On the Emergence of Candida Pathogens

Clement K. M. Tsui, PhD

Department of Pathology                                                                             

Sidra Medicine

Department of Pathology and Laboratory Medicine                                  

Weill Cornell Medicine-Qatar

 
Fungal infections cause about 1.5 to 2 million deaths worldwide per year, far more than malaria and tuberculosis infections, and a quarter of the million death due to candidiasis (Brown et al., 2012).  Invasive candidiasis (IC) caused by Candidaspp. is a major cause of morbidity among immunocompromised adults and children and very low birth weight neonates. IC is of major public health importance because it is associated with increased mortality, higher health care costs, and increased patient length of stay compared with other common healthcare-associated infections (Pappas et al. 2018). This problem is compounded by the progressive increase in antifungal resistance among most clinically relevant species such as C. albicans, C. parapsilosis, C. glabrata, C. tropicalisand C. auris. In the last decade, Candida aurishas become a public health threat worldwide. The incidence of infection caused by C. aurishas increased substantially with cases reported in 33 countries. Candida aurishas the ability to spread via nosocomial transmission and causes outbreaks of invasive infections; large scale outbreaks have been reported in countries such as India, USA and United Kingdom (Rhodes and Fisher 2019). C. aurispresents a great challenge in the public health control and management primarily due to its resistance to most antifungal drugs (Chowdhary et al., 2017, Schelenz et al., 2016). Almost all C. aurisisolates are resistant to fluconazole, the most widely used antifungal drugs; approximately 40% of C. aurisisolates is resistant to 2 or more drug classes and10% could be resistant to all antifungal drugs. Genomics data suggests the simultaneous and independent emergence of C. aurisin different continents and reveals the presence of 5 genetic clusters - East Asian, South Asian, African, South American and Iranian (Rhodes and Fisher 2019). Molecular epidemiological studies also show the clonal expansion of C. aurisin most local outbreaks and ongoing transmission (Sharma et al. 2016). Recently C. aurisoutbreaks are identified in hospitals in Qatar. Using the whole genome sequencing approach, we understand that most isolates in Qatar belong to the South Asian cluster, consistent with the fact that lots of migrant workers are from Pakistan/ India. Preliminary data also reveal low genetic variation among most C. aurisisolates, indicating the possibility of ongoing local transmission in the community. Therefore it is important the source of these isolates and how they are spread efficiently spread from patient to patient in the health care environment.
 
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