Antifungal Resistance Is On The Rise

Although antibiotic-resistant bacterial infections are a widely recognised  health problem, we are now also seeing the emergence and increased rates of serious invasive fungal infections. Just like bacteria, some fungi have developed resistance and no longer respond to the antifungals that are used to treat them.

Some types of Candida are becoming increasingly resistant to first-line and second-line antifungals, namely echinocandins and fluconazole. Approximately 7% of all Candida bloodstream isolates tested at the Centre of Disease Control in the US, are resistant to fluconazole. For now, the CDC’s surveillance data indicate that fluconazole resistance has remained fairly constant over the past 20 years. On the other hand, echinocandin resistance appears to be on the rise. Isolates tested by CDC before 2004 showed no resistance, so this resistance has emerged after the echinocandins became widely used. Today, the prevalence of echinocandin resistance is more than 10% at some hospitals and is continuing to increase. A growing concern is the presence of multidrug-resistant Candida infections (those that are resistant to both fluconazole and echinocandins).

Some studies have indicated that antibiotics may also contribute to antifungal resistance. One of the reasons that this may occur is that antibiotics reduce bacteria in the gut and create favourable conditions for Candida growth. Whether decreasing the use of all or specific antibiotics can reduce Candida resistnt infections is unknown.

Although most resistance has looked at Candida species, resistance in other fungi also occurs. There is increasing resistance to Aspergillus. Since its approval in 2002, the antifungal agent voriconazole has been the primary treatment for invasive aspergillosis. However, over 10 years ago, several countries in Europe began seeing increasing resistance to Aspergillus.

Studies in Europe suggest that resistance in Aspergillus may be partially driven by the use of agricultural antifungals, which protect crops from fungal diseases. Prevalence as high as 30% has been seen in some hospitals in Europe. Patients with these resistant isolates had a much higher mortality—closer to 90%, compared with approximately 40% for patients with susceptible strains.

Parents are often dealing with fungal infections in their Autism Spectrum Disorder (ASD) children. Some parents are constantly battling fungal infections with a variety of antifungals, possibly after antibiotic treatment. This rising incidence of antifungal resistance is an important consideration in not only ASD children, but also in patients dealing with chronic conditions. If there is a suggestion that symptoms are due to an underlying yeast infection, yet antifungals are not working as expected, the possibility of antifungal resistance should be considered.

To deal with yeast, minimising fermentable carbohydrates can help to minimise the substrate on which yeast grows. The Body Ecology Diet (BED) is probably the most useful diet to deal with yeast issues. However, Single Carbohydrate Diet (SCD) and Gut and Psychology Syndrome (GAPS) diet may also be useful. In adult’s suboptimal thyroid function may be a contributing factor. The hormone thyroxine facilitates the absorption of glucose from the gut. Low levels will leave sugar behind in the gut for yeast to feed on and grow.

References

  1. Cleveland AA, Farley MM, Harrison LH, et al. Changes in incidence and antifungal drug resistance in candidemia: results from population-based laboratory surveillance in Atlanta and Baltimore, 2008-2011. Clin Infect Dis. 2012;55:1352-1361.
  2. Lockhart SR, Iqbal N, Cleveland AA, et al. Species identification and antifungal susceptibility testing of Candida bloodstream isolates from population-based surveillance studies in two U.S. cities from 2008 to 2011. J Clin Microbiol. 2012;50:3435-3442.
  3. Hajjeh RA, Sofair AN, Harrison LH, et al. Incidence of bloodstream infections due to Candida species and in vitro susceptibilities of isolates collected from 1998 to 2000 in a population-based active surveillance program. J Clin Microbiol. 2004;42:1519-1527.
  4. Alexander BD, Johnson MD, Pfeiffer CD, et al. Increasing echinocandin resistance in Candida glabrata: clinical failure correlates with presence of FKS mutations and elevated minimum inhibitory concentrations. Clin Infect Dis. 2013;56:1724-1732.
  5. Slavin MA, Sorrell TC, Marriott D, et al; Australian Candidemia Study, Australasian Society for Infectious Diseases. Candidaemia in adult cancer patients: risks for fluconazole-resistant isolates and death. J Antimicrob Chemother. 2010;65:1042-1051.
  6. Snelders E, Camps SM, Karawajczyk A, et al. Triazole fungicides can induce cross-resistance to medical triazoles in Aspergillus fumigatus. PLoS One. 2012;7:e31801.
  7. Snelders E, Huis In’t Veld RA, Rijs AJ, Kema GH, Melchers WJ, Verweij PE. Possible environmental origin of resistance of Aspergillus fumigatus to medical triazoles. Appl Environ Microbiol. 2009;75:4053-4057.