Abstract
Background/objectives Biologic extracellular matrix (ECM) implants are investigated for abdominal wall reconstruction because they may support tissue remodeling while limiting persistent foreign-body reactions. However, their response to contamination with multidrug-resistant pathogens remains insufficiently characterized. This exploratory study compared a bovine-derived peritoneum ECM scaffold with UltraPro mesh in a rat model of Acinetobacter baumannii contamination. Methods Thirty outbred rats were included. Twenty-four animals underwent ECM or UltraPro implantation and were evaluated on postoperative days 10 and 20 ( n = 6 per subgroup); six non-implanted animals receiving sterile saline served as a non-implanted reference group. Abdominal wall defects were reconstructed and inoculated with 200 µL of an A. baumannii suspension at 10 9 CFU/mL. Tissue responses were assessed using semi-quantitative histological scoring based on ISO 10993-6 principles. Conventional microbiological culture was also performed. Results All animals survived, and no clinically evident wound infection, dehiscence, or abscess formation was observed. On day 10, ECM demonstrated greater necrosis and polymorphonuclear-cell infiltration than UltraPro. By day 20, ECM showed reduced necrosis, increased cellular colonization, and greater reticulin fiber deposition, consistent with early tissue organization. UltraPro demonstrated increasing multinucleated giant-cell activity, fibrosis, granulomatous inflammation, and capsule formation. Conventional culture did not recover viable A. baumannii from ECM specimens, whereas the organism was recovered from 2 of 12 UltraPro specimens. Conclusions Under experimental A. baumannii contamination, ECM and UltraPro demonstrated distinct early patterns of tissue response. ECM showed a more pronounced acute inflammatory response followed by histological changes consistent with early tissue organization, whereas UltraPro demonstrated progressive foreign-body and fibrotic changes during the observation period. Because of the small subgroup size, short follow-up, absence of concurrent sterile implant controls, semi-quantitative histological assessment, and lack of quantitative microbiological and biomechanical evaluation, these findings should be considered exploratory and do not establish superior functional or clinical performance of either material. Longer-term microbiological, mechanical, and functional studies are required.