What are antifungal medicines? And what does antifungal resistance mean? Is it somehow related to Antimicrobial Resistance (AMR)? At first glance, these topics may seem difficult to understand. But do not worry, in this blog we will try to shed light on them.
As always, let’s begin with basic concepts. What are antimicrobials? They are medications that can kill or stop the growth of microorganisms, and therefore are used to prevent and treat infections in humans, animals and even plants.
When we talk about microorganisms, we refer to viruses, bacteria, fungi, or parasites. Accordingly, antimicrobials are a big group of medications, including antivirals, antibiotics, antifungals and antiparasitics, depending on the type of microbes they target. For example, you have already heard of antibiotics: they are medicines that treat bacteria. Antifungals are probably less known: these medicines are effective against fungi and yeasts and are used to prevent or treat fungal infections. They are also called antimycotics but, for convenience, in this blog we will only use the word “antifungals”.
Now, you may be wondering: what Antimicrobial Resistance is, also known as AMR? AMR happens when microorganisms develop the ability to defeat the medicines designed to kill them or stop their growth. In other words, microbes can change over time and no longer respond to antimicrobial medicines.
For example, you might know that bacteria can develop resistance to antibiotics, and it is called antibiotic-resistance. In the same way fungi can develop resistance to antifungals: this is called antifungal resistance.
Usually, AMR is discussed in terms of bacteria and antibiotics, and often antifungal resistance remains overlooked. However, drug-resistant fungi are on the rise, and infections caused by these microbes represent a global public health threat.
Yes, you got it right. Indeed, differently from the most common skin or nail infections, the invasive fungal infections are particularly worrying. Fungi and yeasts like Candida species, infecting the deep-seated tissues of the body, can cause life-threatening diseases with high mortality, such as bloodstream, brain, and lung infections, just to give some examples.
Unfortunately, these serious illnesses are increasing since the population at risk continues to grow. People at increased risk are those with health problems, or a weakened immune system, such as people with cancer, HIV, tuberculosis, diabetes, and chronic lung or kidney diseases. Patients in intensive care units, receiving antibiotics or immunosuppressants, or undergoing invasive procedures including surgery are more likely to get fungal infections, as well.
Moreover, access to both quality diagnostics and antifungal drugs is limited in low-resource settings. As a result, a lot of infections are undiagnosed and therefore untreated, contributing to increased mortality. In addition, there is also a limited choice of antifungals: currently only four classes of these drugs are used in clinical practice, and only a few others are under development.
Finally, the rapid emergence and spread of antifungal resistance is worsening the problem. It occurs when fungi no longer respond to medications which are supposed to kill them. Bad news: serious fungal infections can become untreatable, and patients’ survival is compromised.
Fungi can occur as yeasts, molds, or as a combination of both forms. Some fungi can cause superficial, cutaneous, subcutaneous, systemic or allergic diseases.
Yeasts are microscopic fungi consisting of solitary cells that reproduce by budding.
So, what are the main drivers of antifungal resistance? Some species of fungi are naturally resistant to certain types of antifungals. However, resistance can occur for several reasons.
It may result from the overuse or misuse of these medications in healthcare, for example when patients skip doses, or stop therapy too soon, or take a dose which is too low. Moreover, as we have already said, especially in low-resource settings the lack of diagnostic tests may lead physicians in failing to provide a correct diagnosis, and starting an inappropriate antifungal therapy, as a consequence. Even with laboratory support, many fungi are difficult to grow and test against antifungal drugs
Even the use of fungicides (compounds able to protect crops from molds) in agriculture can contribute to antifungal resistance. Indeed, when Aspergillus (a fungus) is exposed to fungicides like antifungals, it can become resistant to the medicines used to treat infections in humans. If people with a weakened immune system breathe Aspergillus resistant spores from the environment, they get infected and can develop severe conditions, among which invasive aspergillosis. Particularly in patients with chronic lung diseases.
Like bacteria, unfortunately fungi can become superbugs, too. Growing resistant to several antifungals commonly used to kill them, they eventually may not respond to any available drug. Candida auris is an example. This fungus, responsible for a very serious infection (invasive candidiasis), is resistant to most available antifungals. Moreover, it is also difficult to eradicate from healthcare facilities, and can cause outbreaks. So, as you can understand, a superbug is not “super” in a good way at all.
You can play a valuable role in tackling antifungal resistance. How? First, wash your hands regularly and thoroughly: it is the most effective way to prevent the spread of infections, the fungal ones included. Then, always remember: take antifungal medicines only when needed and exactly as prescribed by your physician.
Maybe you are thinking: “Uhm, there is not much I can do about it”. But believe me: following these two simple rules you are already saving lives!
Let’s fight antifungal resistance together!
Francesco M. Labricciosa
Francesco M. Labricciosa is a Medical Doctor from Italy. After earning a post-graduate diploma in Primary Care Medicine, he consolidated his experience in different healthcare settings, and then became a specialist in Hygiene and Preventive Medicine.
Antimicrobial Resistance (AMR), optimal and prudent use of antimicrobials, and awareness towards consumption of these medications represent his main fields of interest.
Since 2016, he has been collaborating with the Global Alliance for Infections in Surgery. He participated in several international research projects about prevention and management of healthcare-associated infections, surgical antibiotic prophylaxis, antimicrobial therapy in intra-abdominal infections, and antimicrobial stewardship programs. He has co-authored more than 35 articles published in peer-reviewed medical journals.
Moreover, Francesco works with several medical communication agencies in designing and finalising educational materials aimed at diversified audiences. Finally, he takes an active role in science communication blogging about antimicrobial use and AMR.
With special thanks to:
Reviewed by Prof. Adrian Brink, Head of the Division: Medical Microbiology, Faculty of Health Sciences, University of Cape Town and the National Health Laboratory Services, Cape Town, South Africa and Vanessa Carter, AMR Patient Survivor and Chair of the WHO Taskforce of AMR Survivors
