Synergistic Inhibition of Acinetobacter baumannii Biofilm Formation and Reduction of Lung Inflammation In Vivo by Combination of α-Pinene and Meropenem

Acinetobacter baumannii, a prominent opportunistic pathogen in healthcare settings, causes severe infections and poses significant challenges for clinical treatment. This study investigates the synergistic effects of α-pinene combined with meropenem (MEM) on A. baumannii biofilm formation and lung injury in mice, aiming to develop new strategies to combat persistent infections and antibiotic resistance. α-pinene combined with MEM exhibited strong synergistic antibacterial activity against carbapenem-resistant A. baumannii (CRAB 5E9). The combination significantly inhibited biofilm formation, extracellular polymer production, surface motility, and quorum sensing. The expression of key genes such as ompA, bfmR, bap, csuAB, abaI, and abaR was reduced by up to 61%. In vivo, the treatment alleviated weight loss, decreased the bacterial load in lung tissue, and reduced lung inflammation. Furthermore, it significantly suppressed proteins involved in the inflammatory response and the MAPK pathway, including TLR4, NF-κB, NLRP3, TRAF6, ERK2, p38 MAPK, JNK, and TNF-α. The combination of α-pinene and MEM synergistically inhibits A. baumannii biofilm formation and alleviates the inflammatory response in a mouse model, offering a potential therapeutic approach for combating A. baumannii infections.