cause disease) by stimulating the activity of our immune system and possibly by making antimicrobial chemicals. The immune system's job is to fight disease.

A stained specimen showing Leishmania inside a bone marrow cell
A stained specimen showing Leishmania inside a bone marrow cell | Source

Bacterial Protection from Leishmania

In 2012, researchers at the National Institute of Allergy and Infectious Diseases (NIAID) performed an interesting experiment in mice. The experiment demonstrated the protective role played by one type of skin bacterium. The mice were germ-free and had no microbes in their gut or on their skin, the most common sites for bacteria in both mouse and human bodies.

The researchers added a bacterium called Staphylococcus epidermidis to the skin of some of the germ-free mice. The bacterium multiplied and colonized the skin of the mice. The researchers then added a protozoan parasite called Leishmania major to the skin of the germ-free mice that had been given Staphylococcus and to the skin of germ-free mice without Staphyloccus. The mice with Staphylococcus were able to fight Leishmania; the mice without Staphylococcus were unable to fight the parasite.

Leishmania is also a parasite on human skin and Staphylococcus epidermidis is part of our skin flora. The researchers suspect that the results of their experiment with mice would be the same if the experiment was performed on human skin.

In humans, Leishmania causes a disease called leishmaniasis. The most common type of the disease is restricted to the skin and is called cutaneous leishmaniasis. Visceral leishmaniasis affects the internal organs and is a very dangerous disease.

Staphylococcus aureus, a common bacterium on human skin
Staphylococcus aureus, a common bacterium on human skin | Source

Bacterial Protection from a Fungal Infection

In 2015, the same team that studied the relationship between Staphyloccus epidermidis and Leishmania reported another interesting discovery about the bacterium. Once again, the study was performed in mice.

Once Staphyloccus epidermidis had colonized the skin of the mice, the researchers found an increase in the number of CD8+ T cells in their body. These T cells are part of the immune system in both mice and humans. The cells produce signaling molecules that stimulate other cells in the immune system and cause them to spring into action.

After the T cell level had risen, the researchers applied a pathogenic fungus to the skin of the mice. The mice were able to destroy the fungus. If the T cell and signaling molecule levels were reduced, the mice were unable to fight the pathogen.

Resident skin bacteria are nearly always harmless or possibly helpful. Sometimes they may cause a problem on the surface of the skin, however. Transient bacteria may also cause or contribute to skin problems. In rare cases, bacteria may penetrate the skin and enter the bloodstream, causing an internal health problem.

Folliculitis decalvans

Folliculitis

One skin problem caused by bacteria is folliculitis, or inflammation of the hair follicles. A hair follicle is a structure in the skin that produces a hair. It can become inflamed by either a bacterial infection or an irritation. Folliculitis is most common where skin is damaged. Insect bites, shaving cuts or friction as the skin is rubbed repeatedly against clothing are some ways in which this damage may occur.

Follicuilitis causes groups of small, red bumps to appear on the skin. The skin may also be itchy. If an infection is present, pimples filled with pus may form. Mild folliculitis may not need any treatment. Doctors may prescribe antibiotic creams or tablets for more serious cases.

The video above describes Folliculitis decalvans, a rare disorder in which inflamed hair follicles on the scalp are accompanied by patches of hair loss, or alopecia. The cause isn't known, but it may sometimes be due to an abnormal reaction to Staphylococcus aureus.

How to Treat a Boil

Boils and Carbuncles

Like folliculitis, a boil is produced due to an infection of hair follicles. In this case, however, the infection goes deeper into the skin and a large, painful swelling filled with pus develops over the infected area. Boils are also called furuncles.

Home treatment includes applying warm compresses to the boil for ten minutes at a time, three or four times a day. When the boil ruptures it should be covered with a sterile dressing. It's important to be careful at this stage, since the fluid from the boil contains bacteria which can infect new areas. If a boil is soft, it may not burst on its own. This type of boil requires medical treatment.

A carbuncle is a more extensive infection in which a group of boils form. It often causes more discomfort than single boils and may be harder to treat.

