To investigate the resistance of porcine pathogenic bacteria to chloramphenicol in Taiwan, we sampled 38 pig farms located in northern, central, and southern Taiwan. The E. coli, Salmonella spp., Pasteurella multocida, Streptococcus spp., and Actinobacillus pleuropneumoniae were selected to test the susceptibility of chloramphenicol. The disc diffusion method and broth microdilution method were used in this study. The results were: (1) in the disc diffusion method, we found that the rates of susceptibility towards chloramphenicol were Pasteurella multocida (85.71 %), Actinobacillus pleuropneumonia (73.68%), Streptococcus spp. (66.67%), Salmonella spp. (11.54%), and E. coli (0%); and (2) the results of the broth method were similar to the findings of the disc diffusion method. The MIC50 and MIC90 for these bacteria were: E. coli (415μg/mL, 829.5μg/mL), Salmonella spp. (324.3μg/mL, 798.5μg/mL), Pasteurella multocida (11.05μg/mL, 122.2μg/mL), Streptococcus spp. (6.67μg/mL, 58.3μg/ mL), and Actinobacillus pleuropneumoniae (2.76μg/mL, 134.1μg/mL). The biggest difference between MIC50 and MIC90 was in Actinobacillus pleuropneumoniae which indicates that this bacteria has a large range of susceptibility to chloramphenicol. This present study suggests that (1) chloramphenicol is not suitable to be used in treating porcine E .coli or Salmonella spp. inlection. (2) chloramphenicol is still useful in treating porcine Actinobacillus pleuropneumoniae, Streptococcus spp., and Pasteurella multocida inlection. However, MIC value chloramphenicol is higher and range of susceptibility is larger; therefore, precise measurements of the MIC is necessary to insure the effective treatment.
To investigate the resistance of porcine pathogenic bacteria to chloramphenicol in Taiwan, we sampled 38 pig farms located in northern, central, and southern Taiwan. The E. coli, Salmonella spp., Pasteurella multocida, Streptococcus spp., and Actinobacillus pleuropneumoniae were selected to test the susceptibility of chloramphenicol. The disc diffusion method and broth microdilution method were used in this study. The results were: (1) in the disc diffusion method, we found that the rates of susceptibility towards chloramphenicol were Pasteurella multocida (85.71 %), Actinobacillus pleuropneumonia (73.68%), Streptococcus spp. (66.67%), Salmonella spp. (11.54%), and E. coli (0%); and (2) the results of the broth method were similar to the findings of the disc diffusion method. The MIC50 and MIC90 for these bacteria were: E. coli (415μg/mL, 829.5μg/mL), Salmonella spp. (324.3μg/mL, 798.5μg/mL), Pasteurella multocida (11.05μg/mL, 122.2μg/mL), Streptococcus spp. (6.67μg/mL, 58.3μg/ mL), and Actinobacillus pleuropneumoniae (2.76μg/mL, 134.1μg/mL). The biggest difference between MIC50 and MIC90 was in Actinobacillus pleuropneumoniae which indicates that this bacteria has a large range of susceptibility to chloramphenicol. This present study suggests that (1) chloramphenicol is not suitable to be used in treating porcine E .coli or Salmonella spp. inlection. (2) chloramphenicol is still useful in treating porcine Actinobacillus pleuropneumoniae, Streptococcus spp., and Pasteurella multocida inlection. However, MIC value chloramphenicol is higher and range of susceptibility is larger; therefore, precise measurements of the MIC is necessary to insure the effective treatment.