A Set of Multiresistant Isolates of Subtype ST-1 with a Variable Susceptibility to Quinolones Are Also Circulating in Spain.

() is one of the worldwide most important infectious agents involved in respiratory complex diseases (RCD). In Spain, the endemic presence of subtypes ST-2 and ST-3 with phenotypic differences linked to their susceptibility to fluoroquinolones opened the way to develop control strategies focused on previous diagnosis of the subtype and the use of directed therapies when were involved in RCD. Surprisingly, microbiological studies conducted during 2023 evidenced for the first time the presence of Spanish isolates of a new -subtype, previously classified as ST-1, recovered from calves with respiratory symptoms and pneumonia in different areas of the country ( = 16).