Affiliation:
1. School of Life and Environmental Sciences, The University of Sydney , Sydney , Australia
2. Multidrug Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research , Silver Spring, MD , USA
Abstract
Abstract
Objectives
To examine the causes of antibiotic resistance in the extensively resistant global clone 1 (GC1) Acinetobacter baumannii isolate MRSN 56 recovered at a US military treatment facility.
Methods
MRSN 56 was sequenced using MinION (Oxford Nanopore) and the reads combined with available Illumina MiSeq data using Unicycler. Acquired resistance genes were identified using ABRicate and their environment examined. ISAba1 and ISAba125 copies were located.
Results
MRSN 56 is ST1IP:ST231Ox:KL1:OCL1 and the complete genome includes four small plasmids, none of which carry resistance genes. The acquired resistance genes were found at four locations in the chromosome in addition to AbaR28 (aphA1, aacC1, aadA1, sul1) in comM. Tn2006 (oxa23, carbapenem resistance) was both in AbaR4 and alone elsewhere. Two copies of Tn7 (dfrA1, sat, aadA1) were identified. One was associated with a 22 852 bp adjacent segment [tetA(B), sul2] derived from the AbGRI1 island, and this novel configuration was designated Tn7+. Tn7+ was incorporated in the position preferred by Tn7, downstream of glmS, by transposition using a sequence in AbGRI1 resembling the Tn7 terminal inverted repeats. Tn7 was found at a secondary site. Fluoroquinolone resistance appears to involve a mutation in gyrA combined with inactivation by ISAba1 of the marR gene in the mar operon and constitutive expression of marA from the promoter internal to ISAba1.
Conclusions
MRSN 56 represents a new sublineage of GC1 lineage 1 with novel features that had not been detected previously. The involvement of the mar operon in fluoroquinolone resistance has not been noted previously.
Funder
National Health and Medical Research Council
Defence Medical Research and Development Program
Publisher
Oxford University Press (OUP)
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology,Microbiology (medical)
Reference22 articles.
1. Five decades of genome evolution in the globally distributed, extensively antibiotic-resistant Acinetobacter baumannii global clone 1;Holt;Microb Genom,2016
2. Identification of a marker for two lineages within the GC1 clone of Acinetobacter baumannii;Hamidian;J Antimicrob Chemother,2014
3. The AbaR antibiotic resistance islands found in Acinetobacter baumannii global clone 1 - structure, origin and evolution;Hamidian;Drug Resist Updat,2018
4. Evolution of a clade of Acinetobacter baumannii global clone 1, lineage 1 via acquisition of carbapenem- and aminoglycoside-resistance genes and dispersion of ISAba1;Hamidian;Microb Genom,2019
5. Amplification of aminoglycoside resistance gene aphA1 in Acinetobacter baumannii results in tobramycin therapy failure;McGann;mBio,2014
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献