title: [A novel plasmid-mediated aminoglycosides-modifying enzyme gene, aph (2'')-Ie, in a strain of high-level gentamicin resistant Enterococcus casseliflavus].
abstract: OBJECTIVE
  To identify the aminoglycoside resistance gene in the high-level gentamicin resistant (HLGR) enterococcus and its transmission mechanism.
  
  
  METHODS
  A HLGR strain, HZ95, of Enterococcus casseliflavus was screened by agar dilution method. The aminoglycoside activation enzyme genes were screened by PCR. The PCR products underwent purification, cloned, and sequenced. Plasmids were extracted and underwent Southern hybridization. Plasmid-mediated aminoglycoside modifying enzymes were cloned. The resistance of the HZ05 strain to different antimicrobial agents was determined by K-B method or agar dilution method.
  
  
  RESULTS
  A new aminoglycosides-modifying enzyme, APH (2'')-Ie, leading to HLGR, was found in the plasmid of the HZ95 bacteria. The aph (2'')-Ie gene and partial sequence of a streptomycin adenylyltransferase gene (str) were contained in the 8.7-kb cloned fragment, and the transposase gene (tnpA) was on the upper stream. The aph (2'')-Ie gene was located on the 16-kb plasmid with the amino acid sequence 96.1% homologous with chromosome-mediated APH (2'')-Id aminoglycoside-modifying enzyme.
  
  
  CONCLUSIONS
  HLGR can be caused by a new plasmid-mediated aminoglycosides-modifying enzyme, APH (2'')-Ie, which can be transmitted among plasmids or chromosome with other resistant genes through transposase.
authors: Department of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors: Ting-ting
authors: TT
authors: Qu
authors: Ying
authors: Y
authors: Zhang
authors: Yun-song
authors: YS
authors: Yu
authors: Ya-gang
authors: YG
authors: Chen
authors: Ze-qing
authors: ZQ
authors: Wei
authors: Lan-juan
authors: LJ
authors: Li