​Skin infections occur when bacteria, viruses, or other microorganisms affect the skin or tissues beneath it. Infection can enter through a cut, scrape, bite, puncture, cracked skin, rash, surgical wound, or other break in the skin. Sometimes no obvious entry point is found.
 

Cellulitis
 

Cellulitis is a bacterial infection involving the deeper layers of the skin and tissue beneath it. Symptoms may include:
 

• Spreading redness

• Warmth

• Swelling

• Pain or tenderness

• Fever or chills with more significant infections

How Is Cellulitis Treated?
 

Cellulitis is usually treated with antibiotics. Most uncomplicated cases can be treated at home with oral medication. The border of the redness may be marked to determine whether it continues to spread.
 

Worsening or rapidly spreading infection, significant illness, failure of outpatient treatment, or concern for a deeper infection may require hospital evaluation and IV antibiotics.
 

Erysipelas
 

Erysipelas is a more superficial form of bacterial skin infection.

It commonly causes an area that is:
 

• Bright red

• Warm

• Painful

• Raised

• Sharply identifiable from the surrounding normal skin

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Treatment generally involves antibiotics.
 

Abscesses
 

An abscess is a localized pocket of pus within or beneath the skin.

Symptoms may include:
 

• A painful lump

• Redness

• Warmth

• Swelling

• A soft or compressible center

• Pus or drainage

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How Is an Abscess Diagnosed?
 

Many abscesses by feeling for fluctuance/fluid underneath the skin. Deeper abscesses may require imaging to diagnose and a referral to general surgery, orthopedics, ENT, or the hospital. 
 

How Is an Abscess Treated?
 

An established abscess often requires incision and drainage (I&D), but sometimes small ones improve with warm compresses and drain naturally. Antibiotics may also sometimes be given, but they are not always required. 

Folliculitis & Boils
 

Folliculitis affects individual hair follicles and commonly produces small red bumps or pustules that may itch or feel tender.
 

A boil (furuncle) is a deeper infection involving a hair follicle that develops into a small abscess.

Small lesions may improve with warm compresses, while larger abscesses may require drainage.

 

Infections involving the beard area can be bacterial (sycosis barbae) or fungal (tinea barbae). Both can cause red bumps and pustules around hair follicles. Scaling, broken or easily removed hairs, patchy hair loss, significant swelling, or farm animal exposure may be more suggestive of tinea barbae. Because the conditions can look similar but require different treatments, fungal or bacterial testing may sometimes be needed to determine the cause.

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Pseudofolliculitis barbae ("razor bumps") is not an infection. It occurs when shaved or cut hairs grow back into the skin, causing inflammation that can resemble folliculitis. It commonly causes bumps and sometimes pustules on the beard and neck after shaving. Shaving in the direction of hair growth, avoiding very close shaving, and leaving a small amount of hair with electric clippers can help prevent recurrence.

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Impetigo
 

Impetigo is a contagious superficial skin infection that is especially common in children.

It commonly causes sores or blisters that rupture and develop characteristic yellow or honey-colored crusts. A small number of lesions may be treated with topical antibiotics, while more widespread infections may require oral antibiotics.
 

Handwashing and avoiding shared towels and other personal items can help prevent spread.
 

Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory condition involving blocked hair follicles. It commonly affects areas where skin rubs together, including the armpits, groin, buttocks, and beneath the breasts. In HS, follicles become blocked and rupture beneath the skin, triggering inflammation and causing deep, painful lumps and abscess-like lesions. Repeated inflammation can eventually form draining tunnels beneath the skin and permanent scarring. Although the lesions may look like infected boils or abscesses, HS is not a bacterial skin infection. However, secondary bacterial infections can sometimes occur, often leading to cellulitis

Draining a painful HS abscess may provide temporary relief, but repeated incision and drainage does not treat the underlying disease and recurrence is very likely.
 

Treatment of hidradenitis suppurativa depends on its severity. Weight loss may improve symptoms in patients with overweight or obesity, and smoking cessation is recommended for patients who smoke. Mild disease may be treated with skin care, antiseptic washes, topical medications, or steroid injections into inflamed lesions. Oral antibiotics such as doxycycline may be used for their anti-inflammatory effects. In appropriate patients, especially those with PMOS/PCOS, hormonal treatments such as spironolactone, certain birth-control pills, or metformin may help reduce flare-ups. Moderate-to-severe HS may require biologic medications like Humira that target the immune system. Persistent nodules and tunnels may be treated with special procedures like surgery. Recurrent or progressive disease usually requires dermatology referral. 

