Skin Infections

Bacterial infections are among the most common skin infections and often start when bacteria enter through a cut, scrape, insect bite, or other break in the skin. The most common bacteria that cause skin infections are Staphylococcus aureus and Streptococcus species.

1. Impetigo
Impetigo: is a highly contagious skin infection that most often affects infants and young children. It appears as red sores, usually around the nose and mouth. These sores quickly rupture and ooze for a few days, then form a yellowish-brown crust. Impetigo is spread through close contact or by touching contaminated objects. Doctors usually diagnose impetigo by looking at the skin.
2.  Cellulitis
Cellulitis: is a deeper skin infection that can develop quickly. It often affects the lower legs but can occur anywhere on the body. The infected skin area becomes red, swollen, warm, and painful. It may be accompanied by fever or chills. If left untreated, cellulitis can spread to the bloodstream. A clinical examination is typically sufficient for diagnosis, but blood tests or imaging may be ordered in more severe cases.
3. Folliculitis:
This is an infection of the hair follicles, which may appear as red, pimple-like bumps with a white center. It can develop after shaving, friction, or exposure to contaminated water (such as hot tubs). Doctors usually diagnose folliculitis by examining the skin.

Viral infections are caused by viruses that affect the skin and sometimes other parts of the body. They are often spread through skin-to-skin contact or droplets from coughing or sneezing.

1. Herpes simplex virus (HSV):
HSV causes cold sores (oral herpes) and genital herpes. Cold sores usually appear as painful, fluid-filled blisters around the lips or mouth. The sores break open, crust over, and heal within a couple of weeks. A doctor may diagnose HSV based on appearance. A swab of the sore or a blood test can confirm the diagnosis.
2. Molluscum contagiosum:
This viral infection causes small, shiny, skin-colored bumps with a central dimple. It is most common in children but can also affect adults. The bumps are usually painless and may last for months if untreated. Molluscum is usually diagnosed by visual examination. In uncertain cases, a skin scraping may be examined under a microscope.
3. Warts: (caused by human papillomavirus, HPV)
Warts are rough, raised bumps that can appear anywhere on the skin, commonly on the hands, feet, and knees. Plantar warts develop on the soles of the feet and may be painful.
Warts are typically diagnosed based on their appearance.

Fungal infections often develop in warm, moist areas of the body such as the feet, groin, or armpits. They are caused by fungi like dermatophytes or Candida.

1. Athlete’s foot: (tinea pedis)
Athlete’s foot causes itching, burning, and peeling between the toes or on the soles of the feet. It can spread to the toenails or hands if untreated. A skin scraping examined under a microscope or sent for culture can confirm the presence of fungus.
2. Ringworm: (tinea corporis)
Despite the name, ringworm is not caused by a worm. It is caused by a fungus. It presents as a red, scaly, circular rash with a clearer center, giving it a “ring-like” appearance. It can affect any part of the body. The diagnosis is usually clinical exam.
3. Yeast infections: (cutaneous candidiasis)
Caused by an overgrowth of Candida yeast, these infections can lead to red, itchy, sometimes oozing rashes in skin folds like under the breasts, in the groin, or underarms. Diagnosis is based on appearance, though a swab or scraping may be used to confirm the type of yeast.

Parasitic infections are less common but can cause significant skin irritation and discomfort.

Scabies: Scabies is caused by microscopic mites that burrow into the skin, leading to intense itching, especially at night. It often appears as tiny red bumps or blisters and commonly affects the wrists, elbows, fingers, and waistline. A doctor may take a skin scraping to look for mites, eggs, or mite droppings under a microscope.

Lice (head, body, or pubic lice):
Lice are small insects that feed on blood and cause itching. Head lice cause itching on the scalp; body lice live in clothing and move to the skin to feed; pubic lice affect the groin area.
Lice and their eggs (nits) are usually visible to the naked eye or with a magnifying glass.