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Nystatin: An Antifungal Medication and Candida Infections

Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.

A Useful Medicine for Yeast Infections

Nystatin is a very useful medication that often kills the Candida albicans yeast that infects humans. The yeast is generally harmless and lives permanently in our mouth, in our large intestine, on our skin, or in the vagina. Unfortunately, under certain conditions its population can grow dramatically, causing a disease called candidiasis. This disease ranges in severity from an uncomfortable and annoying condition to a deadly infection.

In most people, candidiasis is unpleasant but not dangerous. In people with weakened or suppressed immune systems, such as AIDS patients, organ transplant patients, and people receiving chemotherapy, candidiasis can be serious.

Nystatin is made by a bacterium called Streptomyces noursei. It was discovered in 1950 by scientists named Elizabeth Lee Hazen and Rachel Fuller Brown. The couple named the chemical after the New York State Health Department. They both worked for this department, though they lived in different cities.

Candida albicans cells and filaments

Candida albicans cells and filaments

Cells and Hyphae of Candida albicans

Yeasts are a type of fungus. Most yeasts consist of a single cell. They produce new individuals in the form of buds that separate from the parent cell. Other fungi have a different structure. Their body consists of branching, thread-like structures called hyphae. The tangle of hyphae that forms is called a mycelium.

Candida albicans exists as single, oval cells, like other yeasts. Its cells are surrounded by a wall made primarily of polysaccharides and proteins. The wall in turn surrounds the cell membrane. Unlike typical yeasts, a C. albicans cell sometimes produces filaments that resemble hyphae, as shown in the photo above. The filaments are present when Candida becomes invasive.

Candida albicans cells are shown below at a higher magnification. The cells have been stained and placed under a light microscope. The nucleus of each cell has absorbed a large quantity of the stain and is darker than its surroundings.

Invasive Candidiasis and Candidemia

The Candida albicans population in our bodies is normally kept at a low level by factors such as other microorganisms in the body, the environment in which the yeast is living, and our immune system. However, under certain conditions the population can increase and cause unpleasant symptoms.

In serious cases, the yeast can spread through the blood away from its initial site of colonization and cause infections in other organs, which is known as a systemic infection or invasive candidiasis. The presence of Candida in the blood is called candidemia.

Candida albicans cells and filaments as viewed under a scanning electron microscope

Candida albicans cells and filaments as viewed under a scanning electron microscope

Although Candida albicans is the most publicized species of the genus Candida, there are over twenty species in the genus that can infect humans.

Candida Infections and Fungal Biofilms

C. albicans causes "opportunistic" infections in humans. Most of the time, opportunistic organisms are not pathogens (ones that cause disease). They are able to increase in population size and cause health problems when there is a suitable change in their environment, however.

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A troubling development with respect to Candida infections is the formation of yeast biofilms on implanted medical devices, such as catheters. A catheter is a thin tube inserted into the body for a medical reason, such as enabling the passage of fluid from a particular area. C. albicans exists in both yeast and hyphal forms in biofilms.

The microbes in a biofilm produce chemicals that help them stick to each other and to the surface on which they're living. They are much harder to kill than free-living microbes. Another problem is that biofilms can release microbes that produce infections in other areas of the body.

Investigating bacterial biofilms is a very active area of scientific research. Scientists are paying increased attention to fungal biofilms as they realize how important they are.

Inhaled corticosteroids increase the chance of thrush development.

Inhaled corticosteroids increase the chance of thrush development.

Thrush or Oral Candidiasis

Candidiasis in the mouth is usually known as thrush or oral candidiasis. The yeast collections appear as white spots on the lining of the mouth or throat, on the gums or tonsils, inside the cheeks, or on the tongue.

The appearance of thrush generally means that there's been a change in the environment in the mouth or the body. Some conditions that promote the growth of the yeast population are listed below.

  • Using inhaled corticosteroids to treat asthma without rinsing out the mouth afterwards
  • Wearing dentures
  • Taking antibiotics for another infection (probably because the antibiotics have killed the bacteria that help keep yeasts under control)
  • Having a weakened immune system
  • Having diabetes (probably due to an increased sugar level in the saliva)
  • Being pregnant
  • Being obese

Babies have an immature immune system and are susceptible to developing thrush, as the video below describes.

Treating Thrush in Newborn Babies

Candidiasis in Other Parts of the Body

In addition to appearing in the mouth, candidiasis may develop on the lips or skin, under a nail, in the gastrointestinal or reproductive tracts, around the anus, in the urinary bladder, or under a baby's diaper.

Although someone with candidiasis may need to take medications to deal with the yeast outbreak, if their immune system is healthy the yeasts are unlikely to travel beyond the external surfaces of the body or beyond the lining of the passageways connected to the external environment. In general, Candida only reaches the lungs in a person whose immune system isn't working efficiently.

Symptoms of a yeast infection depend on where it develops. They may include a thick, white discharge, redness, itching, and a burning sensation.

