Serotypes, antimicrobial susceptibility, and minimal inhibitory concentrations of Actionbacillus pleuropneumoniae isolated from slaughter pigs in Taiwan (2002-2007)

In total, 211 isolates of A. pleuropneumoniae were collected from pigs with hemorrhagic pneumonia at slaughterhouses during 2002-2007. Serotypes, antimicrobial susceptibility and minimum inhibitory concentration (MIC) values were determined for each isolate of A. pleuropneumoniae to 10 antimicrobial agents. Serovar 1 of A. pleuropneumoniae was predominant in Taiwan in 138 of the 211 isolates, followed by serovars 2 and 5. More than 90% of collected isolates were sensitive to ceftiofur, cephalothin, and chloramphenical. However, lincospectin and gentamicin were relatively less susceptible with sensitivities of only 2.4 and 5.7%, respectively. Additionally, ceftiofur had the highest in vitro activity with an MIC(50) of 2.2 μg/ml, followed by cephalothin (2.7 μg/ml) and chloramphenicol (7.9 μg/ml). Lincospectin had the least activity with MIC(50) and MIC(90) values of 73.9 and 114.5 μg/ml, respectively. The data indicate that ceftiofur and cephalothin were extremely active against A. pleuropneumoniae and with minimum MIC values. These drugs are suitable for controlling and treating hemorrhagic pleuropneumonia outbreaks in swine.