Identification of Two Variants of Acinetobacter baumannii Strain ATCC 17978 with Distinct Genotypes and Phenotypes

Abstract

Acinetobacter baumannii is a nosocomial pathogen that exhibits substantial genomic plasticity. Here, the identification of two variants of A. baumannii ATCC 17978 that differ based on the presence of a 44 kb accessory locus, which was named AbaAL44 (“ A. baumannii accessory locus 44 kb”), is described. Analyses of existing deposited data suggest that both variants are found in published studies of A. baumannii ATCC 17978 and that ATCC-derived laboratory stocks are comprised of a mix of these two variants. Yet, each variant exhibits distinct interactions with the host in vitro and in vivo . Infection with the variant that harbors AbaAL44 ( Ab 17978 UN) results in decreased bacterial burdens and increased neutrophilic lung inflammation in a mouse model of pneumonia, and affects the production of IL-1β and IL-10 by infected macrophages. AbaAL44 harbors putative pathogenesis genes including those predicted to encode for a type I pilus cluster, a catalase, and a cardiolipin synthase. The accessory catalase increases A. baumannii resistance to oxidative stress and neutrophil-mediated killing in vitro . The accessory cardiolipin synthase plays a dichotomous role by promoting bacterial uptake and increasing IL-1β production by macrophages, but also enhancing bacterial resistance to cell envelope stress. Collectively, these findings highlight the phenotypic consequences of A. baumannii’s genomic dynamism through the evolution of two variants of a common type strain with distinct infection-related attributes.

Immunosuppression broadens evolutionary pathways to drug resistance and treatment failure during Acinetobacter baumannii pneumonia in mice

“…Reads were aligned to the A. baumannii ATCC 17978 genome and its plasmids (GenBank Accession: CP012004 ; pAB1: CP000522 ; pAB2: CP00523; pAB3: CP012005 ), and variants were identified at 5% cut-off using breseq 0.32 74 . Reads were aligned to A. baumannii ATCC 17978 reference genome ( https://genomes.atcc.org/genomes/e1d18ea4273549a0 ) to include an additional 44 kb gene cluster 75 . The identified mutations are listed in Supplemental Dataset 2 .…”

Acinetobase: the comprehensive database and repository of Acinetobacter strains

“…In contrast, existing databases which provide whole-genome sequencing data on A. baumannii , such as BIGSdb (Jolley et al ., 2018), includes metadata and genotype, however, BIGSdb does not include phenotypic data unrelated to the genotype nor the strains themselves. Moreover, centralization of the laboratory providing strains with the genotype and phenotype characteristics will help to decrease the chance of working with subcultured variants with altered genotype and phenotype, a pitfall that becomes more and more apparent in the A. baumannii field (Whiteway et al ., 2021; Artuso et al ., 2022; Wijers et al ., 2021).…”

Evaluation of a direct phage DNA detection-based Taqman qPCR methodology for quantification of phage and its application in rapid ultrasensitive identification of Acinetobacter baumannii

“…The increasing number of multidrug-resistant A. baumannii have become potential serious threat to public health. Since safe and effective therapeutic options in carbapenem-resistant Acinetobacter baumannii infections are severely limited, characterization of these isolates by phenotypic and molecular methods are important to provide information on the epidemiological characteristics of these pathogens [ 18 , 19 ]. The genome analysis shows that A. baumannii contain mobile genetic elements associated with antimicrobial resistance genes (ARGs), which lead to that A. baumannii can develop drug resistance to more antimicrobial agent [ 20 , 21 ].…”