Only two K. pneumoniae strains were positive to the yersiniabactin gene ybtS, a common virulence factor associated with human infections [25,26], and one of the two also harbored irp1. These genes are involved in the synthesis of the siderophore yersiniabactin by virulent Yersinia strains, which harbor them within the high-pathogenicity island (HPI). Here, ACO1 is linked to infection.