5 tipos de bactérias que vivem em sua pele

 

Updated October 10, 2018

 

Our skin is populated by billions of diverse bacteria. As the skin and outer tissues are in constant contact with the environment, microbes have easy access to colonize these areas of the body. Most of the bacteria that reside on skin and hair are either commensalistic (beneficial to the bacteria but do not help or harm the host) or mutualistic (beneficial to both the bacteria and the host). Some skin bacteria even protect against pathogenic bacteria by secreting substances that prevent harmful microbes from taking up residence. Others protect against pathogens by alerting immune system cells and inducing an immune response.

While most strains of bacteria on the skin are harmless, others can pose serious health problems. These bacteria can cause everything from mild infections (boils, abscesses, and cellulitis) to serious infections of the blood, meningitis, and food poisoning.

Skin bacteria are characterized by the type of environment in which they thrive. There are three main types of skin environments that are populated predominately by three species of bacteria. These environments include the sebaceous or oily areas (head, neck, and trunk), the moist areas (creases of the elbow and between the toes), and the dry areas (broad surfaces of the arms and legs). Propionibacterium are found predominately in the oily areas, Corynebacterium populate the moist areas, and Staphylococcus species typically reside on the dry areas of the skin. The following examples are five common types of bacteria found on the skin from the three categories.

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Propionibacterium acnes

Propionibacterium acnes bacteria are found deep in the hair follicles and pores of the skin, where they usually cause no problems. However, if there is an over-production of sebaceous oil, they grow, producing enzymes that damage the skin and cause acne. Credit: SCIENCE PHOTO LIBRARY/Getty Images

Propionibacterium acnes prosperam nas superfícies oleosas da pele e folículos pilosos. Estas bactérias contribuem para o desenvolvimento da acne, pois elas proliferam devido ao excesso de produção de óleo e poros entupidos. As bactérias Propionibacterium acnes usam o sebo produzido pelas glândulas sebáceas como combustível para o crescimento. O sebo é um lipídio que consiste em gorduras, colesterol e uma mistura de outras substâncias lipídicas. O sebo é necessário para uma boa saúde da pele, uma vez que hidrata e protege os cabelos e a pele. Os níveis anormais de produção de sebo contribuem para a acne, uma vez que obstruem os poros, levam ao crescimento excessivo de bactérias Propionibacterium acnes e induzem uma resposta dos glóbulos brancos que causa inflamação.

Corynebacterium

Corynebacterium diphteriae bacteria produce toxins that cause the disease diptheria. Credit: BSIP/UIG/Universal Images Group/Getty Images

O gênero Corynebacterium inclui espécies de bactérias patogênicas e não patogênicas. As bactérias Corynebacterium diphteriae produzem toxinas que causam a doença difteria. A difteria é uma infecção que normalmente afeta a garganta e as membranas mucosas do nariz. Também é caracterizada por lesões de pele que se desenvolvem quando as bactérias colonizam a pele previamente danificada. A difteria é uma doença grave e, em casos graves, pode causar danos aos rins, coração e sistema nervoso. Mesmo as corinebactérias não diftéricas foram consideradas patogênicas em indivíduos com sistemas imunológicos suprimidos. Infecções não difterias graves estão associadas a dispositivos de implantes cirúrgicos e podem causar meningite e infecções do trato urinário.

Staphylococcus epidermidis

Staphylococcus epidermidis bacteria are part of the normal flora found in the body and on the skin. Credit: Janice Haney Carr/ CDC

A bactéria Staphylococcus epidermidis é habitualmente habitantes inofensivos da pele que raramente causam doenças em indivíduos saudáveis. Essas bactérias formam uma barreira espessa de biofilme (uma substância viscosa que protege as bactérias de antibióticos, substâncias químicas e outras substâncias ou condições perigosas) que podem aderir às superfícies dos polímeros. Como tal, S. epidermidis geralmente causam infecções associadas a dispositivos médicos implantados, como cateteres, próteses, marca-passos e válvulas artificiais. S. epidermidis também se tornou uma das principais causas de infecção sanguínea adquirida no hospital e está se tornando cada vez mais resistente aos antibióticos.

Staphylococcus aureus

Staphylococcus aureus bacteria are found on the skin and mucous membranes of humans and many animals. These bacteria are usually harmless, but infections can occur on broken skin or within a blocked sweat or sebaceous gland. Credit: SCIENCE PHOTO LIBRARY/Science Photo Library/Getty Images

Staphylococcus aureus is a common type of skin bacterium that may be found in areas such as the skin, nasal cavities, and respiratory tract. While some staph strains are harmless, others such as methicillin-resistant Staphylococcus aureus (MRSA), can cause serious health issues. S. aureus is typically spread through physical contact and must breach the skin, through a cut, for example, to cause an infection. MRSA is most commonly acquired as a result of hospital stays. S. aureus bacteria are able to adhere to surfaces due to the presence of cell adhesion molecules located just outside of the bacterial cell wall. They can adhere to various types of surfaces, including medical equipment. If these bacteria gain access to internal body systems and cause infection, the consequences can be fatal.

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Streptococcus pyogenes

Streptococcus pyogenes bacteria cause skin infections (impetigo), abscesses, bronchio-pulmonary infections, and a bacterial form of strep throat that can lead to complications such a acute articular rhumatism. Credit: BSIP/UIG/Universal Images Group/Getty Images

Streptococcus pyogenes bacteria typically colonize the skin and throat areas of the body. S. pyogenes reside in these areas without causing issues in most cases. However, S. pyogenes can become pathogenic in individuals with compromised immune systems. This species is responsible for a number of diseases that range from mild infections to life-threatening illnesses. Some of these diseases include strep throat, scarlet fever, impetigo, necrotizing fasciitis, toxic shock syndrome, septicemia, and acute rheumatic fever. S. pyogenes produce toxins that destroy body cells, specifically red blood cells and white blood cells. S. pyogenes are more popularly known as "flesh-eating bacteria" because they destroy infected tissue causing what is known as necrotizing fasciitis.

Sources

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• Akst, Jef. "Microbes of the Skin." The Scientist. Published 13 Jun. 2014 (http://www.the-scientist.com/?articles.view/articleNo/40228/title/Microbes-of-the-Skin/).
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• Antimicrobial (Drug) Resistance. National Institute of Allergy and Infectious Diseases. Updated 24 Jan. 2014 (http://www.niaid.nih.gov/topics/antimicrobialResistance/Examples/mrsa/Pages/default.aspx).
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• GAS Frequently Asked Questions. Group A Streptococcal (GAS) Disease. Centers for Disease Control and Prevention. Updated 5 Jan. 2014 (http://www.cdc.gov/groupAstrep/about/faqs.html).
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• Otto, Michael. "Staphylococcus Epidermidis – the 'accidental' Pathogen." Nature reviews. Microbiology 7.8 (2009): 555–567. PMC. Web. 29 Jan. 2015 (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807625/).
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• Todar, Kenneth. "The Normal Bacterial Flora of Humans." Online Textbook of Bacteriology. (http://www.textbookofbacteriology.net/normalflora.html).

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