Identification of the emerging fungal pathogens in Brazilian children infected by Giardia lamblia.

Giardia lamblia is the most prevalent intestinal protozoan in Brazilian children and has been associated with alterations in the gut microbiota. While bacterial dysbiosis in giardiasis has been well studied, little is known about the associated fungal communities. This study aimed to investigate whether Giardia infection predisposes preschool children to the emergence of fungal pathogens and to identify which pathogenic fungi coexist in the intestines of Giardia-infected preschoolers. Stool samples from children aged 1-4 years living in a low-income community in Rio de Janeiro were analyzed by PCR for Giardia and subjected to fungal isolation and identification using MALDI-TOF MS and ITS sequencing. Among 25 samples, 13 were Giardia-positive, and 10 of these harbored Candida parapsilosis, with co-occurrence of C. tropicalis and C. krusei in some cases. Saccharomyces cerevisiae was also detected. This is the first report of C. parapsilosis, C. krusei, and S. cerevisiae in Giardia-infected children. The high frequency of C. parapsilosis raises the possibility of a synergistic interaction between protozoan and fungal infections in vulnerable pediatric populations.