Serovars and antimicrobial resistance profiles of Actinobacillus pleuropneumoniae isolates from clinical-case pigs in Taiwan

This study updates the serovar and antimicrobial sensitivity patterns of Taiwanese clinical A. pleuropneumoniae isolates, showing that serovars 15, 5, 1, 7, and 2 collectively predominate in clinical outbreaks. Local A. pleuropneumoniae isolates exhibited high resistance to antimicrobials currently used in the Taiwanese pig production, such as amoxicillin, ampicillin, and florfenicol. However, there was low resistance to cephalexin, cephalothin, tilmicosin and lincospectin (injectable only) which can be recommended for current use in Taiwan, considering both efficacy and public health risks. Notably, isolates of the same serovar collected from the same farm on the same day occasionally displayed distinct resistance patterns, emphasizing the complex dynamics of antimicrobial resistance. Our data will help veterinarians and producers refine vaccination and treatment protocols, highlighting the importance of ongoing surveillance to respond effectively to evolving resistance trends.