Fig. 8

a Gross examination of lungs showing a normal appearance with no evidence of inflammatory signs in the uninfected group. In the control, colistin, and doxycycline groups, pulmonary congestion is observed. The colistin-treated group shows a confluence of consolidation areas and a patch formation at the upper left of the lung. The combination group shows a lung appearance closely resembling normal, except for areas of congestion. b Histologic findings of the H&E-stained lung sections under a light microscope with the top panels showing X100 magnification followed by an inset at X400 magnification. The uninfected group features normal lung parenchymal tissue, thin-walled alveolar septae, and intact bronchiolar epithelium (X100). Ciliated columnar cells and pneumocytes are lining the alveoli (X400). The control and colistin-treated groups show distorted lung parenchyma, alveolar collapse, blood vessel congestion, and perivascular edema (X100). Destruction of the alveoli replaced by an infiltrate consisting of neutrophils, lymphocytes, and plasma cells is depicted (X400). The doxycycline-treated group displays a relatively preserved architecture of the lung parenchyma, except for the thickened alveolar walls, congested blood vessels, and prominent perivascular edema (X100). The inset reveals inflammatory cellular components, including polymorphs, lymphocytes, histiocytes, and plasma cells (X400). The combination group reveals normal lung parenchymal tissue, except for the mildly congested blood vessels (X100) with an inset showing intact bronchiolar epithelium and thin-walled alveolar septae (X400)