Risk factors:

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• Family history

• Female

• Overweight

• Cigarette smoking

• Hormonal influences — polycystic ovary syndrome (PCOS)/polyendocrine metabolic ovarian syndrome (PMOS), menstruation

• Mechanical friction and skin-to-skin rubbing

• Heat and sweating

• Certain medications (lithium)

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Preseptal (Periorbital) Cellulitis
 

Preseptal cellulitis is an infection involving the eyelid and tissues surrounding the eye but in front of the eye socket. It can cause:
 

• Swollen eyelid

• Redness

• Warmth

• Tenderness

Mild uncomplicated cases can often be treated outside the hospital with oral antibiotics and close follow-up.
 

Orbital Cellulitis
 

Orbital cellulitis is a much more serious infection involving the tissues inside the eye socket. Warning signs include:

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• Pain when moving the eye

• Difficulty moving the eye

• Bulging of the eye

• Double vision

• Decreased vision

• Significant systemic illness

Suspected orbital cellulitis requires emergency evaluation and generally requires hospitalization, imaging, IV antibiotics, and specialist treatment.

Animal & Human Bites
 

Animal and human bites can introduce bacteria deep beneath the skin. A small surface wound can sometimes hide a deeper injury.

 

What Should You Do Immediately:

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• Wash the wound thoroughly with soap and clean running water.

• Apply pressure to control bleeding.

• Cover the wound with a clean dressing.

• Seek medical evaluation when appropriate.

 

Not all bite wounds should be closed with stitches. Deep puncture wounds, many cat bites, bites involving the hands or fingers, human bites over the knuckles, infected wounds, and heavily contaminated or damaged wounds are often left open because closing the skin may increase the risk of infection. Facial bite wounds and some clean, uncomplicated lacerations may be closed after thorough cleaning when appropriate. Bite wounds involving a joint, tendon, nerve, blood vessel, or other deep structure require additional evaluation.

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Not every bite requires antibiotics, but preventive antibiotics may be recommended for higher-risk wounds, particularly:

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• Cat bites

• Human bites

• Bites involving the hand or fingers

• Deep puncture or crush wounds

• Wounds involving a joint, tendon, or bone

• Certain facial wounds

• Bites in people with significant immunosuppression

 

An infected bite generally requires antibiotic treatment.

Human “Fight Bites”

A cut over the knuckles after punching someone's mouth can be particularly dangerous.

A tooth can penetrate through the skin and injure a tendon or joint, even when the skin wound looks very small.

These injuries require prompt medical evaluation.

Tetanus
 

Tetanus vaccination status should be reviewed after an animal or human bite. A Tdap or Td booster and, in certain circumstances, tetanus immune globulin may be necessary depending on the wound and vaccination history.

Rabies
 

Some animal exposures also require evaluation for rabies.

The risk depends on the animal, circumstances of the exposure, local rabies activity, and whether the animal can be observed or tested.

Potential rabies exposure should be evaluated promptly because preventive treatment can prevent the disease when given appropriately.

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Herpes Zoster (Shingles)

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Shingles occurs when the virus that causes chickenpox becomes reactivated later in life.

It commonly begins with:

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• Burning

• Tingling

• Increased skin sensitivity

• Pain

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The rash characteristically affects one side of the body and usually does not cross the body's midline.

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Antiviral treatment is most beneficial when started early, preferably within 72 hours after the rash appears.

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Pain can occasionally continue after the shingles rash has disappeared. This is called postherpetic neuralgia and becomes more common with increasing age.

 

Shingles Near the Eye

Shingles affecting the forehead, eyelid, nose, or area around the eye can potentially involve the eye and threaten vision.

Eye pain, redness, visual changes, or suspected eye involvement requires prompt medical and ophthalmologic evaluation.

 

Shingles Around the Ear

Shingles can occasionally affect nerves around the ear and face, causing Ramsay Hunt syndrome.

Symptoms may include:

• Severe ear pain

• Blisters in or around the ear

• Facial weakness or paralysis

• Hearing changes

• Vertigo

These symptoms require prompt medical evaluation.

 

Necrotizing Soft-Tissue Infection

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Rarely, infection can spread rapidly through deeper tissues and cause a necrotizing soft-tissue infection, including necrotizing fasciitis. This is a medical emergency.

Warning signs include:

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• Severe pain that seems much worse than the skin initially appears

• Rapidly spreading redness or swelling

• Rapid worsening

• Blisters

• Purple, gray, or black skin

• Skin numbness

• A crackling sensation beneath the skin

• Severe systemic illness

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                                                                               References & Guidelines

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• Centers for Disease Control and Prevention (CDC)

• Infectious Diseases Society of America (IDSA)

• American Academy of Dermatology (AAD)

• American Academy of Family Physicians (AAFP)

• American Academy of Pediatrics (AAP)

• World Health Organization (WHO)