Staphylococcus Aureus Infection

Staphylococcus Aureus bacteria can cause a variety of infections ranging from small abscesses on the skin to fatal septic shock. The bacteria are commonly present in the population with nearly 20% – 30 % of people carrying the bacteria on their skin without any infection. The areas of the body with the highest concentration of the bacteria are the corners of the nose, armpits and groin areas including the vagina and anus.

Skin and mucous membranes provide an effective mechanical barrier against infection but when this is broken by trauma, including innocuous cracking of dry skin or surgery, bacteria can initiate the infectious process. Once the bacteria have entered the tissue it can spread through the blood stream to the lungs, heart, bone, brain etc. It can also release toxins resulting in toxic shock syndrome.

Some strains of staphylococcus bacteria are resistant to common antibiotics in the beta lactam family like methicillin and are called MRSA – methicillin resistant staphylococcus Aureus. These strains used to be seen exclusively in health care settings like hospitals, nursing homes or associated with medical procedures and devices. However in the past few years these MRSA strains have become prevalent in the general community affecting individuals who have not had any previous health care exposures for up to a year. These strains are called community acquired MRSA and make up nearly 30%-60% of community infections depending on the area of the country.

Where does it occur?

Staphylococcus Aureus bacteria are prevalent worldwide on individuals and surfaces. Crowded environments like gymnasiums, prisons, camps, day care and poor hygienic practices can increase the incidence of staphylococcus infections.

How is it transmitted?

Staphylococcus Aureus is most commonly spread from person to person through ones hands. When one comes in contact with the skin of asymptomatic carriers or those with active infection bacteria are contracted. One can infect themselves if carrying the bacteria by scratching or traumatizing the skin. Contaminated surfaces are also responsible for spread of infection. Individuals with respiratory infections (pneumonia/bronchitis) can transmit the bacteria by airborne secretions.

Is it contagious from person to person?

It is contagious from person to person through contact with their skin or contaminated clothing or surfaces.

What is the risk for travelers?

Generally low.

How soon after exposure will one develop symptoms?

It is entirely unpredictable and depends on the immune status of the individual and virulence of the bacterial strain at time of exposure.

What are the signs and symptoms?

The signs and symptoms are dependent upon the site of infection and will be described as follows:

Folliculitis: small reddish bumps around individual hair follicles

Furuncles: larger and more extensive infection involving hair follicles, these can be up to ½ inches big, red with a pus boil.

Carbuncles: when several hair follicles are involved and can result in local skin necrosis and scarring.

Cellulitis: when the infection spreads uniformly to the underlying soft tissue layer and is manifested by a diffuse area of redness resembling a burn, sometimes with a scalded skin like appearance with blistering. This is associated with fever, chills and sweats.

Abscess: when the infection result in large pus filled boils and lumps, seen most commonly on arms, legs, arm pits and groin but can occur everywhere. Impetigo: a boil like lesion that ruptures and leaves a pus coated area surrounded by redness.

Mastitis: an infection of the breasts manifesting as a red swollen nipples and spreading outward most often seen in first few months of breast feeding.

Endocarditis: When staphylococcus bacteria enters the blood stream and lodges on the heart valves, resulting in fever, chills, fatigue, shortness of breath and is life threatening if not treated.

Osteomyelitis: infection of the bone as staphylococcus bacteria settles through the blood stream onto bony surfaces, commonly the vertebral bones. Symptoms are primarily of pain of the affected bone

Sepsis: a severe multi organ infection resulting from overwhelming staphylococcus infection involving the blood stream which can result in shock and death.

Toxic Shock Syndrome: Certain staphylococcus Aureus bacteria produce a toxin called toxic shock syndrome toxin 1, which upon entering the blood stream results in a rapid and severe illness characterized by fever, muscle pains, nausea, diarrhea, lethargy and extremely low blood pressure (shock). A faint and fleeting red sand paper like rash is also seen. There is multiple organ failure involving the lung, liver and kidneys. This has classically been associated with use of tampons, but it can be seen with diaphragms and vaginal sponges. It does not however need to be associated with gynecologic issues at all and can be seen as a complication of skin infection, surgery etc.

Are there any lab tests to diagnose the illness?

Staphylococcus Aureus bacteria can be cultured from the blood and body fluids and the toxic shock syndrome toxin 1 can be isolated from suspected sources as well

Is there any treatment?

Antibiotics like cefazolin, naficillin, vancomycin, zyvox, and daptomycin are effective along with surgical drainage of abscesses and intensive care support for septic and shock patients

Is the infected person contagious?

The infection can be spread from person to person via their hands and respiratory secretions.

What preventive measures can be taken?

Strict hand washing is the single best measure to prevent infection.

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