Occurrence of exfoliative toxin genes and antimicrobial susceptibility of staphylococcus hyicus isolated form pig farms in central Thailand

Abstract

This study was conducted to investigate the occurrence of exfoliative toxin genes and antimicrobial susceptibility of Staphylococcus hyicus (S. hyicus) in pigs with and without exudative epidermitis (EE) in the central Thailand. Twelve pig farms were chosen in this study. The S. hyicus was isolated from different parts of the pigs with and without EE and was identified by biochemical test, PCR test. Four exfoliative toxin genes (exhA, exhB, exhD, and exhA and exhD) were detected by multiplex PCR test. Forty toxin producing strains and forty non-toxin producing strains from isolated strains were selected for their susceptibility test to 7 antimicrobial agents by using the broth microdilution method. Two hundred and forty eight isolates from collected samples were positive with S. hyicus. Exfoliative toxin genes (exhA, exhB, exhD, and exhA and exhD) were detected in 63 (25.40%) isolates. The exhA gene was the highest prevalent in these toxin genes with 41 isolates (65.07%), following by exhD gene with 13 isolates (20.63%), eight (12.69%) isolates were positive for the combination of exhA and exhD genes. Only one isolate was positive with exhB. The highest susceptibility rate was trimethoprim-sulfamethoxazole (81.25%), followed by methicillin (80%). The highest resistant rate was penicillin (75%), followed by cephalexin (27.5%). In conclusion, the prevalence of exfoliative toxin genes was higher in pigs with EE than that of the pigs without EE. The exhA was the most popular in the pigs in the central Thailand. Antimicrobial susceptibility was not significantly different between toxigenic strains and non-toxigenic strains.