Evaluation of Escherichia coli as a prophylactic treatment of intestinal colonization by extended-spectrum beta-lactamase-producing E. coli in a murine model of antibiotic-induced dysbiosis

BACKGROUND: Intestinal colonization by multidrug-resistant Enterobacteriaceae represents a major public health concern as it can lead to difficult-to-treat infections, environmental contamination, and transmission. This study evaluated the efficacy of a prophylactic treatment using Escherichia coli strains isolated from murine feces [commensal E. coli (comEc)] to reduce intestinal colonization by extended-spectrum beta-lactamase (ESBL)-producing E. coli in a murine model of antibiotic-induced dysbiosis. METHODS AND RESULTS: The comEc treatment was administered intragastrically 1 day prior to ESBL-producing E. coli challenge. Colonization levels were monitored daily using culture-based quantification. Fecal microbiota composition was analyzed before the ESBL-producing E. coli challenge to identify predictors of treatment efficacy. The comEc treatment significantly reduced mean ESBL-producing E. coli levels during the first four days. Notably, 14% of treated mice exhibited marked and sustained decolonization, whereas others had only a limited and transient effect. CONCLUSION: In this proof-of-concept study, prophylactic treatment with murine-derived E. coli strains transiently reduced fecal ESBL-producing E. coli titers, although pronounced efficacy was observed in a small subset of animals.