Materials and methods
In this study, no regular pathogens causing piglet diarrhea were detected in feces and drinking water samples of diarrheal piglets collected in farm areas where diarrhea occurred, but a β-hemolytic bacterium was found, which was also isolated in the drinking water. Subsequently, 16SrRNA primers were used to amplify and sequence, and the results showed that the bacteria were a C. haemolyticum like bacterium by phonotype. The bacteria isolated were used for the challenge trial. Nine 30-day-old healthy piglets were randomly divided into three groups. 2ml of the 3.5x10^9 colony forming unit (CFU) of the bacterium were administered orally or intramuscularly injected respectively, and 2ml of PBS was administered orally to the control group. The isolate GDHYZ30 could cause the same diarrhea symptoms similar to that of the clinical cases when the piglets were challenged. To understand the genetic characteristics of the bacteria, whole gene sequencing was Completed by Sangon Biotech Company. This whole-genome sequencing project has been deposited at GenBank under the accession number: PRJNA802706.