Wastewater surveillance of Candida auris in Baltimore

Candida auris (C. auris), an opportunistic fungus causing disease, poses a growing global health concern due to its significant mortality rate, resistance to antifungal treatment, and ability to persist in healthcare settings. Over a span of 47 weeks, untreated wastewater samples were regularly gathered from two wastewater treatment plants (referred to as WWTP-A and WWTP-B) in Baltimore, from July 27, 2022, to June 23, 2023. Throughout the study period, 110 primary influent (PI) samples were collected from both WWTP-A and WWTP-B. A quantitative polymerase chain reaction (qPCR) method was used to analyze C. auris captured on filters (0.45 μm) from these samples. Positive C. auris detection (11.81%) occurred in the influent samples, with a higher frequency of detection in WWTP-B. Influent wastewater concentrations ranged from 1.2 to 7.9 log10 gene copies per liter (gc/L). Interestingly, seasonal analysis showed that C. auris presence in wastewater was more pronounced during the spring season, indicating a sustained existence of the pathogen as seasons changed. Integration of wastewater surveillance and clinical data reveals temporal correlations in C. auris dynamics. The resulting Pearson correlation coefficient of 0.27 reveals a weak positive correlation between the number of new C. auris cases in Baltimore and the quantity of detected gene copies in wastewater. This study marks the first instance of detecting C. auris in Baltimore's wastewater. The results emphasize that wastewater monitoring could serve as an additional early warning tool for anticipating and managing future outbreaks of C. auris.