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Evolving Fungal Landscape in Asia



Professor Yee-Chun Chen
Professor of Medicine
National Taiwan University Hospital and College of Medicine; and
Investigator, National Institute of Infectious Diseases and Vaccinology
National Health Research Institutes
Taiwan

Fungal pathogens pose a significant threat to public health, food biosecurity and biodiversity. Despite this, they are largely ignored by the public, the press and funding bodies. From a public health perspective, there remains relatively little global recognition that over 300 million people suffer from serious fungal-related diseases, or that fungi are responsible for an estimated 1.6 million deaths each year – a higher mortality rate than that of malaria.1

Cryptococcosis

Around 21–36% of cryptococcosis cases occur in patients with cirrhosis, making it the most common host factor associated with these infections in HIV-uninfected patients.2-4 Furthermore, in a recent multivariate analysis, cirrhosis was 1 of 2 factors (along with cerebrospinal fluid antigen titer) shown to be an independent predictor of mortality.4 The minimum inhibitory concentration (MIC) of different antifungal agents, particularly fluconazole, may vary according to genotype; hence it is important to determine MICs for clinical isolates.

Candidemia

A recent laboratory-based surveillance study conducted in 25 hospitals across Asia demonstrated that candidemia is common across the region, with an overall incidence of more than 1 episode per 1,000 discharges, and a wide distribution across services (Figure).5 Candida tropicalis was the most frequently isolated non-albicans species, particularly in tropical countries.5,6 Risk factors for candidemia include age, moderate-to-severe renal diseases, leukemia, lymphoma, gastrointestinal malignancies, metastatic solid tumors and chronic pulmonary diseases.7

Figure. Distribution of patients with candidemia by hospital service (numbers denote percentages)5

In a pan-Asian study, reduced susceptibility to fluconazole was common in non-albicans Candida species, suggesting that echinocandins should be the antifungal of choice in clinically unstable or high-risk patients with documented candidemia.6 International guidelines recommend echinocandins as initial therapy for candidemia in most cases.8,9

Aspergillosis

In a recent study conducted in 5 Asian countries, Aspergillus species was the most common etiology of microbiologically confirmed cases with proven/probable invasive mold infection (71.6%) – largely due to A. fumigatus and A. flavus.10 The most frequently observed host factor was prolonged steroid use (39.4%) and the most common underlying condition was diabetes (30.9%).10

Azole resistance in A. fumigatus is an emerging global health problem, including in Asia.11-13 This could affect the current primary treatment recommendation, which is based around voriconazole monotherapiy.14 Alternative treatment strategies, including azole-echinocandin combinations or liposomal amphotericin B, may be necessary in areas with environmental resistance rates of ≥10%.15

Highlights of the Medical Mycology Training Network Conference, August 5–6, 2017, Kuala Lumpur, Malaysia.

References

  1. Leading International Fungal Education (LIFE). The burden of fungal disease: New evidence to show the scale of the problem across the globe. February 2017. Available at: www.life-worldwide.org/media-centre/article/the-burden-of-fungal-disease-newevidence-to-show-the-scale-of-the-problem. Accessed September 2017.
  2. Jean SS, et al. QJM 2002;95:511-518.
  3. Chuang YM, et al. Eur J Clin Microbiol Infect Dis 2008;27:307-310.
  4. Tseng HK, et al. PLoS ONE 2013;8:e61921.
  5. Tan BH, et al. Clin Microbiol Infect 2015;21:946-953.
  6. Tan TY, et al. Med Mycol 2016;54:471-477.
  7. Chen PY, et al. J Microbiol Immunol Infect 2014;47:95-103.
  8. Pappas PG, et al. Clin Infect Dis 2016;62:409-417.
  9. Tissot F, et al. Haematologica 2017;102:433-444.
  10. Porpon R, et al. Med Mycol 2017 [Epub ahead of print].
  11. Verweij PE, et al. Clin Infect Dis 2016;62:362-368.
  12. Meis JF, et al. Philos Trans R Soc Lond B Biol Sci 2016;371.
  13. Wu CJ, et al. Mycoses 2015;58:544-549.
  14. Patterson TF, et al. Clin Infect Dis 2016;63:e1-e60.
  15. Verweij PE, et al. Drug Resist Updat 2015;21-22:30-40.

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