What Are Yeast Infections?

When people think of infections, they often think about those caused by bacteria or viruses, but there is another microorganism that can cause infection: yeast. The yeast Candida albicans is found naturally on your skin and on mucous membranes like your mouth, gut, and vagina. Yeast infections (sometimes called candidiasis, candidosis, or thrush) are caused when this yeast, or another variety, overgrows or spreads to another part of the body and begins making you feel sick.

It is difficult to estimate how common yeast infections are, as many people may treat mild infections with over-the-counter (OTC) products and don't see a healthcare provider. Some types of yeast infections are also far more common than others. It is estimated that up to 75 out of 100 women may get a vaginal yeast infection in their lifetime.

Invasive candidiasis, a far more serious type of infection, affected fewer individuals at nine per 100,000 people. Fortunately, medicines exist to treat yeast infections wherever they are in the body. A majority of people are able to recover from a yeast infection quickly.

Types

Yeast infections can occur throughout the body. Although they are all caused by the same fungus, there is an important distinction between what are known as local mucocutaneous infections versus invasive candidiasis.

Local Mucocutaneous Infections

Local mucocutaneous infections are yeast infections that affect the skin and mucus membranes. These infections tend to be less dangerous than invasive candidiasis and can be treated in a week or two. Some examples of local mucocutaneous infections include yeast infections of the mouth (sometimes called thrush), throat, esophagus, skin, penis, and vulva/vagina.

Invasive Candidiasis

Invasive candidiasis occurs when the infection spreads into the bloodstream or internal organs. Candidemia, Candida in the bloodstream, is the most common type of invasive candidiasis with approximately 25,000 cases in the United States per year.

Invasive candidiasis can be life-threatening, with one study finding the mortality rate to be almost 25%. This number may be so high because the majority of people who get candidemia have suppressed immune systems or other existing health issues.

Yeast Infection Symptoms

The symptoms you will experience will vary greatly depending on where your yeast infection is and what type you have.

Those with local mucocutaneous infections often experience redness, itchiness, and soreness around the affected site. Some infections have symptoms specific to the area. Yeast infections in the mouth often cause loss of taste and the appearance of white patches on the tongue and around the inside of the mouth and throat. Vaginal yeast infections can cause pain during sexual intercourse or urination as well as abnormal vaginal discharge.

Invasive candidiasis has similar symptoms to a bacterial or viral infection including fever and chills. Candidiasis is often suspected if you have these symptoms but do not feel better after taking antibiotics, which are used to treat bacterial infections. You may experience additional symptoms if an invasive infection goes beyond the bloodstream to affect other parts of the body.

What Causes Yeast Infections?

Candida albicans, a type of yeast, is found in the mouth, esophagus, and gastrointestinal tract and usually is not an issue. When something causes an overgrowth of this yeast (or any other species of yeast) in one or more parts of the body, then it becomes an infection.

Risk Factors

Yeast infections are "opportunistic infections," which means they typically appear in people with compromised immune systems. Some particular types of yeast infections have their own specific risk factors. For example, risk factors for vaginal candidiasis include using oral contraceptives (birth control), being pregnant, or having diabetes.

Other risk factors for developing a yeast infection include:

• Being an active smoker
• Antibiotic usage
• Chemotherapy
• Deficiencies in vitamins such as vitamin A, B6, and iron
• Being an infant or older adult
• Having dry mouth
• Long or frequent hospital stays
• Certain medical devices like intravenous catheters (a device used to draw blood and/or distribute treatment to the blood)
• Artificial heart valves
• Poorly maintained dentures
  

Diagnosis

Your healthcare provider may perform slightly different tests to diagnose a yeast infection, depending on where in the body you are having symptoms. They will likely begin by asking you to describe your symptoms, list what medications you are taking, and discuss your medical history.

They will likely take a sample from the affected site such as a sample of vaginal discharge for a vaginal yeast infection or a mouth swab for oral candidiasis. If invasive candidiasis is suspected, you may be asked to obtain a blood sample to look for evidence of yeast in your bloodstream. The results from these samples are typically ready in a few days.

There may also be times when a provider is confident in their diagnosis and begin treatment without obtaining a sample first.

Treatments for Yeast Infections

The treatment your provider recommends for your yeast infection will depend on several factors such as:

• Where the infection is
• How severe it is
• Your age
• The status of your immune system

Local mucocutaneous infections are often treated in a week or two by applying an antifungal medicine in forms such as creams, powders, or mouthwashes to the affected area as well as pills that can be taken orally. Common If this first treatment does not work or you have recurrent infections, your provider may recommend a longer course of oral medication, try another type of oral medication, or give you an antifungal medication through an IV.

Invasive Candida is almost always treated by intravenous (IV) medication. A treatment for invasive Candida in the bloodstream should last until symptoms have resolved and there is no longer detected in the bloodstream plus an additional two weeks. An invasive Candida infection that has spread from the blood to other locations like to organs, bones, joints, or the nervous system may need a longer course of treatment.

Unfortunately, antifungal drug resistance (like antimicrobial resistance for treating infections caused by bacteria) is a growing issue. The CDC found 7% of their Candida blood samples to be resistant to the antifungal drug fluconazole. This makes focusing on preventing these infections from starting in the first place all the more important.

Prevention

Some high-risk groups may be given a "prophylactic" antifungal medication. This means you will be given an antifungal medication to prevent an invasive infection from starting instead of treating it. Some populations that may be given antifungal prophylaxis include:

• People in the intensive care unit (ICU)
• People who have had certain types of organ transplants
• People on some kinds of chemotherapy
• People with a low white blood cell count
• Infants with very low birth weights

Steps to prevent localized yeast infections will depend on where on the body they are located. Maintaining good oral hygiene may prevent oral Candida, for example, Some forms of birth control are associated with vaginal yeast infections. If you are prone to getting them, you may want to speak to your provider about finding a birth control that lowers your chances of getting an infection.

Related Conditions

People with certain diseases are at an increased risk for developing yeast infections. Some of these conditions include:

• Human immunodeficiency virus (HIV): HIV weakens your immune system and your body's ability to fight infections.
• Diabetes mellitus: Poorly controlled blood sugar can negatively impact your immune system.
  
• Cancer: Treatments common for many cancers like chemotherapy and radiation can weaken the immune system. People with cancer who are treated with stem cells are also at increased risk for fungal infections because they may need to take anti-rejection medicines or steroids. These medications can weaken the immune system.

Living With Yeast Infections

Yeast infections can range from mild to widespread, severe, and life-threatening. Local infections such as vaginal candidiasis and oral thrush are typically mild and often resolve within a week or two of treatment without long-lasting effects.

Those who develop invasive candidiasis have a more difficult prognosis, with a mortality rate of just under 25%. However, treatment is available and your healthcare provider will work with you to ensure you are treating your yeast infection as effectively as possible.