Identification of New Delhi Metallo-β-lactamase 1 in Acinetobacter lwoffii of Food Animal Origin

Date
2012-05-18
Authors
Wang, Yang
Wu, Conming
Zhang, Qijing
Zhang, Qijing
Qi, Jing
Liu, Hebing
Wang, Yu
He, Tao
Ma, Licai
Lai, Jing
Shen, Zhangqi
Liu, Yuqing
Shen, Jianzhong
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Veterinary Microbiology and Preventive Medicine
Abstract

Background

To investigate the presence of metallo-β-lactamase (MBL) genes and the genetic environment of the New Delhi metallo-β-lactamase gene blaNDM-1 in bacteria of food animal origin.

Methodology/Principal Findings

Gram-negative bacteria with low susceptibility to imipenem (MIC>8 µg/mL) were isolated from swab samples collected from 15 animal farms and one slaughterhouse in eastern China. These bacteria were selected for phenotypic and molecular detection of known MBL genes and antimicrobial susceptibility testing. For the blaNDM-1 positive isolate, conjugation and transformation experiments were carried out to assess plasmid transfer. Southern blotting was conducted to localize the blaNDM-1 genes, and DNA sequencing was performed to determine the sequences of blaNDM-1 and the flanking genes. In total, nine Gram-negative bacteria of four different species presented a MBL phenotype. blaNDM-1 was identified on a mobile plasmid named pAL-01 in an Acinetobacter lwoffii isolate of chicken origin. Transfer of pAL-01 from this isolate to E. coli J53 and JM109 resulted in resistance to multiple β-lactams. Sequence analysis revealed that the blaNDM-1 gene is attached to an intact insertion element ISAba125, whose right inverted repeat (IR-R) overlaps with the promoter sequence of blaNDM-1. Thus, insertion of ISAba125 likely enhances the expression of blaNDM-1.

Conclusion

The identification of a blaNDM-1- carrying strain of A. lwoffii in chickens suggests the potential for zoonotic transmission of blaNDM-1 and has important implications for food safety.

Comments

This article is from PLoS ONE 7(5): e37152. doi:10.1371/journal.pone.0037152. Posted with permissino.

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