LAUSR

Background: Whether there is biofilm (BF) formation in the pleural cavity of empyema is still inconclusive. Objectives: We assumed that there is BF formation in empyema, tried to verify this hypothesis. Methods: We established a model of rabbit empyema infected by Pseudomonas aeruginosa (P.a), and collected pleural tissue and pustule-like specimens. Scanning electron microscope (SEM) was used to observe the P.a-BF on the surface of the pleura. Peptide nucleic acid Fluorescence in situ hybridization (PNA-FISH) was used to observe the P.a-BF in the pus floc. Results: There were BF-like structures on the surface of the pleura observed by SEM (Fig. 1A), P.a-BF in the pus of pleural cavity confirmed by colony counting and PNA-FISH (Fig. 1B). Conclusions: To our knowledge, this was the first experiment to confirm the P.a-BF formation in the pleural cavity of empyema, and it was also a novel animal model. Fig 1A. Biofilm-like structures were observed using SEM at a magnification of 5,000× operating at 30.0 Kv. Fig1B. Fluorescence microscope image showing P.a-BF surrounded by host cell components. The P.a were stained with a Texas-Red-labeled P.aeruginosa-specific PNA-FISH probe ( red ), and the host cells were stained with DAPI ( blue ).