Candida auris has become a global public health threat due to its multidrug resistance and persistence. Currently, there are limited murine models to study C. auris infection. Those models use a combination of cyclophosphamide and cortisone acetate, suppressing both innate and adaptive immunity. Here, we compare C. auris infection in two neutrophil-depleted murine models in which innate immunity is targeted using the monoclonal antibodies 1A8 and RB6-8C5.

Candida auris has become a global public health threat due to its multidrug resistance and persistence in hospital and nursing home settings. Although a skin colonizer, C. auris can cause fatal bloodstream infections and most patients succumb to multi-organ failure. Currently, there are limited animal models to study the progression of C. auris infection. Here we compare two murine models of neutrophil depletion using monoclonal antibodies 1A8, anti-Ly6G+ and RB6-8C5 anti-Ly6G+-Ly6C+. We also compare inoculums of 107 and 108 as well as the intravenous and gavage routes of infection. The results reveal that neutrophil depletion in BALB/c mice is sustained long-term with the 1A8 antibody and short-term with RB6-8C5. Target organs were kidney, heart and brain as these had the highest organ fungal burden in neutrophil depleted and to some extent in infected control mice. We found that C. auris is shed in urine and feces for neutrophil depleted mice. The gavage model is not an ideal route as dissemination was not detected. Eight days post C. auris infection all surviving mice display a unique behavioral phenotype characterized by torticollis and tail spin that progresses to head bobbing and body curling like phenotype by day 22, that continues to persist even 104 days post infection. Lastly, we found C. auris remains in tissues of infected control mice, 34 plus days post infection suggesting that C. auris stays present in the host without causing disease but becomes opportunistic upon a change in the hosts immune status such as neutrophil depletion.

The progression and systemic pathobiology of C. auris in the absence of a microbiota have not been described. Here, we describe the influence of the microbiota during the first 5 days of C. auris infection in germ-free or antibiotic-depleted mice. Depletion of the bacterial microbiota in both germ-free and antibiotic-depleted models results in a modest but important increase in the early stages of C. auris infection. Particularly the heart and lungs, followed by the cecum, uterus, and stomach, of intravenously (i.v.) infected neutropenic mice showed significant fungal organ burden. Understanding disease progression and pathobiology of C. auris in individuals with a depleted microbiota could potentially help in the development of care protocols that incorporate supplementation or restoration of the microbiota before invasive procedures, such as transplantation surgeries.