Murine model of pneumonia.

Five-to-8-week-old female C57BL/6 mice (Jackson Laboratories) were anesthetized with 200 µl of a 0.8 mg/ml ketamine–1.3 mg/ml xylazine cocktail and inoculated intranasally (i.n.) with ~2 × 10⁴ CFU/mouse (KPPR1S and NTUH-K2044) or ~2 × 10⁷ CFU/mouse (MKP103) as described previously (31, 77). Total CFU counts for each inoculum were confirmed by plating dilutions onto LB agar. After 24, 48, or 72 hpi, mice were euthanized by a lethal intraperitoneal injection of 200 µl sodium pentobarbital (52 mg/ml). Organs were removed, homogenized in phosphate-buffered saline (PBS), serially diluted, and plated to quantify the CFU level per gram of tissue.