The molecular characteristics and genetic background of VanB phenotype-van A genotype vancomycin resistant Enterococcus / 中华检验医学杂志

ABSTRACT

Objective To investigate the structure of Tn1546 like elements,the molecular features and genetic background of VanB phenotype-vanA genotype VREs and to explain the difference between phenotype and genotype. Methods Twenty-one VREs were collected in Beijing Hospital from March 2008 to January 2009. Etest was used to determin MICs of ten antibiotics. PCR product sequencing, PFGE and MLST were performed to study the molecular features and genetic background of the 21 VREs. Results All VREs were vanA genotype, but 3 of them( 14. 3% ) exhibited the VanB phenotype. Based on PFGE analysis, 21 VREs belonged to 9 different patterns. Six STs were identified by MLST analysis. The analysis of the structure of Tn1546 like elements showed the deletion of vanY, vanZ and the insertion of ISEfa4 in orf2-vanR intergenic region may be related to the formation of VanB phenotype-wanA genotype. Conclutions VanB phenotype-vanA genotype VREs were rarely found in China. The results of vanA cluster rearrangements could partly explain the causes of difference between phenotype and genotype.