Mouse model of colonization of the digestive tract with Acinetobacter baumannii and subsequent pneumonia

Abstract

Aim: Implementing a mouse model of Acinetobacter baumannii (AB) digestive colonization and studying the propensity of an intestinal reservoir of AB to be at the origin of pneumonia.

Materials & methods: After a disruption of the digestive flora by piperacillin-tazobactam, two multidrug-resistant AB strains were intranasally inoculated to two cohorts of ten mice daily. For each strain, five mice were rendered transiently neutropenic.

Results & conclusion: One strain persisted several weeks in the digestive tract, even after stopping piperacillin-tazobactam injections, leading to the hypothesis that some AB strains can authentically colonize the gut. Most of the immunocompromised mice experienced clinical signs and positive lung cultures, which were associated with positive spleen cultures, an argument in favor of bacterial translocation.

Keywords: Acinetobacter baumannii; digestive-tract colonization; experimental model; from colonization to infection; multidrug resistant; pneumonia.