A Candida albicans Infection

The Discovery and Naming of Nystatin

The discovery of nystatin is an interesting story. The two women who discovered the chemical worked in different cities. Elizabeth Lee Hazen was a microbiologist based in New York City while Rachel Fuller Brown was a chemist who lived in Albany. The women cooperated in the following way.

  • Hazen collected soil samples, grew cultures of the microbes in each sample, and tested them for antifungal action against Candida albicans and another yeast named Cryptococcus neoformans.
  • If she found activity she mailed the culture to Brown in a Mason jar.
  • Brown extracted the active chemical from the culture and then mailed it to Hazen.
  • Hazen then tested the extracted chemical on the two yeasts to see if it killed them. She also checked to see if the extract was toxic to animals.

One soil sample collected by Hazen came from the garden (or farm) of a friend named Walter Nourses. This sample contained a bacterium that produced a chemical that killed the yeasts yet was apparently safe for animals. Hazen named the bacterium Streptomyces noursei, using a species name to honor her friend, and called the active chemical fungicidin. Later the two women discovered that the name fungicidin was already used for another chemical, so they renamed their antifungal substance nystatin.

Value of Collaboration and Methodical Work

Without an efficient mail service and the patient, painstaking, and determined work of Elizabeth Hazen and Rachel Brown, nystatin might never have been discovered. The women lacked the relatively sophisticated lab equipment that we have today, as well as computer software, email, and video communication. Despite these apparent limitations, their methodical work enabled them to discover nystatin as well as other antimicrobial substances. Both women made other valuable contributions to science, but they are best known for their collaborative effort and their discovery of nystatin.

In this ball and stick model of a nystatin molecule, the balls represent atoms and the sticks represent chemical bonds.

In this ball and stick model of a nystatin molecule, the balls represent atoms and the sticks represent chemical bonds.

Nystatin Effects on Fungi

As in all fungi, the membrane around yeast cells contains a chemical called ergosterol. Nystatin targets this ergosterol. Ergosterol is a steroid molecule that helps the yeast membrane to maintain its correct structure. The membrane is a very important part of a cell. It determines which substances are able to enter and leave the cell.

Nystatin binds to ergosterol molecules and causes abnormal channels to appear in the membrane. These channels allow vital substances such as potassium ions to leave the yeast cells, resulting in their death.

Ergosterol is found in fungi but not in animals or humans. Therefore nystatin is able to kill fungal cells but is safe for our cells. There are newer antifungal medications available today, but nystatin is still widely used. It's one of a range of medicines that doctors can prescribe to treat a patient's fungal infection.

The word ergosterol is derived from ergot, a common name for the fungus Claviceps purpurea. This fungus infects rye and other grains. Ergosterol was first found in ergot.

Don't give nystatin to a baby without seeking a doctor's advice.

Don't give nystatin to a baby without seeking a doctor's advice.

Nystatin Effects on Humans

Nystatin is a prescription medication and must be used only after a doctor has been consulted. Other antifungal drugs are available. The doctor will prescribe one that is suitable for the patient’s condition.

Nystatin is administered in an oral form, as a mouthwash, as a cream, in a powder form, or as a suppository. There are several trade names for the medication. For example, mycostatin is the trade name of a medicine that actually consists of nystatin.

Nystatin isn't absorbed into the bloodstream under normal conditions, though if the lining of the digestive tract is damaged, it may be absorbed to some extent. In general, the medication stays at the site of the infection and is unlikely to cause serious side effects. This means that other medicines are needed if a fungal infection is systemic. A systemic infection spreads through the body and affects multiple organs and tissues.

The most common side effects of nystatin treatment—if they appear—are gastrointestinal upset and irritated skin or mucous membranes. As with any substance that enters the body, an allergic reaction is possible.

While nystatin is not normally absorbed, low concentrations may enter the circulation in patients with inflammation and damage to the gastrointestinal tract.

— LiverTox, National Institutes of Health

Precautions and Importance

It's very important that pregnant or nursing women use nystatin only with a doctor's recommendation. It’s unclear whether the drug can enter the fetus or a mother's milk, and if it can do this, how much is likely to enter the baby. A doctor should also be consulted before administering the medication to a baby after birth.

Nystatin is a wonderful medicine whose discovery was very important. If a doctor believes that it’s the best drug for the patient and prescribes its use, it could be a great help for a Candida infection. As is true for any medication, the instructions and precautions for the product's use should be read and followed carefully, and the medication should be stored safely so that no children or pets can reach it.


  • Types of candidiasis from the CDC (Centers for Disease Control and Prevention)
  • Attack by Candida albicans from Tufts University School of Medicine
  • Vaginal yeast infection from MedlinePlus, NIH (National Institutes of Health)
  • Nystatin (vaginal route) from the Mayo Clinic
  • The discovery of nystatin from the Science History Institute
  • Information about nystatin from MedlinePlus
  • Nystatin facts from LiverTox (an NIH publication)

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: What treatment is used for a male urethra infection?

