Occurrence of pathogenic yeast  species in artisanal cheeses from Boyacá, Colombia, including fluconazole resistant isolates

Yeasts are widely known for their application in food production, but also because of their clinical significance. As human pathogens, several species of yeasts, mainly of the genus Candida and other closely related genera, are responsible for a great number of life-threatening infections. The occurrence of yeasts in cheeses, including pathogenic species, has been largely studied, yet the antifungal susceptibility of these microorganisms is rarely reported. Here, we identified the species and determined the antifungal susceptibility profile of 45 yeast Candida isolates recovered from artisanal cheeses from 20 cities in Boyacá, Colombia. Among the species, Pichia fermentans (28.9%) prevailed, followed by Pichia kudriavzevii (24.4%), Kluyveromyces marxianus (22.2%), Clavispora lusitaniae (11.1%), Candida inconspicua (6.7%) Candida parapsilosis (4.4%) and Meyerozyma guillermondii (2.2%). Notably, all seven species have been globally reported, to a greater or lesser extent, to cause fungemia and other invasive infections with high mortality rates. Remarkably, together with the intrinsically resistant P. kudriavzevii, most isolates of P. fermentans, C. inconspicua and C. parapsilosis were resistant to fluconazole, one of the most common drugs to treat candidiasis. Our findings highlight the importance of exploring the ecological niches of pathogenic yeasts, together with their antifungal susceptibility, considering that the emergence of resistance in non-commensal opportunistic pathogens poses a serious threat to public health.