Picture: A staph infection is a group of bacteria that can cause a multitude of diseases as a result of infection of various tissues of the body.
Staph Infection

Staph Infection
(Staphylococcus aureus)

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What is Staphylococcus?

Staphylococcus is a group of bacteria that can cause a number of diseases as a result of infection of various tissues of the body. Staphylococcus is more familiarly known as Staph (pronounced "staff"). Staph-related illness can range from mild and requiring no treatment to severe and potentially fatal.

The name Staphylococcus comes from the Greek staphyle, meaning a bunch of grapes, and kokkos, meaning berry, and that is what Staph bacteria look like under the microscope, like a bunch of grapes or little round berries. (In technical terms, these are gram-positive, facultative anaerobic, usually unencapsulated cocci.)

Over 30 different types of Staphylococci can infect humans, but most infections are caused by Staphylococcus aureus. Staphylococci can be found normally in the nose and on the skin (and less commonly in other locations) of around 25%-30% of healthy adults and in 25% of hospital workers. In the majority of cases, the bacteria do not cause disease. However, damage to the skin or other injury may allow the bacteria to overcome the natural protective mechanisms of the body, leading to infection.

Who is at risk for Staph infections?

Anyone can develop a Staph infection, although certain groups of people are at greater risk, including newborn infants, breastfeeding women, and people with chronic conditions such as diabetes, cancer, vascular disease, and lung disease. Injecting drug users, those with skin injuries or disorders, intravenous catheters, surgical incisions, and those with a weakened immune system due either to disease or a result of immune suppressing medications all have an increased risk of developing Staph infections.

Staph infections are contagious until the infection has resolved. Direct contact with an infected sore or wound, or with personal-care items such as razors, bandages, etc., are common routes of transmission. Casual contact such as kissing or hugging does not pose a great risk for transmission if there is no direct contact with the infected area.

Picture of a Staph infection
What does a Staph infection look like?
Reviewed by William C. Shiel Jr., MD, FACP, FACR on 4/20/2012


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Read about causes, symptoms, and treatment of MRSA infections.

Superbug Staph Spread in Community

MRSA, or methicillin-resistant Staphylococcus aureus, is a bacteriumthat can cause serious infections. It is resistant to numerous antibiotics of the beta-lactam family, including methicillinand penicillin.

MRSA belongs to the large group of bacteria known as Staphylococci, often referred to as Staph. About 25%-30% of all people have Staph within the nose, but it normally does not cause an infection. In contrast, only about 1% of the population have MRSA.

Infections with MRSA are most common in hospitals and other institutional health-care settings, such as nursing homes, where they tend to strike older people, those who are very ill, and people with a weakened immune system. In health-care settings, MRSA is a frequent cause of surgical wound infections, urinary tract infections, bloodstream infections (sepsis), and pneumonia.

MRSA outbreaks, however, are appearing increasingly in the community. Infections can occur in people who have not been hospitalized or had a medical procedure performed in the past year, and who do not have immune deficiency. These infections are termed community-associated MRSA infections (CA-MRSA). The U.S. Centers for Disease Control and Prevention(CDC) estimates that about 12% of MRSA infections are now community-associated, but this percentage can vary by community and patient population.

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