Background : Vancomycin-resistant enterococci (VRE) have been increasingly isolated worldwide as a nosocomial pathogen. In Korea, because avoparcin has been used as a growth promoter in animal feed, vanA-containing enterococci have been found in animals. The aim of this study is to understand the epidimiology of VRE isolated from chicken of diverse geographic areas. 

Methods : Thirty eight isolates of VanA VRE from chicken of diverse geographic areas were investigated. Multiplex PCR was used to confirm the genotype of VRE. Long PCR and restriction fragment length polymorphism (long PCR-RFLP) were performed to analyze the structure of Tn1546. If the RFLP pattern was different from the prototype, PCR amplification of internal regions of Tn1546 and subsequent sequencing analysis was performed. 

Results : All 38 isolates harbored vanA gene and divided into 3 types by long PCR-RFLP. Thirty five isolates (92%) were classified as type I. Two isolates and one isolate were belonging to type II and type III, respectively. Type II revealed an insertion of IS 1216V in vanX-vanY intergenic region. IS element integrated type III did not match any previously reqorted seguence.

Conclusion : Structural analysis of vanA gene cluster from chicken revealed that the majority of isolates (type I) have indistinguishable structure to E. fecium BM4147. This results indicated horizontal spread of resistance gene among isolates from chicken. Genetic rearrangement of Tn1546 was infrequently detected in Korea. (Korean J Clin Microbiol 2003;6(2):114-118)