Clostridium perfringens (C. perfringens) induced necrotic enteritis (NE) and related subclinical disease has become economically significant problems for the broiler industry. The objectives of this study were to determine the toxinotype and the antimicrobial susceptibility of C. perfringens isolated from the intestine of NE-suspicious and clinically healthy chickens in Korea. All of the 110 isolates belong to C. perfringens type A. In addition, these strains harbored the luxS, colA, virS, cpb2, netB and tpeL genes in high percentage order. They do not harbor the cpe gene encoding enterotoxin production. Our results suggest the important roles of the several toxin genes in the pathogenesis of NE except α-toxin, previously thought to be the major virulence factor. In the antimicrobial susceptibility test of 13 antimicrobial agents, none of them is completely susceptible in this study. Remarkably NE-suspicious chickens have higher resistant value than health ones in all of antimicrobial agents. The presence of tetracycline-resistance genes were also tested to analyze the correlation of genotype and phenotype.

Abstract
 INTRODUCTION
 MATERIALS AND METHODS
  Bacterial strains
  Isolation and identification of C. perfringens
  DNA extraction
  Detection of Clostridium perfringens toxin genes
  Antimicrobial susceptibility test
  Detection of tetracycline-resistance genes
 RESULTS
  Genetic characterization of Clostridium perfringensisolates.
  Antimicrobial resistance pattern
  Prevalence of tetracycline-resistance genes
 DISCUSSION
 REFERENCES

• Young Ju Lee(College of Veterinary Medicine, Kyungpook National University) Corresponding Author