The New Silent Threat: The Growing Resistance to Antifungals

Health

Par: Roger-Luc Chayer (Image: AI / Gay Globe)

Nowadays, there is increasing talk about drug resistance. This resistance can concern opioids and narcotics in general, antivirals (especially those used for the treatment of HIV), as well as antibiotics, which are essential for combating many infections, with sexually transmitted infections (STIs) at the forefront. However, a new form of resistance, previously unrecognized, is developing: resistance to antifungals. And in this area, the stakes are high.

What is a fungal infection?

A fungal infection, also known as mycosis, is a disease caused by microscopic fungi that live in our environment. These fungi are present in the air, soil, water, and even on our skin. Most of the time, they coexist with us without causing any problems, but under certain conditions, they can grow excessively and cause an infection.

Fungal infections can affect different parts of the body. The most common are superficial mycoses, such as athlete’s foot (between the toes), nail infections (onychomycosis), or yeast infections like those caused by the Candida fungus. These infections often cause itching, redness, irritated skin, or cracks.

In some cases, fungal infections can become more serious, especially in people with weakened immune systems, such as cancer patients, those with HIV, or those on immunosuppressive treatments. The fungi can then affect internal organs, such as the lungs or brain, and cause invasive infections, sometimes fatal, such as those caused by Aspergillus or Cryptococcus.

Fungal infections often develop in warm, humid environments, which promote the growth of fungi.

Candida Albicans

According to Health Canada, Candida albicans is a unicellular fungus. Asexual reproduction occurs by budding to produce blastoconidia. Smooth white colonies of 2 to 4 mm appear 48 to 72 hours after culturing at 37°C on a fungal growth medium.

C. albicans is a commensal microorganism that is part of the endogenous microbial flora in the gastrointestinal, oropharyngeal, and female genital areas. It is also an opportunistic pathogen in humans under certain conditions, such as immunodeficiency (chemotherapy and HIV infection), reduced intestinal flora (antibiotic treatment), or when it comes into contact with blood (wounds and indwelling catheters). There are two subtypes of C. albicans infection: mucosal and systemic.

The most common mucosal infection caused by C. albicans is oral candidiasis, commonly known as thrush, characterized by the presence of single or multiple white, irregular plaques on the tongue, palate, or other mucosal surfaces. Gum infections are also a common complication of oral surgical procedures.

Invasive candidiasis refers to blood or intra-abdominal infections, peritonitis, or osteomyelitis, with estimated mortality rates for these infections ranging from 10% to 20%. Invasive candidiasis cases are usually associated with stays in intensive care units (ICU) and are typically the result of increased or abnormal colonization in a somewhat compromised host. The clinical manifestations of invasive candidiasis are usually nonspecific.

What are antifungal medications?

Candida albicans is sensitive to several types of antifungal treatments, including:

  • Amphotericin B and nystatin
  • Flucytosine
  • Azole antifungals (such as fluconazole and itraconazole)
  • Echinocandins
  • Combination treatments

Candidiasis affecting the skin and mucous membranes can be treated with azole antifungals such as fluconazole or itraconazole. Sometimes voriconazole and echinocandins are also used, but azoles are generally preferred.

For severe cases, such as systemic invasive candidiasis (when the infection spreads throughout the body), the first-line treatment is an echinocandin. Fluconazole may be used as an alternative, but it is generally less effective.

How does resistance to antifungals develop?

The repeated use of fluconazole, particularly for prophylactic purposes in immunocompromised patients, has been linked to the development of resistance in Candida albicans to this drug. Resistance to echinocandins has also been reported.

Multiple antifungal resistance in species of the genus Candida, and more specifically in C. albicans, is increasing. This situation is exacerbated by the limited number of therapeutic options available to treat these infections.

Currently, a new form of resistance is emerging globally, due to easy and inexpensive access to antifungal medications. Candida albicans can survive on inanimate surfaces for periods ranging from 24 hours to 120 days, and up to 45 minutes on the palms of hands. This fungus has been isolated on various objects such as bedding, children’s beds, and bassinets used in nurseries. It has also been observed that C. albicans can survive and even grow in distilled water kept at room temperature.

This fungus resists drying for 5 hours in darkness and for 1 hour in full light. Under experimental conditions, its cellular viability remains at 10% after 150 days in seawater, 180 days in rainwater, and 210 days in tap water.

How can we avoid developing resistance to antifungals?

Resistance to antifungals is a growing health problem that can make fungal infections more difficult to treat. Several simple and effective measures can be adopted to prevent its occurrence.

First, it is essential to use antifungals only when necessary and prescribed by a healthcare professional. Self-medication or prolonged use of these medications without supervision can promote resistance. For example, an improperly adapted or prematurely interrupted treatment allows fungi to survive and develop defense mechanisms.

Maintaining good personal and environmental hygiene is another way to reduce the risk of infection. Be sure to keep your skin dry and clean, especially in areas where fungi tend to develop, such as skin folds. Wear breathable clothing and avoid synthetic materials that trap moisture.

In healthcare environments, professionals must follow strict disinfection protocols to limit the spread of resistant fungi. Regular disinfection of surfaces and medical equipment is crucial to prevent cross-contamination.

Finally, it is important to avoid excessive use of antifungals in non-medical contexts, such as agriculture, where they are sometimes used to protect crops. These uses can contribute to the development of resistant strains that may later infect humans.

Approximately 70 to 80% of the human population carries Candida under normal conditions, without causing symptoms. That said, the proportion of people suffering from infections caused by Candida (such as thrush or yeast infections) varies and depends on factors such as age, health status, immune system, and other underlying conditions.

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