Histological Analysis of Pneumonia Severity

Sections (5 μm) of 4% formalin-fixed and paraffin-embedded samples were stained with haematoxylin and eosin (H&E). The epithelial goblet cells were stained with periodic acid-Schiff (PAS) reagent. All samples were examined with an Eclipse 80i microscope equipped with a DXM 1200C digital camera (Nikon Instruments, Europe, Amsterdam, Netherlands) and NIS-Elements D Microscope Imaging Software. The severity of pneumonia was graded as follows: Level 1: mild response with healthy tissue in most sections. Level 2: inflammatory response involving nearly half of the area of tissue sections, level 3: strong, diffuse inflammatory response involving most of the section areas, with only a small area of healthy tissue. Level 4: intense response with inflammatory foci leading to a partial loss of alveolar spaces (lung hepatization). Level 5: acute inflammatory response with loss of most alveolar spaces [30 (link), 31 (link)].