Types of Foot Fungus and Bacterial Infections

Common Causes and Tips for Prevention

Fungal or bacterial foot infections can occur when a germ enters a break in the skin or you step on a surface inhabited by the germ, such as a locker room floor. There are many different foot bacteria and foot fungus types, including those that cause abscesses, athlete's foot, cellulitis, or toenail fungus (onychomycosis).

Foot infections are often mild and easily treated at home, particularly fungal ones. Others can get worse and spread into the bloodstream, especially bacterial ones, and require aggressive medical treatment.

This article describes some of the more common fungal and bacterial foot infections, including how to recognize them and avoid them.

how to avoid foot infections
Verywell/Brianna Gilmartin

Fungal Foot Infections

You can get a fungal foot infection by coming into contact with certain types of fungi on floors or other contaminated surfaces. Fungi are especially robust and thrive in moist environments, such as locker rooms, public showers, and spas.

The roots of the fungus can easily penetrate damp, softened tissues. Infection can occur by simply touching a moist, contaminated surface with your foot.

Fungal foot infections can be persistent and hard to treat, but they are rarely life-threatening.

Athlete's Foot (Tinea Pedis)

Athlete's foot, also known as tinea pedis, is an infection caused by several types of fungi, including those linked to ringworm. Athlete's foot is highly contagious and easily passed through contaminated floors, towels, footwear, or clothing.

There are several types of athlete's foot which vary by their location or characteristics:

  • Toe web: This is the most common form of tinea pedis in which the infection occurs between the toes where moisture levels are high. In addition to itching, there may be peeling skin and a yeasty-smelling rash.
  • Moccasin: This occurs when athlete's foot affects the bottom of the feet, mainly the soles, heels, and sides of the heels. It can lead to thick, scaly skin along with cracking and peeling.
  • Vesicular: This is when vesicles (blisters) develop at the site of the infection. The blisters can occur anywhere but are most often seen on the soles or between the toes.
  • Ulcerative: This occurs when athlete's foot causes a break in the skin that allows bacteria to enter. The secondary infection can cause a painful, open sore called an ulcer along with swelling and oozing.

Most cases of athlete's foot can be diagnosed by symptoms alone. More serious or recurrent cases may require a skin scraping and a KOH test (in which collected cells are examined under a microscope) to confirm the diagnosis.

Mild cases can be treated with an over-the-counter (OTC) antifungal cream or spray like Lamisil AF (terbinafine). Serious or persistent infections may require up to six months of treatment with an oral antifungal like Sporanox (itraconazole).

Toenail Fungus

Onychomycosis is the medical term for a fungal toenail infection. Also known as tinea unguium, it often occurs alongside tinea pedis but can occur on its own.

Onychomycosis is more common in people with a weakened immune system or those with peripheral vascular disease (in which blood flow to the limbs is decreased).

Symptoms of toenail fungus include:

Onychomycosis can be diagnosed by a visual examination of the toenail. Your healthcare provider may order a KOH test to confirm the diagnosis. Tissue cultures from nail trimmings can help identify the specific fungus.

Onychomycosis is notoriously difficult to treat, partly because topical creams can't penetrate the nail plate. Oral Lamisil (terbinafine) tends to work best, but it can take up to 12 months for the nail to fully grow back.

Bacterial Foot Infections

Bacterial foot infections are less common than fungal foot infections but can sometimes turn serious, leading to systemic (whole-body) infection.

Most bacterial infections are established when a bacteria enters a sore, cut, or abrasion on a foot. The most common causes are Staphylococcus aureus (staph infection) and Corynebacterium, both of which naturally populate the feet.

Symptoms of a bacterial foot infection include:

  • Swelling, redness, pain, and heat at the site of infection
  • A clear or pus-like drainage
  • Difficulty walking on the foot

Severe infections can lead to systemic symptoms, like fever, chill, nausea, or vomiting.

While anyone can have a bacterial foot infection, people who are older, immunocompromised, or have diabetes may be at risk of severe infections or complications like cellulitis.

Erythrasma

Erythrasma is a bacterial infection frequently mistaken for a fungus. It is mainly caused by Corynebacterium minutissimum and is most common in people with diabetes or obesity.

