Yunxing Yang, Ying Fu, Peng Lan
Jan 8, 2018
Citations
0
Influential Citations
24
Citations
Quality indicators
Journal
Antimicrobial Agents and Chemotherapy
Abstract
ABSTRACT Sulbactam is a plausible option for treating Acinetobacter infections because of its intrinsic antibacterial activity against the members of the Acinetobacter genus, but the mechanisms of sulbactam resistance have not been fully studied in Acinetobacter baumannii. In this study, a total of 2,197 clinical A. baumannii isolates were collected from 27 provinces in China. Eighty-eight isolates with various MICs for sulbactam were selected on the basis of their diverse clonality and underwent multilocus sequence typing (MLST), antimicrobial susceptibility testing, and resistance gene screening. The copy number and relative expression of blaTEM-1D and ampC were measured via quantitative PCR and quantitative reverse transcription-PCR, respectively. The genetic structure of multicopy blaTEM-1D was determined using the whole-genome sequencing technology. The cefoperazone-sulbactam resistance rate of the 2,197 isolates was 39.7%. The rate of positivity for blaTEM-1D or ISAba1-ampC in the sulbactam-nonsusceptible group (64.91% and 78.95%, respectively) was significantly higher than that in the sulbactam-susceptible group (0% and 0%, respectively; P < 0.001). The MIC of sulbactam (P < 0.001) varied considerably between the groups expressing ampC with or without upstream ISAba1. Notably, the genetic structure of the multicopy blaTEM-1D gene in strain ZS3 revealed that blaTEM-1D was embedded within four tandem copies of the cassette IS26-blaTEM-1D-Tn3-IS26. Therefore, blaTEM-1D and ISAba1-ampC represent the prevalent mechanism underlying sulbactam resistance in clinical A. baumannii isolates in China. The structure of the four tandem copies of blaTEM-1D first identified may increase sulbactam resistance.