Necropsies were performed by veterinary pathologists on predetermined endpoint days. During necropsy, lungs were assessed for gross pathology and images were captured with a Nikon D300 camera. Tissue samples were also collected for histopathological analysis. Samples were fixed in 10% neutral buffered formalin (Cancer Diagnostics, Durham, NC) for a minimum of 72 h and processed using a VIP-6 Tissue Tektissue processor (Sakura Finetek, USA). Tissue samples were embedded in Ultraffin paraffin polymer (Cancer Diagnostics, Durham, NC) and sectioned serially at 5 μm. Air-dried slides were stained with hematoxylin and eosin. K. pneumoniae was visualized within tissue sections using rabbit anti-K. pneumoniae CPS2 IgG (1:500 dilution) (14 (link)) and a Discovery ULTRA System (Roche Diagnostics) and Discovery DAB Map detection kit (Roche Diagnostics) according to the manufacturer’s protocol. Images were obtained using an Olympus BX51 microscope and an Olympus DP74 camera (Olympus Corporation). Image brightness and contrast were evenly adjusted using Adobe Photoshop, and figures were created using Adobe Illustrator CC 2019 (Adobe, San Jose, CA).