Impetigo sores
Impetigo sores | Source

Impetigo

Impetigo is a very contagious skin infection that is most common in young children. Red sores or blisters may appear on the face - especially around the nose and mouth - and on the neck, hands, forearms or diaper area. Impetigo may develop on undamaged skin, but it usually appears on skin that has been irritated by being scratched after another injury, such as an encounter with poison ivy.

Large blisters are produced in bullous impetigo while crusted sores are produced in non-bullous impetigo. Non-bullous impetigo is the most common type. Stapyhlococcus aureus can cause either type of impetigo. Non-bullous impetigo may also be caused by a form of Streptococcus.

Impetigo can be spread from one part of the body to another or from one person to another by skin contact. Touching materials like wash cloths, towels or clothes that have come into contact with the sores can also transmit the disease. Impetigo is generally treated with an antibiotic cream or with an antibiotic medication that is swallowed.

Impetigo Information

Cellulitis

Cellulitis is an infection of the tissues below the surface of the skin. It can be treated by antibiotics. It's potentially dangerous, however, because the bacteria may enter the blood or lymph nodes under the skin and then spread through the body. It's important to begin treatment as soon as possible.

Streptococcus and Staphylococcus are common causes of cellulitis. Unfortunately, MRSA (methicillin-resistant Staphylococcus aureus) also causes cellulitis. This bacterium is hard to treat because it's resistant to many common antibiotics, including methicillin. It's a different variety of bacterium from regular Staphylococcus aureus.

A colorized view of the MRSA bacterium
A colorized view of the MRSA bacterium | Source

Risk Factors for Cellulitis

Factors that increase the risk of cellulitis development include:

  • a prior injury that has damaged the skin, making it easier for bacteria to penetrate the deeper layers of the skin
  • disorders that weaken the protective barrier of the skin, such as eczema and psoriasis
  • certain health problems, such as diabetes and disorders that weaken the immune system
  • being an older adult

A Patient With Cellulitis

Symptoms of Cellulitis

Possible symptoms of cellulitis include the following.

  • The infected area is red, warm, swollen and tender. These symptoms may occur in other conditions besides cellulitis, but they are a warning sign and should be watched very carefully.
  • If the red and swollen area is expanding, see a doctor very soon.
  • If the red and swollen area is rapidly getting worse, see a doctor immediately.
  • If a fever is present as well as a red and swollen area, see a doctor immediately.

Acne in a fourteen-year-old boy
Acne in a fourteen-year-old boy | Source

Bacteria and Acne

Propionibacterium acnes is a normal inhabitant of most people's skin. It lives within the hair follicles instead of on the surface of the skin. The bacterium feeds on fatty acids in sebum, chemicals made by cells and cellular debris. It may also be found in our gastrointestinal tract. Like other bacteria in our body, Propionibacterium acnes is metabolically active. It releases digestive enzymes and other chemicals and alters the environment around it.

Despite its activities, Propionibacterium acnes is usually a harmless member of our bacterial community. However, like some other skin bacteria it may occasionally cause problems. During adolescence the amount of sebum that's made increases as a response to hormonal changes. This may cause a corresponding increase in the population of Propionibacterium acnes. At high levels the bacterium can cause inflammation and play a role in the development of acne.

It's important to wash our hands after using a restroom.
It's important to wash our hands after using a restroom. | Source

Hand Hygiene

Like skin bacteria, most bacteria in our intestine are helpful or harmless, but some dangerous bacteria may be present. These can be released in feces. Fecal bacteria can easily be transferred to our hands when we use a toilet or a public washroom. Washing the hands in these situations is therefore extremely important. Washing the hands before eating is also important in order to remove any harmful transient bacteria that we've picked up by touching objects.

It's also necessary to wash the hands after coming into a contact with certain skin problems caused by bacteria. The bacteria are often behaving abnormally or located in an unusual habitat (for them) and can sometimes be transferred from one person to another.

Fortunately, although some bacteria can cause unpleasant or dangerous infections, the majority of the resident bacteria on our skin are friendly. Scientists are making very interesting discoveries about the lives of these organisms and the ways in which they affect us. Skin bacteria may help us in more ways than we realize.

