Multiplication of blaOXA-23 is common in clinical Acinetobacter baumannii, but does not enhance carbapenem resistance

作者：Hua, Xiaoting; Shu, Jianfeng; Ruan, Zhi; Yu, Yunsong; Feng, Ye^*

来源：Journal of Antimicrobial Chemotherapy, 2016, 71(12): 3381-3385.

DOI：10.1093/jac/dkw310

• GENE
• EXPRESSION
• EVOLUTION
• DISSEMINATION
• EMERGENCE

Objectives: To investigate the copy number of bla(OXA-23) and its correlation with carbapenem resistance in carbapenem-resistant Acinetobacter baumannii (CRAB). @@@ Methods: A total of 113 bla(OXA-23)-positive clinical CRAB isolates were collected from two hospitals in Zhejiang province, China. Their genetic relatedness was determined by MLST. The MIC of imipenem was determined using the agar diffusion method and the copy number of bla(OXA-23) was measured using quantitative real-time PCR (qRT-PCR). The complete genomes of five clinical CRAB strains were sequenced using PacBio technology to investigate the multiplication mechanism of bla(OXA-23). @@@ Results: Most of the isolates (100/113) belonged to global clone II and the MIC of imipenem ranged from 16 to 96 mg/L. The gene bla(OXA-23) resided exclusively in Tn2006 or Tn2009. Approximately 38% of the isolates carried two or more copies of bla(OXA-23). The copy number of bla(OXA-23) was not correlated with the MIC of imipenem. Within the five sequenced strains, multiple copies of bla(OXA-23) were either tandemly clustered or independently inserted at different genomic sites. @@@ Conclusions: Multiplication of bla(OXA-23) is common in CRAB, but does not enhance carbapenem resistance. Multiplication can be present in the form of either tandem amplifications or independent insertions at different sites.

• 出版日期2016-12
• 单位浙江大学