Molecular Serotyping and Resistance of Clinical Strains of Haemophilus (Glaesserella) Parasuis in Chinese Pig Farms From 2016 to 2018.

Haemophilus parasuis ( H. parasuis ) is the etiological agent of Glässer's disease and brings great economic losses to the pig industry. The goal of our research is to reveal the serotypes of H. parasuis isolated from large-scale pig farms in China from 2016 to 2018. From 2016 to 2018, 8153 H. parasuis field strains were isolated from 14610 clinical samples of sick pigs with clinical symptoms from 26 provinces and cities of China. Among them, 1386 strains were identified as H. parasuis by PCR, and the isolation rate was 9.49%. Through multiplex PCR, we showed that type 5/12 and type 4 strains had the highest separation rate, followed by type 13 and type 14 strains. Using disk diffusion method, we found cephalosporin antibiotics and peptide antibiotics all had good inhibitory effect on H. parasuis . Our conclusion may play a positive role in the prevention and treatment of H. parasuis .