2025-04-302025-04-302025Fernández-Cuenca, F., Rodríguez-Pallares, S., López Cerero, L., Gutiérrez-Fernández, J., Bautista, M.F., Sánchez Gómez, J.A.,...,Pascual Hernández, Á. (2025). Regional distribution of carbapenemase‑producing Acinetobacter baumannii isolates in southern Spain (Andalusia). European Journal of Clinical Microbiology & Infectious Diseases. https://doi.org/10.1007/s10096-025-05047-2.1435-43730934-9723https://hdl.handle.net/11441/172312Objectives This is the first study conducted in southern Spain to determine i) the population structure (PS) of carbapenemresistant (CR) Acinetobacter baumannii isolates by multilocus sequencing typing (MLST) and core genome MLST (cgMLST) and ii) the association between the sequence type ST and the blaOXA-51 variant, capsule polysaccharide locus (KL) and lipooligosaccharide outer core locus (OCL) types. Methods Of 336 isolates submitted to the Andalusian reference laboratory (PIRASOA; December 2017–2020), 73 were subjected to WGS (MiSeq). The following analyses were performed: bacterial identification (ribosomal MLST), carbapenemase gene detection (Resfinder 4.0), PS delineation (MLST by MLSTfinder 2.0 and cgMLST by Ridom SeqSphere+), and KL types and OCL types (Kaptive tool). Results The carbapenemases detected were blaOXA-23 (n = 41), blaOXA-58 (n = 26), blaOXA-24 (n = 5), blaOXA-72 (n = 1) and blaNDM-1 (n = 2). The PS revealed one major ST2 clone (n = 54) and seven minor ST clones by MLST, and 41 lineages by cgMLST. Thirty-five lineages were detected only in a single hospital whereas five lineages were observed in several hospitals and provinces. blaOXA-66 was the most frequent blaOXA-51 variant and was mainly associated with the ST2 clone. Eleven KL types and 3 OCL types were assigned, with KL2 (n = 27), KL7 (n = 16) and OCL1 being the most frequent. Conclusions The PS of CR A. baumannii in Andalusia is characterized by a dominant ST2/blaOXA-23 clone and several lineages, showing local spread of lineages in most hospitals, and intercenter or interregional spread of a few lineages. Singlelocus blaOXA-51-like typing and KL typing may be useful as complementary preliminary typing tool.application/pdf8engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Acinetobacter baumanniiSouthern of SpainKL typeInterregional spreadinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess10.1007/s10096-025-05047-2