Bacterial skin infections can take many different forms from localized boils to whole-body infections like septicemia (in which the infection moves from the skin into the bloodstream). The infection generally starts when the skin is irritated or disrupted, such as by a cut, scrape, puncture, or rash.
The causes and treatment of a bacterial skin infection can vary by location—such as on the face, genitals, scalp, or hands—and whether the infection occurs in a baby, toddler, adolescent, or adult.
Here is a rundown of the nine most common bacterial skin infections, including their causes, how to identify them, and when to seek medical help.
Cellulitis usually occurs when the skin is broken, such as near ulcers, bruises, burns, or recent surgical wounds. While many types of bacteria can cause cellulitis, Staphylococcus aureus and Streptococcus pyogenes are the most common culprits.
If the cellulitis spreads to your bloodstream, it can be deadly, causing high fever, chills, rapid heart rate, vomiting, and other symptoms of septicemia. Seek emergency care if symptoms like these develop.
Symptoms include areas of extreme redness and swelling with a sharply defined border. It is common on the face and legs but can also affect the arms and trunk.
Erysipelas is similar in appearance to cellulitis. However, cellulitis occurs in the lower layers of the skin.
Minor skin disruption like athlete’s foot or eczema can lead to erysipelas by allowing bacteria into tiny breaks in the skin. It can also occur when bacteria spread to the nasal passages following a nose or throat infection.
Shaving or plucking hairs can increase the risk by providing bacteria easier access to disrupted pores.
Symptoms include tiny, red bumps and/or white-headed pimples filled with pus. Folliculitis tends to affect people with acne more than those with clearer skin.
While bacterial folliculitis usually heals on its own, more severe cases may require topical or oral antibiotics. Left untreated, folliculitis can cause permanent hair loss.
The condition is sometimes called “jacuzzi folliculitis” because it is contracted through contaminated whirlpools and hot tubs (especially wooden ones). People can also become infected through water slides, physiotherapy pools, or even loofah sponges.
Hot tub folliculitis typically affects the chest or groin. The risk is higher in people with acne or eczema as their skin barrier has already been disrupted.
Hot tub folliculitis tends to resolve on its own but may benefit from topical silver sulfadiazine cream. Severe cases may require oral antibiotics.
Unlike folliculitis, which also involves a hair follicle, a furuncle is an infection of the entire pilosebaceous unit (which includes the follicle, hair shaft, and sebaceous gland).
Furuncles are common on the face, neck, armpits, buttocks, and thighs. Applying warm compresses can help drain pus.
But, in severe cases, your healthcare provider may need to lance (cut open) the boil to drain it, followed by a course of oral antibiotics.
Carbuncles usually develop on the back, thighs, or back of the neck. The infection tends to be deeper and more severe than that caused by furuncles. The most common cause is Staphylococcus aureus.
Carbuncles are more difficult to treat and can take longer to resolve than boils. The risk of scarring is high as is the spread of infection to other parts of the body. For this reason, carbuncles generally require medical treatment.
Impetigo usually occurs around the nose and mouth but can spread to other parts of the body through skin-to-skin contact or contaminated clothing or towels. Impetigo is usually treated with topical antibiotics.
Erythrasma develops where skin surfaces rub against each other, such as the armpits, groin, or between the toes. In addition skin discoloration and flaking, mild itching or burning may occur, especially in the groin area.
Erythrasma is most common in warm, humid climates. Other risk factors include poor hygiene, obesity, diabetes, and older age.
Topical or oral antibiotics may be used depending on the severity. Gentle scrubbing can help remove some of the scales.
The symptoms of MRSA can vary by the location of the infection. They typically include redness, swelling, pain, pus, and fever. Some MRSA infections look like other common bacterial infections and can even be confused with a spider bite.
Laboratory tests are usually required to diagnose MRSA. If left untreated, MRSA can easily spread from person to person, particularly in hospital settings.
A bacterial infection may cause localized symptoms (such as with furuncles, carbuncles, erythrasma, and impetigo) or affect larger portions of the body (such as with hot tub folliculitis and erysipelas). Some like MRSA and cellulitis can also spread into the bloodstream and cause septicemia and sepsis.
A Word From Verywell
Bacterial skin infections are common, and they can be hard to tell apart. While most aren’t dangerous, they generally need treatment and can quickly become serious if left untreated.
If in doubt about a skin infection, do not hesitate to speak with your healthcare provider or a skin specialist known as a dermatologist. You can also contact a telehealth provider who may be able to offer advice based on a visual exam using your cell phone camera.
