10 Common Bacterial Skin Infections

Ranging in Severity From Mild to Deadly

Bacterial skin infections are common, ranging in severity from mild and annoying to life-threatening. The majority of these infections are caused by two types of bacteria: Staphylococcus aureus or a variant of Streptococcus (the same bacteria responsible for strep throat).

An infection can take many different forms depending on the location, bacterial type, and even the age of the affected individual. Many bacterial infections may be treated by a general physician. More complex one may require the input of a specialist dermatologist or even a rheumatologist.

Cellulitis

Cellulitis on the foot.
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Cellulitis is a bacterial infection affecting the two deeper layers of the skin: the dermis, and the subcutaneous tissue. Cellulitis is associated with both Staphylococcus and Streptococcus, although many other types of bacteria can cause the condition.

Cellulitis typically develops in areas where the skin has been broken, such as near ulcers or recent surgical wounds.

Erysipelas

Erysipelas on the foot.
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Erysipelas is a bacterial infection that occurs in the top two layers of skin. It is also commonly referred to as St. Anthony's Fire because it can be very painful and cause an intense, burning sensation.

Erysipelas is similar to cellulitis but affects different skin layers. Streptococcus is the usual culprit.

With erysipelas, the skin infection is usually very red and swollen, and there will be a sharply defined border between the normal and infected skin tissue.

Folliculitis

Folliculitis on a child’s back.
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Folliculitis is a relatively common infection of the hair follicles. It may be caused by bacteria and fungus and is characterized by tiny, red bumps that are filled with pus.

Folliculitis is more common among people with acne. Shaving can further increase the risk. While most cases resolve on their own without treatment, severe infections can cause permanent hair loss or scarring and may require a course of antibiotics.

Hot Tub Folliculitis

Hot Tub Folliculitis.
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Hot tub folliculitis is an infection of the hair follicles caused by the bacteria Pseudomonas aeruginosa.

The bacterium is commonly found in contaminated whirlpools, hot tubs, water slides, physiotherapy pools, or even loofah sponges.

Children tend to get it more than adults (in part, because their skin is more vulnerable, and they tend to stay in the water longer).

Furuncles

A furuncle.
Mahdouch/Wikimedia Commons//CC BY 1.0

While folliculitis involves the infection of a hair follicle, a furuncle is an infection of the entire pilosebaceous unit.

Pilosebaceous units are made up of the shaft, follicle, sebaceous gland, and erector pili muscle and are located throughout the body with the exception of the palms, soles of the feet, and lower lip.

A furuncle (also referred to as a boil) is most commonly found on the face, chest, and upper neck and can develop into an abscess if left untreated. Warm compresses can often help the furuncle mature and drain. In severe cases, the boil may need to be lanced in the doctor's office.

Carbuncles

Carbuncle
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A carbuncle is a cluster of several furuncles densely packed together. It is a much more serious infection than a furuncle typically requiring medical attention.

Carbuncles tend to occur in the same areas as a furuncle but also can develop on the buttocks, thighs, groin, or armpits.

Impetigo

Impetigo on child's mouth
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Impetigo is a bacterial infection of the top layer of skin called the epidermis. It is a highly contagious and more commonly seen in children than adults.

The hallmark of impetigo is a honey-colored crust. The sores usually occur around the nose and mouth but can be spread to other parts of the body through skin-to-skin contact, clothing, and towels. Impetigo can be caused by either ​Streptococcus and Staphylococcus aureus.

Impetigo is usually treated with a topical rather than oral antibiotic.

Erythrasma

Erythrasma on armpit
Caliendo/Custom Medical Stock Photo

Erythrasma is a bacterial skin infection that develops in areas where skin touches skin (such as the armpits, groin, or between the toes). Due to its location and appearance, erythrasma is often confused with fungal infections such as athlete's foot and jock itch.

If an infection in these areas does not respond to antifungal treatment, you may, in fact, have erythrasma and require a short course of antibiotics.

Hidradenitis Suppurativa

Hidradenitis Suppurativa
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Hidradenitis suppurativa is a complex and often persistent bacterial infection involving the sweat glands of the armpits, groin, buttocks, or scalp. The infection can also develop under the female breasts.

People don't get hidradenitis suppurativa until well after puberty. The infection can sometimes persist for years and manifest with small, painful lumps that break open and smell. Over time, these ruptures can lead to unsightly tunneling in the skin.

While there is no cure for hidradenitis suppurativa, a combination of antibiotics, steroid injections, hormones, and immune suppressive drugs like Humira (adalimumab) may help manage and alleviate the symptoms.

MRSA Infections

A MRSA skin infection

CDC/Bruno Coignard, M.D.; Jeff Hageman, M.H.S.
/Wikimedia Commons/Public Domain

Methicillin-resistant Staphylococcus aureus (MRSA) is a concerning and hard-to-treated bacterium that is resistant to standard antibiotic treatment.

It will often cause a mild, ulcerative sore on the skin but can sometimes lead to serious infections and spread (disseminate) through the bloodstream to infect other organs such as the lungs or urinary tract.

If left untreated, systemic MRSA can be life-threatening. It is easily spread for person-to-person and is often contracted in hospital following a surgery.

Treatment may involve multiple antibiotics such as (Bactrim) sulfamethoxazole, Cleocin (clindamycin), trimethoprim, and rifampin depending on the severity of the infection.

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