Supporting Data- Methods for detecting and monitoring Salmonella infection and chronic carriage in living mice using bioluminescent in vivo imaging

Salmonella enterica serovar Typhi primarily persists in chronic carriers by forming biofilms on gallstones in the gallbladder. We have developed a gallstone mouse model to study chronic carriage. To better understand the infection timeline and differentiate between mice that have maintained long-term gallbladder carriage from those that have cleared infection, we utilized bioluminescent S. Typhimurium and in vivo imaging to detect and track the organ-specific presence of bacteria in living mice. All mice used in this study were housed and maintained in the animal facilities at the Abigail Wexner Research Institute at Nationwide Children’s Hospital under an approved Institutional Animal Care and Use Committee (IACUC) protocol. 

S. Typhimurium 14028 (WT) was transduced with the lux operon from the S. Typhimurium Xen33 strain from Perkin Elmer©, creating 14028lux. 129X1/SvJ mice were fed a lithogenic diet for 6 weeks to induce gallstone formation. After cessation of diet, these mice were infected with 5x103-1x104 colony forming units (CFU) of either the 14028lux isolate, WT (non-luminescent) isolate, or an equal volume of sterile phosphate buffered saline (PBS) via an intraperitoneal injection. Mice were serially imaged (IVIS SpectrumCT) every 2-3 days for up to 63 days. Images were quantified by measuring average radiance over selected regions of interest. The presence of bioluminescent bacteria in the gallbladder, liver, spleen, and cecum were confirmed by imaging the abdominal cavity and individual organs. Organs were homogenized and CFUs per mg of tissue were quantified and compared between each group.