Staphylococcal infection

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 29, 2016
StartDiseasesStaphylococcal infection

A staphylococcal infection or staph infection is caused by the gram-positive Staphylococcus bacteria. This is a common germ that is often found on the skin or in the nose of otherwise healthy individuals. In most cases, the staph bacteria cause no symptoms or only minor infections; however, a staph infection can be potentially life-threatening if it gets into the bloodstream, bones, joints, or vital organs. 


Definition & Facts

Impetigo, boils, cellulitis, food poisoning, and toxic shock syndrome are all examples of infections that can be caused by Staphylococcus bacteria. Most staph infections begin with a cut or another type of skin injury that then gets infected. Those most at risk for staph infections include individuals with weakened immune systems or health conditions such as diabetes, people with serious skin injuries or surgical wounds, and individuals who have recently had invasive medical devices, such as catheters.

Athletes who play contact sports are also more susceptible to staph infections due to skin-to-skin contact, frequent abrasions, and sharing of equipment. Individuals who do not practice good hand hygiene can also transfer staph from their skin to the food they are preparing. 

Symptoms & Complaints

The symptoms of a staph infection vary widely depending on the severity and location of the infection. The most common symptom of a Staphylococcus skin infection is a boil, which is a red, swollen pocket of pus that develops in an oil gland or hair follicle.

Impetigo causes oozing blisters that typically have a honey-colored crust. Cellulitis is characterized by swelling and redness on the surface of the skin and most often affects the lower extremities. Young children may develop a blistering rash that can make the skin appear burned or scalded. 

Staph-related food poisoning typically results in nausea, vomiting, and diarrhea, which can lead to dehydration and low blood pressure. Staph infections can also cause septic arthritis, which is characterized by fever and severe joint pain and swelling.

If the bacteria enter the bloodstream, a person can develop infections in their bones, joints, or internal organs, such as endocarditis. Toxic shock syndrome is most often associated with tampon use, surgery, and skin wounds. The infection can cause a sudden high grade fever, confusion, abdominal pain, nausea and vomiting, diarrhea, muscle aches, and a sunburn-like rash on the soles of the feet.


Staphylococcus bacteria are extremely hardy. Staph can withstand temperature extremes and high salt levels. Approximately 25 percent of people carry staph bacteria in their mouth, nose, genitals, or around their anal area. Most people with the bacteria never develop an infection. Individuals who do develop an infection have most likely carried the bacteria on their body for a considerable time.

Staph bacteria are easily transmitted from person to person and by contact with inanimate objects, such as towels, razors, and pillowcases. A strain of staph called methicillin-resistant Staphylococcus aureus, or MRSA, is most often associated with healthcare settings and the use of invasive medical procedures or devices. A MRSA infection is particularly dangerous since it is resistant to most forms of antibiotics.

Diagnosis & Tests

In the case of a minor skin infection, the doctor will often provide a diagnosis based on the patient’s symptomology and a physical examination. If the patient presents with a more serious skin infection or if the doctor suspects a systemic infection, the doctor will order lab tests to check for the presence of Staphylococcus bacteria.

This involves taking a small sample of tissue, blood, or nasal or wound secretions for culturing. The sample is placed in a culture medium and allowed to grow for approximately 48 to 72 hours to determine if colonies of staph bacteria develop.

A positive culture is typically followed by an antibiotic sensitivity test to determine which antibiotic is most effective against the particular strain of staph. This involves placing discs containing various antibiotics over the bacteria culture, which is then incubated for 24 hours.

The different areas are then measured against standards established by the National Committee for Clinical Laboratory Standards to determine if they are resistant, susceptible, or intermediately susceptible to a particular antibiotic. Real-time lab tests that check for staph DNA are now available that can provide results within a few hours as opposed to several days. 

Treatment & Therapy

The traditional treatment for staph infections is antibiotics. The most common antibiotics used to treat staph include cephalosporins, nafcillin, and sulfa drugs. Unfortunately, an increasing number of staph bacteria are proving to be resistant to most traditional antibiotics. Today, only about 10 percent of staph infections respond to penicillin or similar antibiotics. It is believed that this is due to the rampant overprescribing of antibiotics, which has led to a new generation of drug-resistant “super bugs.”

Vancomycin, which is typically given intravenously, often has to be used for more serious infections. These high-powered antibiotics carry a higher risk of side effects, including flushing, ringing in the ears, kidney problems, and yeast infections. Individuals given oral antibiotics for a staph infection should ensure that they take the full course as prescribed to reduce the risk of the infection recurring or becoming drug resistant.

A staph-related skin infection may require an incision to allow the pus and other fluid to drain from the wound. In some cases, surgery may be required to remove pacemakers or other prosthetic devices that may be affected by the infection. 

Prevention & Prophylaxis

The best way to prevent staph or any other type of infection is with thorough and frequent hand washing. Hands should be washed with soap and water for at least 20 seconds. It is best to dry hands using a disposable towel and to turn off faucets using a towel. All cuts and abrasions should be cleaned and covered with dry, sterile dressings until they are healed.

Women can reduce their risk of toxic shock syndrome by using the lowest absorbency tampon possible and changing tampons every four to eight hours. It is also a good idea to never share personal items, such as razors or towels and to wash all towels and bedding in hot water.