Skin Infections

What causes skin infections?

There are a variety of common skin infections seen in our clinic including various fungal, bacterial, and viral infections. Skin infections can be a significant source or pain, itching, or discomfort. Most skin infections can be contagious and some can even be dangerous so proper evaluation and treatment is important. Below we will review some of the most common infections seen in the skin. 

Fungal Infections

Fungal infections are the most common type of infection seen in a dermatology clinic. There are numerous different types of fungus that infect the skin. They can appear in just about any location, but are most common on the feet, toenails, and groin. Fungal infections are commonly referred to as "ringworm" due to the fact that fungi often create a ring-like rash on the skin. There is no "worm" involved in these infections, so the term isn't commonly used by dermatologists. Infections are named based on the location on the body such as tinea pedis (feet), tinea cruris (groin), tinea capitis (scalp), and tinea unguium or onychomycosis (nails). Fungal infections are spread by coming into contact with a surface where a fungus resides. This could be from skin-to-skin contact with someone who is infected, or from stepping on a contaminated floor without shoes. 

 

Fungal infections are best diagnosed by a skin expert such as a dermatologist since these infections may often be confused with other types of rashes. Using the wrong treatment such as a topical steroid can actually make the infection many times worse. Diagnosis can typically be done in-office by removing a small amount of scale from the skin and then examining it under the microscope. Other times a culture must be sent off for testing. 

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Once the diagnosis is made, fungal infections are treated with either topical creams for limited or minor disease, or oral medications for severe or widespread disease. Most infections can be cleared in a matter of weeks. 

Bacterial Infections

There are over a trillion bacteria currently living on your skin. Most are considered normal skin flora, meaning they are a normal and healthy part of your skin and actually prevent harmful bacteria from taking over. From time to time, unhealthy bacteria grow and cause a skin infection. This most commonly occurs after cutting or scraping the skin and not adequately cleaning the wound. Infections do happen after skin surgeries, although this is rare as infections only occur in about 3% of skin surgeries. 

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The most common bacteria to the infect the skin is staphylococcus aureus (commonly referred to as staph aureus or "staph"), followed by streptococcus. When these organisms infect the skin, the can cause the skin to become red, hot to the touch, painful, and for pus to form. Different types of infections include cellulitis where the bacteria primarily grow under the surface of the skin, or impetigo where the bacteria grow on the surface and form a honey-colored crust. If a large pocket of pus forms under the skin, this is referred to as an abscess. 

 

Bacterial infections are typically treated with oral antibiotics. Sometimes a culture is done to make sure the antibiotic chosen is capable of killing the bacteria. Some bacteria have become resistant to common treatments and require specific antibiotics. An example of this is MRSA which stands for methicillin resistant staphylococcus aureus. This relatively common skin infection requires antibiotics targeted for the particular strain of bacteria causing the infection. For milder, superficial infections a topical antibiotic may be all that is required. 

Viral Infections

The most common skin viral infections are from warts and molluscum which are covered in other sections of this website. There are many other viral infections common to the skin briefly discussed below:

 

• Herpes Simplex Virus - Infections with HSV type I commonly occur around the mouth and are referred to as cold sores or fever blisters. HSV Type 2 is a separate strain of herpes that infects the genitals and is spread sexually.

• Shingles - This rash is caused by reactivation of the virus that causes chickenpox (varicella) and causes a painful, blistering rash that develops in a stripe-like pattern on one side of the body.

• Pityriasis rosea - This common viral rash appears as many round to oval, slightly scaly spots on the trunk.

• Hand, foot, and mouth disease - This rash is caused by coxsackie or enteroviral infections. It is more commonly seen in children and causes painful blisters on the hands, feet, and mouth.

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There are many other types of viral infections each with their own characteristic appearance and symptoms. Diagnosis of these infections can be quite difficult and are best done by a skin expert such as a dermatologist. After diagnosis is made, a proper treatment plan can be developed. Treatments sometimes include anti-viral medications or medications to help alleviate symptoms.