Incidental Tracheocele as an Unusual Presentation of Pneumomediastinum in the Trauma Setting.

BACKGROUND Tracheocele are rarely encountered air cysts formed due to tracheal wall outpouching through a weak vantage point. The majority are acquired in the adult population and are associated with conditions that weaken the tracheal wall. Most tracheoceles are diagnosed incidentally since many are asymptomatic or present with nonspecific symptoms. Multidetector computed tomography (MDCT) scans are the most common imaging modality for diagnosis of silent tracheal cysts. Tracheocele have been very rarely documented in the trauma setting; therefore, in the setting of multiple body trauma diagnosis can be challenging. CASE REPORT We report a case of an acquired tracheocele after a high-impact blunt thoracic trauma with an admission diagnosis of suspected tracheal perforation. MDCT of the neck and chest demonstrated an irregularly multicystic-shaped air collection at the right posterolateral trachea upon evaluation. Flexible laryngoscopy and bronchoscopy results were unremarkable. CONCLUSIONS Tracheocele are rare and asymptomatic pseudo-diverticulum of the tracheal wall. Many are diagnosed incidentally with imaging studies for other conditions. Nevertheless, in the trauma setting its diagnosis can be challenging and misleading. Consideration of conditions such as tracheocele is important to prevent any unwarranted treatment modalities.

Clostridioides difficile uses amino acids associated with gut microbial dysbiosis in a subset of patients with diarrhea.

The gut microbiota plays a critical role in pathogen defense. Studies using antibiotic-treated mice reveal mechanisms that increase susceptibility to Clostridioides difficile infection (CDI), but risk factors associated with CDI in humans extend beyond antibiotic use. Here, we studied the dysbiotic gut microbiota of a subset of patients with diarrhea and modeled the gut microbiota of these patients by fecal transplantation into germ-free mice. When challenged with C. difficile, the germ-free mice transplanted with fecal samples from patients with dysbiotic microbial communities showed increased gut amino acid concentrations and greater susceptibility to CDI. A C. difficile mutant that was unable to use proline as an energy source was unable to robustly infect germ-free mice transplanted with a dysbiotic or healthy human gut microbiota. Prophylactic dietary intervention using a low-proline or low-protein diet in germ-free mice colonized by a dysbiotic human gut microbiota resulted in decreased expansion of wild-type C. difficile after challenge, suggesting that amino acid availability might be important for CDI. Furthermore, a prophylactic fecal microbiota transplant in mice with dysbiosis reduced proline availability and protected the mice from CDI. Last, we identified clinical risk factors that could potentially predict gut microbial dysbiosis and thus greater susceptibility to CDI in a retrospective cohort of patients with diarrhea. Identifying at-risk individuals and reducing their susceptibility to CDI through gut microbiota-targeted therapies could be a new approach to preventing C. difficile infection in susceptible patients.