© 2013 Linda Crampton

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Comments 28 comments

mnkk profile image

mnkk 3 years ago from Brunswick, Maine

Very well written and with a perfect amount of information. I enjoy reading your health hubs!


vocalcoach profile image

vocalcoach 3 years ago from Nashville Tn.

Very useful information. I'm passing this on as we all need to read about bacteria on the skin. Thanks so much for writing this hub.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much, mnkk! I appreciate the comment.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment and for passing the hub on, vocalcoach! I appreciate your visit.


billybuc profile image

billybuc 3 years ago from Olympia, WA

Wow! Great job of compiling information, Alicia. This is a treasure chest of knowledge and written very well.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment, Bill!!


gags3480 profile image

gags3480 3 years ago from Kanpur, India

Thanks for this useful info. You did a really good job.

Voted up & Shared.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment, the vote and the share, gags3480!


kashmir56 profile image

kashmir56 3 years ago from Massachusetts

Hi my friend, very interesting and well written and informative article with some useful information on these skin conditions . Well done !

Vote up and more !!!


Sue Bailey profile image

Sue Bailey 3 years ago from South Yorkshire, UK

Voted up and interesting. Great hub. I was amazed when I was in hospital not long ago just how many of the nurses and doctors didn't wash their hands or use the antibac gel. No wonder there's MRSA running rife.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the comment, Tom. I appreciate the votes, too!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Sue. Your experience in hospital sounds scary! Thanks for the comment and the votes.


bdegiulio profile image

bdegiulio 3 years ago from Massachusetts

Great job Alicia. I think we all need an education about bacteria. With all of the anti-bacterial soaps, lotions, etc. out there people are convinced that all bacteria is bad for us. This was a great explanation of how bacteria works and what to watch for. Thanks for the education. Voted up, shared, etc....


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the vote and the share, Bill! Yes, bacteria are interesting creatures. Some are so helpful and some are so harmful!


aviannovice profile image

aviannovice 3 years ago from Stillwater, OK

I didn't realize there was so much going on with bacteria in our daily lives. A great article.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks, Deb. Yes, the bacteria on our skin are busy creatures! It's strange that so much is happening without us seeing it.


Nell Rose profile image

Nell Rose 3 years ago from England

Wow all those little bugs! seriously though its fascinating to know that we have good bacteria as well as the bad, and the bit about the mice was interesting too, to think that without their bacteria they were more suseptible to illness compared to the others, fascinating hub, and voted and shared, nell


self-counsel profile image

self-counsel 3 years ago

Thanks for a very informative hub! Skin has a normal bacterial flora that serves useful purpose. Some of these organisms produce organic acids that prevent harmful organisms from accumulating.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks for the comment, Nell. I appreciate the vote and the share, too! It is very interesting that we have both good and bad bacteria sharing our body with us.


starbright profile image

starbright 3 years ago from Scandinavia

It's a bit creepy and a good thing we can't see everything that's going on with our bodies. Fantastic hub and very interesting despite the creepiness :-) Thanks for sharing. Voted and shared.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, self-counsel. Thank you for the comment!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the vote and the share, starbright! I appreciate your visit and comment.


Peggy W profile image

Peggy W 3 years ago from Houston, Texas

Well written and researched hub Alicia. I will be happy to pin this to my Health Related Subjects board on Pinterest. Also voting this up and useful. So glad that you stressed the importance of washing hands! It is one of the simplest ways to avoid getting ill.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment, Peggy. I appreciate the pin and the votes, too. I agree with you - washing the hands is a very important step for preventing disease!


RTalloni profile image

RTalloni 3 years ago from the short journey

A very interesting look at bacteria on the skin and the various disorders related to it. Thanks for putting the information together for us in an easy-to-read format!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you, RTalloni! I appreciate your comment.


drbj profile image

drbj 3 years ago from south Florida

Since the skin is our largest organ, it well deserves the comprehensive compendium of information you have provided, Alicia. Thanks for your enormous and fascinating research.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you so much, drbj! I appreciate your visits and kind comments a great deal.

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