AUTHOR=Rodea Gerardo E. , Montiel-Infante Francisco X. , Cruz-Córdova Ariadnna , Saldaña-Ahuactzi Zeus , Ochoa Sara A. , Espinosa-Mazariego Karina , Hernández-Castro Rigoberto , Xicohtencatl-Cortes Juan 

TITLE=Tracking Bioluminescent ETEC during In vivo BALB/c Mouse Colonization

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00187

DOI=10.3389/fcimb.2017.00187

ISSN=2235-2988

ABSTRACT=<p>Enterotoxigenic <italic>Escherichia coli</italic> (ETEC) is a leading cause of diarrhea worldwide. Adhesion to the human intestinal tract is crucial for colonization. ETEC adhesive structures have been extensively studied; however, colonization dynamics remain uncharacterized. The aim of this study was to track bioluminescent ETEC during <italic>in vivo</italic> infection. The promoter region of <italic>dnaK</italic> was fused with the <italic>luc</italic> gene, resulting in the pRM<italic>kluc</italic> vector. <italic>E. coli</italic> K-12 and ETEC FMU073332 strains were electroporated with pRM<italic>kluc</italic>. <italic>E. coli</italic> K-12 pRM<italic>kluc</italic> was bioluminescent; in contrast, the <italic>E. coli</italic> K-12 control strain did not emit bioluminescence. The highest light emission was measured at 1.9 OD<sub>600</sub> (9 h) and quantified over time. The signal was detected starting at time 0 and up to 12 h. Streptomycin-treated BALB/c mice were orogastrically inoculated with either ETEC FMU073332 pRM<italic>kluc</italic> or <italic>E. coli</italic> K-12 pRM<italic>kluc</italic> (control), and bacterial colonization was determined by measuring bacterial shedding in the feces. ETEC FMU073332 pRM<italic>kluc</italic> shedding started and stopped after inoculation of the control strain, indicating that mouse intestinal colonization by ETEC FMU073332 pRM<italic>kluc</italic> lasted longer than colonization by the control. The bioluminescence signal of ETEC FMU073332 pRM<italic>kluc</italic> was captured starting at the time of inoculation until 12 h after inoculation. The bioluminescent signal emitted by ETEC FMU073332 pRM<italic>kluc</italic> in the proximal mouse ileum was located, and the control signal was identified in the cecum. The detection of maximal light emission and bioluminescence duration allowed us to follow ETEC during <italic>in vivo</italic> infection. ETEC showed an enhanced colonization and tropism in the mouse intestine compared with those in the control strain. Here, we report the first study of ETEC colonization in the mouse intestine accompanied by <italic>in vivo</italic> imaging.</p>