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.
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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.