Species distribution of clinical Acinetobacter isolates revealed by different identification techniques

PLoS One. 2014 Aug 13;9(8):e104882. doi: 10.1371/journal.pone.0104882. eCollection 2014.

Abstract

A total of 2582 non-duplicate clinical Acinetobacter spp. isolates were collected to evaluate the performance of four identification methods because it is important to identify Acinetobacter spp. accurately and survey the species distribution to determine the appropriate antimicrobial treatment. Phenotyping (VITEK 2 and VITEK MS) and genotyping (16S rRNA and rpoB gene sequencing) methods were applied for species identification, and antimicrobial susceptibility test of imipenem and meropenem was performed with a disk diffusion assay. Generally, the phenotypic identification results were quite different from the genotyping results, and their discrimination ability was unsatisfactory, whereas 16S rRNA and rpoB gene sequencing showed consistent typing results, with different resolution. Additionally, A. pittii, A. calcoaceticus and A. nosocomialis, which were phylogenetically close to A. baumannii, accounted for 85.5% of the non-A. baumannii isolates. One group, which could not be clustered with any reference strains, consisted of 11 isolates and constituted a novel Acinetobacter species that was entitled genomic species 33YU. None of the non-A. baumannii isolates harbored a blaOXA-51-like gene, and this gene was disrupted by ISAba19 in only one isolate; it continues to be appropriate as a genetic marker for A. baumannii identification. The resistance rate of non-A. baumannii isolates to imipenem and/or meropenem was only 2.6%, which was significantly lower than that of A. baumannii. Overall, rpoB gene sequencing was the most accurate identification method for Acinetobacter species. Except for A. baumannii, the most frequently isolated species from the nosocomial setting were A. pittii, A. calcoaceticus and A. nosocomialis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter / classification
  • Acinetobacter / drug effects
  • Acinetobacter / genetics*
  • Anti-Bacterial Agents / pharmacology*
  • Base Sequence
  • DNA Primers / genetics
  • Disk Diffusion Antimicrobial Tests
  • Drug Resistance, Bacterial / genetics*
  • Genotype*
  • Imipenem
  • Meropenem
  • Molecular Sequence Data
  • Phenotype*
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Species Specificity
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Thienamycins

Substances

  • Anti-Bacterial Agents
  • DNA Primers
  • RNA, Ribosomal, 16S
  • Thienamycins
  • Imipenem
  • Meropenem

Grants and funding

This work was supported by National Natural Science Foundation of China (No. NSFC81378158 and NSFC81230039). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.