Probiotics enhance susceptibility of mice to cryptosporidiosis

Abstract

Cryptosporidiosis is a leading cause of diarrhea in infants and immune-compromised individuals. The lack of effective drugs against this enteric infection is motivating research to develop alternative treatments. To this aim, the impact of probiotics on the course of cryptosporidiosis was explored. The native intestinal microbiota of specific pathogen-free immunosuppressed mice was initially depleted with orally administered antibiotics. Then, a commercially available probiotic product intended for human consumption was added (or not) to the drinking water. Probiotic treated and untreated mice were orally infected with Cryptosporidium parvum oocysts. On average, mice treated with probiotic excreted more oocysts, indicative of a more severe infection. The probiotic treatment significantly altered the fecal microbiota, but taxonomic analyses showed no direct association between ingestion of probiotic bacteria and their abundance in fecal microbiota. These results suggest that probiotics indirectly alter the intestinal microenvironment in such a way that favors proliferation of C. parvum. The increase in the relative abundance of facultative anaerobes observed in mice with severe cryptosporidiosis indicates that dysbiosis is a consequence of severe cryptosporidiosis. The increase in the abundance of facultative anaerobes observed in severely infected animals is consistent with analyses of microbiota from individuals infected with other enteric pathogens. The results are significant because they show that C. parvum responds to changes in the intestinal microenvironment induced by a nutritional supplement.\n\nOne Sentence SummaryMice treated with probiotics develop more severe symptoms of cryptosporidiosis.