Abstract: Bacterial isolation was carried out from 86 samples of pigs with suspected multiple serositis and arthritis from 60 pig farms in Nanning,Guilin and Yulin,Guangxi province during May 2009 to November 2010. 26 strains of Hemophilus parasuis(H.parasuis) were identified by bacterial morphological and cultural characteristics,biochemical characteristics as well as PCR. Isolation rate was 30.2%. Serological typing,animal challenge and drug sensitive test were performed on the 26 strains of H.parasuis. The results showed that 26 strains of H.parasuis were composed of 5 strains of serotype 4,3 strains of serotype 5,1 strains of serotype 11,13,14,15,respectively,and 12 strains of unknown serotype. Serotype 13,14 and 5 strains of unknown serotype could cause mouse death; however,pathogenicities of other strains were weak. Drug sensitive test indicated that 70% strains of H.parasuis were high sensitive to Enrofloxacin and Florfenicol,but some strains of H.parasuis were resistant to other drugs. Our investigation results provided an epidemiological basis for prevention and control of H.parasuis infection in Guangxi.

Key words: Haemophilus parasuis; epidemiological investigation; Guangxi province