Intradermal Infection of Mice with Bacteria

Eight-week old female OF1 mice (Charles River, France) were anesthetized by intraperitoneal injection of 10 mg.kg^-1 Xylazine (Rompun 2%, Bayer, Germany) + 100 mg.kg^-1 Ketamine (Imalgène 1000, Merial, France) and infected as described [16 (link),45 (link)]. Briefly, bacteria grown overnight on LBH agar medium were adjusted to the desired concentration in saline, based on A₆₀₀ measurement, and 10 μl (5,000 cfu) were injected id into the mouse ear pinna. Cfu counts were verified by plating on LBH. Control mice received the same volume of saline without bacteria. Mice were followed up for 21 days for survival. For cfu enumeration or histology examination of the LN, infected mice were euthanized by cervical dislocation at 48h post-infection (pi), unless otherwise specified, and the ipsilateral superficial parotid LN [46 (link)], which drains the injection site [16 (link)], was harvested.