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Complete genome of multiply antibiotic resistant ST10 Acinetobacter baumannii isolate NL6 from Vietnam and relationship to available ST10 genomes.

The genome of NL6, a multiply antibiotic-resistant Acinetobacter baumannii ST10:KL49:OCL2 carriage isolate from Vietnam, was sequenced using Nanopore technology, and complete chromosome and plasmid sequences were assembled from the long reads and available short reads. Resistance genes and their locations were identified, and transfer of a conjugative plasmid carrying several resistance genes into a new host was tested. The acquired resistance genes in NL6 were distributed between the chromosome and two of three plasmids present. The chromosome carries multiple copies of several insertion sequences, an incomplete copy of the ISAba1-bounded Tn6250 that includes the sul2 and strAB genes, and an integrative element carrying copper resistance genes designated IECuR. Plasmid pNL6-2 (r3-T5; 15 Kbp) is a Rep_3/OrfX plasmid that includes a tet39 dif module, and pNL6-3 (r3-T20; 66.9 Kbp) carries aacC2d, aphA6, and blaCARB-16 and a second ampC gene preceded by an ISAba1. Conjugation of pNL6-3 into derivatives of ATCC17978 was demonstrated, confirming that the ampC gene confers resistance to third-generation cephalosporins. NL6 was compared to other complete ST10 genomes. Several acquired elements in the chromosome were shared with the ST10 isolate LAC-4 (USA), indicating shared ancestry, but the plasmid content differed. The KL and plasmid content were variable in 17 further complete ST10 genomes downloaded from GenBank. Tn6250 and IECuR were only found together in the chromosome of two further KL49 isolates. Antibiotic resistance in ST10 A. baumannii was acquired mainly via plasmid acquisition, but resistance genes varied, and a variety of plasmids was involved.IMPORTANCEMembers of the CC10 clonal complex of Acinetobacter baumannii comprising ST10 plus single and double locus variants are known to be particularly virulent. However, antibiotic resistance in members of this group has rarely been examined. Here, determination of the complete genome (chromosome and plasmids) of a representative ST10 isolate from Vietnam allowed the context and location of acquired antibiotic resistance genes and of other mobile genetic elements to be determined. Mobile genetic element locations in completed chromosomes facilitate comparisons of potentially related genomes, revealing those with recent shared ancestry. Differences in plasmid content can also be examined.

Acinetobacter baumannii

Carbapenemase-producing Acinetobacter baumannii from Spanish hospitals, 2016-2020: Interregional spread of ST2PAS isolates co-harbouring blaOXA-23, blaOXA-66 and armA genes.

INTRODUCTION AND AIMS: Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a serious global threat, prioritized by the World Health Organization for new antibiotic development. The European Centre for Disease Prevention and Control proposed the integration of genomic sequencing into surveillance. This study characterizes phenotypic and genotypic features of nationwide-collected CRAB isolates from Spanish hospitals (2016-2020). MATERIALS AND METHODS: A total of 822 CRAB isolates sent to the Spanish reference laboratory were analysed, and 108 representative isolates were selected from 48 hospitals in 25 Spanish provinces. Antibiotic susceptibility was determined according to European Committee on Antimicrobial Susceptibility Testing guidelines, and WGS was performed by Illumina. Resistome, virulome, phylogeny (core-genome Multi-Locus Sequence-Typing; 2390 genes), insertion sequences and plasmids were analysed. RESULTS: Of the 108 representative isolates, 68.5% produced OXA-23, 10.2% OXA-24, 7.4% OXA-58, 1.9% NDM-1 and 2.7% others. 3.7% co-produced two acquired carbapenemases, and six that did not have them showed the ISAba1 upstream of the blaOXA-51 like. The predominant sequence types were ST2pas (82.4%) and ST218Oxf (61.1%). blaOXA-66 chromosomal carbapenemase allele was present in 75% of the 108 isolates, armA 16 s rRNA methyltransferase gene in 61.1%, and the kL-7/OCL-18 was present in 59.3% of the isolates. The most active antibiotic was colistin. Overall, 65.4% of invasive cases were caused by isolates harbouring all 38 virulence genes tested. In 64.8% of isolates a plasmid type was detected, mainly pS32-1-like (54.6%). CONCLUSIONS: In Spain, CRAB dissemination is driven by interregional spread of isolates belonging to the ST218Oxf/ST2Pas clones, characterized by the blaOXA-23/blaOXA-66 genotype, the presence of armA, the KL7/OCL18 capsular profile and the presence of pS32-1 plasmid.

K Locus