Erythrasma is primarily seen in folds of skin, such as the armpits, under the breasts, in the groin, or between the toes. On light skin, erythrasma causes pinkish or reddish patches that gradually turn brownish and scaly. The lesions can be harder to spot on dark skin.

On the foot, erythrasma is most often seen on the webbing of the third, fourth, and fifth toes.

Erythrasma can often be diagnosed with a Wood's lamp that makes the bacteria look coral-pink under ultraviolet light. This infection is best treated with a topical fusidic acid cream or an oral antibiotic like Zithromax (azithromycin) or Erythrocin (erythromycin).

Foot Abscess

Bacterial foot infections sometimes go beyond the outer layers of skin, forming a pocket of pus known as an abscess. Foot abscesses are often caused by puncture wounds or hair follicles that become infected. They're similar to boils but involve deeper tissues.

On the foot, an abscess can look like a little pimple that grows into a painful, inflamed lump that is red and warm to the touch. There may also be generalized achiness and low-grade fever. In some cases, an abscess can be extremely firm (indurated).

Abscesses are most often caused by Staphylococcus aureus, but other bacteria can also cause deep tissue infection.

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Foot abscess

Reproduced with permission from ©DermNet NZ www.dermnetnz.org 2022

Abscesses can often be diagnosed with a physical exam. Your healthcare provider may order a bacterial culture to identify the bacterial culprit and prescribe the most effective antibiotic.

Treatment usually involves the draining of the abscess followed by a course of oral and/or topical antibiotics. An OTC painkiller like Tylenol (acetaminophen) can reduce pain and fever.

Cellulitis

Cellulitis is a potentially serious condition that involves the rapid spread of a local bacterial infection to adjacent tissues. With cellulitis, the infection will spread from the top layer of the skin (epidermis) into underlying layers (called the dermis and subcutaneous tissue).

Risk factors for cellulitis include obesity, diabetes, and peripheral edema (fluid overload in the lower extremities, often seen in people with heart failure).

Cellulitis is most common on the legs and feet, causing:

  • Increasing redness, swelling, and pain
  • A pitted, orange peel-like texture
  • Blistering and peeling
  • Red streaks moving outward from the initial site of infection

The red streaks (lymphangitis) are caused by the migration of the infection to your lymph nodes. If the infection gets there, it can become systemic and cause septicemia (the spread of infection into the bloodstream).

Septicemia, in turn, can trigger a potentially, life-threatening inflammatory reaction known as sepsis.

Simple cases of cellulitis may be treated with broad-spectrum antibiotics for between five and 14 days. Serious cases may require hospitalization with intravenous (IV) antibiotics and fluids.

When to Seek Emergency Care

Cellulitis is always a medical emergency. If you see a red streak moving up your foot, get immediate medical help.

Prevention

You can prevent bacterial and fungal foot infections by:

  • Keeping your feet clean and dry
  • Washing daily with soap and water
  • Not going barefoot in public spaces
  • Wearing plastic or rubber slippers in public showers or locker room
  • Not sharing footwear or nail clippers
  • Keeping your toenails trimmed
  • Regularly changing your socks and shoes to prevent moisture build-up

If your feet are especially sweaty or prone to fungal infection, use a daily OTC antifungal foot powder or spray.

If the skin on your foot is cut or scraped, wash it immediately with soap and water. Then cover it with a sterile bandage.

If your foot is prone to dryness and cracking, use a petrolatum-based foot cream to soften the skin.

Summary

Fungal foot infections include athlete's foot and onychomycosis (toenail fungus). They're easy to spread but can be readily treated with topical or oral antifungals.

Bacterial foot infections include erythrasma, abscesses, and cellulitis. Oral or topical antibiotics can clear them up.

You can prevent infections by keeping your feet clean, wearing slippers in public showers or locker rooms, and treating foot injuries immediately.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
Catherine Moyer

By Catherine Moyer, DPM
Catherine Moyer, DPM, is a podiatrist experienced in the diagnosis, treatment, and prevention of disorders of the foot and ankle.