Drug resistance problem while treating fungal diseases

Most people must have heard about drug resistant bacteria. But there are some fungi too that can cause havoc in human systems and what is the worst scenario is some of them are drug resistant too!

Much of our understanding of multidrug resistance in fungi comes from studies in the generally nonpathogenic yeast Saccharomyces cerevisiae, in which the multidrug-resistant phenotype is referred to as pleiotropic drug resistance or Pdr ( reference 1). With the development of powerful new genetic and molecular biological techniques, researchers have provided important new insights into the physiology of multidrug resistance from experiments performed directly in pathogenic organisms. 

Antifungal drugs save lives by treating dangerous fungal infections, just like antibacterial drugs (antibiotics) are used to treat bacterial infections. Unfortunately, germs like bacteria and fungi can develop the ability to defeat the drugs designed to kill them. This is known as antimicrobial resistance. That means the germs are not killed and continue to grow. When this occurs with fungi that no longer respond to antifungal drugs, it is called antifungal resistance. This is especially a concern for patients with invasive infections like those caused by the fungus Candida, a yeast, which can cause serious health problems, including disability and death.

A deadly, drug-resistant fungus called Candida auris is spreading on a global scale right now. In 2009, doctors first found Candida auris in the ear discharge of a patient in Japan. Since then, the fungus has spread to numerous other countries, including Colombia, India, US and South Korea. This fungus affects people with weakened immune systems who are in the hospital or have severe illnesses. In fact, Candida auris outbreaks have been reported in hospitals and healthcare centers around the world. Invasive fungal infections can cause disability and death. Patients can get fungal infections while receiving care for something else in a healthcare facility.

Candida auris worries healthcare experts because it can't be contained with existing drug treatments. It even has the ability to survive on surfaces like walls and furniture for weeks on end. People who contract these drug-resistant diseases typically die soon after contracting them because of their untreatable nature.

Patients may not realize they have Candida auris infection if they are also sick with another illness making matters worse. Fever and chills that don't go away following drug treatment are common Candida auris symptoms, but the only way to diagnose the fungus is through a lab test. There are different strains of Candida auris in different parts of the world, causing doctors to think the fungus didn't come from a single place. Some experts think heavy use of pesticides and other antifungal treatments caused this fungus to pop up in a variety of locations around the same time. In 2013, researchers reported on another drug-resistant fungus called Aspergillus and observed that it existed in places where a pesticide that targeted that specific ....

As pesticides, antifungals, and antibiotics continue to be heavily used on crops and in livestock, it's possible that the fungi and bacteria they're targeting learn how to evolve to stay alive in spite of the treatments.

Antifungal resistance is a particular problem with Candida infections. Some types of Candida are increasingly resistant to the first-line and second-line antifungal medications, such as fluconazole and the echinocandins (anidulafungin, caspofungin, and micafungin). About 7% of all Candidab loodstream isolates (pure samples of a germ) tested  are resistant to fluconazole. More than 70% of these resistant isolates are the species Candida glabrata or Candida krusei. There is growing evidence to suggest that patients who have drug-resistant candidemia are less likely to survive than patients who have candidemia that can be treated by antifungal medications.

Although the most common antifungal resistance occurs in Candida species, resistance in other types of less common fungi is also a problem. In Aspergillus (a mold) infections, emerging resistance to the first-line treatment threatens the effectiveness of life-saving medications.

In general, Aspergillus infections are associated with high rates of death, especially in patients with weakened immune systems or underlying disease. Aspergillus is the leading cause of invasive mold infections, with an estimated 300,000 cases worldwide every year. Up to 12% of Aspergillus infections are estimated to be resistant to antifungal medications (2). In a large US study, antifungal resistance was identified in up to 7% of Aspergillus specimens from patients with stem cell and organ transplants.

A few years back one of my friends who donated her kidney to her father was inconsolable, when he died of fungal infection six months after the operation.  

What causes antifungal resistance?

Some species of fungi are naturally resistant to treatment with certain types of antifungal medications. Other species can develop resistance over time due to improper antifungal use—for example, dosages too low or treatment courses that are not long enough.

Some studies have indicated that antibacterial medications may also contribute to antifungal resistance. This resistance could occur for a variety of reasons. For example, antibacterial drugs can reduce good and bad bacteria in the gut, which creates favorable conditions for Candida growth (3). It is not yet known if decreasing the use of all or certain antibiotics can reduce Candida infections, but appropriate use of antibacterial and antifungal medications is one of the most important factors in fighting drug resistance.

Now what can you do to stop the spread of drug resistance fungi? Take these important steps ...

• Clean your hands whenever you do some dirty work.
• Be sure everyone clean their hands before entering your room if you have weak immune system.
• If you have a catheter, ask each day if it is necessary.
• Talk to your healthcare provider about your risk for certain infections, especially if you have a weakened immune system.
• Learn more about using antibiotics, including when they are needed and when they are not.

References:

1. Balzi, E., and A. Goffeau. 1995. Yeast Multidrug Resistance: the PDR network. J. Bioenerget. Biomembr.27:71-76.