Abstract Description

Considering the emerging concern and severity posed by invasive fungal infections, it is important to study the dissemination and proliferation of pathogenic fungi in our surrounding environments. It is crucial to identify major vectors that aid in the spread and/or act as a hub for pathogenic yeast to prevent infections in susceptible individuals, which include those who are immunocompromised or immunosuppressed. One system that shows promise in aiding this endeavour is wastewater surveillance or wastewater-based epidemiology (WBE). This system has repeatedly shown its potential with its latest application in monitoring Covid-19 infection incidence within various communities. This begs the question if WBE can be applied to other life-threatening infectious agents such as pathogenic yeast. This was the aim of our study. Using culture-dependent and independent techniques, we investigated the presence of pathogenic yeasts in the wastewater influent of six different sampling points in Bloemfontein, South Africa. A multiplex PCR protocol was adapted to target major and minor pathogenic yeast species found in wastewater over 12 months. Furthermore, several yeast isolated from wastewater were identified using Sanger sequencing and culture-dependent and independent data were compared to data on fungal infections in public hospitals situated in the Bloemfontein Mangaung Metropole area. It was also observed that wastewater seems to select resistant yeast species while also supporting the growth of susceptible dose-dependent isolates which might develop acquired resistance to fluconazole in this environment. The multiplex PCR as well as Sanger sequencing identified pathogenic yeast, including species from the Candida and Cryptococcus genera with the emerging pathogen of concern Candidozyma auris frequently detected. Following the release of the World Health Organisation (WHO) fungal priority pathogens list, the need to adapt or develop methods to monitor fungal pathogens circulating within the community is becoming a pressing matter and WBE is a potential tool to aid in this. All in all, wastewater surveillance shows promise, but a few limitations must be overcome.