Influence of microorganisms

What are the Different Types of microbes?

Propionibacterium acnes bacteria are found deep in the hair follicles and pores of the skin, where they usually causes 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 thrive on the oily surfaces of the skin and hair follicles. These bacteria contribute to the development of acne as they proliferate due to excess oil production and clogged pores. Propionibacterium acnes bacteria use the sebum produced by sebaceous glands as fuel for growth. Sebum is a lipid consisting of fats, cholesterol, and a mixture of other lipid substances. Sebum is necessary for proper skin health as it moisturizes and protects hair and skin. Abnormal production levels of sebum contributes to acne as it clogs pores, leads to excess growth of Propionibacterium acnes bacteria, and induces a white blood cell response that causes inflammation.

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

The genus Corynebacterium includes both pathogenic and non-pathogenic bacteria species. Corynebacterium diphteriae bacteria produce toxins that cause the disease diphtheria. Diphtheria is an infection that typically affects the throat and mucous membranes of the nose. It is also characterized by skin lesions that develop as the bacteria colonize previously damaged skin. Diphtheria is a serious disease and in severe cases can cause damage to the kidneys, heart and nervous system. Even non-diphtherial corynebacteria have been found to be pathogenic in individuals with suppressed immune systems. Severe non-diphtherial infections are associated with surgical implant devices and can cause meningitis and urinary tract infections.

Staphylococcus epidermidis

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

Staphylococcus epidermidis bacteria are typically harmless inhabitants of the skin that rarely cause disease in healthy individuals. These bacteria form a thick biofilm (slimy substance that protects bacteria from antibiotics, chemicals, and other substances or conditions that are hazardous) barrier that can adhere to polymer surfaces. As such, S. epidermidis commonly cause infections associated with implanted medical devices such as catheters, prostheses, pacemakers, and artificial valves. S. epidermidis has also become one of the leading causes of hospital-acquired blood infection and is becoming increasingly resistant to antibiotics.

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 instruments, including medical equipment. If these bacteria gain access to internal body systems and cause infection, the consequences could be fatal.

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 area 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

• Todar, Kenneth. "The Normal Bacterial Flora of Humans." Online Textbook of Bacteriology. Accessed 28 Jan. 2015 (
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• Akst, Jef. "Microbes of the Skin." The Scientist. Published 13 Jun. 2014 (
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• Otto, Michael. "Staphylococcus Epidermidis – the 'accidental' Pathogen." Nature reviews. Microbiology 7.8 (2009): 555–567. PMC. Web. 29 Jan. 2015 (
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• Antimicrobial (Drug) Resistance. National Institute of Allergy and Infectious Diseases. Updated 24 Jan. 2014 (