TLR4 and pneumonia: As shown in Figure 5, our results showed that compared with the Control group, the expressions of TLR4, MyD88, NF-κB, and ICAM-1 of the Model group were significantly higher (P < 0.01), indicating that the TLR4/MyD88/NF-κB signaling pathway was activated during the development of MDR PA-induced pneumonia in rats.