Pharmacodynamic Studies of Difloxacin against Experimentally Induced Mycoplasmal Pneumonia and Streptococcosis in Pigs

This paper described the pharmacodynamic studies of difloxacin and enrofloxacin against experimentally induced mycoplasmal pneumonia and streptococcosis in pigs.Minimal inhibitory concentrations (MICs) of the two drugs were determined for Mycoplasma hyopneumoniae or Streptococcus equisilis by two-fold dilution method in vitro.The therapeutic trials of difloxacin (2.5,5 and 10 mg/kg)and enrofloxacin (2.5 mg/kg) against artificially induced mycoplasmal pneumonia were performed in pigs following intramuscular administration,twice daily for 5 successive days.The therapeutic trials of difloxacin (2.5,5 and 10 mg/kg) and enrofloxacin (2.5 mg/kg) against experimentally induced streptococcosis were carried out in pigs following intramuscular administration,twice daily for 4 successive days.MICs of difloxacin and enrofloxacin were 0.16 and 0.04 mg/L for Mycoplasma hyopneumoniae,respectively.MICs of difloxacin and enrofloxacin were 1.6 and 0.8mg/L for Streptococcus equisimilis,respectively.Following the treatment with difloxacin (2.5,5 and 10 mg/kg) and enrofloxacin (2.5 mg/kg)against mycoplasmal pneumonia for 5 days,the curative rates of the infected pigs were 80%,90%,100% and 90%,respectively.The self curative rate of the infected and untreated group was 10%.Following the treatment with difloxacin (2.5,5 and 10 mg/kg) and enrofloxacin (2.5 mg/kg)against streptococcosis for 4 days,the curative rates of the infected pigs were 50%,80%,80% and 80%,respectively.The mortality of the infected and untreated group was 50%.