Description – Staph Infection
Staph infection is caused by staphylococcus bacteria, types of germs commonly found on the skin or in the nose of even healthy individuals.
Most of the time, these bacteria cause no problems or result in relatively minor skin infections. But staph infections can turn deadly if the bacteria invade deeper into your body, entering your bloodstream, joints, bones, lungs or heart.
A growing number of otherwise healthy people are developing life-threatening staph infections. Treatment usually involves antibiotics and drainage of the infected area. However, some staph infections no longer respond to common antibiotics.
What are some types of staph infections?
Types of staph infections include:
- Blisters – These look similar to a whitehead or a pimple. Once it breaks open and the pus drains out, the infection’s threat goes away.
- Boils – Deeper than blisters, with the skin surrounding a boil, appear red, swollen and sore. It’s often very painful.
- Impetigo – This contagious skin infection looks like a rash with a yellow crust. Impetigo sometimes secretes fluid and also is painful. You often see impetigo among children. It’s typically not serious and can be treated with a topical antibiotic.
- Cellulitis – This skin inflammation occurs when your infection gets under the layers of your skin and spreads. It causes redness and painful swelling. You may even develop sores. Cellulitis can become more serious if it’s not treated immediately.
- Sepsis – If your skin infection is severe it can progress to a more advanced stage known as sepsis. This inflammation, which enters your bloodstream, is more dangerous to older adults.
- Endocarditis – Endocarditis occurs when staph enters your bloodstream and attacks your heart. Doctors typically treat it with strong antibiotics. Surgery is sometimes necessary if the infection damages your heart valves.
Pathophysiology of staph infection
For the majority of diseases caused by S. aureus, pathogenesis is multifactorial, so it is difficult to determine precisely the role of any given factor. However, there are correlations between strains isolated from particular diseases and expression of particular virulence determinants, which suggests their role in a particular disease. The application of molecular biology has led to advances in unraveling the pathogenesis of staphylococcal diseases. Genes encoding potential virulence factors have been cloned and sequenced, and many protein toxins have been purified. With some staphylococcal toxins, symptoms of human disease can be reproduced in animals with the purified protein toxins, lending an understanding of their mechanism of action.
Human staphylococcal infections are frequent but usually remain localized at the portal of entry by the normal host defenses. The portal may be a hair follicle, but usually it is a break in the skin which may be a minute needle-stick or a surgical wound. Foreign bodies, including sutures, are readily colonized by staphylococci, which may make infections difficult to control. Another portal of entry is the respiratory tract. Staphylococcal pneumonia is a frequent complication of influenza.
The localized host response to staphylococcal infection is inflammation, characterized by an elevated temperature at the site, swelling, the accumulation of pus, and necrosis of tissue. Around the inflamed area, a fibrin clot may form, walling off the bacteria and leukocytes as a characteristic pus-filled boil or abscess.
More serious infections of the skin may occur, such as furuncles or impetigo. Localized infection of the bone is called osteomyelitis. Serious consequences of staphylococcal infections occur when the bacteria invade the bloodstream. Resulting septicemia may be rapidly fatal; bacteremia may result in seeding other internal abscesses, other skin lesions, or infections in the lung, kidney, heart, skeletal muscle or meninges.
What causes staphylococcal infection?
Despite being harmless in most individuals, S aureus is capable of causing various infections of the skin and other organs. S aureus infection is common in people with frequent skin injuries, particularly if the skin is dry. Staph skin infections are seen most commonly in prepubertal children and certain occupational groups such as healthcare workers. But they may occur for no obvious reason in otherwise healthy individuals.
Most staphylococcal infections occur in normal individuals, but underlying illness and certain skin diseases increase the risk of infection. These include:
- Severe atopic dermatitis
- Poorly controlled diabetes
- Kidney failure, especially those on dialysis
- Blood disorders such as leukemia and lymphoma
- Iron deficiency
- Intravenous drug users
- Presence of foreign body, eg prosthetic joint, pacemaker, indwelling catheter, hemodialysis, recent surgical procedure
- Medication with systemic steroids, retinoids, cytotoxics or immunosuppressives
- Immunoglobulin M deficiency
- Chronic granulomatous disease
- Chediak-Higashi syndrome
- Job and Wiskott Aldrich syndromes (associations of severe staphylococcal infection with eczema, raised immunoglobulin E and abnormal white cell function)
Who Is at Risk for Staph Infections?
While anyone can get a Staph infection, some conditions put people at higher risk including:
- Women who are breastfeeding
- Vascular or lung disease
- Weakened immune system
- Those who inject drugs or medications
- Skin injuries or disorders
- Surgical incisions
- Use of intravenous catheters
What Are the Signs & Symptoms of a Staph Skin Infection?
