High DNA Uptake Capacity of International Clone II Acinetobacter baumannii Detected by a Novel Planktonic Natural Transformation Assay.

Yuan Hu,Fanliang Meng,Lihua He,Xiaoxia Tao,Jianzhong Zhang

doi:10.3389/fmicb.2019.02165

Yuan Hu, Fanliang Meng + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2019.02165

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Abstract

Acquisition of novel resistance genes is a key driver of multidrug resistance in the nosocomial pathogen Acinetobacter baumannii. To investigate the DNA uptake ability among clinical A. baumannii strains, a planktonic salt-free transformation assay was developed. A total of 142 clinical A. baumannii isolates with divergent genetic distance were selected, and 86 of them belong to international clonal lineage II (ICL2). Using this new transformation assay, 38% of the clinical A. baumannii isolates were natural competent. Among the multidrug-resistant (MDR) isolates, the transformable isolates all belonging to the ICLs, and showed significant higher transformation frequency compared with sensitive isolates. In addition, some of the ICL2 isolates triggered competence much earlier than the sensitive isolates with similar transformation frequencies. This may give them more opportunities to obtain successful transformation in their natural environment and provides an important clue to explain the severe drug resistance and clinical successfulness of ICL2.

Highlights

Acinetobacter baumannii is an important opportunistic pathogen that has caused enormous public health concerns worldwide because of its remarkable ability to develop antibiotic resistance (Howard et al, 2012)
We aimed to investigate the natural competence induction and DNA uptake ability of clinical A. baumannii isolates with different drug resistant levels
The capacity to undergo natural competence has been studied for many bacterial species

Summary

Introduction

Acinetobacter baumannii is an important opportunistic pathogen that has caused enormous public health concerns worldwide because of its remarkable ability to develop antibiotic resistance (Howard et al, 2012). Among the horizontal gene transfer mechanisms, natural transformation provides a convenient route for genetic exchanges and has been demonstrated in some A. baumannii isolates (Maria Soledad et al, 2010; Harding et al, 2013; Wilharm et al, 2013; Traglia et al, 2016; Godeux et al, 2018; Domingues et al, 2019). Most of the sequenced Acinetobacter plasmids do not harbor the genes required for conjugative transfer, so it proposed that natural transformation may play an important role in plasmid transfer for A. baumannii (Fondi et al, 2010)

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