Bacterial skin infections are quite common. As the largest organ in the human body, the skin is the front line of defense against dangerous organisms. It is also home to a healthy balance of good and bad bacteria, which are generally not problematic until an imbalance in the skin’s defenses creates an opportunity for unfriendly bacteria to cause skin infections.

Furuncles and Carbuncles

Commonly referred to as boils, furuncles are pus-filled follicular infections. Furuncles, as well as carbuncles — clusters of boils — can appear on any part of the body. If they are large enough, they may contain infected pus that a doctor must drain and lance. Boils occur when bacteria under the skin multiply too quickly for the immune system to kill them off. These infections may resolve on their own or may require antibiotics.

Folliculitis

Folliculitis is a common infection that affects the hair follicles. The infection commonly occurs due to shaving facial hair. Shaving causes cracks in the skin that allow bacteria to enter the follicles, resulting in bumpy, irritated skin. Hot tub folliculitis can develop when aquatic facilities fail to maintain tubs properly; a bacterium called Pseudomonas aeruginosa, which thrives in hot, poorly chlorinated water, often causes these infections. The best treatment is to keep skin dry and clean; seek a doctor’s advice if the issue does not resolve within 72 hours.

Acne Vulgaris

Acne vulgaris is a painful skin condition often caused by the bacterium Propionibacterium acnes. The sebaceous glands secrete excess skin oil — sebum — which mixes with dead skin and provides the ideal environment for P. acnes to flourish. The result is painful blackheads and whiteheads that, if squeezed, could further spread the infection. Treatments range from over-the-counter cleansers to prescriptions for benzoyl peroxide and topical antibiotics that minimize the risk of scarring.

Impetigo

Impetigo can affect adults but is most common in children. Yellowish-white blisters pop up around the mouth and nose, as well as on the hands and feet; they burst, and the secretion eventually crusts over. Before the blisters dry up, the fluid inside is extremely contagious, and children often transmit the infection through direct contact. Doctors advise affected individuals to cover blisters until the infection passes. Because strains of staph and strep bacteria cause impetigo, it can be easy to treat and may be rendered non-contagious 24 hours after taking antibiotics.

Lymphangitis

Lymphangitis occurs when bacteria enter the body through cut skin and infect the lymphatic system. Symptoms range from headache to increased heart rate, as well as visible markings on the skin near the lymph nodes. The nodes are typically tender and swollen; once the doctor identifies the cause of the infection, he or she will prescribe appropriate antibiotics.

Cellulitis

Cellulitis develops when Staphylococcus or Streptococcus bacteria enter broken skin through bites, cuts, or cracks. Depending on the location of the infection, it can spread quickly and impair function. For example, if the infection is near the eye, cellulitis can impact eyesight, or even spread to the brain. In mild cases, redness and swelling often resolve on their own. More serious cases require antibiotics and possibly a hospital stay. If left untreated, cellulitis can become life-threatening if bacteria enter the bloodstream.

Hidradenitis Suppurativa

Hidradenitis suppurativa is a rare inflammation of hair follicles that occurs near areas of skin that rub together, such as the armpits or groin. The lumps caused by the friction can burst. In more severe cases, tunnels form and leak pus. H. suppurativa is a recurring infection that can worsen over time and lead to life-threatening complications, including squamous cell carcinoma. Doctors will often prescribe retinoids or hormone therapy for this condition, or the patient may require surgery.

Ecthyma

Ecthyma starts with the infection of a pre-existing wound and evolves into a painful, deep dermal ulcer. Lesions often develop on the lower body, such as the buttocks and feet. People with diabetes and weak immune systems are more prone to infection because of their impaired ability to heal. Ecthyma treatments include antibiotics, and if the ulcers are extensive, may require surgical removal of dead and infected skin.

Necrotizing Fasciitis

Necrotizing fasciitis is a flesh-eating disease caused by both bacteria and fungi. It can develop in a variety of settings, including pools of water. Once the infection passes through the skin, it degrades any tissue it encounters, from fat and muscle to blood vessels, and can lead to death if not diagnosed quickly. In the beginning, symptoms include skin redness and swelling, pain, and fever. More advanced symptoms are dark-colored spots covering the skin, oozing ulcers, and nausea. Doctors will administer a rapid course of IV antibiotics and may perform surgery to remove dead tissue and irreparably damaged limbs.

MRSA

MRSA, Methicillin-resistant Staphylococcus Aureus, is caused by a form of staph that resists most common antibiotics. Patients residing in places where invasive medical treatment occurs, such as hospitals and dialysis treatment centers, are at risk of contracting MRSA. The infection starts as a boil and leads to fever as the bacteria enter the bloodstream and lungs. Treating MRSA is difficult, but once doctors identify the bacterium’s unique DNA, there is a better chance of curing the infection. Proper hygiene and sanitary practices in healthcare facilities are the best way to prevent MRSA.