Antimicrobial Susceptibility Testing of Two Lawsonia intracellularis Isolates Associated with Proliferative Hemorrhagic Enteropathy and Porcine Intestinal Adenomatosis in South Korea

ABSTRACT This study represents the first published data on antimicrobial susceptibility of Asian isolates of Lawsonia intracellularis. We assessed MICs of 16 antimicrobials for two isolates of L. intracellularis recovered from diseased pigs in South Korea, one from a finisher pig with acute proliferative hemorrhagic enteropathy in 2002 and the other from a grower pig with porcine intestinal adenomatosis in 2010. Tylosin and tilmicosin were found to be the most active against L. intracellularis both intracellularly (MICs, 0.25 to 0.5 μg/ml and 0.125 μg/ml, respectively) and extracellularly (MICs, 0.25 to 0.5 μg/ml and 1 μg/ml, respectively).