Answer: Males can have urinary tract infections. They are rare in younger men, but are more common in those over the age of fifty. The infections are often caused by bacteria, which produce inflammation as a major symptom. Men may also experience a penile yeast infection known as Balanitis. According to the Merck Manual, however, it’s uncertain whether Candida can cause urethral symptoms in men.

A doctor must be consulted to receive a diagnosis and treatment for a urinary tract problem. It’s important to discover where the inflammation is located in the man’s tract, as well as its cause. An antibiotic is often prescribed to treat an uncomplicated UTI triggered by bacteria. The doctor will prescribe the best antibiotic for the patient’s condition and overall health status. Medicines can have side effects, which a doctor will take into account.

Question: Can a male receive damage from a urethra infection?

Answer: It is possible for an untreated infection to cause urethral damage in men, though this seems to be true only in an infection by specific organisms. An untreated or recurrent infection by these organisms may injure the wall of the urethra and cause the passageway to become narrower, making urination difficult. The complete prevention of urination is a very serious condition.

Other potentially serious effects may result from an untreated urinary tract infection. The organisms that caused the UTI may spread to the kidneys and the bloodstream. The kidneys may be permanently damaged. The bloodstream will transport the microbes to other parts of the body. A very serious and life-threatening condition known as Sepsis may appear in this situation.

In Sepsis, the body secretes chemicals into the blood in an attempt to fight the infection. The chemicals cause inflammation, which can often be a helpful process. In Sepsis, however, the inflammation is severe, widespread, and dangerous. Sepsis may be accompanied by a very dangerous condition known as Septic shock. In this disorder, blood pressure falls dramatically.

© 2012 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on August 15, 2012:

Thank you for the visit and the comment, teaches. Yes, it would be a very good idea to try to maintain a healthy immune system in order to prevent the Candida population from growing out of control. Candida infections are very unpleasant!

Dianna Mendez on August 15, 2012:

I read through this and was fascinated by the many conditions that may cause candida. Glad that nystatin was discovered to combat this infection. I guess it also supports the fact that we must maintain a healthy diet and immune system to avoid these types of conditions.

Linda Crampton (author) from British Columbia, Canada on August 12, 2012:

Thank you for the comment, unknown spy. It's nice to meet you!

Linda Crampton (author) from British Columbia, Canada on August 12, 2012:

Hi, Augustine. Thanks for the visit and the comment. Yes, yeast infections are certainly annoying. Streptomyces noursei is actually a bacterium, but it's still very interesting that one microbe can be used to fight another!

Life Under Construction from Neverland on August 11, 2012:

that was an interesting to read. it helps you better understand how to protect yourself from this infection

Augustine A Zavala from Texas on August 11, 2012:

Acommon condition that is very annoying I'm sure. Using a fungus to kill another fungus? Fascinating...

Linda Crampton (author) from British Columbia, Canada on August 10, 2012:

Hi, drbj. Thank you for the comment. I appreciate your visit - and all your visits - very much! I found the collaboration between Hazen and Brown very interesting too. They worked so methodically and made such an important discovery.

drbj and sherry from south Florida on August 10, 2012:

Terrific painstaking research, Alicia, and much needed information. Particularly interesting was the collaboration between Hazen and Brown. Thanks for sharing this knowledge.

Linda Crampton (author) from British Columbia, Canada on August 10, 2012:

Thank you, Tom. I appreciate your comment and your vote. Have a great weekend!

Thomas Silvia from Massachusetts on August 10, 2012:

Hi my friend, great well written and well researched article, found all the information interesting .

Vote up and more !!!

Linda Crampton (author) from British Columbia, Canada on August 10, 2012:

Hi, GoodLady. Thanks for the visit and the vote. No, unfortunately yeast infections - especially Candida albicans infections - are not rare. They are something that many people have to deal with at some time or other.

Penelope Hart from Rome, Italy on August 10, 2012:

Ugh...but read on and absorbed (oops wrong word perhaps). Good to know about the cure for yeast infection which isn't THAT rare is it? Very interesting and many thanks. Wont be pinning it though aliciaC! Shall vote instead

Linda Crampton (author) from British Columbia, Canada on August 10, 2012:

I appreciate the comment, susiebrown48. Thank you very much for the visit.

susiebrown48 from Clearwater, FL on August 10, 2012:

Fascinating, well-researched article. Loved it.

Linda Crampton (author) from British Columbia, Canada on August 09, 2012:

Thank you for the visit and the vote, Jennzie. Yes, I hope the child was soon cured of that yeast infection!

Jenn from Pennsylvania on August 09, 2012:

That definitely looks unpleasant! Very informative hub, voted up!

Linda Crampton (author) from British Columbia, Canada on August 09, 2012:

Thanks for the comment and vote, Judi. The condition of that tongue does look sad. The thrush must have been an unpleasant experience for the child!

Judi Brown from UK on August 09, 2012:

I just had to read this after seeing that child's tongue - poor thing! Interesting hub - voted up.

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