Is a Staph Infection Contagious?

Symptoms of a staph infection of the skin include pus-filled abscesses.

Staph is a term that is used to substitute for the genus name Staphylococcus; it is a general term that refers to all the various species and subtypes of these gram-positive, coccal-shaped (round) bacteria. The organisms, depending on the species, cause skin infections, (for example, cellulitis, boils, and wound infections), pneumonia, food poisoning, endocarditis, toxic shock syndrome, and many other illnesses. MRSA (methicillin-resistant Staphylococcus aureus) can be difficult to treat since it is resistant to several antibiotics.

Because many people carry several types and/or species of staph on their bodies, some researchers question whether or not some staph infections are truly contagious or if they arise from overgrowth of these organisms usually present on a person's skin and/or mucous membranes. However, it is known that given the right circumstances, even if the staph infection arises from organisms present on one's body, if another person has direct contact with the infectious staph bacteria and has a break in the skin or mucous membranes, the organisms and potentially the disease can be contagious. Casual contact, such as hugging or kissing an infected person, usually does not transfer the organisms. However, those staph organisms that cause food poisoning do so by producing a toxin; the toxin is not contagious but may occur in groups of people who eat the same contaminated food. Similarly, individuals who develop toxic shock syndrome have staph-produced toxins that are secreted from the infection site into the body.

The incubation period for staph infections unfortunately is variable and considered to be indefinite. This is because many staph infections arise from bacteria that are already present on the skin and/or mucous membranes. However, for most staph infections, the incubation period commonly ranges from about four to 10 days.

The most common staph infections (for example, boils, impetigo, and MRSA) occur in the skin.

• Common features include redness and swelling of the skin; there may be abscess formation and/or pus production.
• More serious infections may develop if staph infections spread (pneumonia, heart failure, organ infections, and sepsis); serious infections can cause
  • high fever,
  • chills,
  • low blood pressure,
  • shock, and
  • even death.
• Staph infections may occur in individuals of any age group.

Staphylococcal food poisoning produces symptoms of

• nausea,
• vomiting,
• diarrhea, and
• dehydration.

These symptoms usually come on quickly (from about one to six hours after eating the contaminated food) and usually resolve in one to three days.

Toxic shock syndrome, originally described in menstruating women using tampons, occurs rapidly with

• high fever,
• vomiting,
• diarrhea, and
• muscle aches.
• Patients often develop a skin rash and peeling skin with this syndrome.
• Patients can also develop hypotension (low blood pressure) and shock and may even die.

Although the majority of staph infections are fairly benign in the skin, some can become severe. Although usually a physician will not need to run laboratory tests for a diagnosis, if MRSA, food poisoning, or toxic shock syndrome is suspected, samples from blood and tissue can be examined and cultures may be performed to identify the specific type of staph.

• Most staph infections are spread by direct person-to-person contact, usually requiring some break in the skin or mucous membranes to allow transfer of the bacteria.
• This can occur in direct contact like wrestling, through gym clothing, or depending on the activity, through sexual contact.
• Staph spread by other mechanisms, such as droplets or indirect contact such as clothing or other objects, is less frequent.
• The toxins that cause food poisoning and toxic shock syndrome are not spread from person to person.
• Staph infections are infrequently or rarely spread by airborne droplets, in swimming pools or by saliva, although it is possible.

• Most staph skin infections are cured with antibiotics; with antibiotic treatment, many skin infections are no longer contagious after about 24-48 hours of appropriate therapy.
• Some skin infections, such as those due to MRSA, may require longer treatment.
• For more complicated infections caused by staph, in general, when the symptoms resolve, the patient is usually cured of staph infection.

Although many minor staph infections, especially on the skin, may not require a physician to treat, there are other instances in which it is advisable to contact a physician about possible staph infections. A person should contact a physician if they develop the following:

• An area of red, irritated, and/or painful skin
• Pus-filled structures like blisters, boils, abscesses, or wounds that leak pus
• Skin infections that fail to respond to topical antibiotics
• Fever
• Reddish skin areas that are peeling
• Skin infections or other infections after close association with someone infected with MRSA
• Infections associated with tampon use or surgical or other wounds that require treatment with gauze packing
• Dehydration associated with food poisoning

If any of the above symptoms or signs are severe, the person should be brought to an emergency department.