{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T02:00:12Z","timestamp":1791597612337,"version":"4.3.4"},"reference-count":50,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T00:00:00Z","timestamp":1776124800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["32172928"],"award-info":[{"award-number":["32172928"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100018608","name":"High-end Foreign Experts Recruitment Plan of China","doi-asserted-by":"publisher","award":["G2022108009L, H20240556"],"award-info":[{"award-number":["G2022108009L, H20240556"]}],"id":[{"id":"10.13039\/501100018608","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"\n Background<\/jats:title>\n \n Bovine mastitis causes substantial economic losses worldwide.\n Acinetobacter baumannii<\/jats:italic>\n has emerged as a pathogen in bovine mastitis, raising considerable concerns due to its multidrug resistance and potential zoonotic transmission. However, characteristics of\n A. baumannii<\/jats:italic>\n involved in bovine mastitis in China remain poorly understood, particularly with emergence of novel sequence types.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n From 135\n Acinetobacter<\/jats:italic>\n spp. isolates isolated in China from bovine mastitis (2021-2024), we identified a novel sequence type, ST3475. Using the known bovine strain ST3256 for comparison, we conducted hybrid whole-genome sequencing, antimicrobial susceptibility testing, and multiple phenotypic pathogenicity assays (including biofilm formation, cell adhesion\/invasion, and\n in vivo<\/jats:italic>\n infection models).\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The\n A. baumannii<\/jats:italic>\n ST3475 chromosome is 3,875,774 bp with 1 plasmid (158,806 bp); it has an expanded repertoire of 70 virulence genes, including\n csu<\/jats:italic>\n and\n bap<\/jats:italic>\n , and 18 antimicrobial resistance genes. Furthermore, its genome contains a complement of phage elements, carbohydrate-active enzymes, and a unique carbapenemase gene\n bla<\/jats:italic>\n OXA-344<\/jats:sub>\n , indicating distinct evolution. Phenotypically, ST3475 demonstrated enhanced biofilm formation, adhesion, invasion, and cytotoxicity against bovine mammary epithelial cells. It also promoted secretion of IL-1\u03b2, IL-6, and TNF-\u03b1. In\n Galleria mellonella<\/jats:italic>\n , the median lethal dose of ST3475 was 2 orders of magnitude lower than ST3256 (LD\n 50<\/jats:sub>\n \u00a0=\u00a01,378,077 CFU\/larva). In a murine mammary infection model, ST3475 caused substantial alveolar destruction and inflammatory infiltration.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n Phylogenetically, ST3475 belongs to clonal complex CC2 but represents a distinct, putative bovine-adapted lineage separate from major human clone CC1. Although currently susceptible to last-resort antimicrobials like carbapenems, carriage of high-risk resistance genes highlights livestock as a potential reservoir for clinically relevant resistance determinants. This study reveals ST3475 as a novel, virulent, and putative bovine-adapted lineage, underscoring the importance of One Health surveillance.<\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1804085","type":"journal-article","created":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T05:40:08Z","timestamp":1776145208000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["A newly identified sequence type: genomic and pathogenic profiling of the highly virulent Acinetobacter baumannii ST3475 from bovine mastitis"],"prefix":"10.3389","volume":"16","author":[{"given":"Tian","family":"Wang","sequence":"first","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]},{"name":"College of Animal Science and Technology, Tarim University","place":["Alar, Xinjiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xian","family":"Deng","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maolin","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zimeng","family":"Zhu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuxin","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Herman W.","family":"Barkema","sequence":"additional","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary","place":["Calgary, AB, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eduardo R.","family":"Cobo","sequence":"additional","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary","place":["Calgary, AB, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John P.","family":"Kastelic","sequence":"additional","affiliation":[{"name":"Faculty of Veterinary Medicine, University of Calgary","place":["Calgary, AB, Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Gao","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bo","family":"Han","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, China Agricultural University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,14]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1016\/j.rvsc.2025.105702","article-title":"Environmental bovine subclinical mastitis Gram-negative pathogens: Prevalence, antimicrobial resistance with special reference to extended-spectrum \u03b2-lactamases and carbapenemase production","volume":"192","author":"Abdel-Hameed","year":"2025","journal-title":"Res. 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