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

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Introduction and aims : Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a serious global threat, prioritized by the WHO for new antibiotic development. The ECDC 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 analyzed, and 108 representative isolates were selected from 48 hospitals in 25 Spanish provinces. Antibiotic susceptibility was determined according to EUCAST guidelines, and WGS was performed by Illumina. Resistome, virulome, phylogeny (cgMLST; 2390 genes), insertion sequences and plasmids were analyzed. 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 IS Aba1 upstream of the bla OXA-51 like. The predominant STs were ST2 pas (82.4%) and ST218 Oxf (61.1%). bla OXA-66 chromosomal carbapenemase allele was present in 75% of the 108 isolates, arm A 16s 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. 65.4% of invasive cases were caused by isolates harboring all 38 virulence genes tested. In the 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 ST218 Oxf /ST2 Pas clones, characterized by the bla OXA-23 / bla OXA-66 genotype, the presence of arm A, the KL7/OCL18 capsular profile and the presence of pS32-1 plasmid.

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