This study investigates seven A. haemolyticum strains from a donkey and human patients, 15 A. pluranimalium strains from various animals, and 12 strains representing four novel species—A. canis, A. phocisimile, A. pinnipediorum, and A. wilhelmae—alongside reference strains from nine previously described species. The novel species were isolated from a dog, harbor seals, and a rhinoceros, characterized through a polyphasic taxonomic approach that included 16S rRNA gene phylogenetic analysis, DNA-DNA hybridization, and chemotaxonomical investigations. The 34 strains were phenotypically characterized using traditional microbiological methods and MALDI-TOF MS analysis. Molecular investigations involved 16S rDNA sequence analysis and the sequencing of several genes, including those encoding virulence factors such as aranolysin and phospholipase D. A. pluranimalium was further characterized by a newly described gene, pla, encoding pluranimaliumlysin, which may clarify the pathogenic roles of these virulence factors in infections. While A. haemolyticum is known for causing disease in humans, the pathogenic significance of A. pluranimalium, A. canis, A. phocisimile, A. pinnipediorum, and A. wilhelmae, isolated in mixed cultures with other bacteria, warrants further investigation.