Staph skin infections show up in lots of different ways. Conditions often caused by S. aureus include:
- Folliculitis: This is an infection of the hair follicles, the tiny pockets under the skin where hair shafts (strands) grow. In folliculitis, tiny white-headed pimples appear at the base of hair shafts, sometimes with a small red area around each pimple. This happens often where people shave or have irritated skin from rubbing against clothing.
- A furuncle, commonly known as a boil: These swollen, red, painful lumps in the skin usually are due to an infected hair follicle. The lump fills with pus, growing larger and more painful until it ruptures and drains. Furuncles often begin as folliculitis and then worsen. They most often appear on the face, neck, buttocks, armpits, and inner thighs, where small hairs can get irritated. A cluster of several furuncles is called a carbuncle. Someone with a carbuncle may feel ill and have a fever.
- Impetigo: This superficial skin infection is most common in young children, usually on the face, hands, or feet. It begins as a small blister or pimple and then develops a honey-colored crust.
- Cellulitis: This begins as a small area of redness, pain, swelling, and warmth on the skin, usually on the legs. As this area spreads, a child may feel feverish and ill.
- A stye: Kids with one of these have a red, warm, uncomfortable bump near the edge of the eyelid.
- MRSA: This type of staph bacteria is resistant to the antibiotics used to treat staph infections. MRSA infections can be harder to treat, but most heal with proper care. Most MRSA infections involve the skin.
- Scalded skin syndrome: This most often affects newborns and kids under age 5. It starts with a small staph skin infection, but the staph bacteria make a toxin that affects skin all over the body. The child has a fever, rash, and sometimes blisters. As blisters burst and the rash passes, the top layer of skin sheds and the skin surface becomes red and raw, like a burn. This serious illness affects the body in the same way as serious burns. It needs to be treated in a hospital. After treatment, most kids make a full recovery.
- Wound infections: These cause symptoms (redness, pain, swelling, and warmth) similar to those from cellulitis. A person might have a fever and feel sick in general. Pus or a cloudy fluid can drain from the wound and a yellow crust can develop.
What are the complications of staph infections?
Scalded skin syndrome is a potentially serious side effect of infection with staph bacteria that produce a specific protein that loosens the “cement” holding the various layers of the skin together.
This allows blister formation and sloughing of the top layer of skin. If it occurs over large body regions, it can be deadly, similar to a large surface area of the body having been burned.
It is necessary to treat scalded skin syndrome with intravenous antibiotics and to protect the skin from allowing dehydration to occur if large areas peel off.
The disease occurs predominantly in children but can occur in anyone. It is known formally as staphylococcal scalded skin syndrome
Treatment for staph infection
Treatment of a staph infection may include:
Antibiotics. Your doctor may perform tests to identify the staph bacteria behind your infection and to help choose the antibiotic that will work best. Antibiotics commonly prescribed to treat staph infections include certain cephalosporins, nafcillin or related antibiotics, sulfa drugs, or vancomycin. Vancomycin increasingly is required to treat serious staph infections because so many strains of staph bacteria have become resistant to other traditional medicines. But vancomycin and some other antibiotics have to be given intravenously. If you’re given an oral antibiotic, be sure to take it as directed, and to finish all of the medication prescribed by your doctor. Ask your doctor what signs and symptoms you should watch for that might indicate your infection is worsening.
Wound drainage. If you have a skin infection, your doctor will likely make an incision into the sore to drain fluid that has collected there.
Device removal. If your infection involves a device or prosthetic, prompt removal of the device is needed. For some devices, removal might require surgery.
Diagnosis of staph infection
- For skin infections, a doctor’s evaluation
- For other infections, a culture of blood or infected body fluids
Staphylococcal skin infections are usually diagnosed based on their appearance.
Other infections require samples of blood or infected fluids, which are sent to a laboratory to grow (culture), identify, and test the bacteria. Laboratory results confirm the diagnosis and determine which antibiotics can kill the staphylococci (called susceptibility testing).
If a doctor suspects osteomyelitis, X-rays, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Radionuclide Bone Scanning, or a combination is also done. These tests can show where the damage is and help determine how severe it is. A bone biopsy is done to obtain a sample for testing. The sample may be removed with a needle or during surgery.
How can you prevent a staph infection?
- Practice good hygiene.
- Wash your hands often with soap and clean, running water. You can also use an alcohol-based hand sanitizer. Hand-washing is the best way to avoid spreading bacteria.
- Keep cuts and scrapes clean. Cover them with a bandage. Avoid contact with other people’s wounds or bandages.
- Don’t share personal items such as towels, face cloths, razors, or clothing.
- Keep your environment clean by using a disinfectant to wipe surfaces you touch a lot. These include countertops, doorknobs, and light switches.
- If you’re in the hospital, remind doctors and nurses to wash their hands before and after they touch you.